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1

Experimental results obtained during fatigue testing of a spot-welded lap-shear structural-joint specimen are  

E-print Network

1 ABSTRACT 1 Experimental results obtained during fatigue testing of a spot-welded lap the relevant frequency range. Fatigue testing was applied to initiate and propagate crack damage of controlled joining techniques, the spot welding and weldbonding (spot weld + adhesive bonding) are widely used

Giurgiutiu, Victor

2

Ultrasonic Welding of Hybrid Joints  

NASA Astrophysics Data System (ADS)

A central research field of the Institute of Materials Science and Engineering at the University of Kaiserslautern (WKK), Germany, is the realization of innovative hybrid joints by ultrasonic metal welding. This article gives an overview of suitable ultrasonic welding systems as well as of essential machine and material parameters, which influence the quality of the welds. Besides the ultrasonic welding of dissimilar metals such as Al to Cu or Al to steels, the welds between newly developed materials like aluminum foam sandwiches or flat flexible cables also can be realized. Moreover, the joining of glass and ceramic to sheet metals is a point of interest at the WKK. By using the ultrasonic metal welding process, it is possible to realize metal/glass welds with tensile shear strengths of 50 MPa. For metal/ceramic joints, the shear strengths values up to 150 MPa were measured. Finally, selected results about the occurring bonding mechanisms will be discussed.

Wagner, Guntram; Balle, Frank; Eifler, Dietmar

2012-03-01

3

Plating To Reinforce Welded Joints  

NASA Technical Reports Server (NTRS)

Electrodeposition used to strengthen welded joints gouged, nicked, or suffered other mechanical damage. Plating cell, typically of acrylic plastic such as poly (Methylmetacrylate), is assembled around part to be plated. Areas not to be plated are masked with plater's tape. Weld area is plated in standard nickel-plating process.

Otousa, J. E.

1982-01-01

4

Strength of Welded Aircraft Joints  

NASA Technical Reports Server (NTRS)

This investigation is a continuation of work started in 1928 and described in NACA-TR-348 which shows that the insertion of gusset plates was the most satisfactory way of strengthening a joint. Additional tests of the present series show that joints of this type could be improved by cutting out the portion of the plate between the intersecting tubes. T and lattice joints in thin-walled tubing 1 1/2 by 0.020 inch have somewhat lower strengths than joints in tubing of greater wall thickness because of failure by local buckling. In welding the thin-walled tubing, the recently developed "carburizing flux" process was found to be the only method capable of producing joints free from cracks. The "magnetic powder" inspection was used to detect cracks in the joints and flaws in the tubing.

Brueggeman, W C

1937-01-01

5

Effect of weld schedule variation on the weldability and durability of AHSS spot weld joints  

NASA Astrophysics Data System (ADS)

Tensile strength testing and high cycle fatigue testing of advanced high strength steel spot welded shear lap joints were performed for the various weld conditions. The materials used in this study were DP 980, DP 780 and TRIP 780. The microstructure and microhardness of the shear lap joints were examined in an effort to identify the effect of microstructural changes on the strength and fatigue durability of the spot weld specimens. The occurrence of interfacial failure was recorded for the differing weld processes. Several weld schedules were examined and used to produce shear lap spot weld joints, specifically varying the squeeze force and the average current. The weld force used to produce a spot weld does not have a significant effect on the fracture mode of the specimen given the average current is constant. The average current used to produce a spot weld has a significant effect on the fracture mode of the spot weld for several squeeze forces. Interfacial failure of spot welded TRIP 780 can be mitigated using a certain range of currents when welding. This appears to come as a tradeoff for sacrificing the strength of the joint. Higher values of weld strength were obtainable; however, welds that failed with higher strengths also experienced interfacial failure. A fracture mechanics approach to estimating the high cycle fatigue life of the shear lap specimen is also proposed and represents a conservative estimate of the shear lap specimen durability.

Weishaupt, Eric Raymond

6

Effects of friction welding conditions and weld flash on fatigue strength of steel friction?welded joints  

Microsoft Academic Search

As?welded hot? and cold?drawn mild steel solid round bar specimens are used to determine the effect of flash on the fatigue strength of friction?welded joints in rotating bending fatigue tests. The results obtained may be summarised as follows. 1. The fatigue strength of the hot? and cold?drawn friction?welded joints with flash decreases with an increasing upset pressure.2. The fracture location

M. Hasegawa

1996-01-01

7

Polyimide weld bonding for titanium alloy joints  

NASA Technical Reports Server (NTRS)

Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system. A new polyimide laminating resin, BFBI/BMPM, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219 K (-65 F) to 561 K (+550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of the weld-through weld-bonding process for fabricating stringer stiffened skin panels.

Vaughan, R. W.; Kurland, R. M.

1974-01-01

8

Joint geometry influence on mechanized pipe welding  

Microsoft Academic Search

The report describes the development of a joint geometry for pulsed gas tungsten arc welding of austenitic stainless steel pipe in all positions. Preliminary work was performed with bead-on-pipe experiments and square-groove welds to determine approximate root face thicknesses. These values were used with U-groove weld designs to establish a basic joint configuration that is suitable for mechanized and manual

J. F. Key; P. W. Turner

1978-01-01

9

Thermographic Analysis of Stress Distribution in Welded Joints  

NASA Astrophysics Data System (ADS)

The fatigue life prediction of welded joints based on S-N curves in conjunction with nominal stresses generally is not reliable. Stress distribution in welded area affected by geometrical inhomogeneity, irregular welded surface and weld toe radius is quite complex, so the local (structural) stress concept is accepted in recent papers. The aim of this paper is to determine the stress distribution in plate type aluminum welded joints, to analyze the reliability of TSA (Thermal Stress Analysis) in this kind of investigations, and to obtain numerical values for stress concentration factors for practical use. Stress distribution in aluminum butt and fillet welded joints is determined by using the three different methods: strain gauges measurement, thermal stress analysis and FEM. Obtained results show good agreement - the TSA mutually confirmed the FEM model and stresses measured by strain gauges. According to obtained results, it may be stated that TSA, as a relatively new measurement technique may in the future become a standard tool for the experimental investigation of stress concentration and fatigue in welded joints that can help to develop more accurate numerical tools for fatigue life prediction.

Pirši?, T.; Krstulovi? Opara, L.; Domazet, Ž.

2010-06-01

10

Measurement of micro weld joint position based on magneto-optical imaging  

NASA Astrophysics Data System (ADS)

In a laser butt joint welding process, it is required that the laser beam focus should be controlled to follow the weld joint path accurately. Small focus wandering off the weld joint may result in insufficient penetration or unacceptable welds. Recognition of joint position offset, which describes the deviation between the laser beam focus and the weld joint, is important for adjusting the laser beam focus and obtaining high quality welds. A new method based on the magneto-optical (MO) imaging is applied to measure the micro weld joint whose gap is less than 0.2 mm. The weldments are excited by an external magnetic field, and an MO sensor based on principle of Faraday magneto effect is used to capture the weld joint images. A sequence of MO images which are tested under different magnetic field intensities and different weld joint widths are acquired. By analyzing the MO image characteristics and extracting the weld joint features, the influence of magnetic field intensity and weld joint width on the MO images and detection of weld joint position is observed and summarized. Project supported by the National Natural Science Foundation of China (Grant No. 51175095), the Natural Science Foundation of Guangdong Province, China (Grant No. 10251009001000001), the Guangdong Provincial Project of Science and Technology Innovation of Discipline Construction, China (Grant No. 2013KJCX0063), and the Science and Technology Plan Project of Guangzhou City, China (Grant No. 1563000554).

Gao, Xiang-Dong; Chen, Zi-Qin

2015-01-01

11

In-process heat treatments to improve FS-welded butt joints  

Microsoft Academic Search

Friction-stir welding (FSW) is a relatively new but already well known solid-state welding process whose main advantage with\\u000a respect to fusion welding processes is the possibility to successfully weld light alloys, traditionally considered difficult\\u000a to weld or unweldable. Despite the good mechanical performances that can be obtained, there exists the possibility to further\\u000a improve the joints’ effectiveness through post-welding heat

L. Fratini; G. Buffa; R. Shivpuri

2009-01-01

12

Joint strength of Inconel 718 alloy and its improvement by post-weld heat treatment – joint performance and its controlling factors in friction welding of Inconel 718 alloy  

Microsoft Academic Search

The influences of welding parameters on tensile properties of friction-welded joints of Inconel 718 alloy (subjected to a post-weld heat treatment (PWHT) consisting of a solution treatment at 1253 K and double ageing treatments at 993 and 893 K) have been investigated to reveal the controlling factor of the joint performance. All joints obtained were fractured near the bond interface at smaller

Hongjie Wang; Kenji Ikeuchi; Masatoshi Aritoshi; Makoto Takahashi; Akio Ikeda

2009-01-01

13

Comparison of fatigue strength in light alloy welded joints  

Microsoft Academic Search

This paper deals with the experimental investigation of fatigue strength of AA 5083 and AA 6009 aluminium alloy welded joints. Testpieces consisted of 3 mm thick plates with different welded joints: butt welds and lap fillet joints, both MIG welded.Fatigue tests under constant amplitude loading, as well as tension tests and reverse bend tests were conducted. Tests were repeated, taking

B. Atzori; R. Tovo

1998-01-01

14

Fatigue of welded joints under complex loading  

Microsoft Academic Search

The majority of fatigue data for welded joints are for plate specimens under simple uniaxial direct tension, whereas in practice, joints in large structures are frequently subjected to more complex loading. There are very few fatigue test results for such conditions and hence design must currently be based on the published design curves for uniaxial stressing. The objective of the

P. J. Tubby

1997-01-01

15

Welding technology transfer task/laser based weld joint tracking system for compressor girth welds  

NASA Technical Reports Server (NTRS)

Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

Looney, Alan

1991-01-01

16

Effect of Welding Time on the Joining Phenomena of Diffusion Welded Joint Between Aluminum Alloy and Stainless Steel  

Microsoft Academic Search

In the present study, direct diffusion welding of aluminum alloy 5A02 and stainless steel SUS304 has been carried out in vacuum in the welding time range of 35-110 minutes. The effect of welding time on the interfacial microstructure and tensile shear strength of the joint were investigated. The joint with tensile shear strength of 101.3 MPa was obtained under the condition

Hongxin Shi; Shuang Qiao; Ranfeng Qiu; Jinhong Zhu; Hua Yu

2012-01-01

17

Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies  

SciTech Connect

The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce compressive residual stress at weld toe for weld fatigue resistance.

Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

2005-04-15

18

Properties of wet welded joints  

Microsoft Academic Search

The increasing interest taken by the international diving industry in wet welding plays an important part in determining research activities to improve the process and consumables for offshore applications, particularly for higher strength steels at greater water depths. On the basis of an investigation comparing the properties of existing electrodes for underwater applications, specially modified electrodes have been tested by

P. Szelagowski; H. Stuhff; H. G. Schafstall; J. Blight; I. Pachniuk

1993-01-01

19

Failure Behavior of Three-Steel Sheets Resistance Spot Welds: Effect of Joint Design  

NASA Astrophysics Data System (ADS)

There is a lack of comprehensive understanding concerning failure characteristics of three-steel sheet resistance spot welds. In this article, macro/microstructural characteristics and failure behavior of 1.25/1.25/1.25 mm three-sheet low carbon steel resistance spot welds are investigated. To evaluate the mechanical properties of the joint, the tensile-shear test was performed in three different joint designs. Mechanical performance of the joint was described in terms of peak load, energy absorption, and failure mode. The critical weld nugget size required to insure pullout failure mode was obtained for each joint design. It was found that the joint design significantly affects the mechanical properties and the tendency to fail in the interfacial failure mode. It was also observed that stiffer joint types exhibit higher critical weld size. Fusion zone size along sheet/sheet interface proved to be the most important controlling factor of spot weld peak load and energy absorption.

Pouranvari, M.; Marashi, S. P. H.

2012-08-01

20

Effect of welding parameters on mechanical and microstructural properties of AA6056 joints produced by Friction Stir Welding  

Microsoft Academic Search

The effect of processing parameters on mechanical and microstructural properties of AA6056 joints produced by Friction Stir Welding was analysed in the present study. Different samples obtained by employing rotating speeds of 500, 800 and 1000rpm and welding speeds of 40, 56 and 80mm\\/min were produced. The mechanical properties of the joints were evaluated by means of microhardness (HV) and

P. Cavaliere; G. Campanile; F. Panella; A. Squillace

2006-01-01

21

Characterization of AZ31B wrought magnesium alloy joints welded by high power fiber laser  

SciTech Connect

A 6 kW fiber laser is used to weld AZ31B wrought magnesium alloy and the characterization of welded joints are studied by the observations of bead size, microstructure and mechanical properties. The accepted joints without macro-defects can be obtained when the laser power is in the range of 2.5 to 4.0 kW. Typical hexagonal dendrites are observed in the fusion zone, whose average semi-axis length increases with increasing heat input or decreasing welding speed. The minimum ultimate tensile strength of welded joints reaches 227 MPa, 94.6% of the base metal. And when the heat input reduces to 48 J/mm or lower, the joints are fractured in the base metal, showing stronger failure strength compared to the base metal. For the joints ruptured in the weld metal, the fracture surface is characterized by a ductile-brittle mixed pattern consisting of both dimples and cleavages. Finally, the formation mechanism of pore in the welds is discussed and summarized by the pore morphologies on the fracture surface. - Highlights: {yields} Accepted joints of AZ31B Mg alloy are produced by high power fiber laser. {yields} Optimal welding parameters are summarized by experimental observations. {yields} Obvious hexagonal dendrites are observed in the fusion zone. {yields} The joints are stronger than base metal as the heat input is lower than 48 J/mm. {yields} Pore formation mechanism of welded joints is discussed and summarized.

Wang Zemin; Gao Ming, E-mail: mgao@mail.hust.edu.cn; Tang Haiguo; Zeng Xiaoyan

2011-10-15

22

49 CFR 195.216 - Welding: Miter joints.  

Code of Federal Regulations, 2013 CFR

...Transportation 3 2013-10-01 2013-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

2013-10-01

23

49 CFR 195.216 - Welding: Miter joints.  

Code of Federal Regulations, 2012 CFR

...Transportation 3 2012-10-01 2012-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

2012-10-01

24

49 CFR 195.216 - Welding: Miter joints.  

Code of Federal Regulations, 2011 CFR

...Transportation 3 2011-10-01 2011-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

2011-10-01

25

49 CFR 195.216 - Welding: Miter joints.  

Code of Federal Regulations, 2010 CFR

...Transportation 3 2010-10-01 2010-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

2010-10-01

26

Diffusion welding in air. [solid state welding of butt joint by fusion welding, surface cleaning, and heating  

NASA Technical Reports Server (NTRS)

Solid state welding a butt joint by fusion welding the peripheral surfaces to form a seal is described along with, autogenetically cleaning the faying or mating surfaces of the joint by heating the abutting surfaces to 1,200 C and heating to the diffusion welding temperature in air.

Moore, T. J.; Holko, K. H. (inventors)

1974-01-01

27

Effect of weld geometry on the fatigue life of non-load-carrying fillet welded cruciform joints  

Microsoft Academic Search

In the present study, the effect of weld geometry on the fatigue life of non-load-carrying fillet welded cruciform joints was experimentally investigated. The weld geometry of the cruciform specimens was intentionally varied, and fatigue tests were carried out on various weld geometry configurations. The configurations included weld flank angle, weld toe radius and weld throat thickness. Constant amplitude fatigue tests

Chin-Hyung Lee; Kyong-Ho Chang; Gab-Chul Jang; Chan-Young Lee

2009-01-01

28

Frictional properties of jointed welded tuff  

SciTech Connect

The results of the experiments on simulated joints in welded tuff from the Grouse Canyon Member of the Belted Range Tuff warrant the following conclusions: (1) The coefficient of friction of the joints is independent of normal stress at a given sliding velocity. (2) The coefficient of friction increases with both increasing time of stationary contact and decreasing sliding velocity. (3) Time and velocity dependence of friction is due to an increase in the real area of contact on the sliding surface, caused by asperity creep. (4) Joints in water-saturated tuff show a greater time and velocity dependence of friction than those in dehydrated tuff. (5) The enhanced time and velocity dependence of friction with water saturation is a result of increased creep at asperity contacts, which is in turn due to a reduction in the surface indentation hardness by hydrolytic weakening and/or stress corrosion cracking.

Teufel, L.W.

1981-07-01

29

Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology  

SciTech Connect

Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

2005-06-30

30

Fracture resistance of a steel weld joint under fatigue loading  

Microsoft Academic Search

Fatigue crack growth tests are performed to examine the variation of crack growth resistance in the weld joint of AH36 TMCP steel. Plate materials are joined together by single-pass SEGARC welding. Residual stresses are removed by heat treatment to focus the study on the microstructural effect. Single edge notch specimens are made from the welded plate with cracks at varying

H. K. Lee; K. S. Kim; C. M. Kim

2000-01-01

31

A study of the role of adhesives in weld-bonded joints  

SciTech Connect

Using a three-dimensional finite element analysis (FEA) method, the effect of elastic modulus and thickness of adhesives on the stress distribution in weld-bonded joints was studied to address the role of adhesive layer. Normal stress and shear stress distributed at the edges of a spot weld and in the lap region were computed for weld-bonded joints made with adhesives of different elastic moduli or thicknesses. The results showed great stress concentration at the edge of the spot weld in weld-bonded joints when the adhesive layer was thick or had a low elastic modulus. Shear stress values in adhesive layers were low under the same circumstances. Stress concentration around the spot weld was reduced and the shear stress in the adhesive layer was increased by increasing the elastic modulus or decreasing the thickness of the adhesive layer. An adhesive layer with appropriate thickness and elastic modulus is necessary to obtain reasonable distribution of stresses in the whole lap region of a weld-bonded joint. A thin adhesive layer of high elastic modulus is favorable to the fatigue properties of weld-bonded joints, and it is recommended on certain conditions.

Chang, B.H. (Xi'an Jiaotong Univ. (China). School of Mechanical Engineering); Shi, Y.W. (Beijing Polytechnic Univ., Beijing (China). School of Materials Science and Engineering); Dong, S.J. (Hubei Automotive Industries Inst., Shiyan (China). Materials Dept.)

1999-08-01

32

Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue  

Microsoft Academic Search

This paper presents a comparison of three post weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post weld treatment for implementation in mass production of certain crane components manufactured from very high strength steel. The processes investigated are; burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation

M. M. Pedersen; O. Ø. Mouritsen; M. R. Hansen; J. G. Andersen; J. Wenderby

33

Investigation of Fatigue Crack Propagation in Spot-Welded Joints Based on Fracture Mechanics Approach  

NASA Astrophysics Data System (ADS)

In this paper, fatigue crack propagation life of resistance spot welds in tensile-shear specimens is investigated based on the calculation of stress intensity factors and J-integral using three-dimensional finite element method. For comparison, experimental works on 5083-O aluminum alloy spot-welded joints have been carried out to verify the numerical predictions of fatigue crack propagation of welded joints. A lot of analyses have been performed to obtain stress intensity factors and J-integral in tensile-shear specimens of spot-welded joints by using commercial software ANSYS. These gathered data have been formulated by using statistical software SPSS. The results of fatigue propagation life and predicted fatigue crack path revealed very good agreement with the experimental fatigue test data and photograph of cross-section of the fatigued spot-weld specimens.

Hassanifard, S.; Bonab, M. A. Mohtadi; Jabbari, Gh.

2013-01-01

34

Fatigue Behavior of Friction Stir-Welded Joints Repaired by Grinding  

NASA Astrophysics Data System (ADS)

Fatigue is undoubtedly the most important design criterion in aeronautic structures. Although friction stir-welded joints are characterized by a high mechanical performance, they can enclose some defects, especially in their root. These defects along with the relatively low residual stresses of the friction stir-welding thermomechanical cycle can turn into primary sources of crack initiation. In this context, this article deals with the fatigue behavior of friction stir-welded joints subjected to surface smoothing by grinding improvement technique. The 4-mm-thick aluminum alloy 2024-T351 was used in this study. The fatigue strength of the base material, joints in the as-welded condition, and the sound and defective friction stir-welded joints improved by grinding were investigated in detail. The tests were carried out with a constant amplitude loading and with a stress ratio of R = 0. The fatigue results show that an improvement in fatigue behavior was obtained in the joints repaired by superficial grinding technique. The weld grinding technique is better especially for lower loads and increases the high cycle fatigue strength. The fatigue strength of the improved welded joints was higher than that of the base material.

Vidal, C.; Infante, V.

2014-04-01

35

Predicting welding distortion in a panel structure with longitudinal stiffeners using inherent deformations obtained by inverse analysis method.  

PubMed

Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results. PMID:25276856

Liang, Wei; Murakawa, Hidekazu

2014-01-01

36

Predicting Welding Distortion in a Panel Structure with Longitudinal Stiffeners Using Inherent Deformations Obtained by Inverse Analysis Method  

PubMed Central

Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results. PMID:25276856

Liang, Wei; Murakawa, Hidekazu

2014-01-01

37

Mechanical behavior study of laser welded joints for DP steel  

NASA Astrophysics Data System (ADS)

Advanced High Strength Steels (AHSS) are gaining considerable market shares in the automotive industry. The development and application of Dual Phase (DP) steel is just a consistent step towards high-strength steel grades with improved mechanical behavior. Tailor welded blanks with DP steel are promoted in the application of Body-In-White (BIW) structure by the automotive industry. A tailor welded blank consists of several flat sheets that are laser welded together before stamping. Applied cases of tailor welded blanks of high strength steels on the automotive structural parts are investigated in this paper. The mechanical behavior of laser welded joints for DP steel is studied. Microstructure of laser welded joints for DP steel was observed by SEM. Martensite in the weld seam explains the higher strength of welded joints than the base metal. Results show that the strain safety tolerance of laser welded seam for high strength steel can meet the requirement of automobile parts for stamping if the location of laser welded seam is designed reasonably.

Yan, Qi

2008-03-01

38

An inelastic analysis of a welded aluminum joint  

NASA Technical Reports Server (NTRS)

Butt-weld joints are most commonly designed into pressure vessels which then become as reliable as the weakest increment in the weld chain. In practice, weld material properties are determined from tensile test specimen and provided to the stress analyst in the form of a stress versus strain diagram. Variations in properties through the thickness of the weld and along the width of the weld have been suspect but not explored because of inaccessibility and cost. The purpose of this study is to investigate analytical and computational methods used for analysis of welds. The weld specimens are analyzed using classical elastic and plastic theory to provide a basis for modeling the inelastic properties in a finite-element solution. The results of the analysis are compared to experimental data to determine the weld behavior and the accuracy of prediction methods. The weld considered in this study is a multiple-pass aluminum 2219-T87 butt weld with thickness of 1.40 in. The weld specimen is modeled using the finite-element code ABAQUS. The finite-element model is used to produce the stress-strain behavior in the elastic and plastic regimes and to determine Poisson's ratio in the plastic region. The value of Poisson's ratio in the plastic regime is then compared to experimental data. The results of the comparisons are used to explain multipass weld behavior and to make recommendations concerning the analysis and testing of welds.

Vaughan, R. E.

1994-01-01

39

Effect of modifying micro-additions on the corrosion resistance of oil and gas pipeline welded joints  

Microsoft Academic Search

The effect of modifying additions of REE, AEE, and Zr on the corrosion resistance of oil and gas pipeline welded joints is\\u000a studied. Optimum concentrations are established for micro-additions of cerium, yttrium, calcium, barium, and zirconium to\\u000a fuzed metal providing good welded joint corrosion properties. Mathematical models are obtained for engineering and predicted\\u000a estimates of the service life for welded

V. D. Makarenko; I. O. Makarenko; A. N. Khalin; V. V. Ob’edkova; M. Yu. Mukhin; E. N. Galich

2009-01-01

40

The effects of sheet spacing on the fatigue life of spot­welded joints  

NASA Astrophysics Data System (ADS)

While investigating the fatigue strength of spot-welded joints, the effects of sheet spacing or gap amounts between sheet joints may be considered as one of the most important parameters on the fatigue life duration of the joints. The main goal of the present work is to study the influence of sheet spacing on the fatigue life of 5083-O aluminium alloy spot welded tensile-shear joints. The amounts of sheet spacing are the average values over three measurements of photograph observation of the cut-off surfaces from the nugget centre of the spot-welded joints. The amounts of gap distances between spot weld sheet joints for three different electrode clamping force levels were 0.09mm, 0.11mm and 0.13mm, respectively. The values of notch strength reduction factors have been obtained at all levels of applied loads based on volumetric approach. The fatigue lives of spot welded joints have been obtained according to the volumetric method using the notch strength reduction factors and the available smooth S-N curve of 5083-O aluminium alloy sheets. The results based on the volumetric approach have been compared with the experimental fatigue test data and there is good agreement between numerical predictions and experimental results.

Hassanifard, S.; Zehsaz, M.; Esmaeili, F.

2010-06-01

41

A fatigue crack initiation approach for naval welded joints  

Microsoft Academic Search

This work deals with the study of the fatigue behavior of welded joints of naval structures taking the residual stresses into account. Our approach is based on the study of the cyclic behavior of the base metal in order to study the shakedown of a welded structure. Then, under the assumption of a fast elastic shakedown, applications on representative elements

Nicolas Lautrou; David Thevenet; Jean-Yves Cognard

2005-01-01

42

Apparatus for maintaining aligment of a shrinking weld joint in an electron-beam welding operation  

DOEpatents

The invention is directed to an apparatus for automatically maintaining a shrinking weld joint in alignement with an electron beam during an electron-beam multipass-welding operation. The apparatus utilizes a bias means for continually urging a workpiece-supporting face plate away from a carriage mounted base that rotatably supports the face plate. The extent of displacement of the face plate away from the base in indicative of the shrinkage occuring in the weld joint area. This displacement is measured and is used to move the base on the carriage a distance equal to one-half the displacement for aligning the weld joint with the electron beam during each welding pass.

Trent, J.B.; Murphy, J.L.

1980-01-03

43

Apparatus for maintaining alignment of a shrinking weld joint in an electron-beam welding operation  

DOEpatents

The present invention is directed to an apparatus for automatically maintaining a shrinking weld joint in alignment with an electron beam during an electron-beam multipass-welding operation. The apparatus utilizes a biasing device for continually urging a workpiece-supporting face plate away from a carriage mounted base that rotatably supports the face plate. The extent of displacement of the face plate away from the base is indicative of the shrinkage occuring in the weld joint area. This displacement is measured and is used to move the base on the carriage a distance equal to one-half the displacement for aligning the weld joint with the electron beam during each welding pass.

Trent, Jett B. (Knoxville, TN); Murphy, Jimmy L. (Oak Ridge, TN)

1981-01-01

44

Reduced heat input keyhole welding through improved joint design  

NASA Technical Reports Server (NTRS)

An improved high energy density welding method for reducing input keyhole welding prepares the weld joint (8) between two edges (10, 14) of at least one member by separating the edges (10, 14) of the member (12, 16) with a controllable gap (22) by a projecting portion (24) selectively positioned on one edge (10, 14) of the member (12, 16). The projecting portion (24) closely abuts the other edge of the member for maintaining the controlled distance (d) of the controllable gap (22) to enhance the welding method.

Sanders, John M. (Inventor); Harwig, Dennis D. (Inventor)

1993-01-01

45

Effects of Welding Processes and Post-Weld Aging Treatment on Fatigue Behavior of AA2219 Aluminium Alloy Joints  

NASA Astrophysics Data System (ADS)

AA2219 aluminium alloy square butt joints without filler metal addition were fabricated using gas tungsten arc welding (GTAW), electron beam welding (EBW), and friction stir welding (FSW) processes. The fabricated joints were post-weld aged at 175 °C for 12 h. The effect of three welding processes and post-weld aging (PWA) treatment on the fatigue properties is reported. Transverse tensile properties of the welded joints were evaluated. Microstructure analysis was also carried out using optical and electron microscopes. It was found that the post-weld aged FSW joints showed superior fatigue performance compared to EBW and GTAW joints. This was mainly due to the formation of very fine, dynamically recrystallized grains and uniform distribution of fine precipitates in the weld region.

Malarvizhi, S.; Balasubramanian, V.

2011-04-01

46

Crack resistance of the near-weld region of welded joints of titanium and aluminum alloys  

Microsoft Academic Search

We studied the crack resistance Kc (KIc) of the near-weld region of welded joints of VT3-1 and VT14 titanium alloys and AMg6NPP, 12401, and 1420 high-strength aluminum\\u000a alloys under fatigue and static loading. By the methods of fracture mechanics and according to the results of testing cylindrical\\u000a specimens with external circular cracks initiated in the weld metal, fusion zone, zone

N. M. Lebid’; M. S. Kohut

1998-01-01

47

46 CFR 154.524 - Piping joints: Welded and screwed couplings.  

Code of Federal Regulations, 2012 CFR

...welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld must be double welded or must be welded...gauge (142 psig) must be removed after the weld is completed; (2) A consumable...

2012-10-01

48

46 CFR 154.524 - Piping joints: Welded and screwed couplings.  

Code of Federal Regulations, 2011 CFR

...welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld must be double welded or must be welded...gauge (142 psig) must be removed after the weld is completed; (2) A consumable...

2011-10-01

49

46 CFR 154.524 - Piping joints: Welded and screwed couplings.  

Code of Federal Regulations, 2010 CFR

...welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld must be double welded or must be welded...gauge (142 psig) must be removed after the weld is completed; (2) A consumable...

2010-10-01

50

46 CFR 154.524 - Piping joints: Welded and screwed couplings.  

...welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld must be double welded or must be welded...gauge (142 psig) must be removed after the weld is completed; (2) A consumable...

2014-10-01

51

46 CFR 154.524 - Piping joints: Welded and screwed couplings.  

Code of Federal Regulations, 2013 CFR

...welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld must be double welded or must be welded...gauge (142 psig) must be removed after the weld is completed; (2) A consumable...

2013-10-01

52

Effects of laser power density on static and dynamic mechanical properties of dissimilar stainless steel welded joints  

NASA Astrophysics Data System (ADS)

The mechanical properties of laser welded joints under impact loadings such as explosion and car crash etc. are critical for the engineering designs. The hardness, static and dynamic mechanical properties of AISI304 and AISI316 L dissimilar stainless steel welded joints by CO2 laser were experimentally studied. The dynamic strain-stress curves at the strain rate around 103 s-1 were obtained by the split Hopkinson tensile bar (SHTB). The static mechanical properties of the welded joints have little changes with the laser power density and all fracture occurs at 316 L side. However, the strain rate sensitivity has a strong dependence on laser power density. The value of strain rate factor decreases with the increase of laser power density. The welded joint which may be applied for the impact loading can be obtained by reducing the laser power density in the case of welding quality assurance.

Wei, Yan-Peng; Li, Mao-Hui; Yu, Gang; Wu, Xian-Qian; Huang, Chen-Guang; Duan, Zhu-Ping

2012-10-01

53

The influence of welding heat input on submerged arc welded duplex steel joints imperfections  

Microsoft Academic Search

The influence of the heat input submerged arc welding (SAW) of duplex steel UNS S31803 on kind and quantity of welded butt joints defects has been determined. Defects were identified by a radiographic method. For the defectiveness rate in the ratio of quantity negative test results RN to complete radiographic test RC were taken. Radiograms have been classified on the

Jerzy Nowacki; Pawe? Rybicki

2005-01-01

54

Influence of weld size on fatigue crack growth characteristics of flux cored arc welded cruciform joints  

Microsoft Academic Search

The influence of weld size (L\\/Tp) on fatigue crack growth characteristics of flux cored arc welded (FCAW) cruciform joints, containing lack of penetration (LOP) defect, has been studied. Quenched and tempered (Q&T) steel of ASTM 517 ‘F’ grade has been used as the base material. Fatigue crack growth experiments were carried out in a vertical pulsar under constant amplitude loading

V. Balasubramanian; B. Guha

1999-01-01

55

Modeling and design of energy concentrating laser weld joints  

SciTech Connect

The application of lasers for welding and joining has increased steadily over the past decade with the advent of high powered industrial laser systems. Attributes such as high energy density and precise focusing allow high speed processing of precision assemblies. Other characteristics of the process such as poor coupling of energy due to highly reflective materials and instabilities associated with deep penetration keyhole mode welding remain as process limitations and challenges to be overcome. Reflective loss of laser energy impinging on metal surfaces can in some cases exceed ninety five percent, thus making the process extremely inefficient. Enhanced coupling of the laser beam can occur when high energy densities approach the vaporization point of the materials and form a keyhole feature which can trap laser energy and enhance melting and process efficiency. The extreme temperature, pressure and fluid flow dynamics of the keyhole make control of the process difficult in this melting regime. The authors design and model weld joints which through reflective propagation and concentration of the laser beam energy significantly enhance the melting process and weld morphology. A three dimensional computer based geometric optical model is used to describe the key laser parameters and joint geometry. Ray tracing is used to compute the location and intensity of energy absorption within the weld joint. Comparison with experimentation shows good correlation of energy concentration within the model to actual weld profiles. The effect of energy concentration within various joint geometry is described. This method for extending the design of the laser system to include the weld joint allows the evaluation and selection of laser parameters such as lens and focal position for process optimization. The design of narrow gap joints which function as energy concentrators is described. The enhanced laser welding of aluminum without keyhole formation has been demonstrated.

Milewski, J.O. [Los Alamos National Lab., NM (United States); Sklar, E. [OptiCad Corp., Santa Fe, NM (United States)

1997-04-01

56

Creep Rupture Properties of Welded Joints of Heat Resistant Steels  

NASA Astrophysics Data System (ADS)

In this study, the high-temperature mechanical and creep rupture properties of Grade 91/Grade 91 (Mod. 9Cr-Mo) similar welded joints and Grade 91/Inconel 82/SUS304 dissimilar welded joints were examined. The effects of temperature and stress on the failure location in the joints were also investigated. Creep rupture tests were conducted at 823, 873, and 923 K; the applied stress ranges were 160-240, 80-160, and 40-80 MPa, respectively. The creep rupture strengths of the specimens with welded joints were lower than those of the specimens of the base metal at all temperature levels; in addition, these differences in creep strength increased with temperature. After being subjected to long-term creep rupture tests, the fracture type exhibited by the dissimilar welded joints was transformed from Types V and VII to Type IV. It was estimated that the fracture type exhibited by the dissimilar welded joints after 100,000-h rupture strength tests at 823 K and 873 K was Type IV fracture.

Yamazaki, Masayoshi; Watanabe, Takashi; Hongo, Hiromichi; Tabuchi, Masaaki

57

Mechanical and structural characteristics of commercially pure grade 2 Ti welds and solder joints.  

PubMed

This study aimed at determining whether data previously gathered for a laser welds and IR brazings using a Au-Pd alloy were applicable to titanium joints. As to its resistance under fatigue loading, Au-Pd alloy had shown a poor response to pre-ceramic laser welding and post-ceramic brazing. The present study was designed to assess the mechanical resistance, the microstructure and the elemental diffusion of laser welded, electric arch welded and brazed joints using commercially pure titanium as substrate metal. Mechanical resistance was determined by determining the joints' ultimate tensile strength and their resistance to fatigue loading. Elemental diffusion to and from the joints was assessed using microprobe tracings. Optical micrographs of the joints were also obtained and evaluated. Under monotonic tensile stress, three groups emerged: (1) the GTAW and the native (i.e. as received) substrate, (2) the annealed substrate and the laser welds and (3) the brazed joints. Under fatigue stress, the order was: first the native and annealed substrate, second the brazings and laser welds, third the GTAW joints. No Au-filler brazing withstood the applied fatigue loading. The micrographs showed various patterns, an absence of HAZ cracking and several occurrences of Widmanstätten structures. Elemental diffusion to and from the Ti substrate was substantial in the Ti filler brazings and virtually nil in the Au-based brazings. Under fatigue stress application, the titanium-based brazings as well as the laser- and electric arc welds performed equally well if not better than a previously tested AuPd alloy. There was a definite increase in grain size with increased heat application. However, no feature of the microstructures observed or the elemental analysis could be correlated with the specimen's resistance to fatigue stress application. PMID:15348244

Anselm Wiskott, H W; Doumas, T; Scherrer, S S; Belser, U C; Susz, C

2001-08-01

58

Strength of Welded Joints in Tubular Members for Aircraft  

NASA Technical Reports Server (NTRS)

The object of this investigation is to make available to the aircraft industry authoritative information on the strength, weight, and cost of a number of types of welded joints. This information will, also, assist the aeronautics branch in its work of licensing planes by providing data from which the strength of a given joint may be estimated. As very little material on the strength of aircraft welds has been published, it is believed that such tests made by a disinterested governmental laboratory should be of considerable value to the aircraft industry. Forty joints were welded under procedure specifications and tested to determine their strengths. The weight and time required to fabricate were also measured for each joint.

Whittemore, H L; Brueggeman, W C

1931-01-01

59

Residual stress distribution depending on welding sequence in multi-pass welded joints with x-shaped groove  

SciTech Connect

Residual stress in a large-diameter multi-pass butt-welded pipe joint was calculated for various welding pass sequences by thermal elastic-plastic analysis using the finite element method. The pipe joint used had an X-shaped groove, and the sequences of welding passes were changed. The distribution of residual stress depends on the welding pass sequences. The mechanism that produces residual stress in the welded pipe joint was studied in detail by using a simple prediction model. An optimum welding sequence for preventing stress-corrosion cracking was determined from the residual stress distribution.

Mochizuki, Masahito; Hayashi, Makoto; Hattori, Toshio

2000-02-01

60

Effect of Peculiarities of Heat Transfer, Diffusion and Phase Transformation on Joint Formation During Welding of Dissimilar Materials by High Power Fiber Laser  

NASA Astrophysics Data System (ADS)

The article describes mathematical models of diffusion and thermal processes for welding of dissimilar materials and kinetic model of diffusion-controlled deposition and growth of intermetallic inclusions in the weld. Developed models were combined and implemented in the model of weld joint formation for dissimilar materials. To verify a model the microstructure analysis of weld joints and elemental analysis in the diffusion zone by SEM has been made for welding of systems Fe-Cu, Al-Ti, Fe-Al. The good agreement between calculated and experimental data has been obtained. Examples of developed technologies of welding of dissimilar materials using high-power fiber lasers were discussed also.

Turichin, Gleb; Klimova, Olga; Valdaytseva, Ekaterina

61

Laser beam welding of dissimilar ferritic/martensitic stainless steels in a butt joint configuration  

NASA Astrophysics Data System (ADS)

This paper investigates laser beam welding of dissimilar AISI430F and AISI440C stainless steels. A combined welding and pre-and-postweld treatment technique was developed and used successfully to avoid micro-crack formation. This paper also examined the effects of laser welding parameters and line energy on weld bead geometry and tried to obtain an optimized laser-welded joint using a full factorial design of experiment technique. The models developed were used to find optimal parameters for the desired geometric criteria. All the bead characteristics varied positively as laser power increased or welding speed decreased. Penetration size factor decreased rapidly due to keyhole formation for line energy input in the range of 15-20 kJ/m. Laser power of 790-810 W and welding speed of 3.6-4.0 m/min were the optimal parameters providing an excellent welded component. Whatever the optimization criteria, beam incident angle was around its limiting value of 15° to achieve optimal geometrical features of the weld.

Khan, M. M. A.; Romoli, L.; Dini, G.

2013-07-01

62

Effect of friction stir lap welding conditions on joint strength of aluminium alloy 6060  

Microsoft Academic Search

Strength of lap joints made by friction stir welding (FSW) depends strongly on how material flows forming the weld nugget zone during FSW and also on how the joint is loaded during testing. Understanding of this processing-property relationship is currently inadequate. In this study, the effects of pin length, welding speed and rotation rate on weld strength using aluminium alloy

S. Yazdanian; Z. W. Chen

2009-01-01

63

Tensile strength of simulated and welded butt joints in W-Cu composite sheet  

NASA Technical Reports Server (NTRS)

The weldability of W-Cu composite sheet was investigated using simulated and welded joints. The welded joints were produced in a vacuum hot press. Tensile test results showed that simulated joints can provide strength and failure mode data which can be used in joint design for actual weldments. Although all of the welded joints had flaws, a number of these joints were as strong as the W-Cu composite base material.

Moore, Thomas J.; Watson, Gordon K.

1994-01-01

64

Explosive Welding of Tubular Configurated Joints for Critical Applications  

NASA Technical Reports Server (NTRS)

Explosive welding can provide the answer to problems of permanently joining metals typically used in the aerospace industry. The explosive bonding process is a solid state bonding process enabling material incompatibility problems associated with fusion welding to be overcome. In addition, heat affected zones are eliminated thus, enhancing joint strength, properties and performance. The process requires the parts being joined to be impelled, by means of explosives, to collide with each other. Certain critical collision parameters must be met and controlled and these parameters are defined. Various component geometries which satisfy the collision parameters are described. Examples of transition joints used in the aerospace industry are described and illustrated.

Hardwick, R.

1985-01-01

65

SHRINK-FITTING AND DOWEL WELDING IN MORTISE AND TENON STRUCTURAL WOOD JOINTS  

E-print Network

SHRINK-FITTING AND DOWEL WELDING IN MORTISE AND TENON STRUCTURAL WOOD JOINTS E.Mougel1 , C.Segovia1-fitting, a common bonding technique in metal assemblies, was used for mortise and tenon wood joints. The joints had time allowing decreasing the number of welded dowels needed. Keywords: shrink-fitting, wood welding

Paris-Sud XI, Université de

66

S. Chataigner, L. Dieng, K. Guiot, M. Grasset 1 IMPROVING WELDED JOINT FATIGUE LIFE USING SHOT  

E-print Network

S. Chataigner, L. Dieng, K. Guiot, M. Grasset 1 IMPROVING WELDED JOINT FATIGUE LIFE USING SHOT the fatigue life expectancy of welded steel joints in civil engineering structures. It includes both numerical. It is therefore10 momentous to lead research works on the fatigue of welded joints and the existing strengthening

Paris-Sud XI, Université de

67

Hybrid laser-arc welding of galvanized high-strength steels in a gap-free lap-joint configuration  

NASA Astrophysics Data System (ADS)

In order to meet the industry demands for increased fuel efficiency and enhanced mechanical and structural performance of vehicles as well as provided excellent corrosion resistance, more and more galvanized advanced high-strength steels (AHSS) have been used to fabricate automobile parts such as panels, bumpers, and front rails. The automotive industry has shown tremendous interest in using laser welding to join galvanized dual phase steels because of lower heat input and higher welding speed. However, the laser welding process tends to become dramatically unstable in the presence of highly pressurized zinc vapor because of the low boiling point of zinc, around 906°C, compared to higher melting point of steel, over 1500°C. A large number of spatters are produced by expelling the liquid metal from the molten pool by the pressurized zinc vapor. Different weld defects such as blowholes and porosities appear in the welds. So far, limited information has been reported on welding of galvanized high strength dual-phase steels in a gap-free lap joint configuration. There is no open literature on the successful attainment of defect-free welds from the laser or hybrid welding of galvanized high-strength steels. To address the significant industry demand, in this study, different welding techniques and monitoring methods are used to study the features of the welding process of galvanized DP steels in a gap-free lap joint configuration. The current research covers: (i) a feasibility study on the welding of galvanized DP 980 steels in a lap joint configuration using gas tungsten arc welding (GTAW), laser welding, hybrid laser/arc welding with the common molten pool, laser welding with the assistance of GTAW preheating source and hybrid laser-variable polarity gas tungsten arc welding (Laser-VPGTAW) techniques (Chapter 2-4); (ii) a welding process monitoring of the welding techniques including the use of machine vision and acoustic emission technique (Chapter 5); (iii) Modeling of hybrid laser-GTAW as a preheating source welding process of galvanized steels in a gap-free lap joint configuration (Chapter 6). Experimental results demonstrated that completely defect-free lap joints in galvanized high strength steels can be obtained in a gap-free configuration by using the laser welding process with the GTAW torch preheating and hybrid laser-VPGTAW welding technique. Effects of the welding parameters on the weld quality are discussed. The mechanical properties of the welded joints are studied. A machine vision system and an acoustic emission (AE) signal acquisition system are employed to acquire the images of the molten pool and the emitted AE signals on-line. Furthermore, image processing and Short Time Fourier Transform (STFT) techniques are employed to analyze the acquired images of the molten pool and the collected AE signals. The acquisition attempts are composed of (1) monitoring the weld defects by machine vision; (2) monitoring the formation of spatters from the AE signals; (3) detecting the weld modes by the induced plume; and (4) monitoring the instability of the welding process by machine vision. In addition, the numerical results have been validated by the experimental data.

Yang, Shanglu

68

Carbon diffusion in friction welded joints of refractory metals in a liquid  

Microsoft Academic Search

The effect of carbon on materials joined by friction welding in a liquid was studied. Titanium and tantalum specimens resistance-heated in a liquid and then specimens friction-welded in a liquid were tested. Same-metal (titanium, vanadium, tantalum) joints and dissimilar-metal joints were friction welded. The distribution of microhardness in the friction welded joints and their microstructure and linear concentration profiles were

Andrzej Ambroziak

2010-01-01

69

Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding  

NASA Astrophysics Data System (ADS)

The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic ?' and the application of TC-1 welding rods in the TIG-welded joint.

Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

2014-12-01

70

Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding  

NASA Astrophysics Data System (ADS)

The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic ?' and the application of TC-1 welding rods in the TIG-welded joint.

Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

2014-09-01

71

Influences of post-weld heat treatment on tensile properties of friction stir-welded AA6061 aluminum alloy joints  

SciTech Connect

This paper reports on studies of the influences of various post-weld heat treatment procedures on tensile properties of friction stir-welded AA6061 aluminum alloy joints. Rolled plates of 6-mm thick AA6061 aluminum alloy were used to fabricate the joints. Solution treatment, an artificial aging treatment and a combination of both were given to the welded joints. Tensile properties such as yield strength, tensile strength, elongation and joint efficiency were evaluated. Microstructures of the welded joints were analyzed using optical microscopy and transmission electron microscopy. A simple artificial aging treatment was found to be more beneficial than other treatment methods to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.

Elangovan, K. [Department of Mechanical and Production Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu (India); Balasubramanian, V. [Centre for Materials Joining Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu (India)], E-mail: visvabalu@yahoo.com

2008-09-15

72

Significance of weld profile on the fatigue lives of tubular joints  

SciTech Connect

This paper presents the results of a major joint industry project which investigated the influence of weld profile on the fatigue performance of tubular joints. Fatigue tests were performed on steel tubular T-joints under in-plane bending, with the main aim of ``testing`` the value of the weld profile control measures laid down by AWS. The range of welds produced enabled the effects of as-welded surface finish, weld leg length, and hence weld angle, and weld toe grinding to be explored. The results throw serious doubt on the value of the AWS weld profile control measures. However, they do confirm the potential benefit of the increased weld leg length if it moves the weld toe into a lower stressed region. Recommendations are made for changes to current design codes.

Maddox, S.J.; Wylde, J.G. [TWI, Cambridge (United Kingdom); Yamamoto, Noboru [Kawasaki Steel Corp., Chiba (Japan). R and D Center

1995-12-31

73

Nuclear Technology. Course 28: Welding Inspection. Module 28-4, Weld Joint Verification.  

ERIC Educational Resources Information Center

This fourth in a series of ten modules for a course titled Welding Inspection discusses the nomenclature, symbols, and the purposes of most common joint designs, preparations, and fit-ups. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to…

Espy, John

74

Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies  

Microsoft Academic Search

The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high

Z. Yang; P. Dong; S. Liu; S. Babu; G. Olson; T. DebRoy

2005-01-01

75

High-Cycle Constant Amplitude Fatigue Life Variability of Welded Round HSS Y-Joints  

E-print Network

High-Cycle Constant Amplitude Fatigue Life Variability of Welded Round HSS Y-Joints By John L 2003 #12;i Preface The variability in fatigue life estimates for welded pipe joints commonly found. The primary goal of this thesis was to quantify the variability in the fatigue life of welded round HSS Y

Foley, Christopher M.

76

Effect of UIT on Fatigue Life in Web-Gusset Welded Joints  

NASA Astrophysics Data System (ADS)

Ultrasonic impact treatment (UIT), which is a peening method, is usually used as a post-weld treatment in order to improve the fatigue strength of welded joints. In this study, fatigue tests were carried out on web-gusset welded joints treated by UIT and the results were compared with the fatigue lives of as-welded joints in order to examine the effects of UIT on the fatigue lives of welded joints. The fatigue lives of web-gusset welded joints treated by UIT increased to more than ten times those of as-welded joints. The introduction of compressive residual stress, relaxation of stress concentration at a weld toe, and refinement of grains under the weld toes were considered as possible reasons for the improvement in fatigue life caused by UIT. Residual stress near weld toes was measured using the X-ray diffraction method. The stress concentration factor at the weld toes was analyzed using the finite element method (FEM). The grain size under the weld toes was measured using electron backscatter diffraction pattern (EBSD) analysis.

Togasaki, Yu; Tsuji, Hirokazu; Honda, Takashi; Sasaki, Tetsuya; Yamaguchi, Atsushi

77

Some investigations on microstructure and mechanical properties of submerged arc welded HSLA steel joints  

Microsoft Academic Search

This paper investigates the influence of the submerged arc welding (SAW) process parameters (welding current and welding speed)\\u000a on the microstructure, hardness, and toughness of HSLA steel weld joints. Attempts have also been made to analyze the results\\u000a on the basis of the heat input. The SAW process was used for the welding of 16 mm thick HSLA steel plates. The

Keshav Prasad; D. K. Dwivedi

2008-01-01

78

Fatigue strength improvement of MIG-welded joint by shot peening  

NASA Astrophysics Data System (ADS)

In this study, the effect of controlled shot peening (CSP) treatment on the fatigue strength of an ASTM A516 grade 70 carbon steel MIG-welded joint has been studied quantitatively. Metallurgical modifications, hardness, elemental compositions, and internal discontinuities, such as porosity and inclusions found in treated and untreated fusion welded joints, were characterized. The fatigue results of as-welded and peened skimmed joints were compared. It was observed that the effect of the CSP and skimming processes improved the fatigue life of the fusion weld by 63% on MIG-welded samples.

Azida Che Lah, Nur; Ali, Aidy

2011-02-01

79

Effect of welding on impact toughness of butt-joints in a titanium alloy  

E-print Network

Effect of welding on impact toughness of butt-joints in a titanium alloy Wei Zhou a, *, K.G. Chew b Abstract Impact toughness of a gas tungsten arc welded TiÁ/6AlÁ/4V alloy butt-joint was evaluated at room in the investigation were extracted from a butt-welded joints of a TiÁ/6AlÁ/4V titanium * Corresponding author E

Zhou, Wei

80

Tensile Properties of Under-Matched Weld Joints for 950 MPa Steel.  

NASA Astrophysics Data System (ADS)

In welding of 950 MPa-class high tensile strength steel, preheating is crucial in order to avoid cold cracks, which, however, eventually increases welding deformations. One way to decrease welding deformations is lowering preheating temperature by using under-matched weld metal. Toyota and others clarify that although breaking elongation can decrease due to plastic constraint effect under certain conditions, static tensile of under-matched weld joints is comparable to that of base metal. However, there has still been no report about joint static tensile of under-matched weld joints applied to 950 MPa-class high tensile strength steel. In this study, we aim to research tensile strength and fatigue strength of under-matched weld joints applied to 950 MPa-class high tensile steel.

Yamamoto, Kouji; Arakawa, Toshiaki; Akazawa, Nobuki; Yamamoto, Kousei; Matsuo, Hiroki; Nakagara, Kiyoyuki; Suita, Yoshikazu

81

Numerical and experimental evaluation of Nd:YAG laser welding efficiency in AZ31 magnesium alloy butt joints  

NASA Astrophysics Data System (ADS)

In this paper, energy aspects related to the efficiency of laser welding process using a 2 kW Nd:YAG laser were investigated and reported. AZ31B magnesium alloy sheets 3.3 mm thick were butt-welded without filler using Helium and Argon as shielding gases. A three-dimensional and semi-stationary finite element model was developed to evaluate the effect of laser power and welding speed on the absorption coefficient, the melting and welding efficiencies. The modeled volumetric heat source took into account a scale factor, and the shape factors given by the attenuation of the beam within the workpiece and the beam intensity distribution. The numerical model was calibrated using experimental data on the basis of morphological parameters of the weld bead. Results revealed a good correspondence between experiment and simulation analysis of the energy aspects of welding. Considering results of mechanical characterization of butt joints previously obtained, the optimization of welding condition in terms of mechanical properties and energy parameters was performed. The best condition is represented by the lower laser power and higher welding speed that corresponds to the lower heat input given to the joint.

Scintilla, Leonardo Daniele; Tricarico, Luigi

2013-02-01

82

Effect of a copper filler metal on the microstructure and mechanical properties of electron beam welded titanium-stainless steel joint  

SciTech Connect

Cracking in an electron beam weld of titanium to stainless steel occurred during the cooling process because of internal thermal stress. Using a copper filler metal, a crack free joint was obtained, which had a tensile strength of 310 MPa. To determine the reasons for cracking in the Ti/Fe joint and the function of the copper filler metal on the improvement of the cracking resistance of the Ti/Cu/Fe joint, the microstructures of the joints were studied by optical microscopy, scanning electron microscopy and X-ray diffraction. The cracking susceptibilities of the joints were evaluated with microhardness tests on the cross-sections. In addition, microindentation tests were used to compare the brittleness of the intermetallics in the welds. The results showed that the Ti/Fe joint was characterized by continuously distributed brittle intermetallics such as TiFe and TiFe(Cr){sub 2} with high hardness ({approx} 1200 HV). For the Ti/Cu/Fe joint, most of the weld consisted of a soft solid solution of copper with dispersed TiFe intermetallics. The transition region between the weld and the titanium alloy was made up of a relatively soft Ti-Cu intermetallic layer with a lower hardness ({approx} 500 HV). The formation of soft phases reduced the cracking susceptibility of the joint. - Highlights: Black-Right-Pointing-Pointer Electron beam welded Ti/Fe joint cracked for the brittleness and residual stress. Black-Right-Pointing-Pointer Electron beam welded Ti/Cu/Fe joint with tensile strength of 310 MPa was obtained. Black-Right-Pointing-Pointer Cu diluted Ti and Fe contents in weld and separated the TiFe{sub 2} into individual blocks. Black-Right-Pointing-Pointer Interfacial hard Ti-Fe compounds were replaced by soft Ti-Cu compounds in the weld. Black-Right-Pointing-Pointer A large amount of solid solution of copper formed in the weld.

Wang, Ting, E-mail: fgwangting@163.com [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China)] [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China); Zhang, Binggang, E-mail: zhang_bg@126.com [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)] [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China); Feng, Jicai, E-mail: fengjc@hit.edu.cn [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China) [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China); Tang, Qi, E-mail: tangqi@163.com [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)] [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)

2012-11-15

83

Electron microscopy and microanalysis of steel weld joints after long time exposures at high temperatures  

NASA Astrophysics Data System (ADS)

The structural changes of three trial weld joints of creep resistant modified 9Cr-1Mo steels and low alloyed chromium steel after post-weld heat treatment and long-term creep tests were investigated. Smooth cross-weld specimens ruptured in different zones of the weld joints as a result of different structural changes taking place during creep exposures. The microstructure of the weld joint is heterogeneous and consequently microstructural development can be different in the weld metal, the heat affected zone, and the base material. Precipitation reactions, nucleation and growth of some particles and dissolution of others, affect the strengthening of the matrix, recovery at high temperatures, and the resulting creep resistance. Therefore, a detailed study of secondary phase's development in individual zones of weld joints can elucidate mechanism of cracks propagation in specific regions and the causes of creep failure. Type I and II fractures in the weld metal and Type IV fractures in the fine prior austenite grain heat affected zones occurred after creep tests at temperatures ranging from 525 to 625 °C and under stresses from 40 to 240 MPa. An extended metallographic study of the weld joints was carried out using scanning and transmission electron microscopy, energy-dispersive and wave-dispersive X-ray microanalysis. Carbon extraction replicas and thin foils were prepared from individual weld joint regions and quantitative evaluation of dislocation substructure and particles of secondary phases has been performed.

Jandová, D.; Kasl, J.; Rek, A.

2010-02-01

84

The Effect of Weld Profile and Geometries of Butt Weld Joints on Fatigue Life Under Cyclic Tensile Loading  

Microsoft Academic Search

The fatigue life of welded joint was calculated based on numerical integration of simple Paris’ law and a reliable solution\\u000a of the stress intensity factor (SIF). The initial crack length (a\\u000a i) was assumed to be equal to 0.1 mm in case of weld toe. This length was satisfactory for different butt joints geometries.\\u000a The comparisons with the available data from

A. M. Al-Mukhtar; H. Biermann; P. Hübner; S. Henkel

85

Characteristics of microstructure and fatigue resistance of hybrid fiber laser-MIG welded Al-Mg alloy joints  

NASA Astrophysics Data System (ADS)

In this study, the microstructures, mechanical properties and fatigue strengths of the hybrid laser-MIG welded joints were investigated. The detailed microstructures of the hybrid welded joints were carried out using OM and TEM. The causes of the strengths loss of the hybrid welded joints were studied from aspects of solute strengthening, precipitates hardening, and grain boundary strengthening. The fatigue strengths of the hybrid welded joints, MIG welded joints, and base metals were investigated. The results showed that the fatigue strength of the hybrid welded joints was better than that of the MIG welded joint. The conditional fatigue strength (Nf > 107) of the hybrid welded joints could reach up to 84.6% of the base metal's conditional fatigue strength (130 MPa). The fatigue fracture surfaces were examined by SEM, and the result showed that the main reason for the decrease of the fatigue strength was porosity.

Yan, Shaohua; Nie, Yuan; Zhu, Zongtao; Chen, Hui; Gou, Guoqing; Yu, Jinpeng; Wang, Guiguo

2014-04-01

86

Weld cracking in corner joints by submerged-arc welding with high heat input  

SciTech Connect

One-pass submerged arc welding (SAW) with high heat input is widely employed in Japan for the comer seam of box-shaped columns with a plate thickness of up to 70mm. The welding efficiency of one-pass SAW is several times higher than that of multipass welding. However, an internal crack similar to lamellar tearing occasionally occurs in the center-thickness position of the flange plate. ne mechanism of this crack and appropriate countermeasures to cracking were studied. It was found that this cracking was a kind of hydrogen induced cracking(HIC), and that the dominant material factors of this cracking were an elongated manganese sulfide (MnS) in the center segregation band, and martensite-austenite constituents (M-A) around MnS formed by intercritical heat affection of one-pass SAW. Drying of the flux was the most effective countermeasure in the welding conditions. As a groove for the one-pass SAW comer joint, a bevel groove was preferable to a V groove to prevent cracking. These effects were also clarified by the finite differential method(FDM) for the diffusion of hydrogen. As countermeasures in the production of steel plates, addition of Ca, soft reduction in continuous casting, and application of thermo-mechanical-control-process (TMCP) were effective.

Wada, T. [NKK Corp., Fukuyama (Japan); Satoshi, I. [Tokyo Metropolitan Univ., Hachioji (Japan); Terasaki, T. [Kyushu Inst. of Technology, Kitakyushu (Japan)

1995-12-31

87

Evaluation of the Joint-Interface Properties of SCM440-S45C Steels Joined by Friction Welding  

NASA Astrophysics Data System (ADS)

The purpose of this study is to investigate experimentally the hardness distributions and micro-structural properties of the dissimilar joints using chrome molybdenum steel (SCM440) to carbon steel (S45C) parts. The experiments were carried out using a beforehand designed and constructed experimental friction welding set-up, constructed as a continuous-drive brake type. The pilot dissimilar welding experiments under different friction pressure and friction time were carried out to obtain optimum welding parameters using visual examination and tensile tests. Vicker's hardness distributions and microstructures in the interfaces of the dissimilar joints for PWHT were also obtained and examined. The obtained results were compared with those of the previous study.

Kim, Seon-Jin; Kong, Yu-Sik; Yoon, Han-Ki; Jung, Won-Taek; Choi, Sung-Woong

88

Type IV Creep Damage Behavior in Gr.91 Steel Welded Joints  

NASA Astrophysics Data System (ADS)

Modified 9Cr-1Mo steel (ASME Grade 91 steel) is used as a key structural material for boiler components in ultra-supercritical (USC) thermal power plants at approximately 873 K (600 °C). The creep strength of welded joints of this steel decreases as a result of Type IV creep cracking that forms in the heat-affected zone (HAZ) under long-term use at high temperatures. The current article aims to elucidate the damage processes and microstructural degradations that take place in the HAZ of these welded joints. Long-term creep tests for base metal, simulated HAZ, and welded joints were conducted at 823 K, 873 K, and 923 K (550 °C, 600 °C, and 650 °C). Furthermore, creep tests of thick welded joint specimens were interrupted at several time steps at 873 K (600 °C) and 90 MPa, after which the distribution and evolution of creep damage inside the plates were measured quantitatively. It was found that creep voids are initiated in the early stages (0.2 of life) of creep rupture life, which coalesce to form a crack at a later stage (0.8 of life). In a fine-grained HAZ, creep damage is concentrated chiefly in an area approximately 20 pct below the surface of the plate. The experimental creep damage distributions coincide closely with the computed results obtained by damage mechanics analysis using the creep properties of a simulated fine-grained HAZ. Both the concentration of creep strain and the high multiaxial stress conditions in the fine-grained HAZ influence the distribution of Type IV creep damage.

Hongo, Hiromichi; Tabuchi, Masaaki; Watanabe, Takashi

2012-04-01

89

Studying of micro-bonding in diffusion welding joint for composite  

Microsoft Academic Search

This paper reports the preliminary investigation of the micro-bonding of reinforcement\\/matrix and reinforcement\\/reinforcement in a diffusion welded joint for Al2O3p\\/6061Al composite and analyzes the microstructure and performance of the welded joint. Experimental results show that the interface of the matrix\\/reinforcement has better bonding only when the diffusion welding temperature is higher than the solid phase line of Al2O3p\\/6061Al composite. It

Liu Liming; Zhu Meili; Pan Longxiu; Wu Lin

2001-01-01

90

Effect of weld metal mismatch on joint efficiency and measured fracture toughness  

SciTech Connect

Fracture toughness tests of deep-notched and shallow-notched SENB specimens at various sub-zero temperatures were conducted to study the effect of weld metal mismatch on measured fracture toughness. Tensile tests of cross-weld tensile specimens were also conducted to study the effect of weld metal mismatch on joint efficiency. These specimens were machined from butt welds that were fabricated with the same welding consumable and welding procedure using HSLA 100 steel plates heat treated to different tensile strengths. No significant differences were found between the joint efficiencies and ductilities of the cross-weld tensile specimens with overmatching weld metal and those of specimens with up to 9% weld metal undermatch in terms of yield strength (3% in terms of ultimate tensile strength). Furthermore, 100% joint efficiency was still achieved in the cross-weld tensile specimens with intact reinforcements and 17% undermatching weld metal in terms of yield strength (9% in terms of ultimate tensile strength). No correlation was found between the degree of weld metal mismatch and the measured fracture toughness of the SENB specimens.

Yee, R.; Malik, L. [Fleet Technology Ltd., Kanata, Ontario (Canada); Morrison, J. [CFB Esquimalt, Victoria, British Columbia (Canada). Esquimalt Defence Research Detachment

1997-12-31

91

Application of thermal methods for characterization of steel welded joints  

NASA Astrophysics Data System (ADS)

Despite the large number of proposals in the field of fatigue prediction of welded joints, a globally accepted and unified theory, which applies easily to any load condition, does not exist. Real life components, indeed, differ in geometry and/or type of load from the structural design for which they are regarded by Standards, so that a lot of precautionary safety factors are used that lead to an underestimation of the actual fatigue life of joints. Infrared thermography has a great potential in this field, both from structural and thermomechanical points of view. It enables a full field stress analysis with a sufficient spatial resolution so that the complexity of the stress state at the weld toe and its time evolution are taken into account, emphasizing anomalies that may predict structural failure. A new methods for evaluation fatigue limit damage is presented in this paper and in particular interesting results derived from analysis of the evolution of thermoelastic signal phase. Variations in the value of signal phase indicate a not elastic behaviour and plastic dissipation in the material.

Galietti, U.; Palumbo, D.

2010-06-01

92

Effects of Initial Temper Condition and Postweld Heat Treatment on the Properties of Dissimilar Friction-Stir-Welded Joints between AA7075 and AA6061 Aluminum Alloys  

NASA Astrophysics Data System (ADS)

In this study, dissimilar AA7075-O/6061-O and AA7075-T6/6061-T6 butt joints were produced by friction stir welding (FSW), and postweld heat treatment (PWHT) was applied to the joints obtained. The effects of initial temper condition and PWHT on the microstructure and mechanical properties of the dissimilar joints were thus investigated. It was demonstrated that sound dissimilar joints can be produced for both temper conditions. A hardness increase in the joint area ( i.e., strength overmatching) was obtained in the joints produced in the O-temper condition, whereas a hardness loss was observed in the joint area of the joints obtained in the T6 temper condition. It was also well demonstrated that PWHT could be used in order to improve the joint properties for both O and T6 joints provided that the joint is defect-free prior to subsequent heat treatment.

?peko?lu, Güven; Çam, Gürel

2014-06-01

93

Corrosion fracture resistance of welded joints in 16GMYuCh steel  

SciTech Connect

This paper studies the effect of combined welding of thick-wall gas and oil chemical equipment consisting of welding the weld root by automatic submerged-arc welding and electrosag welding (ESW) with the control of thermal cycles (CWC) of the main joint, on the corrosion resistance of welded joints in low-alloy normalized 16GMYuCh steel 50 mm thick. The chemical composition of the steel, % 0.16 C; 1.05 Mn; 0.25 Si; 0.42 Mo; 0.14 Ni; 0.1 Cu; 0.11 Cr; 0.049 Al; 0.032 S; 0.019 P. The authors determined the effect of cooling rate in the temperature range of diffusion transformation of austenite on the corrosion resistance of the weld zone. Attention was then given to the corrosion resistance of the welded joints produced by conventional ESW welding and ESW with CWC. The investigations show that the corrosion resistance of the parent metal is lower than that of the welded joints.

Steklov, O.I.; Efimenko, L.A.; Khakimov, A.M.; Paul', A.I.; Pushkina, O.A.

1986-01-01

94

Higher-Quality Weld Joints for Tube Sections  

NASA Technical Reports Server (NTRS)

Less material in weld inserts results in better fusion. Redesigned insert for joining tubes by welding improves quality of weld. In new insert, leg of T shorter so it does not protrude into tube cavity.

Olszewski, John T.

1987-01-01

95

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2011 CFR

...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...when designing for these systems. (c) Socket welds (Modifies 127.3.3A. ). (1) Each...

2011-10-01

96

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2010 CFR

...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...when designing for these systems. (c) Socket welds (Modifies 127.3.3A. ). (1) Each...

2010-10-01

97

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2013 CFR

...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...when designing for these systems. (c) Socket welds (Modifies 127.3.3A. ). (1) Each...

2013-10-01

98

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2012 CFR

...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...when designing for these systems. (c) Socket welds (Modifies 127.3.3A. ). (1) Each...

2012-10-01

99

Effect of Welding Consumables on Fatigue Performance of Shielded Metal Arc Welded High Strength, Q&T Steel Joints  

NASA Astrophysics Data System (ADS)

Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to their high strength-to-weight ratio and high hardness. These steels are prone to hydrogen-induced cracking in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel consumables to weld the above steel was the only remedy because of higher solubility for hydrogen in austenitic phase. Recent studies proved that high nickel steel and low hydrogen ferritic steel consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. In this investigation an attempt has been made to study the effect of welding consumables on high cycle fatigue properties of high strength, Q&T steel joints. Three different consumables namely (i) austenitic stainless steel, (ii) low hydrogen ferritic steel, and (iii) high nickel steel have been used to fabricate the joints by shielded metal arc (SMAW) welding process. The joints fabricated using low hydrogen ferritic steel electrodes showed superior fatigue properties than other joints.

Magudeeswaran, G.; Balasubramanian, V.; Madhusudhan Reddy, G.

2009-02-01

100

The Diagnostic Method of Inner Parts of Welded Joints at Nuclear Power Plant  

SciTech Connect

There is no possibility to check any inner part at real welded joint at nuclear power station (NPS) during operation because any destructive test cannot be used. In practice there is checked surface of weld. There are used four methodical instructions for the check of real welds: 1. The visual inspection, 2. The measurement of hardness, 3. The chemical composition checking and 4. The microstructure replica analysis. It is necessary to know how these information of weld surface are in accordance with characteristics of inner parts of weld. If there is not any difference between surface weld microstructure and internal weld microstructure of experimental weld it is supposed to that there is not any difference in other measured properties of welds. If is changed structural characteristics of microstructure, it is changed also hardness, chemical analysis etc. It was observed that the microstructure of real welds is almost the same with simulated weld and also the surface microstructure of experimental weld is in accordance with microstructure of inner parts of this weld. It can be supposed extension of lifetime of NPS if there is not any difference between replicas microstructure taken after six year operation of NPS and microstructure of inner parts of simulated weld is almost the same with surface microstructure.

Bednarova, O.; Janovec, J. [Department of Materials Engineering, Mechanical Engineering Faculty, Czech Technical University in Prague, Karlovo namesti 13, 121 35 Prague 2 (Czech Republic)

2010-06-22

101

The Diagnostic Method of Inner Parts of Welded Joints at Nuclear Power Plant  

NASA Astrophysics Data System (ADS)

There is no possibility to check any inner part at real welded joint at nuclear power station (NPS) during operation because any destructive test cannot be used. In practice there is checked surface of weld. There are used four methodical instructions for the check of real welds: 1. The visual inspection, 2. The measurement of hardness, 3. The chemical composition checking and 4. The microstructure replica analysis. It is necessary to know how these information of weld surface are in accordance with characteristics of inner parts of weld. If there is not any difference between surface weld microstructure and internal weld microstructure of experimental weld it is supposed to that there is not any difference in other measured properties of welds. If is changed structural characteristics of microstructure, it is changed also hardness, chemical analysis etc. It was observed that the microstructure of real welds is almost the same with simulated weld and also the surface microstructure of experimental weld is in accordance with microstructure of inner parts of this weld. It can be supposed extension of lifetime of NPS if there is not any difference between replicas microstructure taken after six year operation of NPS and microstructure of inner parts of simulated weld is almost the same with surface microstructure.

Bednarova, O.; Janovec, J.

2010-06-01

102

Residual Stress Evaluation of AA2024-T3 Friction Stir Welded Joints  

NASA Astrophysics Data System (ADS)

The main aim of this study was to evaluate the residual stress field in friction stir welded joints of 2024-T3 aluminum alloy plates using the slitting method. This is based on the fact that when a cut, simulating a growing crack, is incrementally introduced into a part, residual stresses are relieved on the slot surfaces created, causing the part to deform. Such deformation can be measured by strain gages attached to specific regions of the part and the residual stress profile that originally existed can be evaluated. Cuts were introduced by wire electro discharge machining (WEDM), in finishing mode, either perpendicularly or longitudinally to the weld nugget, in 3.2 × 60 × 120 mm3 rectangular testpieces. For the longitudinal testpieces, the slot was introduced in two different positions: on the center of the weld nugget and 5 mm distant from the weld center line, in order to sample the thermomechanically/heat affected zone. The residual stress intensity factor, K r, was calculated using a fracture mechanics approach and the inverse weight function method was employed to obtain the initial residual stress profile. Residual stress redistribution profiles ahead of the slot tip could also be derived using the inverse weight function method. However, for cracked components subjected to compressive residual stress fields, when the crack faces are in contact, a non-linear problem arises and the zero displacement condition has to be taken into account in order to provide a more accurate solution of the residual stress field.

Milan, M. T.; Bose Filho, W. W.; Tarpani, J. R.; Malafaia, A. M. S.; Silva, C. P. O.; Pellizer, B. C.; Pereira, L. E.

2007-02-01

103

Determination of Residual Stress Profiles in A Friction Stir Welded Stringer-to-Skin Lap Joint  

NASA Astrophysics Data System (ADS)

Riveting has been for many years the conventional method of joining aluminum components such as aircraft stringer-to-skin panels in the lap joint configuration. Due to a demand for a more economical and improved joining method, friction stir welding has been proposed as an alternative welding process. Residual stresses left behind from the friction stir welding process caused the stringer-to-skin lap joint to twist after the clamps are removed. A post-welding process of hammer peening was able to remove the distortion in the plate. In this thesis, the crack compliance method is used to calculate the residual stresses in the friction stir welded lap joints in the through thickness, transverse, and longitudinal direction. A non-destructive residual stress measurement technique known as neutron diffraction was used on the lap joint in both as-welded and hammer peened conditions. The residual stress profiles in the through thickness, transverse and longitudinal directions were successfully measured and compared with the residual stress from the compliance method. It was determined that the compliance method was successful in calculating the residual stresses in the through thickness and transverse direction but was not able to calculate the residual stress in the longitudinal direction. Distortion in the plate was a result of a combination of non-uniform residual stress profile in the three principal directions. Fatigue testing was performed on the as-welded and hammer peened configuration and it was determined that the hammer peened condition outlived that of the as-welded condition under the same loading frequency. An examination of the failure locations in the friction stir welded lap joints concluded that the as-welded specimens failed at a location in the weld region with a combination of weld defects, lowest hardness value and highest tensile residual stresses.

Bach, Michael

104

Effects of Sealing Run Welding with Defocused Laser Beam on the Quality of T-joint Fillet Weld  

NASA Astrophysics Data System (ADS)

Fillet weld is the predominant weld type used for connecting different elements e.g. in shipbuilding, offshore and bridge structures. One of prevalent research questions is the structural integrity of the welded joint. Post weld improvement techniques are being actively researched, as high stress areas like an incomplete penetration on the root side or fluctuations in penetration depth cannot be avoided. Development of laser and laser-arc hybrid welding processes have greatly contributed to increase of production capacity and reduction of heat-induced distortions by producing single pass full penetration welds in thin- and medium thickness structural steel parts. Present study addresses the issue of how to improve the quality of the fillet welds by welding the sealing run on the root side with defocused laser beam. Welds having incomplete or excessive penetration were produced with several beam angles and laser beam spot sizes on surface. As a conclusion, significant decrease or even complete elimination of the seam irregularities, which act as the failure starting points during service, is achieved.

Unt, Anna; Poutiainen, Ilkka; Salminen, Antti

105

Fatigue Performance of Gas Tungsten Arc, Electron Beam, and Laser Beam Welded Ti-6Al-4V Alloy Joints  

NASA Astrophysics Data System (ADS)

Titanium alloys have been successfully applied for aerospace, ship, and chemical industries because they possess many good characteristics such as high strength to weight ratio, superior corrosion resistance, and excellent high temperature resistance. Though these alloys show reasonable weldability characteristics, the joint properties are greatly influenced by the welding processes. The evaluation and prediction of fatigue life are very important for the welded joints to avoid catastrophic failure particularly in titanium alloys. This article compares the fatigue performance of Ti-6Al-4V alloy fabricated by gas tungsten arc welding, laser beam welding, and electron beam welding processes. The resultant fatigue properties of the welded joints are correlated with the tensile properties and microstructural characteristics. Of the three processes considered the joint welded by laser beam welding exhibits higher fatigue limit when compared with the other two processes due to the presence of fine lamellar microstructure in the weld metal region.

Balasubramanian, T. S.; Balasubramanian, V.; Muthumanikkam, M. A.

2011-12-01

106

Terahertz imaging: a new non-destructive technique for the quality control of plastic weld joints  

NASA Astrophysics Data System (ADS)

We present the first investigation of plastic weld joints using terahertz waves. Terahertz time-domain spectroscopy clearly reveals contaminations like metal or sand within the weld joint of two high-density polyethylene sheets. Furthermore, areas can be identified where the welding process has failed and the parts to be joined are separated by a small air gap. We show that a three layer structure of polyethylene-air-polyethylene has a characteristic, frequency-dependent transmission behaviour. This allows for a distinction between welded and non-welded material as well as for the calculation of the air layer thickness from the relative transmission spectrum. Consequently, terahertz time-domain spectroscopy provides a promising new non-destructive and even contactless technique, which is desired by the plastics industry for detecting a variety of deviations from the ideal welding process.

Wietzke, S.; Jördens, C.; Krumbholz, N.; Baudrit, B.; Bastian, M.; Koch, M.

2007-04-01

107

Fracture behavior under monotonic and low cycle loadings in carbon steel pipes and welded pipe joints with a defect  

SciTech Connect

To evaluate the structural integrity of power plant piping during earthquakes, fracture behavior under monotonic and low cycle loadings was examined, using 4-inch carbon steel pipes made of base metal and welded pipe joints with a circumferential defect at room and elevated temperatures in air. In the monotonic bending tests, the maximum loads increased slightly with the loading rates for base metal pipes and welded pipe joints. The maximum loads in welded pipe joints were about 10% higher than those in base metal pipes for various displacement rate. In the cyclic bending tests, the number of cycles to failure, N{sub f} was closely correlated with the ratio of the load amplitude, Pa to the maximum load, Pmax obtained in the monotonic bending tests, in spite of the difference in the maximum loads for base metal pipes and welded pipe joints. The number of loading cycles during an earthquake was assumed as about 100 cycles in design. The relationship between Pa/Pmax and the number of cycles to failure showed that the allowable load amplitude ratio was estimated as about 0.7.

Miyazaki, Katsumasa; Kanno, Satoshi; Hayashi, Makoto [Hitachi Limited, Ibaraki (Japan); Ishiwata, Masayuki; Gotoh, Nobuho [Hitachi Limited, Ibaraki (Japan). Dept. of Nuclear Engineering; Miura, Naoki; Fujioka, Terutaka; Kashima, Koichi [Central Research Inst. of Electric Power Industry, Tokyo (Japan)

1996-12-01

108

Influences of welding processes on fatigue life of cruciform joints of pressure vessel grade steels containing LOP defects  

Microsoft Academic Search

The influences of two welding processes, namely, shielded metal arc welding (SMAW) and flux cored arc welding (FCAW), on fatigue life of cruciform joints, containing lack of penetration (LOP) defects, have been studied. Load carrying cruciform joints were fabricated from high strength, quenched and tempered steels of pressure vessel (ASTM 517 ‘F’) grade. Fatigue crack growth experiments were carried out

V Balasubramanian; B Guha

2000-01-01

109

Microstructure and Mechanical Properties of 316L Stainless Steel Filling Friction Stir-Welded Joints  

NASA Astrophysics Data System (ADS)

Keyhole left at 316L stainless steel friction stir welding/friction stir processing seam was repaired by filling friction stir welding (FFSW). Both metallurgical and mechanical bonding characteristics were obtained by the combined plastic deformation and flow between the consumable filling tool and the wall of the keyhole. Two ways based on the original conical and modified spherical keyholes, together with corresponding filling tools and process parameters were investigated. Microstructure and mechanical properties of 316L stainless steel FFSW joints were evaluated. The results showed that void defects existed at the bottom of the refilled original conical keyhole, while excellent bonding interface was obtained on the refilled modified spherical keyhole. The FFSW joint with defect-free interface obtained on the modified spherical keyhole fractured at the base metal side during the tensile test due to microstructural refinement and hardness increase in the refilled keyhole. Moreover, no ? phase but few Cr carbides were formed in the refilled zone, which would not result in obvious corrosion resistance degradation of 316L stainless steel.

Zhou, L.; Nakata, K.; Tsumura, T.; Fujii, H.; Ikeuchi, K.; Michishita, Y.; Fujiya, Y.; Morimoto, M.

2014-10-01

110

Experimental and numerical study of static and fatigue properties of titanium alloy welded joints  

Microsoft Academic Search

Titanium and its alloys have high specific strength, good mechanical properties at high temperature, high resistance to corrosion and to attack by most acid solutions. Such characteristics make this material attractive for numerous applications because of recent improvements in welding techniques that allow to realize high quality welded joints. For example, new utilizations of titanium alloys are currently being studied

C. Casavola; C. Pappalettere; F. Tattoli

2009-01-01

111

Experimental study on repair of fatigue cracks at welded web gusset joint using CFRP strips  

Microsoft Academic Search

This paper presents repair methods of fatigue cracks using CFRP strips. In particular, the subject of repair is fatigue cracks initiated at welded web gusset joints, which are the typical details in steel bridges. Several repair methods were investigated experimentally focusing on weld details. In addition, more effective repair methods were also investigated using combination of CFRP strips and drill-holes.

Hitoshi Nakamura; Wei Jiang; Hiroyuki Suzuki; Ken-ichi Maeda; Takao Irube

2009-01-01

112

Electrical resistance determination of actual contact area of cold welded metal joints  

NASA Technical Reports Server (NTRS)

Method measures the area of the bonded zone of a compression weld by observing the electrical resistance of the weld zone while the load changes from full compression until the joint ruptures under tension. The ratio of bonding force to maximum tensile load varies considerably.

Hordon, M. J.

1970-01-01

113

A mathematical model to predict geometry magnification factor for stress intensity factor of butt welded joints  

SciTech Connect

An approximate mathematical expression of geometry magnification factor (M{sub k}) for stress intensity factor subjected to various butt weld profile geometry parameters was derived by using Linear Elastic Fracture Mechanics (LEFM), Finite Element Analysis (FEA) and Dimensional Analysis Techniques (DAT). It has been found that the effect of plate thickness on stress intensity factor and on fatigue strength of butt welded joints is less significant than that of other weld geometry parameters such as flank angle and weld toe radius. The effect of plate thickness on stress intensity factor is significant only at very small crack length of the order of 0.025 times plate thickness while weld toe radius and flank angle affect stress intensity factor at crack length of the order of 0.05 and 0.15 times plate thickness respectively. The strong effect of plate thickness on fatigue strength of butt welded joints known from literature is revealed as the co-influence effect of plate thickness with other weld geometry parameters such as weld toe radius, flank angle and plate-edge preparation angle. The predicted values of M{sub k} agreed well with that calculated by using Bueckner`s weight function and superposition principle. The calculated values of fatigue strength of butt welded joint using the equations developed for M{sub k} agreed well with the available data from literature.

Nguyen, T.N.; Wahab, M.A. [Univ. of Adelaide, South Australia (Australia). Dept. of Mechanical Engineering

1994-12-31

114

Improvement of the mechanical characteristics and corrosion resistance of welded joints of maraging steels  

Microsoft Academic Search

We show that the specific character of a structural state of welded joints of Kh11N10M2T steel as a sequence of structural\\u000a changes in the course of accelerated heating of maraging steels causes a regular inhomogeneity of their mechanical characteristics\\u000a and low corrosion resistance. We develop a procedure of thermal treatment which guarantees homogeneity of welded joints in\\u000a strength, plasticity, and

S. B. Nizhnik; G. I. Usikova

1999-01-01

115

Electrical properties of cold-pressing welded NbTi persistent joints  

NASA Astrophysics Data System (ADS)

The cold-pressing welding method is employed to fabricate persistent joints between NbTi multifilamentary conductors, and a series of persistent joints are thus made at different mechanical pressures. The electrical properties of these persistent joints are tested by a joint resistance measurement device based on the current decay measurement method. Test results show that the cold-pressing welding method is reliable and applicable to NMR and MRI applications. Experiment results also shows that the joint resistances and current-carrying capacities of the joints seem to have no apparent relevance to the mechanical pressure in a wide range of 4-20 MPa, but the current decay ratio due to flux creep has obvious relevance to the mechanical pressure. Further research is needed to advance this joint manufacturing technology. Besides, measured current increase under 1 T background magnetic field is observed and explained, which has a reference meaning for testing persistent joint resistances.

Liu, Jianhua; Cheng, Junsheng; Zhou, Feng; Wang, Qiuliang; Chang, Kun; Li, Xian

2013-12-01

116

Numerical simulation of the effect of constraints on welding deformations and residual stresses in a pipe flange joint  

NASA Astrophysics Data System (ADS)

This paper presents a detailed three-dimensional finite element (FE) study to investigate the effect of mechanical constraints on welding distortions and residual stresses in a pipe-flange joint. The FE model of a pipe-flange joint is subjected to sequentially couple nonlinear transient thermo-mechanical analysis to simulate complex welding phenomena. Single-pass gas metal arc welding for single 'V' butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI flange class #300 of low carbon steel is simulated. Two tack-welds at 90° and 270° from the weld start position are modelled. Four different constraint conditions representing the welding of unassembled joints, welding of assembled joints, welding of assembled joints with reflective symmetry and welding of perfectly constrained joints are analysed. To model the constraints and boundary conditions more realistically contact pairs are used between the matching surfaces of different structural components. Basic FE models are validated with experimental data for temperature distribution and deformations. Predicted welding distortions and residual stresses are compared and discussed in detail. From the results, axial displacement and tilt of the flange face are found to be strongly dependant on the constraint conditions. Minimum axial distortion on the flange face is found for rigidly clamped flanges. However, residual stresses have a weak dependence on the constraints set.

Abid, Muhammad; Siddique, Muhammad

2005-09-01

117

Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy  

NASA Astrophysics Data System (ADS)

Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 °C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

2014-11-01

118

Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy  

NASA Astrophysics Data System (ADS)

Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 °C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

2015-02-01

119

The joint properties of copper by friction stir welding  

Microsoft Academic Search

The objective of this work was to demonstrate the feasibility of friction stir welding (FSW) for joining of copper. Defect free weld were produced on 4 mm thick copper plate at travel speed of 61 mm\\/min and tool rotation speed of 1250 rpm using a general tool steel as the welding tool. The stir zone showed the very fine and

Won-Bae Lee; Seung-Boo Jung

2004-01-01

120

Study on electron beam weld joints between pure vanadium and SUS316L stainless steel  

NASA Astrophysics Data System (ADS)

The mechanical and metallographical properties of the electron beam weld joints between pure vanadium (V) and SUS316L austenitic stainless steel and the effect of post-welding heat treatment (PWHT) at 873 and 1273 K for 1 h on these properties were investigated. The electron beam was shifted by 0.2 mm (EB02S), 0.4 mm (EB04S), and 0.6 mm (EB06S) on the SUS316L side. No significant defects (e.g., pores, macro-cracks, or micro-cracks) were observed in the as-welded EB02S and EB04S joints, whereas a non-welded region was formed in the as-welded EB06S joint. Much higher hardness was observed in the weld metal (WM) of the as-welded EB02S and EB04S joints than in the base metals (BMs), which might be attributed to solution hardening. A significant increment in the hardness of the WM of EB02S joint occurred due to the PWHT at 873 and 1273 K, which might be attributed to solution hardening and formation of Ni2V3 and NiV3 precipitates. Almost no change in the hardness due to the PWHT at 873 and 1273 K occurred in the WM of the EB04S joint. The interlayer was formed at the edge of the WM of the V side only in the post-welding heat-treated EB04S joint. The interlayer showed much higher hardness than the BMs and WM, which might be attributable to solution hardening, formation of ? phase of the Fe-V system, and formation of Ni2V3 and NiV3 precipitates.

Nogami, Shuhei; Miyazaki, Jumpei; Hasegawa, Akira; Nagasaka, Takuya; Muroga, Takeo

2013-11-01

121

The Effect of Weld Profile and Geometries of Butt Weld Joints on Fatigue Life Under Cyclic Tensile Loading  

NASA Astrophysics Data System (ADS)

The fatigue life of welded joint was calculated based on numerical integration of simple Paris' law and a reliable solution of the stress intensity factor (SIF). The initial crack length ( a i) was assumed to be equal to 0.1 mm in case of weld toe. This length was satisfactory for different butt joints geometries. The comparisons with the available data from standards and literature were demonstrated. It was shown numerically that the machining of weld reinforcements will increase the fatigue life. The increase of plate thickness decreases the fatigue strength (FAT) and the number of cycles to failure when using the proportional scaling of crack length. The validation processes of the current calculations have been shown. Therefore, it can be concluded that it will prevent the unnecessary waste of time consumed to carry out the experiments.

Al-Mukhtar, A. M.; Biermann, H.; Hübner, P.; Henkel, S.

2011-11-01

122

Joint strength in high speed friction stir spot welded DP 980 steel  

SciTech Connect

High speed friction stir spot welding was applied to 1.2 mm thick DP 980 steel sheets under different welding conditions, using PCBN tools. The range of vertical feed rates used during welding was 2.5 mm – 102 mm per minute, while the range of spindle speeds was 2500 – 6000 rpm. Extended testing was carried out for five different sets of welding conditions, until tool failure. These welding conditions resulted in vertical welding loads of 3.6 – 8.2 kN and lap shear tension failure loads of 8.9 – 11.1 kN. PCBN tools were shown, in the best case, to provide lap shear tension fracture loads at or above 9 kN for 900 spot welds, after which tool failure caused a rapid drop in joint strength. Joint strength was shown to be strongly correlated to bond area, which was measured from weld cross sections. Failure modes of the tested joints were a function of bond area and softening that occurred in the heat-affected zone.

Saunders, Nathan; Miles, Michael; Hartman, Trent; Hovanski, Yuri; Hong, Sung Tae; Steel, Russell

2014-05-01

123

Establishing a Mathematical Model to Predict the Tensile Strength of Friction Stir Welded Pure Copper Joints  

NASA Astrophysics Data System (ADS)

This investigation was undertaken to predict the tensile strength of friction stir welded pure copper. Response surface methodology based on a central composite rotatable design with four welding parameters, five levels, and 31 runs was used to conduct the experiments and to develop the mathematical regression model by means of Design-Expert software. Four welding parameters considered were tool profile design, rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted model. Confirmation experiments including microstructural characterization and conducted tensile tests showed that developed models are reasonably accurate. The results showed that the joints welded using the square and triangular tools had higher tensile strength compared to the joints welded using other tools. The increase in tool rotational speed, welding speed, and axial force resulted in increasing the tensile strength of the joints up to a maximum value. Also, the developed model showed that the optimum parameters to get a maximum of tensile strength were rotational speed, welding speed, and axial force of 942 rpm, 84 mm/min, and 1.62 kN, respectively.

Heidarzadeh, A.; Saeid, T.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

2013-02-01

124

Analysing the influences of weld size on fatigue life prediction of FCAW cruciform joints by strain energy concept  

Microsoft Academic Search

The effect of weld size on fatigue life of flux cored arc welded (FCAW) cruciform joints containing lack of penetration (LOP) defect has been analysed by using the strain energy density factor (SEDF) concept. Moreover, new fracture mechanics equations have been developed to predict the fatigue life of the cruciform joints. Load carrying cruciform joints were fabricated from ASTM 517

V Balasubramanian; B Guha

1999-01-01

125

Examination of the low-cycle corrosion fatigue of welded joints in a chrome-nickel-molybdenum steel  

Microsoft Academic Search

Cyclic tests were conducted on specimens produced from welded joints in a chrome-nickelmolybdenum steel welded with austenitic and low-alloy materials. The ratio of the yield stresses of the weld metal aT wm and parent metal aTPm as equal to 0.5-0.6 in welding with the austentic materials, and to 0.75-0.85 in welding with the low-alloy materials. Tests were conducted on specimens

A. V. Il'in; A. V. Kobzaruk; V. P. Leonov

1988-01-01

126

Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution  

NASA Technical Reports Server (NTRS)

The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

Poorman, R. M.; Lovoy, C. V.

1972-01-01

127

Comparison of the Stress Intensity Factor of Load-Carrying Cruciform Welded Joints with Different Geometries  

NASA Astrophysics Data System (ADS)

The investigation of fatigue strength needs an accurate solution and reliable values of the stress intensity factor (SIF). In this study, SIF of load-carrying cruciform welded joints has been evaluated using finite element method (FEM), and compared with the available solutions from literature. Load-carrying cruciform welded joints with isosceles triangles and non-isosceles triangle fillet weld shapes were considered and have been analyzed by the FEM-based simulator FRANC2D program. Moreover, the effects of plate thickness and penetration depth have been considered. The aim of this work was to study the effects of these geometrical variables on fatigue SIF of the load-carrying welded joints with lack of penetration. The ability of FRANC2D to find an appropriate SIF solution is shown and compared with available solutions.

Al-Mukhtar, A.; Biermann, H.; Henkel, S.; Hübner, P.

2010-08-01

128

A Study of Microstructure and Mechanical Properties of Grade 91 Steel A-TIG Weld Joint  

NASA Astrophysics Data System (ADS)

In the present study, A-TIG welding was carried out on grade 91 steel plates of size 220 × 110 × 10 mm using the in-house developed activated flux to produce butt-joints. The room-temperature impact toughness of the A-TIG as-welded joint was low due to the presence of untempered martensite matrix despite the low microinclusion density caused by activated flux and also low ?-ferrite (<0.5 %) content. Toughness after postweld heat treatment (PWHT) at 760 °C-2 h was 20 J as against the required value of 47 J as per the specification EN: 1557:1997. However, there was a significant improvement in impact toughness after PWHT at 760 °C for 3 h. The improvement in toughness was attributed to softening of martensite matrix caused by precipitation of carbides due to tempering reactions. The precipitates are of type M23C6, and they are observed at grain boundary as well as within the grains. The A-TIG-processed grade 91 steel weld joint was found to meet the toughness requirements after PWHT at 760 °C-3 h. Observations of fracture surfaces using SEM revealed that the as-welded joint failed by brittle fracture, whereas post-weld heat-treated weld joints failed by decohesive rupture mode.

Arivazhagan, B.; Vasudevan, M.

2013-12-01

129

Comparison of joint designs for laser welding of cast metal plates and wrought wires.  

PubMed

The purpose of the present study was to compare joint designs for the laser welding of cast metal plates and wrought wire, and to evaluate the welded area internally using X-ray micro-focus computerized tomography (micro-CT). Cast metal plates (Ti, Co-Cr) and wrought wires (Ti, Co-Cr) were welded using similar metals. The specimens were welded using four joint designs in which the wrought wires and the parent metals were welded directly (two designs) or the wrought wires were welded to the groove of the parent metal from one or both sides (n = 5). The porosity and gap in the welded area were evaluated by micro-CT, and the maximum tensile load of the welded specimens was measured with a universal testing machine. An element analysis was conducted using an electron probe X-ray microanalyzer. The statistical analysis of the results was performed using Bonferroni's multiple comparisons (? = 0.05). The results included that all the specimens fractured at the wrought wire when subjected to tensile testing, although there were specimens that exhibited gaps due to the joint design. The wrought wires were affected by laser irradiation and observed to melt together and onto the filler metal. Both Mo and Sn elements found in the wrought wire were detected in the filler metal of the Ti specimens, and Ni was detected in the filler metal of the Co-Cr specimens. The four joint designs simulating the designs used clinically were confirmed to have adequate joint strength provided by laser welding. PMID:22080283

Takayama, Yasuko; Nomoto, Rie; Nakajima, Hiroyuki; Ohkubo, Chikahiro

2013-01-01

130

Effect of weld design on the fatigue strength of laser and resistance spot welded tubular T-joints for automotive applications  

SciTech Connect

The increasing interest in laser beam welding for automotive applications has directed the attention of many researchers to investigating the durability of laser beam welded components. In this study, a comprehensive experimental study, augmented by finite element analysis, was performed to assess the effect of laser weld pattern and location on the durability of box section T-joints. Two laser beam weld configurations were assessed: straight and optimized. Additionally, for comparison purposes, fatigue of resistance spot-welded T-joints was also evaluated. Inplane bending, at an R ratio (R = min/max load) of [minus]1, was employed for all the tests. Test results showed that, on the basis of comparable weld area, laser weld configuration has a strong influence on the fatigue resistance of the T-joints. An optimized laser weld configuration was shown to provide fatigue resistance superior to a resistance spot-welded T-joint. In order to incorporate the advantages of laser beam welding, optimization of weld design should be part of the early stages of vehicle development.

Wang, P.C.; Ewing, K.M. (General Motors Corp. Warren, MI (United States))

1994-09-01

131

Microstructural Characteristics of a Stainless Steel/Copper Dissimilar Joint Made by Laser Welding  

NASA Astrophysics Data System (ADS)

The microstructures and its formation mechanism of a stainless steel/copper dissimilar joint by laser welding were investigated. It was found that the two modes of joining, i.e., welding-brazing and fusion welding, depend on different processing parameters. In the welding-brazing mode, the interface between copper and the fusion zone has scraggy morphology because the molten pool is frozen by solid copper with high thermal conductivity. The interdiffusion of elements occurs in the neighborhood of the interface, which leads to the metallurgy bond of the mode. In the fusion welding mode, the liquid phase in the fusion zone undergoes not only primary but also secondary liquid separation due to the high cooling rate and high supercooling level of laser welding. Some microcracks generated in the fusion zone by thermal stress mismatch are healed by liquid copper filling.

Chen, Shuhai; Huang, Jihua; Xia, Jun; Zhang, Hua; Zhao, Xingke

2013-08-01

132

Numerical evaluation of the monotonic and cyclic behavior of a welded beam-to-column joint  

Microsoft Academic Search

Summary A numerical model of a welded beam-to-column joint subjected to both monotonic and cyclic loading is presented. Experimental results from a test on a similar joint are used for the purpose of validation and calibration of the numerical model. Results are discussed within the framework of the component method.

S. Jordão; L. Simões da Silva; R. Simões

133

Effect of post-weld heat treatment on the mechanical properties of electron beam welded joints for CLAM steel  

NASA Astrophysics Data System (ADS)

In this paper the microstructure and mechanical properties of electron beam weld (EBW) joints for China low activation martensitic (CLAM) steel, which underwent a series of different post weld heat treatments (PWHTs) were studied. The aim of the study was to identify suitable PWHTs that give a good balance between strength and toughness of the EBW joints. The microstructural analyses were performed by means of optical microscope (OM) and scanning electron microscope (SEM). The mechanical properties were determined via tensile tests and Charpy impact tests. The results showed that the tensile strength of the as-weld joint (i.e. without any PWHT) were close to that of the base metal, but the impact toughness was only 13% of that of the base metal due to the existence of a delta-ferrite microstructure. To achieve a significant improvement in toughness a PWHT needs to be performed. If a one-step PWHT is applied tempering at 760 °C for 2 h gives EBW joints with high strength at a still acceptable toughness level. If a two-step PWHT is applied, a process involving quenching at 980 °C for 0.5 h followed by tempering at 740 °C or 760 °C for 2 h gives EBW joints with high strength and toughness properties. Whenever possible a two-step PWHT should be applied in favor of a one-step process, because of higher resulting strength and toughness properties.

Wu, Qingsheng; Zheng, Shuhui; Liu, Shaojun; Li, Chunjing; Huang, Qunying

2013-11-01

134

Effect of friction stir lap welding conditions on joint strength of aluminium alloy 6060  

NASA Astrophysics Data System (ADS)

Strength of lap joints made by friction stir welding (FSW) depends strongly on how material flows forming the weld nugget zone during FSW and also on how the joint is loaded during testing. Understanding of this processing-property relationship is currently inadequate. In this study, the effects of pin length, welding speed and rotation rate on weld strength using aluminium alloy 6060 were investigated. It has been found that the pin length needed to be slightly greater than the thickness of the sheet for an adequate joint to be established. However, further increase in pin length did not benefit the joint strength. The major factor affecting joint strength has been found to be the rotation speed. An increase in rotation speed resulted in lowering the joint strength. Various modes of fracture have been observed and these modes relate to the degree of hooking and softening. Explanation of how the speed values relate to heat input and material flow and then to the joint strength is given.

Yazdanian, S.; Chen, Z. W.

2009-08-01

135

Laser Beam Oscillation Strategies for Fillet Welds in Lap Joints  

NASA Astrophysics Data System (ADS)

Laser beam oscillation opens up new possibilities of influencing the welding process in terms of compensation of tolerances and reduction of process emissions that occur in industrial applications, such as in body-in-white manufacturing. The approaches are to adapt the melt pool width in order to generate sufficient melt volume or to influence melt pool dynamics, e.g. for a better degassing. Welding results are highly dependent on the natural frequency of the melt pool, the used spot diameter and the oscillation speed of the laser beam. The conducted investigations with an oscillated 300 ?m laser spot show that oscillation strategies, which are adjusted to the joining situation improve welding result for zero-gap welding as well as for bridging gaps to approximately 0.8 mm. However, a complex set of parameters has to be considered in order to generate proper welding results. This work puts emphasize on introducing them.

Müller, Alexander; Goecke, Sven-F.; Sievi, Pravin; Albert, Florian; Rethmeier, Michael

136

Effect of Welding Current and Time on the Microstructure, Mechanical Characterizations, and Fracture Studies of Resistance Spot Welding Joints of AISI 316L Austenitic Stainless Steel  

NASA Astrophysics Data System (ADS)

This article aims at investigating the effect of welding parameters, namely, welding current and welding time, on resistance spot welding (RSW) of the AISI 316L austenitic stainless steel sheets. The influence of welding current and welding time on the weld properties including the weld nugget diameter or fusion zone, tensile-shear load-bearing capacity of welded materials, failure modes, energy absorption, and microstructure of welded nuggets was precisely considered. Microstructural studies and mechanical properties showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Electron microscopic studies indicated different types of delta ferrite in welded nuggets including skeletal, acicular, and lathy delta ferrite morphologies as a result of nonequilibrium phases, which can be attributed to a fast cooling rate in the RSW process. These morphologies were explained based on Shaeffler, WRC-1992, and pseudo-binary phase diagrams. The optimum microstructure and mechanical properties were achieved with 8-kA welding current and 4-cycle welding time in which maximum tensile-shear load-bearing capacity or peak load of the welded materials was obtained at 8070 N, and the failure mode took place as button pullout with tearing from the base metal. Finally, fracture surface studies indicated that elongated dimples appeared on the surface as a result of ductile fracture in the sample welded in the optimum welding condition.

Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

2014-09-01

137

Determination of Some Parameters for Fatigue Life in Welded Joints Using Fracture Mechanics Method  

NASA Astrophysics Data System (ADS)

In this work, the parameters stress intensity factor (SIF), initial and final crack lengths ( a i and a f), crack growth parameters ( C and m), and fatigue strength (FAT) are investigated. The determination of initial crack length seems to be the most serious factor in fatigue life and strength calculations for welded joints. A fracture mechanics approach was used in these calculations based on SIF which was calculated with the finite element method (FEM). The weld toe crack was determined to be equal to 0.1 mm, whereas the weld root crack's length was varied depending on the degree of the weld penetration. These initial crack length values are applicable for all types of joints which have the same crack phenomenon. As based on the above calculated parameters, the new limits of FAT for new geometries which are not listed yet in recommendations can be calculated according to the current approach.

Al-Mukhtar, A. M.; Biermann, H.; Hübner, P.; Henkel, S.

2010-12-01

138

Microstructural Characterization of Internal Welding Defects and Their Effect on the Tensile Behavior of FSW Joints of AA2198 Al-Cu-Li Alloy  

NASA Astrophysics Data System (ADS)

Internal features and defects such as joint line remnant, kissing bond, and those induced by an initial gap between the two parent sheets were investigated in AA2198-T851 friction stir welded joints. They were compared with the parent material and to defect-free welds obtained using a seamless sheet. The cross-weld tensile strength was reduced by the defects by less than 6 pct. The fracture elongation was not significantly affected in view of experimental scatter. Fracture location, however, changed from the thermomechanically affected zone (retreating side) to the defect in the weld nugget for the welds bearing a kissing bond and for some of the gap welds. The kissing bond was shown by EBSD to be an intergranular feature; it fractured under a normal engineering stress close to 260 MPa during an in situ SEM tensile test. Synchrotron tomography after interrupted tensile testing confirmed opening of the kissing bond. For an initial gap of 23 pct of the sheet thickness, intergranular fracture of copper-enriched or oxide-bearing grain boundaries close to the nugget root was evidenced. The stress and strain state of cross-weld specimens loaded under uniaxial tension was assessed using a 3D finite element, multi-material model, determined on the basis of experimental data obtained on the same specimens using digital image correlation.

Le Jolu, Thomas; Morgeneyer, Thilo F.; Denquin, Anne; Sennour, Mohamed; Laurent, Anne; Besson, Jacques; Gourgues-Lorenzon, Anne-Françoise

2014-11-01

139

Microstructural Characterization of Internal Welding Defects and Their Effect on the Tensile Behavior of FSW Joints of AA2198 Al-Cu-Li Alloy  

NASA Astrophysics Data System (ADS)

Internal features and defects such as joint line remnant, kissing bond, and those induced by an initial gap between the two parent sheets were investigated in AA2198-T851 friction stir welded joints. They were compared with the parent material and to defect-free welds obtained using a seamless sheet. The cross-weld tensile strength was reduced by the defects by less than 6 pct. The fracture elongation was not significantly affected in view of experimental scatter. Fracture location, however, changed from the thermomechanically affected zone (retreating side) to the defect in the weld nugget for the welds bearing a kissing bond and for some of the gap welds. The kissing bond was shown by EBSD to be an intergranular feature; it fractured under a normal engineering stress close to 260 MPa during an in situ SEM tensile test. Synchrotron tomography after interrupted tensile testing confirmed opening of the kissing bond. For an initial gap of 23 pct of the sheet thickness, intergranular fracture of copper-enriched or oxide-bearing grain boundaries close to the nugget root was evidenced. The stress and strain state of cross-weld specimens loaded under uniaxial tension was assessed using a 3D finite element, multi-material model, determined on the basis of experimental data obtained on the same specimens using digital image correlation.

Le Jolu, Thomas; Morgeneyer, Thilo F.; Denquin, Anne; Sennour, Mohamed; Laurent, Anne; Besson, Jacques; Gourgues-Lorenzon, Anne-Françoise

2014-09-01

140

Eutectic structures in friction spot welding joint of aluminum alloy to copper  

NASA Astrophysics Data System (ADS)

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; dos Santos, Jorge F.

2014-05-01

141

Sensitization resistance of friction stir welded AISI 409 M grade ferritic stainless steel joints  

Microsoft Academic Search

Friction stir welded low chromium AISI 409 M ferritic stainless steel was investigated for susceptibility to intergranular\\u000a corrosion by oxalic and double-loop electrochemical potentiodynamic reactivation tests, and the degree of sensitization were\\u000a evaluated by the ratio of the reactivating and activating currents. Stir zone of friction stir welded joint exhibited smaller\\u000a degree of sensitization compared to the base metal and it

A. K. Lakshminarayanan; V. Balasubramanian

142

Eutectic structures in friction spot welding joint of aluminum alloy to copper  

SciTech Connect

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Solid-State Joining Processes, Max-Planck-Str. 1, 21502 Geesthacht (Germany)

2014-05-12

143

Characterization of lap joints laser beam welding of thin AA 2024 sheets with Yb:YAG disk-laser  

NASA Astrophysics Data System (ADS)

Lap joints obtained by overlapping two plates are widely diffused in aerospace industry. Nevertheless, because of natural aging, adhesively bonded and riveted aircraft lap joints may be affected by cracks from rivets, voids or corrosion. Friction stir welding has been proposed as a valid alternative, although large heat affected zones are produced both in the top and the bottom plate due to the pin diameter. Interest has therefore been shown in studying laser lap welding as the laser beam has been proved to be competitive since it allows to concentrate the thermal input and increases productivity and quality. Some challenges arise as a consequence of aluminum low absorptance and high thermal conductivity; furthermore, issues are due to metallurgical challenges such as both micro and macro porosity formation and softening in the fused zone. Welding of AA 2024 thin sheets in a lap joint configuration is discussed in this paper: tests are carried out using a recently developed Trumpf TruDisk 2002 Yb:YAG disk-laser with high beam quality which allows to produce beads with low plates distortion and better penetration. The influence of the processing parameters is discussed considering the fused zone extent and the bead shape. The porosity content as well as the morphological features of the beads have been examined.

Caiazzo, Fabrizia; Alfieri, Vittorio; Cardaropoli, Francesco; Sergi, Vincenzo

2012-06-01

144

Creep Strength of Dissimilar Welded Joints Using High B-9Cr Steel for Advanced USC Boiler  

NASA Astrophysics Data System (ADS)

The commercialization of a 973 K (700 °C) class pulverized coal power system, advanced ultra-supercritical (A-USC) pressure power generation, is the target of an ongoing research project initiated in Japan in 2008. In the A-USC boiler, Ni or Ni-Fe base alloys are used for high-temperature parts at 923 K to 973 K (650 °C to 700 °C), and advanced high-Cr ferritic steels are planned to be used at temperatures lower than 923 K (650 °C). In the dissimilar welds between Ni base alloys and high-Cr ferritic steels, Type IV failure in the heat-affected zone (HAZ) is a concern. Thus, the high B-9Cr steel developed at the National Institute for Materials Science, which has improved creep strength in weldments, is a candidate material for the Japanese A-USC boiler. In the present study, creep tests were conducted on the dissimilar welded joints between Ni base alloys and high B-9Cr steels. Microstructures and creep damage in the dissimilar welded joints were investigated. In the HAZ of the high B-9Cr steels, fine-grained microstructures were not formed and the grain size of the base metal was retained. Consequently, the creep rupture life of the dissimilar welded joints using high B-9Cr steel was 5 to 10 times longer than that of the conventional 9Cr steel welded joints at 923 K (650 °C).

Tabuchi, Masaaki; Hongo, Hiromichi; Abe, Fujio

2014-10-01

145

Effect of Postweld Aging Treatment on Fatigue Behavior of Pulsed Current Welded AA7075 Aluminum Alloy Joints  

NASA Astrophysics Data System (ADS)

This article reports the effect of postweld aging treatment on fatigue behavior of pulsed current welded AA 7075 aluminum alloy joints. AA7075 aluminum alloy (Al-Zn-Mg-Cu alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers, and railway transport systems. The preferred welding processes of AA7075 aluminum alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 10 mm thickness have been used as the base material for preparing multipass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt.%)) grade aluminum alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW), and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Rotary bending fatigue testing machine has been used to evaluate fatigue behavior of the welded joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. Grain refinement is accompanied by an increase in fatigue life and endurance limit. Simple postweld aging treatment applied to the joints is found to be beneficial to enhance the fatigue performance of the welded joints.

Balasubramanian, V.; Ravisankar, V.; Madhusudhan Reddy, G.

2008-04-01

146

The role of residual stress and heat affected zone properties on fatigue crack propagation in friction stir welded 2024-T351 aluminium joints  

Microsoft Academic Search

The effects of weld residual stress and heat affected zone on the fatigue propagation of cracks parallel and orthogonal to the weld direction in friction stir welded (FSW) 2024-T351 joints were investigated. Crack propagation behaviour was sensitive to both weld orientation and the distance of the crack from the weld line. Growth rates both faster and slower than in the

G Bussu; P. E Irving

2003-01-01

147

Microstructures and Mechanical Properties of Electron Beam-Welded Titanium-Steel Joints with Vanadium, Nickel, Copper and Silver Filler Metals  

NASA Astrophysics Data System (ADS)

Electron beam welding experiments of titanium alloy to stainless steel with V, Ni, Cu and Ag filler metals were carried out. The interfacial microstructures of the joints were examined by optical microscopy, scanning electron microscopy, and x-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics formed in the Ti/Fe joint. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. And the type of solid solution and interfacial intermetallics were depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti + Ni3Ti + NiTi2, TiFe, Ti2Ag, and Cu2Ti + CuTi + CuTi2 in the joints welded with Ni, V, Ag, and Cu filler metals, respectively. The tensile strengths of the joints were primarily determined by the hardness of the interfacial intermetallics. The highest tensile strength was obtained in the joint welded with silver filler metal, which is about 310 MPa.

Wang, Ting; Zhang, Binggang; Wang, Houqin; Feng, Jicai

2014-04-01

148

Tensile properties and fracture locations of friction-stir-welded joints of 2017-T351 aluminum alloy  

Microsoft Academic Search

Friction stir welding (FSW) is a new and promising welding process that can produce low-cost and high-quality joints of heat-treatable aluminum alloys because it does not need consumable filler materials and can eliminate some welding defects such as crack and porosity. In order to demonstrate the friction stir weldability of the 2017-T351 aluminum alloy and determine optimum welding parameters, the

H. J Liu; H Fujii; M Maeda; K Nogi

2003-01-01

149

Effect of Welding Parameters on Microstructure, Thermal, and Mechanical Properties of Friction-Stir Welded Joints of AA7075-T6 Aluminum Alloy  

NASA Astrophysics Data System (ADS)

A high-strength Al-Zn-Mg-Cu alloy AA7075-T6 was friction-stir welded with various process parameter combinations incorporating the design of the experiment to investigate the effect of welding parameters on the microstructure and mechanical properties. A three-factors, five-level central composition design (CCD) has been used to minimize the number of experimental conditions. The friction-stir welding parameters have significant influence on the heat input and temperature profile, which in turn regulates the microstructural and mechanical properties of the joints. The weld thermal cycles and transverse distribution of microhardness of the weld joints were measured, and the tensile properties were tested. The fracture surfaces of tensile specimens were observed by a scanning electron microscope (SEM), and the formation of friction-stir processing zone has been analyzed macroscopically. Also, an equation was derived to predict the final microhardness and tensile properties of the joints, and statistical tools are used to develop the relationships. The results show that the peak temperature during welding of all the joints was up to 713 K (440 °C), which indicates the key role of the tool shoulder diameter in deciding the maximum temperature. From this investigation, it was found that the joint fabricated at a rotational speed of 1050 rpm, welding speed of 100 mm/min, and shoulder diameter of 14 mm exhibited higher mechanical properties compared to the other fabricated joints.

Lotfi, Amir Hossein; Nourouzi, Salman

2014-06-01

150

Microstructures forming in friction welding of Inconel 718 alloy – joint performance and its controlling factors in friction welding of Inconel 718 alloy  

Microsoft Academic Search

Microstructures forming in the friction welding of Inconel 718 alloy have been investigated in order to understand the phenomena occurring during the welding process and to determine the factor controlling the joint performance from a metallographic point of view. In the interfacial zone, liquation microstructures characterized by a eutectic structure consisting of ? and Laves phases, and Nb-rich microstructures along

Hongjie Wang; Kenji Ikeuchi; Masatoshi Aritoshi; Makoto Takahashi; Akio Ikeda

2009-01-01

151

Modeling and analyzing the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas welding  

Microsoft Academic Search

The objective of this paper is to present the mathematical models for modeling and analysis of the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas (TIG) welding. The process of heat treatment adopts the tempering process with varying processing parameters, including tempering temperature and tempering time. The microstructure and mechanical properties

Te-Chang Tsai; Chih-Chung Chou; Deng-Maw Tsai; Ko-Ta Chiang

2011-01-01

152

Structure and microhardness of cu-ta joints produced by explosive welding.  

PubMed

The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20?40? ? m thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5?500 nm, with a predominance of 5?50 nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280 HV, which far exceeds the microhardness of copper (~130 HV) and tantalum (~160 HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150 HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper. PMID:24453818

Maliutina, Iu N; Mali, V I; Bataev, I A; Bataev, A A; Esikov, M A; Smirnov, A I; Skorokhod, K A

2013-01-01

153

Structure and Microhardness of Cu-Ta Joints Produced by Explosive Welding  

PubMed Central

The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20?40??m thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5?500?nm, with a predominance of 5?50?nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280?HV, which far exceeds the microhardness of copper (~130?HV) and tantalum (~160?HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150?HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper. PMID:24453818

Maliutina, Iu. N.; Mali, V. I.; Bataev, I. A.; Bataev, A. A.; Esikov, M. A.; Smirnov, A. I.; Skorokhod, K. A.

2013-01-01

154

Effects of welding pulse energy and fluoride ion on the cracking susceptibility and fatigue behavior of Nd:YAG laser-welded cast titanium joints.  

PubMed

In this study, the cracking susceptibility and fatigue behavior of Nd:YAG laser-welded cast Ti joints (welding pulse energy: 11, 15, and 18 J) in fluoride-containing (0 and 0.5% NaF) artificial saliva were evaluated using constant elongation rate test (CERT) and fatigue test (FT), respectively. Both CERT and FT were also carried out in open air as controls. Results showed that increasing the welding energy increased the elongation and fatigue life, but decreased the tensile strength, of cast Ti joints in open-air environment. With a welding energy of 11 J, the fluoride ions in the artificial saliva increased the cracking susceptibility and decreased the fatigue life of Ti joints. When the welding energy exceeded 15 J, the presence of fluoride ions still increased the cracking susceptibility, but did not reduce the fatigue life of Ti joints. Rupture of Ti joints--if it occurred--occurred only at the welded metal (versus the non-welded part). PMID:17076339

Huang, Her-Hsiung; Lin, Mau-Chin; Lin, Chien-Chan; Lin, Sheng-Chieh; Hsu, Chii-Chih; Chen, Fang-Lung; Lee, Shyh-Yuan; Hung, Chun-Cheng

2006-09-01

155

Local, Semilocal and Nominal Approaches to Estimate the Fatigue Strength of Welded Joints  

NASA Astrophysics Data System (ADS)

This paper is concerned with the analysis and the comparison of several so-called “local approaches” to estimate the fatigue strength of welded joints. The considered approaches are based on numerical analyses or strain gauges evaluations of the stress or strain state in the vicinity of the weld toe. The notch stress intensity factor (NSIF) approach applied to fillet-welded joints, as far as the opening angle between the weld and the main plate surface is constant (e.g. 135°, typical for many fillet welds), is able to rationalise the fatigue strength data both for different joint geometries and absolute dimensions. The NSIF approach has been previously developed as an extension of the Linear Elastic Fracture Mechanics (LEFM) to open V notches and is based on the exponential local stress field around the V-notch tip. Several proposed “local approaches”, although simpler to use than the NSIF approach, are based on the stress (or strain) field beyond the exponential local one. To distinguish such approaches from the NSIF-based one, we define the former ones as semilocal approaches while the latter is a local approach. The paper underlines that the ability to unify fatigue strength data in a single scatter band is not the same for the semilocal approaches if compared to the local approach.

Atzori, Bruno; Lazzarin, Paolo; Meneghetti, Giovanni

156

Joints, fissures, and voids in rhyolite welded ash-flow tuff at Teton damsite, Idaho  

USGS Publications Warehouse

Several kinds of joints, fissures, and voids are present in densely welded rhyolite ash-flow tuff at Teton damsite. Older fissures and voids probably were formed in the ash-flow sheet during secondary flowage, which probably was caused by differential compaction or settling over irregular topography. The younger, more abundant fissures are mostly steep cooling joints that probably have been opened farther by horizontal tectonic extension and gravitational creep, perhaps aided by lateral stress relief.

Prostka, Harold J.

1977-01-01

157

Structure and ductility of the heat-affected zone of welded joints of a high-strength steel  

NASA Astrophysics Data System (ADS)

Methods of optical microscopy and scanning and transmission electron microscopy have been used to study the structure of welded joints of a high-strength structural steel with different types of the weld metal. The impact toughness of the heat-affected zone (HAZ) has been determined at temperatures of +20 and -40°C. Based on the fractograph investigations of the character of the fracture of the welded joints after tests for impact bending, the regions that are the most dangerous for crack initiation have been determined. Structural factors that affect the brittleness of the near-weld zone of welded joints with the austenite metal of the weld are indicated, including the existence of an austenite-bainite structure and coarse carbides, as well as the specific distribution of hydrogen.

Tabatchikova, T. I.; Nosov, A. D.; Goncharov, S. N.; Gudnev, N. Z.; Delgado Reina, S. Yu.; Yakovleva, I. L.

2014-12-01

158

An investigation of residual stress in welded joints  

E-print Network

was made of the same steel as the plates so that temperature changes would affect both equally. Plates, marks, and gage are shown in Fig. 2. These strain measurements were made before and after welding. Follow1ng this, the extent of the area in which... that the temperature at the gage (0, ) will not be increased enough to harm the gage. If the width of the specimen is increased appreciably, two strai~ gages could be used, side by side. The stra1n may be read shortly after the weld is completed, at short 1ntervals...

Moffat, William Hugh

1951-01-01

159

Structural Performance Evaluation of Composite-To-Steel Weld Bonded Joint  

SciTech Connect

The Automotive Composites Consortium (ACC), a collaboration of Chrysler, Ford, General Motors, and the US Department of Energy is conducting a focal project to demonstrate the use of composite materials in high volume structural applications such as an underbody capable of carrying crash loads. One of the critical challenges is to attach the composite part to the steel structure in a high-volume automotive manufacturing environment and meet the complex requirements for crash. Weld-bonding, a combination of adhesive bonding and spot welding, was selected as the primary joining method. A novel concept of bonding doubler steel strips to composite enabled the spot welding to the steel structure, ensuring the compability with the OEM assembly processes. The structural performance of the joint, including durability, was assessed via analytical and physical testing under quasi-static loading at various temperatures. This paper discusses the results of the experiments designed to generate key modeling parameters for Finite Element Analysis of the joint.

Shah, Bhavesh [General Motors Corporation-R& D; Frame, Barbara J [ORNL; Dove, Caroline [ACC, USCAR; Fuchs, Hannes [Multimatic Engineering

2010-01-01

160

Parallel-gap welding for joints between copper conductors and Kovar  

NASA Technical Reports Server (NTRS)

Welding technique produces more reliable joints than soldering. Investigation used different sizes of copper conductors and component lead ribbons, corrosion protection platings, and melting points of metals being joined. Optimum combination is gold-plated component lead ribbons and solder-plated copper conductors.

Mc Daniel, G. E.

1971-01-01

161

Reactor cooling water expansion joint bellows: The role of the seam weld in fatigue crack development  

Microsoft Academic Search

The secondary cooling water system pressure boundary of Savannah River Site reactors includes expansion joints utilizing a thin-wall bellows. While successfully used for over thirty years, an occasional replacement has been required because of the development of small, circumferential fatigue cracks in a bellows convolute. One such crack was recently shown to have initiated from a weld heat-affected zone liquation

S. L. West; D. Z. Nelson; M. R. Jr. Louthan

1992-01-01

162

A structural stress definition and numerical implementation for fatigue analysis of welded joints  

Microsoft Academic Search

A mesh-size insensitive structural stress definition is presented in this paper. The structural stress definition is consistent with elementary structural mechanics theory and provides an effective measure of a stress state that pertains to fatigue behavior of welded joints in the form of both membrane and bending components. Numerical procedures for both solid models and shell or plate element models

P. Dong

2001-01-01

163

Fatigue Life Improvement for Cruciform Welded Joint by Mechanical Surface Treatment using Hammer Peening and UNSM  

NASA Astrophysics Data System (ADS)

For the improvement of fatigue strength of welded structures, mechanical post treatments have been applied in various industrial fields and have in most cases been founded to give substantial increases in their fatigue lives. These methods, generally, consist of the modification of weld toe geometry and the introduction of compressive residual stresses. In mechanical surface treatments, e.g. PHP (pneumatic hammer peening) and UNSM (ultrasonic nano-crystal surface modification), the weld profile is modified due to remove or reduce minute crack-like flaws, and compressive residual stresses are also induced. In this study, a pneumatic hammer peening procedure and a UNSM device were introduced, and a quantitative measure of fatigue strength improvement was performed. The fatigue strength at 2 × 106 cycles of hammer-peened and UNSM treated on a non-load carrying cruciform welded joint shows 220 and 260MPa, respectively, which are more than two times higher than that of as-welded specimen. Especially, the surface layer in the vicinity weld toe treated by the UNSM provides nano-crystal structure created by an ultrasonic cold forging and introduces very high welding residual stress in compression.

Han, Seung-Ho; Han, Jeong-Woo; Nam, Yong-Yun; Cho, In-Ho

164

Upsetting Butt Edge Increases Weld-Joint Strength  

NASA Technical Reports Server (NTRS)

Mechanical upsetting /a mode of cold forging/ of butt edges to be welded is accomplished by the use of hydraulic rams and pressure rollers. The mechanical upsetting increases the thickness of the material in the heat-affected zone and compensates for the lower specific strength per unit thickness common to this area.

Vesco, D.

1964-01-01

165

Low Cycle and Thermo-Mechanical Fatigue of Friction Welded Dissimilar Superalloys Joint  

NASA Astrophysics Data System (ADS)

The high temperature strengths of the dissimilar friction welded superalloys joint between the cast polycrystalline Mar-M247 and the forged IN718 alloys have been investigated under low cycle and thermo-mechanical fatigue loadings, in comparison with those of the base metals. The experiments showed that the lives of the dissimilar joints were significantly influenced by the test conditions and loading modes. Not only the lives themselves but also the failure positions and mechanisms were sensitive to the loading mode. The fracture behaviors depending on the loading modes and test conditions were discussed, based on the macroscopic elastic follow-up mechanism and the microstructural inhomogeneity in the friction weld joint.

Sakaguchi, Motoki; Sano, Atsushi; Tran, Tra Hung; Okazaki, Masakazu; Sekihara, Masaru

166

Experimental and numerical evaluation of the fatigue behaviour in a welded joint  

NASA Astrophysics Data System (ADS)

Welded joints are an important part in structures. For this reason, it is always necessary to know the behaviour of them under cyclic loads. In this paper a S - N curve of a butt welded joint of the AISI 1015 steel and Cuban manufacturing E6013 electrode is showed. Fatigue tests were made in an universal testing machine MTS810. The stress ratio used in the test was 0,1. Flaws in the fatigue specimens were characterized by means of optical and scanning electron microscopy. SolidWorks 2013 software was used to modeling the specimens geometry, while to simulate the fatigue behaviour Simulation was used. The joint fatigue limit is 178 MPa, and a cut point at 2 039 093 cycles. Some points of the simulations are inside of the 95% confidence band.

Almaguer, P.; Estrada, R.

2014-07-01

167

Acoustic emissions during deformation of intact and jointed welded tuff  

NASA Astrophysics Data System (ADS)

Monitoring of acoustic emissions (AE) has been widely used as a means of detecting failure in intact rock. For intact rock the technique is simple, because an increasing rate of AE is usually a sign of impending failure. However, most large rock masses contain numerous joints and the behavior of the joints controls the properties of the rock mass In particular, the failure mode often becomes stable or unstable slip (stick-slip) on a joint at stresses well below those required for failure of the intact rock. As an aid to understanding and monitoring the behavior of jointed rock masses, we have done a series of experiments on intact and artificially jointed samples of Grouse Canyon tuff. The tuff was selected because it is under consideration as a disposal medium for nuclear wastes. The samples were instrumented to measure axial and transverse displacements and AE rates.

Holcomb, D. J.; Teufel, L. W.

1982-07-01

168

Estimate of the allowable dimensions of diagnosed defects in category III and IV welded pipeline joints{sup 1}  

SciTech Connect

An approach for estimating the permissible dimensions of technological defects in butt welded joints in category III and IV pipelines is described. The allowable size of a welding defect is determined from the condition of compliance with the specifications on strength for a reference cross section (damaged joint) of the pipeline taking into account its weakening by a given defect.With regard to the fairly widespread discovery of technological defects in butt welded joints during diagnostics of auxiliary pipelines for thermal electric power plants, the proposed approach can be used in practice by repair and consulting organizations.

Grin', E. A.; Bochkarev, V. I. [JSC 'All-Russia Thermal Engineering Institute' (JSC 'VTI') (Russian Federation)] [JSC 'All-Russia Thermal Engineering Institute' (JSC 'VTI') (Russian Federation)

2013-01-15

169

Integrity assessment of the ferritic / austenitic dissimilar weld joint between intermediate heat exchanger and steam generator in fast reactor  

SciTech Connect

Integrity of the modified 9Cr-1Mo / alloy 800 dissimilar joint welded with Inconel 182 electrodes has been assessed under creep condition based on the detailed analysis of microstructure and stress distribution across the joint by finite element analysis. A hardness peak at the ferritic / austenitic weld interface and a hardness trough at the inter-critical heat affected zone (HAZ) in ferritic base metal developed. Un-tempered martensite was found at the ferritic / austenitic weld interface to impart high hardness in it; whereas annealing of martensitic structure of modified 9Cr-1Mo steel by inter-critical heating during welding thermal cycle resulted in hardness tough in the inter-critical HAZ. Creep tests were carried out on the joint and ferritic steel base metal at 823 K over a stress range of 160-320 MPa. The joint possessed lower creep rupture strength than its ferritic steel base metal. Failure of the joint at relatively lower stresses occurred at the ferritic / austenitic weld interface; whereas it occurred at inter-critical region of HAZ at moderate stresses. Cavity nucleation associated with the weld interface particles led to premature failure of the joint. Finite element analysis of stress distribution across the weld joint considering the micro-mechanical strength inhomogeneity across it revealed higher von-Mises and principal stresses at the weld interface. These stresses induced preferential creep cavitation at the weld interface. Role of precipitate in enhancing creep cavitation at the weld interface has been elucidated based on the FE analysis of stress distribution across it. (authors)

Jayakumar, T.; Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, S.; Kumar, J. G.; Mathew, M. D. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam- 603 102 (India)

2012-07-01

170

Development of phased array ultrasonic testing in lieu of radiography for testing complete joint penetration (CJP) welds  

NASA Astrophysics Data System (ADS)

The past decade has seen new, emerging innovation of Ultrasonic Testing (UT). Specifically, multiple manufacturers have produced Phased Array Ultrasonic Testing (PAUT) systems. The PAUT systems embed a matrix of multiple (some up to 128) single transducers into one probe used for scanning elastic materials. Simultaneously exciting multiple transducers offers distinct advantages; depending on the sequencing of transducer excitation, the ultrasonic beam could be steered within the material and multiple beams help develop extra dimensional data to assist with visualization of possible flaws including the discontinuity size, shape and location. Unfortunately, there has not been broad acceptance of PAUT in the bridge fabrication industry because it is currently not a recognized inspection technology in AWS D1.5. One situation in which the technology would excel would be inspection of Complete Joint Penetration (CJP) butt welds. Currently, AWS D1.5 required CJP welds subjected to tensile or reversal stresses only be inspected by Radiographic Testing (RT). However, discontinuities normally seen by RT can also be seen with PAUT. Until specification language is adopted into D1.5, there will continue to be hesitancy to use PAUT for the inspection of CJP butt welds. Developmental work must first be performed to develop the acceptance criteria and the specification language. The developmental work from the inspections carried out on butt-weld specimens and transition butt-weld specimens are presented in this paper. Specific scan plans were developed using the ES-Beam simulation software for each of the test specimens. In depth analysis of PAUT data obtained to determine exact location and sizing information of the defects was performed. The results also present the comparison of results from PAUT to those obtained using conventional UT and radiography.

Haldipur, P.; Boone, Shane D.

2014-04-01

171

Study on fatigue crack propagation characteristics around welded joint interface in complexed conditions  

NASA Astrophysics Data System (ADS)

Marine structures are often constructed by welding, and they are subject to repeated loading such as waves and mechanical vibrations which can create fatigue cracks and consequently break the structures. Fatigue crack propagation properties of welded joints are studied under random loading in the air, synthetic sea water, and compressive cycling. It was found that the most crucial factor that controls fatigue crack propagation was high tensile residual stress fields of welded joints. This stress constantly kept the cracks open, simplifying fatigue crack propagation, and therefore, the rate of crack propagation could be assessed with high accuracy. In the transverse matching welded joints with cracks in the center, crack closure did not occur due to the tensile residual stress constantly induced at the crack ends in the center of the test samples. Fatigue crack propagation was accelerated both in artificial sea water and in compressive cycling compared to that in the air, and the fatigue lowest values were about half. Serious crack closures occurred in compressive cycling in which dry hours exceeded 45 minutes, and the fatigue crack propagation rate deteriorated remarkably. Mean fatigue crack propagation rate under the random loading is estimated precisely using equivalent stress intensity factor limit.

Ota, Akihiko; Suzuki, Naoyuki; Maeda, Yoshio; Mawari, Toshio; Matsuoka, Saburo; Nishijima, Satoshi

1993-01-01

172

Synchrotron X-ray CT characterization of friction-welded joints in tial turbocharger components  

NASA Astrophysics Data System (ADS)

Titanium aluminide (TiAl) is an advanced intermetallic material and is being investigated for application in turbocharger components for diesel engines. A TiAl turbocharger rotor consists of a cast TiAl turbine wheel and a Ti-alloy shaft that are joined by friction welding. Although friction welding is an established industrial process, it is still challenging to join dissimilar materials especially for brittle intermetallics. These joints are therefore required to be inspected using a nondestructive evaluation (NDE) method. In this study, synchrotron X-ray computed tomography (CT) developed at the Advanced Photon Source at Argonne National Laboratory was used for NDE characterization of friction-welded joint in three TiAl turbocharger rotors. The filtered synchrotron X-ray source has high peak energies to penetrate thick metallic materials, and the detector (imager) has high spatial resolutions to resolve small flaws. The CT inspections revealed detailed 3D crack distributions within poorly welded joints. The crack detection sensitivity and resolution was calibrated and found to be correlated well with destructive examination.

Sun, J. G.; Kropf, A. J.; Vissers, D. R.; Sun, W. M.; Katsoudas, J.; Yang, N.; Fei, D.

2012-05-01

173

Laser-assisted friction stir welding of aluminum alloy lap joints: microstructural and microhardness characterizations  

NASA Astrophysics Data System (ADS)

Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. The laser Assisted Friction Stir Welding (LAFSW) combines a Friction Stir Welding machine and a laser system. Laser power is used to preheat and to plasticize the volume of the workpiece ahead of the rotating tool; the workpiece is then joined in the same way as in the conventional FSW process. In this work an Ytterbium fiber laser with maximum power of 4 kW and a commercial FSW machine were coupled. Both FSW and LAFSW tests were conducted on 3 mm thick 5754H111 aluminum alloy plates in lap joint configuration with a constant tool rotation rate and with different feed rates. The two processes were compared and evaluated in terms of differences in the microstructure and in the micro-hardness profile.

Casalino, Giuseppe; Campanelli, Sabina L.; Contuzzi, Nicola; Angelastro, Andrea; Ludovico, Antonio D.

2014-02-01

174

Effects of weld profile and undercut on fatigue crack propagation life of thin-walled cruciform joint  

Microsoft Academic Search

Fatigue may occur in undercarriages and support systems of trailers, haymakers, graders and swing-ploughs made up of thin-walled tubular sections with wall thicknesses less than 4 mm. Little research has been done on the fatigue of thin-walled tubular sections below 4 mm thickness. The weld profile and weld undercut may affect the fatigue crack propagation life of welded joints especially

F. R. Mashiri; X. L. Zhao; P. Grundy

2001-01-01

175

Welding.  

ERIC Educational Resources Information Center

This curriculum guide is designed for use by South Carolina vocational education teachers as a continuing set of lesson plans for a two-year course on welding. Covered in the individual sections of the guide are the following topics: an orientation to welding, oxyacetylene welding, advanced oxyacetylene welding, shielded metal arc welding, TIG…

South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

176

Effects of the Heterogeneity in the Electron Beam Welded Joint on Mechanical Properties of Ti6Al4V Alloy  

NASA Astrophysics Data System (ADS)

The aim of this investigation was to evaluate the effect of microstructure heterogeneity on the tensile and low cycle fatigue properties of electron beam welded (EBW) Ti6Al4V sheets. To achieve this goal, the tensile and low cycle fatigue property in the EBW joints and base metal (BM) specimens is compared. During the tensile testing, digital image correlation technology was used to measure the plastic strain field evolution within the specimens. The experimental results showed that the tensile ductility and low cycle fatigue strength of EBW joints are lower than that of BM specimens, mainly because of the effect of microstructure heterogeneity of the welded joint. Moreover, the EBW joints exhibit the cyclic hardening behavior during low fatigue process, while BM specimens exhibit the cyclic softening behavior. Compared with the BM specimens with uniform microstructure, the heterogeneity of microstructure in the EBW joint is found to decrease the mechanical properties of welded joint.

Liu, Jing; Gao, Xiao-Long; Zhang, Lin-Jie; Zhang, Jian-Xun

2015-01-01

177

Acoustic emissions during deformation of intact and jointed welded tuff  

SciTech Connect

Monitoring of acoustic emissions (AE) has been widely used as a means of detecting failure in intact rock. For intact rock the technique is simple, because an increasing rate of AE is usually a sign of impending failure. However, most large rock masses contain numerous joints and the behavior of the joints controls the properties of the rock mass. In particular, the failure mode often becomes stable or unstable slip (stick-slip) on a joint at stresses well below those required for failure of the intact rock. As an aid to understanding and monitoring the behavior of jointed rock masses, we have done a series of experiments on intact and artificially jointed samples of Grouse Canyon tuff. The tuff was selected because it is under consideration as a disposal medium for nuclear wastes. The samples were instrumented to measure axial and transverse displacements and AE rates. Testing was done in a servo-controlled machine at axial displacement rates of 5 x 10{sup -5} cm/sec, and confining pressures ranging from 10 to 40 MPa. For the jointed samples four modes of slip were identified. First, stable sliding accompanied by a steady rate of AE. Second, stick-slip with a sharp drop in load, large displacements but no premonitory AE or slip. Third, stick-slip, as in mode 2, but with premonitory AE and slip. Fourth, slow stick-slip where the load dropped and the displacements increased but the process was slow and culminated in stable sliding. Mode 4 exhibited premonitory AE and slip and after the event, a steady rate of AE during sliding. There seemed to be no way to predict which mode would occur at a given point in the test. In all cases where stable or unstable slip occurred there was a corresponding occurrence of AE. This indicates that slip is related to damage to the joint surfaces and adjacent material. Monitoring AE would be a useful method of detecting slip.

Holcomb, D.J.; Teufel, L.W.

1982-07-01

178

Combination Effects of Nocolok Flux with Ni Powder on Properties and Microstructures of Aluminum-Stainless Steel TIG Welding-Brazing Joint  

NASA Astrophysics Data System (ADS)

A flux consisting of Nocolok and nickel powder was first applied for TIG welding-brazing of aluminum-stainless steel. Results of tensile and impact tests illustrated that a significant improvement in mechanical properties of the butt joint was obtained with the flux, tensile strength increased from 116 to 158 MPa, and impact energy increased from 3.2 to 6.7 J. Investigation results on microstructures of interfaces and seams suggested that Ni addition significantly decreased the thickness of intermetallic compound (IMC) layer on the interfaces, but did not change the phase structure of Al13Fe4. Furthermore, precipitate phase in the welded seams changed from Al6Fe to Al9FeNi, and the quantity of precipitate phases decreased from 12 to 9% approximately. Finally, effect of Ni powder's addition on the joint was analyzed and discussed. The reduction in the thickness of IMC and quantity of precipitate phases are beneficial to joint properties.

He, Huan; Lin, Sanbao; Yang, Chunli; Fan, Chenglei; Chen, Zhe

2013-11-01

179

High-temperature strength analysis of welded joint of RAFs by small punch test  

NASA Astrophysics Data System (ADS)

Type IV creep damage has recently been a worldwide issue for high Cr ferritic steels. The small punch (SP) creep test has been successfully applied to evaluate this damage of low alloy ferritic steel by the author's group. However, the heat affected zone (HAZ) of fusion reactor material welded by electron-beam (EB) welding is so thin that it is not easy to evaluate its mechanical properties by the conventional SP test. In this study, the SP test using a further miniaturized specimen was applied to the EB welded joint of reduced activation ferritic steel (RAFs), for evaluating high-temperature tensile properties of the HAZs. As the result, the ?y and ?B of the tempered HAZ at 873 K were estimated to be as low as 275-300 MPa and 325-340 MPa, respectively.

Kato, Taichiro; Komazaki, Shin-ichi; Kohno, Yutaka; Tanigawa, Hiroyasu; Kohyama, Akira

2009-04-01

180

Site-Dependent Tension Properties of Inertia Friction-Welded Joints Made From Dissimilar Ni-based Superalloys  

NASA Astrophysics Data System (ADS)

Microstructure, tensile properties, and fracture behavior of the inertia friction weld joints of dissimilar superalloys, cast Mar-M247 and wrought LSHR, were studied to assess the weld quality. Tensile tests were conducted at 23 and 704 °C on the samples containing different areas of the weld interface of the same welded material. The stress-strain curves were registered at different axial distances from the weld interface. In all tested samples, plastic deformation was localized on Mar-M247 side, outside the heat-affected zone (HAZ), and the resistance to plastic deformation of Mar-M247 increased with a decrease in the distance from the weld interface inside HAZ. Only elastic deformation occurred on the LSHR side. Fracture occurred on the Mar-M247 side, outside HAZ, or at the weld interface. In the latter case, welding defects in the form of clusters of nanometer-sized oxide and carbide particles were observed at the fracture surfaces. These results revealed that the IFW process is capable of producing the weld joints between Mar-M247 and LSHR with the fracture strength higher than that of Mar-M247. However, optimization of the IFW processing parameters is required to minimize clustering of oxide/carbide particles at the weld interface in this alloy pair.

Senkov, O. N.; Mahaffey, D. W.; Semiatin, S. L.; Woodward, C.

2015-01-01

181

Evaluation of fatigue properties of 316FR stainless steel welded joints at elevated temperature  

SciTech Connect

316FR is an improved version of type 316 stainless steel for elevated temperature use with lower carbon content than conventional type 316 stainless steel. Fatigue properties of GTAW joints of 316FR stainless steel have been investigated. Heat affected zone (HAZ) of 316FR becomes harder than base metal. A method based on the stress-strain relationship of three elements, which are base metal, HAZ and weld portions, has been proposed and applied to the evaluations of fatigue tests. The tri-metal analysis model gives good agreements between experimental results and predicted fatigue lives of the 316FR welded joints. This material is to be used in the DFBR reactor in Japan.

Kaguchi, Hitoshi; Koto, Hiroyuki [Mitsubishi Heavy Industries, Ltd., Kobe (Japan); Fujioka, Terutaka [Japan Atomic Power Co., Tokyo (Japan); Taguchi, Kosei [Toshiba Corp., Yokohama (Japan); Sukekawa, Masayuki [Hitachi Ltd. (Japan)

1996-12-01

182

High Temperature Plasticity of Bimetallic Magnesium and Aluminum Friction Stir Welded Joints  

NASA Astrophysics Data System (ADS)

The high temperature deformation of a bimetallic AZ31/AA6061 Friction Stir Welded joint was investigated in the present study by constant load creep experiments carried out at 473 K (200 °C). The microstructural analysis revealed the strongly inhomogeneous nature of the weld, which was characterized by an extremely fine grain size in the magnesium-rich zones and by the extensive presence of intermetallic phases. In the high stress regime, the creep strain was concentrated in the refined and particle-rich microstructure of the weld zone, while the AA6061 base metal remained undeformed. In the low stress regime, deformation became more homogeneously distributed between the AZ31 base metal and the weld zone. The creep behavior of the weld was found to obey the constitutive equation describing the minimum creep rate dependence on applied stress for the base AZ31, slightly modified to take into account the finer microstructure and the role of secondary phase particles, i.e., the retardation of grain growth and the obstruction of grain boundary sliding.

Regev, Michael; El Mehtedi, Mohamad; Cabibbo, Marcello; Quercetti, Giovanni; Ciccarelli, Daniele; Spigarelli, Stefano

2014-02-01

183

Effect of high temperature aging on bonded and weld bonded joints  

NASA Technical Reports Server (NTRS)

Development of adhesives for applications requiring long-term service at temperatures up to 600 F is discussed. This development work utilizes polyimide (PI) and polyphenylquinoxaline (PPQ) resin technology worked out previously. The resultant adhesives are evaluated in structural joints of titanium, steel and composite adherends and in honeycomb sandwich panels. Suitable adhesives also are evaluated in weld bonded titanium alloy joints. Testing includes determination of long-term aging of stressed and unstressed specimens at temperatures from about 450 F to 600 F as well as under dynamic fatigue conditions.

Vaughan, R. W.

1975-01-01

184

Microstructure and performance in diffusion-welded joints of Fe 3Al\\/Q235 carbon steel  

Microsoft Academic Search

Fe3Al and Q235 carbon steel were joined successfully at 1080°C for 60min by vacuum diffusion welding technology. A Fe3Al\\/Q235 diffusion-welded joint was thus formed. The microstructure features in the Fe3Al\\/Q235 diffusion-welded joint were analyzed by a variety of characterization techniques such as scanning electron microscope (SEM) with energy-dispersive spectroscopy (EDS), electronic probe microanalysis (EPMA) and an X-ray diffractometer. The micro-hardness

Juan Wang; Yajiang Li; Peng Liu; Huiqiang Wu

2004-01-01

185

Microstructure and creep characteristics of dissimilar T91/TP316H martensitic/austenitic welded joint with Ni-based weld metal  

SciTech Connect

This paper deals with characterization of microstructure and creep behavior of dissimilar weldment between the tempered martensitic steel T91 and the non-stabilized austenitic steel TP316H with Ni-based weld metal (Ni WM). Microstructure analyses were performed using light microscopy, scanning and transmission electron microscopy and energy-dispersive X-ray spectroscopy. The martensitic part of the welded joint exhibited a wide heat-affected zone (HAZ) with typical microstructural gradient from its coarse-grained to the fine-grained/intercritical region. In contrast, the HAZ of austenitic steel was limited to only a narrow region with coarsened polygonal grains. The microstructure of Ni WM was found to be very heterogeneous with respect to the size, morphology and distribution of grain boundaries and MC-type precipitates as a result of strong weld metal dilution effects and fast non-equilibrium solidification. Cross-weld creep tests were carried out in a temperature range from 600 to 650 Degree-Sign C at applied stresses from 60 to 140 MPa. The obtained values of apparent stress exponents and creep activation energies indicate thermally activated dislocation glide to be the governing creep deformation mechanism within the range of used testing conditions. The creep samples ruptured in the T91 intercritical HAZ region by the 'type IV cracking' failure mode and the creep fracture mechanism was identified to be the intergranular dimple tearing by microvoid coalescence at grain boundaries. The TEM observations revealed pronounced microstructural differences between the critical HAZ region and the T91 base material before as well as after the creep exposure. - Highlights: Black-Right-Pointing-Pointer Phase transformations affect the microstructures of T91 and TP316H HAZ regions. Black-Right-Pointing-Pointer High weld metal dilution results in heterogeneous microstructure with MC carbides. Black-Right-Pointing-Pointer Creep behavior of the studied weldment is controlled by its martensitic T91 part. Black-Right-Pointing-Pointer The lowest hardness of T91 ICHAZ region corresponds with its lowest creep strength.

Falat, Ladislav, E-mail: lfalat@imr.saske.sk [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice (Slovakia)] [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice (Slovakia); Svoboda, Milan [Institute of Physics of Materials, Academy of Sciences of Czech Republic, Zizkova 22, 616 62 Brno (Czech Republic)] [Institute of Physics of Materials, Academy of Sciences of Czech Republic, Zizkova 22, 616 62 Brno (Czech Republic); Vyrostkova, Anna; Petryshynets, Ivan; Sopko, Martin [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice (Slovakia)] [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice (Slovakia)

2012-10-15

186

Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration  

NASA Astrophysics Data System (ADS)

Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-03-01

187

Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration  

NASA Astrophysics Data System (ADS)

It is advantageous for the transportation industry to use lightweight components in the structure in order to save mass and reduce CO2 emissions. One of the lightest structural metals, magnesium, fulfills the need for mass reduction within the automotive industry. Many of the body structure components in the automotive industry are assembled using joining processes such as fusion welding. Furthermore, laser welding offers a low heat impact, high process rate, joining method which is becoming increasingly popular as the cost for laser systems continues to decrease. However, there is a limited body of work investigating the laser welding of magnesium and therefore, in the current study, different techniques and methods for laser welding of magnesium alloys are numerically and experimentally studied in order to optimize process parameters to achieve high quality welds. A feasibility study was designed in order to study the effect of various laser welding process parameters (such as laser power levels and welding speeds) on weld quality. Three regression models were developed to find the best fit model that relates process parameters to the shear load of the weld. Furthermore, to understand the effect of laser welding parameters on temperature distribution in laser welding of AZ31B magnesium alloy, a numerical model was developed. A rotary Gaussian volumetric body heat source was applied in this study to obtain the temperature history during the laser welding process. Cross-sectional views of the weld beads, temperature history recorded by thermocouples, and temperature history recorded by infrared camera were used to validate the numerical model. In order to study the real-time dynamic behavior of the molten pool and the keyhole during the welding process, a high speed charge-coupled device (CCD) assisted with a green laser as an illumination source was used. In order to observe the presence of pores, prior studies destructively evaluated the weld bead however; in the current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two different methods including focused beam laser welding (FBLW) and defocused beam laser welding

Harooni, Masoud

188

FATIGUE STRENGTH IMPROVEMENT OF OUT-OF-PLANE GUSSET WELDED JOINTS OF STEEL GIRDER MADE OF HIGH YIELD STEEL  

NASA Astrophysics Data System (ADS)

In this research, additional welding with low temperature transformation welding material and improvement method which combined cleaning treatment with a grinder and hammer peening treatment have been investigated. The improvement effect is clarified from the fatigue test of girder specimen with the out-of-plane gusset plate. Although the improvement effect by peening treatment varied, the fatigue strength at weld toe of out-of-plane welded joint increased to more than D class. The improvement effect by the additional welding decreases since the compressive residual stress on the front side is lost due to the additional welding on rear side. When using maximum principal stress range for structural hot spot stress range, the effects of shear stress and the difference of stress concentration on fatigue strength improvement can be considered.

Tai, Masayuki; Miki, Chitoshi; Suzuki, Keigo

189

Effect of weld size on fatigue crack growth behaviour of cruciform joints by strain energy density factor approach  

Microsoft Academic Search

The effect of weld size on fatigue crack growth behaviour of cruciform joints containing lack of penetration defect has been analysed by using the strain energy density factor concept. Load carrying cruciform joints were fabricated from ASTM 517`F' grade steel. Fatigue crack growth experiments were carried out in a mechanical resonance vertical pulsator (SCHENCK 200 kN capacity) with a frequency

V. Balasubramanian; B. Guha

1999-01-01

190

Impact of tool wear on joint strength in friction stir spot welding of DP 980 steel  

SciTech Connect

Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Recently a new tool alloy has been developed, using a blend of PCBN and tungsten rhenium (W-Re) in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re, and one with 70% PCBN and 30% W-Re. The sheet material used for all wear testing was 1.4 mm DP 980. Lap shear testing was used to show the relationship between tool wear and joint strength. The Q70 tool provided the best combination of wear resistance and joint strength.

Miles, Michael; Ridges, Chris; Hovanski, Yuri; Peterson, Jeremy; Santella, M. L.; Steel, Russel

2011-09-14

191

The susceptibility of low carbon steel welded joint to sulphide stress cracking (SSC)  

NASA Astrophysics Data System (ADS)

The resistance of low carbon steel pipes API 5L GR.B as welded joints to sulphide stress cracking SSC was tested using NACE Standard test method TM 0177_Method (C). Two stress levels of the material's yield strength were applied, 75 % ?y and 100 % ?y in three different conditions; as received, as welded, and stress relieved samples. Total of seventeen samples were tested; two as received samples without any welding process, six samples as heat treated, and nine samples as welded. The effect of hardness level on material's susceptibility to sulphide stress cracking was examined. Raw Natural Gas was used as a source of Hydrogen Sulphide (H2S) in the test, which represents the real environment that the material was exposed to. Results show that samples with high hardness (higher than 22 HRC) were failed the test which was expected as in the NACE Standard MR175. Samples with low hardness (lower than 22 HRC) were passed the test which was expected as in the NACE Standard MR175. The received samples of low hardness failed the test which was not expected.

Alshwigi, Mohamed A. M.; Musa, Salem. M.; Basir, Ali

2013-12-01

192

Reactor cooling water expansion joint bellows: The role of the seam weld in fatigue crack development  

SciTech Connect

The secondary cooling water system pressure boundary of Savannah River Site reactors includes expansion joints utilizing a thin-wall bellows. While successfully used for over thirty years, an occasional replacement has been required because of the development of small, circumferential fatigue cracks in a bellows convolute. One such crack was recently shown to have initiated from a weld heat-affected zone liquation microcrack. The crack, initially open to the outer surface of the rolled and seam welded cylindrical bellows section, was closed when cold forming of the convolutes placed the outer surface in residual compression. However, the bellows was placed in tension when installed, and the tensile stresses reopened the microcrack. This five to eight grain diameter microcrack was extended by ductile fatigue processes. Initial extension was by relatively rapid propagation through the large-grained weld metal, followed by slower extension through the fine-grained base metal. A significant through-wall crack was not developed until the crack extended into the base metal on both sides of the weld. Leakage of cooling water was subsequently detected and the bellows removed and a replacement installed.

West, S.L.; Nelson, D.Z.; Louthan, M.R. Jr.

1992-01-01

193

Reactor cooling water expansion joint bellows: The role of the seam weld in fatigue crack development  

SciTech Connect

The secondary cooling water system pressure boundary of Savannah River Site reactors includes expansion joints utilizing a thin-wall bellows. While successfully used for over thirty years, an occasional replacement has been required because of the development of small, circumferential fatigue cracks in a bellows convolute. One such crack was recently shown to have initiated from a weld heat-affected zone liquation microcrack. The crack, initially open to the outer surface of the rolled and seam welded cylindrical bellows section, was closed when cold forming of the convolutes placed the outer surface in residual compression. However, the bellows was placed in tension when installed, and the tensile stresses reopened the microcrack. This five to eight grain diameter microcrack was extended by ductile fatigue processes. Initial extension was by relatively rapid propagation through the large-grained weld metal, followed by slower extension through the fine-grained base metal. A significant through-wall crack was not developed until the crack extended into the base metal on both sides of the weld. Leakage of cooling water was subsequently detected and the bellows removed and a replacement installed.

West, S.L.; Nelson, D.Z.; Louthan, M.R. Jr.

1992-12-01

194

Experimental and numerical investigations of hybrid laser arc welding of aluminum alloys in the thick T-joint configuration  

NASA Astrophysics Data System (ADS)

In the present investigation, a numerical finite element model was developed to simulate the hybrid laser arc welding of different aluminum alloys, namely 5××× to 6××× series. The numerical simulation has been considered two double-ellipsoidal heat sources for the gas metal arc welding and laser welding. The offset distance of the metal arc welding and laser showed a significant effect on the molten pool geometry, the heat distribution and penetration depth during the welding process. It was confirmed that when the offset distance is within the critical distance the laser and arc share the molten pool and specific amount of penetration and dilution can be achieved. The models and experiments show that the off-distance between the two heat sources and shoulder width have considerable influence on the penetration depth and appearance of the weld beads. The experiments also indicate that the laser power, arc voltage and type of the filler metal can effectively determine the final properties of the bonds, specifically the bead appearance and microhardness of the joints. The experiments verified the numerical simulation as the thermocouples assist to comprehend the amount of heat distribution on the T-joint coupons. The role of the welding parameters on the mechanism of the hybrid laser welding of the aluminum alloys was also discussed.

Mazar Atabaki, M.; Nikodinovski, M.; Chenier, P.; Ma, J.; Liu, W.; Kovacevic, R.

2014-07-01

195

EFFECT OF TOOL FEATURE ON THE JOINT STRENGTH OF DISSIMILAR FRICTION STIR LAP WELDS  

SciTech Connect

Several variations of friction stir tools were used to investigate the effects on the joint strengths of dissimilar friction stir lap welds. In the present lap weld configuration the top sheet was a 2.32 mm thick Mg (AZ 31) alloy. The bottom sheet consisted of two different steels, a (i) 0.8 mm thick electro-galvanized (EG) mild steel, or a (ii) 1.5 mm thick hot dip galvanized (HDG) high strength low alloy (HSLA) steel. Initially the tool shape was modified to accommodate the material, at which point the tool geometry was fixed. With a fixed tool geometry an additional feature was added to the pin bottom on one of the tools by incorporating a short hard insert, which would act as a stronger bottom sheet cutter. The effects of such modification on the unguided lap shear strength, and associated microstructural changes are discussed in this study.

Jana, Saumyadeep; Hovanski, Yuri; Grant, Glenn J.; Mattlin, Karl F.

2011-04-25

196

Methods for Improving Laser Beam Welding Efficiency  

NASA Astrophysics Data System (ADS)

The aim of this paper is to evaluate methods for improving laser beam welding efficiency, namely, obtaining increased penetration depth and enhanced weld quality without an increase in laser power or a decrease in welding speed. Increased efficiency can be realized with several techniques: butt joint edge surface modifications, preheating and modifications of ambient atmospheric conditions.

Sokolov, Mikhail; Salminen, Antti

197

Long-Term Integrity of Waste Package Final Closure for HLW Geological Disposal, (IV) Influence of Welding and Prediction of Long-Term Integrity of Weld Joint  

Microsoft Academic Search

Overpack, a high-level radioactive waste container for geological disposal in the Japanese waste management program, is required to isolate the sealed vitrified waste from contact with groundwater for 1,000 years. This means that the weld joint between the body and the lid of the overpack is also required to endure for this period of time. The authors have already started

Hidekazu ASANO; Shigeki KATAOKA; Kazuto MAEDA; Masanori ARITOMI

2006-01-01

198

Welding.  

ERIC Educational Resources Information Center

This curriculum guide provides materials for a 12-unit secondary course in welding. Purpose stated for the flexible entry and exit course is to help students master manipulative skills to develop successful welding techniques and to gain an understanding of the specialized tools and equipment used in the welding field. Units cover oxyacetylene…

Lehigh County Area Vocational-Technical School, Schnecksville, PA.

199

Long-term strength and structural features of welded joints of chromium steels  

NASA Astrophysics Data System (ADS)

Results obtained from studies of long-term strength and structural features of homogeneous and welded connections of chromium steel are presented. Information is also given on the new Grade 10Kh9V2MFBR steel developed for the piping systems of power units designed for ultrasupercritical steam conditions.

Skorobogatykh, V. N.; Shchenkova, I. A.; Tugolukov, E. A.

2010-01-01

200

The influence of surface geometry and topography on the fatigue cracking behaviour of laser hybrid welded eccentric fillet joints  

NASA Astrophysics Data System (ADS)

Laser hybrid welding of an eccentric fillet joint causes a complex geometry for fatigue load by 4-point bending. The weld surface geometry and topography were measured and studied in order to understand the crack initiation mechanisms. The crack initiation location and the crack propagation path were studied and compared to Finite Element stress analysis, taking into account the surface macro- and micro-geometry. It can be explained why the root and the upper weld toe are uncritical for cracking. The cracks that initiate from the weld bead show higher fatigue strength than the samples failing at the lower weld toe, as can be explained by a critical radius for the toe below which surface ripples instead determine the main stress raiser location for cracking. The location of maximum surface stress is related to a combination of throat depth, toe radius and sharp surface ripples along which the cracks preferably propagate.

Alam, M. M.; Barsoum, Z.; Jonsén, P.; Kaplan, A. F. H.; Häggblad, H. Å.

2010-01-01

201

Formation of intermetallic phases in diffusion-welded joints of aluminium and magnesium alloys  

Microsoft Academic Search

Basic research has been done on diffusion-welded joints with the overall aim of an adjusted interface design. The phase formation\\u000a of aluminium alloy\\/magnesium alloy bonds has been revealed by X-ray diffraction, energy-dispersive spectroscopy and electron\\u000a back-scatter diffraction. The presence of Al12Mg17 and Al3Mg2 phases in a bi-layer has been confirmed. The distribution and microstructure of the formed intermetallics and the

D. Dietrich; D. Nickel; M. Krause; T. Lampke; M. P. Coleman; V. Randle

2011-01-01

202

Enhancement of the durability of structural steels and their welded joints by plastic deformation  

Microsoft Academic Search

Conclusions  The fatigue and corrosion-fatigue resistance of low-alloy steels increases as degree of plastic prestraining increases to\\u000a 29%. The resistance of the 08kp steel prestrained and hardened by surface plastic deformation and its welded joints to fatigue\\u000a and corrosion-fatigue fracture is higher than for the 08GSYuT alloyed steel. The procedures of pneumatic shot blasting and\\u000a shot blasting prove to be efficient

M. P. Berezhnyts’ka; H. P. Huslyakova; V. I. Tkachov

2000-01-01

203

Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion  

NASA Astrophysics Data System (ADS)

The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment (LHT) on H2S stress corrosion in the National Association of Corrosion Engineers (NACE) solution were analyzed by a slow strain rate test. The fracture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydrogen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2% to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

Kong, De-jun; Ye, Cun-dong

2014-09-01

204

Evaluation of creep damage in a welded joint of modified 9Cr-1Mo steel  

NASA Astrophysics Data System (ADS)

This paper aims to evaluate the creep damage of modified 9Cr-1Mo steel under 600 °C operating conditions, using constitutive equations based on the continuum damage mechanics. The accumulation of voids over a long period is believed to contribute to the formation of Type IV cracking, which in turn leads eventually to the failure of weldment under conditions of higher temperatures and lower stresses. Specimens of base metal, a simulated fine-grained heat affected zone, and a thin (thick) welded joint were kept under stress from 80 to 160 MPa at 600 °C. During the creep tests of thick plate welded joint specimens, the application of stress was suspended several times, and the creep damage as indicated by the void distribution was examined quantitatively using a laser microscope. The combined effect of the equivalent creep strain and the stress triaxial factor was considered and introduced into the constitutive equations with the aid of a finite element method. The logarithms of m and 1/? in the continuum damage mechanics equations were determined to have a linear correlation with the ratio of the applied stress to the yield stress for homogeneous materials. In this way, the damage distribution and evolution in the fine-grained heat affected zone were evaluated successfully.

Li, Yongkui; Monma, Yoshio; Hongo, Hiromichi; Tabuchi, Masaaki

2010-10-01

205

Columnar jointing in vapor-phase-altered, non-welded Cerro Gal??n Ignimbrite, Paycuqui, Argentina  

USGS Publications Warehouse

Columnar jointing is thought to occur primarily in lavas and welded pyroclastic flow deposits. However, the non-welded Cerro Gal??n Ignimbrite at Paycuqui, Argentina, contains well-developed columnar joints that are instead due to high-temperature vapor-phase alteration of the deposit, where devitrification and vapor-phase crystallization have increased the density and cohesion of the upper half of the section. Thermal remanent magnetization analyses of entrained lithic clasts indicate high emplacement temperatures, above 630??C, but the lack of welding textures indicates temperatures below the glass transition temperature. In order to remain below the glass transition at 630??C, the minimum cooling rate prior to deposition was 3.0 ?? 10-3-8.5 ?? 10-2??C/min (depending on the experimental data used for comparison). Alternatively, if the deposit was emplaced above the glass transition temperature, conductive cooling alone was insufficient to prevent welding. Crack patterns (average, 4.5 sides to each polygon) and column diameters (average, 75 cm) are consistent with relatively rapid cooling, where advective heat loss due to vapor fluxing increases cooling over simple conductive heat transfer. The presence of regularly spaced, complex radiating joint patterns is consistent with fumarolic gas rise, where volatiles originated in the valley-confined drainage system below. Joint spacing is a proxy for cooling rates and is controlled by depositional thickness/valley width. We suggest that the formation of joints in high-temperature, non-welded deposits is aided by the presence of underlying external water, where vapor transfer causes crystallization in pore spaces, densifies the deposit, and helps prevent welding. ?? 2011 Springer-Verlag.

Wright, H.M.N.; Lesti, C.; Cas, R.A.F.; Porreca, M.; Viramonte, J.G.; Folkes, C.B.; Giordano, G.

2011-01-01

206

Effect of Application of Short and Long Holds on Fatigue Life of Modified 9Cr-1Mo Steel Weld Joint  

NASA Astrophysics Data System (ADS)

Modified 9Cr-1Mo steel is a heat-treatable steel and hence the microstructure is temperature sensitive. During welding, the weld joint (WJ) is exposed to various temperatures resulting in a complex heterogeneous microstructure across the weld joint, such as the weld metal, heat-affected zone (HAZ) (consisting of coarse-grained HAZ, fine-grained HAZ, and intercritical HAZ), and the unaffected base metal of varying mechanical properties. The overall creep-fatigue interaction (CFI) response of the WJ is hence due to a complex interplay between various factors such as surface oxides and stress relaxation (SR) occurring in each microstructural zone. It has been demonstrated that SR occurring during application of hold in a CFI cycle is an important parameter that controls fatigue life. Creep-fatigue damage in a cavitation-resistant material such as modified 9Cr-1Mo steel base metal is accommodated in the form of microstructural degradation. However, due to the complex heterogeneous microstructure across the weld joint, SR will be different in different microstructural zones. Hence, the damage is accommodated in the form of preferential coarsening of the substructure, cavity formation around the coarsened carbides, and new surface formation such as cracks in the soft heat-affected zone.

Shankar, Vani; Mariappan, K.; Sandhya, R.; Mathew, M. D.; Jayakumar, T.

2013-11-01

207

Narrow gap laser welding  

DOEpatents

A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables.

Milewski, John O. (Santa Fe, NM); Sklar, Edward (Santa Fe, NM)

1998-01-01

208

The use of ion beam cleaning to obtain high quality cold welds with minimal deformation  

NASA Technical Reports Server (NTRS)

This paper describes a variation of cold welding which utilizes an ion beam to clean mating surfaces prior to joining in a vacuum environment. High quality solid state welds were produced with minimal deformation. Due to experimental fixture limitation in applying pressure work has been limited to a few low yield strength materials.

Sater, B. L.; Moore, T. J.

1978-01-01

209

Formation mechanism of linear friction welded Ti-6Al-4V alloy joint based on microstructure observation  

SciTech Connect

The microstructure of the linear friction welded Ti-6Al-4V titanium alloy joint was investigated by optical microscope, scanning electronic microscope and transmission electron microscope. Results show that the dynamic recovery and recrystallization resulting from the intensive plastic deformation and fast heating and cooling processes during linear friction welding account for the superfine {alpha} + {beta} grains in the weld center. Fine {alpha} grains distribute in the {beta} matrix or at the boundaries of {beta} grains. A mass of dislocations networks and metastructures present within the {alpha} and {beta} grains. - Research Highlights: {yields} TEM is employed in the analysis. {yields} The dynamic recovery is the main mechanism in thermal deformation of TC4. {yields} Superfine grains in the weld result from dynamic recovery and dynamic recrystallizaion, but the recrystallization is inadequate.

Ma Tiejun; Chen Tao, E-mail: ctwc-13@163.com; Li Wenya; Wang Shiwei; Yang Siqian

2011-01-15

210

Multiscale characterization of deformation mechanisms in the weld joint of a nickel-based superalloy  

SciTech Connect

Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the gamma' - phase particles during heating and secondary precipitation of gamma' during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, gamma' - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (10-20nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the gamma matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with Burgers vector b=[110] and dislocation lines [1-12] and [1-1-2] ; or b=[-110], dislocation lines [112] and [11-2] . Each of these two dislocation groups forms two Z-shaped dislocation lines fluctuating around two cubic directions [100] and [010]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

Barabash, Oleg M [ORNL; Horton Jr, Joe A [ORNL; Babu, Sudarsanam S [ORNL; Vitek, John Michael [ORNL; David, Stan A [ORNL; Ice, Gene E [ORNL; Barabash, Rozaliya [ORNL

2005-01-01

211

Multiscale Characterization of Deformation Mechanisms in the Weld Joint of a Nickel-based Superalloy  

SciTech Connect

Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the {gamma} - phase particles during heating and secondary precipitation of {gamma} - phase during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, {gamma} - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (50-70nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the ? matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with typical Burgers vector b=[110]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

Barabash, Oleg M.; Horton, Joe; Babu, Suresh; Vitek, John; David, Stan; Ice, Gene; Barabash, Rozaliya (ORNL)

2007-12-19

212

Establishing Mathematical Models to Predict Grain Size and Hardness of the Friction Stir-Welded AA 7020 Aluminum Alloy Joints  

NASA Astrophysics Data System (ADS)

In this study, response surface methodology in conjunction with a central composite design was applied to predict the grain size and hardness of friction stir-welded AA 7020 aluminum alloy joints. For this purpose, three welding parameters, including tool rotational speed, traverse speed, and tool axial force, at five levels and 20 runs were considered. In order to validate the predicted models, the analysis of variance was performed. Hardness and microstructural features of the joints were investigated using microhardness test and optical microscopy, respectively. In addition, the influences of friction stir welding parameters on grain size and hardness of the joints were examined thoroughly. The analysis of variance results revealed that the developed models were significant and accurate to predict the responses. Furthermore, with increasing the heat input, the hardness of the joints decreased, where the grain size increased continuously. In addition, the optimized condition for achieving the lowest grain size and highest hardness of the joints was reached as 800 rpm, 125 mm/min and 8 kN.

Rahimzadeh Ilkhichi, A.; Soufi, R.; Hussain, G.; Vatankhah Barenji, R.; Heidarzadeh, A.

2015-02-01

213

Welding  

NSDL National Science Digital Library

Teachers' Domain presents this video as part of a series on advanced technological education. Around 500,000 people are currently employed in welding in the United States, and as more highways, bridges and other structures need crucial updates, welders will continue to be in demand. The video clip demonstrates welding techniques, including what constitutes a bad weld and how to recognize one. Careers in welding are also discussed. The video may be viewed online or downloaded. To download the clip, users must create a free login for Teachers' Domain. Running time for this QuickTime video is 3:56. Educators will also find a background essay, discussion questions, and standards alignment for the material.

2010-09-29

214

Detection of defects in laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration by a real-time spectroscopic analysis  

NASA Astrophysics Data System (ADS)

The effect of surface oxide layer existing at the lap-joint faying surface of magnesium sheets is investigated on the keyhole dynamics of the weld pool and weld bead qualities. It is observed that by removing the oxide layer from the faying surface of the lap joint, a high quality weld can be achieved in the laser welding process. However, the presence of an oxide layer deteriorates the quality of the weld by forming pores at the interface of the two overlapped sheets. The purpose of this paper is to identify the correlation between the integrity of the weld and the interaction between the laser and material. A spectroscopy sensor was applied to detect the spectra emitted from a plasma plume during the laser welding of AZ31B magnesium alloy in a zero-gap lap joint configuration. The electron temperature was calculated by applying a Boltzmann plot method based on the detected spectra, and the correlation between the pore formation and the spectral signals was studied. The laser molten pool and the keyhole condition were monitored in real-time by a high speed charge-coupled device (CCD) camera. A green laser was used as an illumination source in order to detect the influence of the oxide layer on the dynamic behavior of the molten pool. Results revealed that the detected spectrum and weld defects had a meaningful correlation for real-time monitoring of the weld quality during laser welding of magnesium alloys.

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-05-01

215

Microstructural Evolution of Inconel 625 and Inconel 686CPT Weld Metal for Clad Carbon Steel Linepipe Joints: A Comparator Study  

NASA Astrophysics Data System (ADS)

Microstructural evolution of Inconel 625 and Inconel 686CPT filler metals, used for the fusion welding of clad carbon steel linepipe, has been investigated and compared. The effects of iron dilution from the linepipe parent material on the elemental segregation potential of the filler metal chemistry have been considered. The results obtained provide significant evidence to support the view that, in Inconel 686CPT weld metal, the segregation of tungsten is a function of the level of iron dilution from the parent material. The data presented indicate that the incoherent phase precipitated in the Inconel 686CPT weld metal has a morphology that is dependent on tungsten enrichment and, therefore, iron dilution. Furthermore, in the same weld metal, a continuous network of finer precipitates was observed. The Charpy impact toughness of each filler metal was evaluated, and the results highlighted the superior impact toughness of the Inconel 625 weld metal over that of Inconel 686CPT.

Maltin, Charles A.; Galloway, Alexander M.; Mweemba, Martin

2014-07-01

216

Influence of structural features of welded joints of low-alloy steels on magnetic and micromagnetic properties  

Microsoft Academic Search

Variations of magnetic (coercive force H\\u000a \\u000a c\\u000a , residual induction B\\u000a \\u000a r\\u000a , maximum magnetic permeability ?max, maximum magnetic-permeability field H\\u000a ?max, saturation magnetization J\\u000a max) and micromagnetic (number of pulses N and RMS Barkhausen-noise amplitude U) characteristics along the parent metal-welded joint direction were studied for welds of steels 10XCH?, 15XCH?, 09?2C, and\\u000a X70.

E. S. Gorkunov; S. Yu. Mitropol’skaya; K. E. Solov’ev; E. A. Tueva

2009-01-01

217

Fatigue Strength and Related Characteristics of Aircraft Joints I : Comparison of Spot-Weld and Rivet Patterns in 24s-t Alclad and 75s-t Alclad  

NASA Technical Reports Server (NTRS)

Report contains detailed results of a number of fatigue tests on spot-welded joints in aluminum alloys. The tests described include: (1) fatigue tests on spot-welded lap joints in sheets of unequal thickness of alclad 24s-t. These tests indicate that the fatigue strength of a spot-welded joint in sheets of two different gages is slightly higher than that of a similar joint in two sheets of the thinner gage but definitely lower than that of a similar joint in two sheets of the thicker gage. (2) Fatigue tests on spot-welded alclad 75s-t spot-welded lap-joint specimens of alclad 75s-t were not any stronger in fatigue than similar specimens of alclad 24s-t. (3) Fatigue tests on lap-joint specimens spot -welded after various surface preparations--these included ac welding wire-brushed surfaces, dc welding wire-brushed surfaces, and dc welding chemically cleaned surfaces. While the ac welds were strongest statically, the dc welds on wire-brushed surfaces were strongest in fatigue. Specimens prepared in this way were very nearly as strong as the best riveted specimens tested for comparison. (4) Fatigue tests on specimens spot-welded with varying voltage so as to include a wide range of static spot-weld strengths. The fatigue strengths were in the same order as the static strengths but showed less range. (author)

Russell, H W; Jackson, L R; Grover, H J; Beaver, W W

1944-01-01

218

Weld penetration and defect control  

SciTech Connect

Highly engineered designs increasingly require the use of improved materials and sophisticated manufacturing techniques. To obtain optimal performance from these engineered products, improved weld properties and joint reliability are a necessarily. This requirement for improved weld performance and reliability has led to the development of high-performance welding systems in which pre-programmed parameters are specified before any welding takes place. These automated systems however lack the ability to compensate for perturbations which arise during the welding process. Hence the need for systems which monitor and control the in-process status of the welding process. This report discusses work carried out on weld penetration indicators and the feasibility of using these indicators for on-line penetration control.

Chin, B.A.

1992-05-15

219

Effect of Welding Consumables on Fatigue Performance of Shielded Metal Arc Welded High Strength, Q&T Steel Joints  

Microsoft Academic Search

Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to their high strength-to-weight\\u000a ratio and high hardness. These steels are prone to hydrogen-induced cracking in the heat affected zone (HAZ) after welding.\\u000a The use of austenitic stainless steel consumables to weld the above steel was the only remedy because of higher solubility\\u000a for hydrogen

G. Magudeeswaran; V. Balasubramanian; G. Madhusudhan Reddy

2009-01-01

220

Interfacial ultrafine-grained structures on aluminum alloy 6061 joint and copper alloy 110 joint fabricated by magnetic pulse welding  

Microsoft Academic Search

Magnetic pulse welding is a solid state impact welding process, similar to explosive welding, which produces metallurgical\\u000a bond by oblique high-speed impact between two metal bodies. This violent impact removes the metal surface oxide layers and\\u000a then joins the two atomic level clean metal surfaces together by the incidental compression pressure. The impact velocity\\u000a is at 200–400 m\\/s and the being

Yuan ZhangSudarsanam; Sudarsanam Suresh Babu; Glenn S. Daehn

2010-01-01

221

Corrosion cracking of welded joints of pipelines from steel 08Kh18N10T in power units with RBMK-type reactors  

Microsoft Academic Search

The effect of coolant parameters (temperature, content of oxygen and chlorine ions, acidity parameter pH) and of residual\\u000a stresses on the susceptibility of welded joints of pipelines from steel 08Kh18N10T at power units with RBMK-type reactors\\u000a to intercrystalline corrosion cracking is studied. It is shown that the endurance of the pipelines depends on the heat treatment\\u000a of welded joints and

A. S. Zubchenko; I. L. Kharina; A. E. Runov; A. V. Mukhin; N. Yu. Korovin

2007-01-01

222

Effects of the heterogeneity in the electron beam welded joint on fatigue crack growth in Ti–6Al–4V alloy  

Microsoft Academic Search

The heterogeneity of electron beam (EB)-welded joints in thick Ti–6Al–4V alloy plates is defined and described. The microstructure, hardness, and fatigue crack growth rate (FCGR) in the fuse zone (FZ) and the heat-affected zone (HAZ) of thick Ti–6Al–4V alloy EB-welded joint are studied using a new testing and interception method. The fatigue fractographs, crack growth paths and the microscopic deformation

Xingzhi Li; Shubing Hu; Jianzhong Xiao; Longbo Ji

2011-01-01

223

Welding.  

ERIC Educational Resources Information Center

This curriculum guide is intended to assist vocational instructors in preparing students for entry-level employment as welders and preparing them for advanced training in the workplace. The package contains an overview of new and emerging welding technologies, a competency/skill and task list, an instructor's guide, and an annotated bibliography.…

Baldwin, Harold; Whitney, Gregory

224

Welding.  

ERIC Educational Resources Information Center

The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

Cowan, Earl; And Others

225

The Anti-fatigue Mechanisms on Alterations of Structures and Performances of Alloy Welded Joints with Ultrasonic Impact Treatment  

NASA Astrophysics Data System (ADS)

The specimens of aluminum alloy welded joint were prepared by gas tungsten arc welding using 2A12 sheets and ER5356 welding wires. Some specimens were full coverage strengthened by ultrasonic impact treatment and the others were not strengthened. The surface layer microstructures of the ultrasonic impact treated and untreated specimens were investigated by optical microscopy and transmission electron microscopy. The surface layer hardness and residual stress distributions along the thickness direction were measured by micro-hardness tester and X-ray diffraction method. The results showed that a grain refinement layer which depth extended up to about 150?200 ?m was produced by ultrasonic impact treatment. The average hardness value of the treated specimens was up to 110 HV, increasing by 45% compared with 76 HV of the untreated specimen. A residual compressive stress layer was also produced by ultrasonic impact treatment, and the depth was close to 900 ?m. The maximum residual compressive stress was -285 MPa. At the same time, the anti-fatigue mechanisms on grain refinement, work hardening and residual compressive stress of aluminum alloy welded joint with ultrasonic impact treatment were also discussed.

Li, Z. M.; Zhu, Y. L.; Du, X. K.

226

Development and application of a photogrammetric endoscopic system for measurement of misalignment and internal profile of welded joints in pipelines  

NASA Astrophysics Data System (ADS)

This paper presents a new optical system to measure internal cylindrical surfaces combining photogrammetry and fringe projection. The device uses two identical cameras, equipped with spherical and conical lenses, facing each other and aligned with the optical axis. A 360° helical fringe projector is used to project a sequence of phase shifted helical fringe pattern in the inner surface to be measured. The phase patterns are used to identify corresponding points and to reconstruct the surface in a regular cylindrical mesh using an alternative approach. A prototype was built, calibrated and tested. The paper presents the results of an application where two welded joints were measured in a 150 mm (6") diameter pipe. The goal was to inspect for defects in the internal part of the welding seams and to measure the transversal misalignment between the jointed parts.

Albertazzi G., Armando, Jr.; Hofmann, Allan C.; Fantin, Analucia V.; Santos, João M. C.

2009-06-01

227

Reliability of Laser Welding Process for ZE41AT5 Magnesium Alloy Sand Castings  

Microsoft Academic Search

Laser welding is a promising joining method for magnesium alloys. The process reliability of 2-mm ZE41A-T5 butt joints welded by a 4 kW Nd:YAG laser was investigated from weld geometries, defects and mechanical properties using Weibull statistical distribution. Smooth, geometrically regular and macroscopically defect-free sound joints were obtained. However, sag, undercut, surface misalignment, and some variations in weld width and

Haider Al-Kazzaz; Xinjin Cao; Mohammad Jahazi; Mamoun Medraj

2008-01-01

228

Joint properties of tilted angles of spin for 6061 aluminum alloys in friction stir welded experiments  

Microsoft Academic Search

The applicability of friction stir welding to 6061 aluminum alloy with a cylinder-screw-shaped S45C steel spin has been investigated. Three different tilted angles of spin were designed in the friction stir welding experiments. Experimental results have shown that surface defects at spin tilted angle were not observed at the weld zone such as face, toe and root of the weld,

Ming-Der Jean; Wei-Jen Chen; Jeng-Der Lin

2012-01-01

229

On the Use of Infrared Thermography for Analysis of Fatigue Damage in Ti6Al4V-Welded Joints  

NASA Astrophysics Data System (ADS)

The present work is aimed at comparatively studying fatigue damage evolution of a pulsed Nd:YAG laser beam-welded (LBW) joint and the base metal (BM) of Ti6Al4V alloy subjected to cyclic loading. To reveal crack nucleation and propagation during the fatigue process, in situ fatigue was generated using infrared measurement methods. The results indicate that the rate of damage accumulated in the LBW joint was higher than in the BM specimens during a fatigue test, which decreased the fatigue life of the LBW joint. This observation is attributable to the LBW joint fusion zone microstructure, which has a higher void nucleation and growth rate compared with the BM microstructure.

Liu, Jing; Gao, Xiao-Long; Zhang, Lin-Jie; Zhang, Jian-Xun

2014-08-01

230

APPLICATION OF MAGNETIC PULSE WELDING FOR ALUMINIUM ALLOYS AND SPCC STEEL SHEET JOINTS  

Microsoft Academic Search

The magnetic pulse welding (MPW) is a cold weld process of conductive metals to the similar or dissimilar material. MPW uses magnetic pressure to drive the primary metal against the target metal sweeping away surface contaminants while forcing intimate metal-to- metal contact, thereby producing a solid-state weld. In this paper the MPW method and its application for several aluminium alloy

Tomokatsu Aizawa; Mehrdad Kashani; Keigo Okagawa

231

Optimization of FS Welding Parameters for Improving Mechanical Behavior of AA2024-T351 Joints Based on Taguchi Method  

NASA Astrophysics Data System (ADS)

In the present study, the design of an experiment technique, the Taguchi method, has been used to optimize the friction stir welding (FSW) parameters for improving mechanical behavior of AA2024-T351 joints. The parameters considered were vertical downward forging force, tool travel speed, and probe length. An orthogonal array of L9 (34) was used; ANOVA analyses were carried out to identify the significant factors affecting tensile strength (Global Efficiency to Tensile Strength—GETS), bending strength (Global Efficiency to Bending—GEB), and hardness field. The percentage contribution of each parameter was also determined. As a result of the Taguchi analysis in this study, the probe length is the most significant parameter on GETS, and the tool travel speed is the most important parameter affecting both the GEB and the hardness field. An algebraic model for predicting the best mechanical performance, namely fatigue resistance, was developed and the optimal FSW combination was determined using this model. The results obtained were validated by conducting confirmation tests, the results of which verify the adequacy and effectiveness of this approach.

Vidal, C.; Infante, V.

2013-08-01

232

Joints in fiber-reinforced aluminum alloys  

NASA Technical Reports Server (NTRS)

Problems of joining involving structural components made of aluminum alloys with boron-fiber reinforcements are discussed, giving attention to a diffusion-welding process. The tension characteristics and weight factors in the case of various types of welded joints are considered. Diffusion-welding equipment used in the experimental investigation is described. The strength characteristics obtained in various cases of weld and component design are examined, taking into account static and dynamic stresses.

Gerber, K.; Vanrensen, E.

1988-01-01

233

The microstructure and strength properties of MA957 nanostructured ferritic alloy joints produced by friction stir and electro-spark deposition welding  

NASA Astrophysics Data System (ADS)

The nanostructured ferritic alloy (NFA) MA957 was joined by friction stir welding (FSW) and electro-sparked deposition (ESD) welding. Transmission electron microscopy (TEM) and small angle neutron scattering (SANS) characterization studies showed a uniform fine-scale equiaxed ferrite structure with a high dislocation density and slightly coarsened nm-scale particles in the joint region of the FSW weld compared to the base metal. Microhardness and tensile measurements on the FSW showed a modest reduction in the strength of the joint compared to the as-processed MA957. In contrast, the ESD-welds contained considerable porosity and the nm-scale particles dissolved or coarsened significantly, resulting in a larger degradation of the joint region strength. Thus FSW is a promising method for joining NFAs.

Miao, P.; Odette, G. R.; Gould, J.; Bernath, J.; Miller, R.; Alinger, M.; Zanis, C.

2007-08-01

234

Deconvoluting the Friction Stir Weld Process for Optimizing Welds  

NASA Technical Reports Server (NTRS)

In the friction stir welding process, the rotating surfaces of the pin and shoulder contact the weld metal and force a rotational flow within the weld metal. Heat, generated by the metal deformation as well as frictional slippage with the contact surface, softens the metal and makes it easier to deform. As in any thermo-mechanical processing of metal, the flow conditions are critical to the quality of the weld. For example, extrusion of metal from under the shoulder of an excessively hot weld may relax local pressure and result in wormhole defects. The trace of the weld joint in the wake of the weld may vary geometrically depending upon the flow streamlines around the tool with some geometry more vulnerable to loss of strength from joint contamination than others. The material flow path around the tool cannot be seen in real time during the weld. By using analytical "tools" based upon the principles of mathematics and physics, a weld model can be created to compute features that can be observed. By comparing the computed observations with actual data, the weld model can be validated or adjusted to get better agreement. Inputs to the model to predict weld structures and properties include: hot working properties ofthe metal, pin tool geometry, travel rate, rotation and plunge force. Since metals record their prior hot working history, the hot working conditions imparted during FSW can be quantified by interpreting the final microstructure. Variations in texture and grain size result from variations in the strain accommodated at a given strain rate and temperature. Microstructural data from a variety of FSWs has been correlated with prior marker studies to contribute to our understanding of the FSW process. Once this stage is reached, the weld modeling process can save significant development costs by reducing costly trial-and-error approaches to obtaining quality welds.

Schneider, Judy; Nunes, Arthur C.

2008-01-01

235

Joining of 1050\\/5052 by resistance seam welding and materials evaluation of joints  

Microsoft Academic Search

Spot welding is extensively used for joining aluminium alloys, although it is necessary to have available a large-capacity power source with a maximum capacity of around 300 000 A for joining by resistance seam welding, low-current applications not being very often encountered. Recently developed welders, however, allow welding to proceed with ease at low currents of 20 or so kA.

H. Abdel-Aleem; M. Kato; K. Nishio; T. Yamaguchi; K. Furukawa

2005-01-01

236

Effect of pulsed current welding on fatigue behaviour of high strength aluminium alloy joints  

Microsoft Academic Search

High strength aluminium alloys (Al–Zn–Mg–Cu alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due

V. Balasubramanian; V. Ravisankar; G. Madhusudhan Reddy

2008-01-01

237

Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys  

NASA Technical Reports Server (NTRS)

A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

1972-01-01

238

Mechanical Characteristics of 9% Ni Steel Welded Joint for Lng Storage Tank at Cryogenic  

NASA Astrophysics Data System (ADS)

To confirm the safety performance of LNG storage tank, the change in fatigue crack growth rate and fracture toughness within X-grooved weld heat-affected zone (HAZ) of newly developed 9% Ni steel, which was SMAW welded, was investigated. These materials were produced by QT (quenching, tempering) heat treatment. The weld metal specimens were prepared by taking the same weld procedure applied in actual inner shell of LNG storage tank. All tests were performed in the temperature ranging from R.T. and -162°C. The fatigue crack growth behavior was carried out using CT specimen. Investigation has been carried out to study the influence of temperature and weld effect on fatigue crack growth behavior. Also, Fracture surfaces after tests were observe by scanning electron microscope (SEM).

Yoon, Yong-Keun; Kim, Jae-Hoon; Shim, Kyu-Taek; Kim, Young-Kyun

239

49 CFR 179.300-9 - Welding.  

Code of Federal Regulations, 2013 CFR

... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks. Welding...171.7 of this subchapter). (b) Fusion-welded joints must be in...

2013-10-01

240

49 CFR 179.300-9 - Welding.  

Code of Federal Regulations, 2011 CFR

... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks. Welding...171.7 of this subchapter). (b) Fusion-welded joints must be in...

2011-10-01

241

49 CFR 179.300-9 - Welding.  

Code of Federal Regulations, 2012 CFR

... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks. Welding...171.7 of this subchapter). (b) Fusion-welded joints must be in...

2012-10-01

242

The Influence of Temperature-Time Parameter of Welded Joints Thermal Treatment on Strength-Related Characteristics of Chromium-Molybdenum and Low-Alloy Manganese Steels  

Microsoft Academic Search

The article deals with the analysis of the dependence of strength-related characteristics of welded joints from chromium-molybdenum steel (ASTM A335 Grd. P5) and low-alloy manganese steel (S355J2G3 EN10025-2) upon the parameters of heat treatment. Steel mechanical properties after post-weld heat treatment were analyzed. Chromium- molybdenum (Cr - 5 %) steel and structural low-alloy manganese steel (Mn - 1.4 %) was

Algirdas Vaclovas VALIULIS

2007-01-01

243

Influence of incomplete annealing of titanium (a + ?)-alloy and its welded joints on fatigue resistance and corrosion-fatigue resistance  

Microsoft Academic Search

We investigate the influence of incomplete annealing (675?C, 10 h) on fatigue, corrosion-fatigue, and high-temperature (up\\u000a to 500?C) fatigue resistance of titanium (a+ ?)-alloy Ti-5A1- 1.5V- IMo with nominal composition as well as its welded joints\\u000a made by the electron-beam method. The effect of annealing depends on a totality of factors which dominate in different ways\\u000a under fatigue fracture in

O. S. Kalakhan; V. I. Pokhmurs’kyi

2000-01-01

244

Residual Stress Distribution of 600MPa Grade High Tensile Strength Steel Pipe Using Welding fe Simulation  

NASA Astrophysics Data System (ADS)

This paper aims to determine the residual stress distribution of 600MPa grade high tensile strength steel pipe (STKT590) by girth welding. Welding FE simulation is achieved considering temperature dependent physical constants and mechanical properties, obtained by the temperature elevated tensile tests. Comparative analyses clarify the characteristics of residual stress profile near weld joint of STKT590 pipe.

Chang, Kyong-Ho; Jang, Gab-Chul

2011-06-01

245

JFIT: a framework to obtain combined experimental results through joint fits  

E-print Network

A framework is presented for obtaining combined experimental results through joint fits of datasets from several experiments. The JFIT framework allows such fits to be performed keeping the data separated, in its original format, and using independent fitting environments, thus simplifying the process with respect to data access policies. It is based on a master-server architecture, using the network communication classes from ROOT. The framework provides an optimal way to exploit data from several experiments: it ensures that correlations are correctly taken into account and results in a better determination of nuisance parameters. Its advantages are discussed and illustrated by two examples from the domain of high energy physics.

Eli Ben-Haim; René Brun; Bertrand Echenard; Thomas E. Latham

2014-09-17

246

Hot cracking of welded joints of the 7CrMoVTiB 10-10 (T/P24) steel  

NASA Astrophysics Data System (ADS)

Bainitic steel 7CrMoVTiB10-10 is one the newest steels for waterwalls of modern industrial boilers [1]. In Europe, attempts have been made to make butt welded joints of pipes made of this steel of the diameter up to 51 mm and thickness up to 8 mm. Many cracks have been observed in the welded joint, both during welding and transport and storage [2-4]. The reasons of cracking and the prevention methods have not been investigated. No comprehensive research is carried out in Europe in order to automate the welding process of the industrial boiler elements made of modern bainitic steel, such as 7CrMoVTiB10-10. There is no information about its overall, operative and local weldability, influence of heat treatment, as well as about resistance of the joints to cracking during welding and use. The paper presents experience of Energoinstal SA from development of technology and production of waterwalls of boilers made of the 7CrMoVTiB 10-10 steel on a multi-head automatic welder for submerged arc welding.

Adamiec, J.

2011-05-01

247

Weld penetration and defect control. Final report  

SciTech Connect

Highly engineered designs increasingly require the use of improved materials and sophisticated manufacturing techniques. To obtain optimal performance from these engineered products, improved weld properties and joint reliability are a necessarily. This requirement for improved weld performance and reliability has led to the development of high-performance welding systems in which pre-programmed parameters are specified before any welding takes place. These automated systems however lack the ability to compensate for perturbations which arise during the welding process. Hence the need for systems which monitor and control the in-process status of the welding process. This report discusses work carried out on weld penetration indicators and the feasibility of using these indicators for on-line penetration control.

Chin, B.A.

1992-05-15

248

Effects of CaF2 Coating on the Microstructures and Mechanical Properties of Tungsten Inert Gas Welded AZ31 Magnesium Alloy Joints  

NASA Astrophysics Data System (ADS)

The effects of CaF2 coating on the macromorphologies of the welded seams were studied by morphological analysis. Microstructures and mechanical properties of butt joints welded with different amounts of CaF2 coatings were investigated using optical microscopy and tensile tests. The welding defects formed in the welded seams and the fracture surfaces were analyzed by scanning electron microscopy. An increase in the amount of CaF2 coating deteriorated the appearances of the welded seams but it improved the weld penetration depth and the depth/width ( D/ W) ratio of the tungsten inert gas (TIG) welded joints. The ?-Mg grains and Mg17(Al,Zn)12 intermetallic compound (IMC) were coarser in the case of a higher amount of CaF2 coating. The increase in the amount of CaF2 coating reduced the porosities and total length of solidification cracks in the fusion zone (FZ). The ultimate tensile strength (UTS) value and elongation increased at first and then decreased sharply.

Shen, Jun; Wang, Linzhi; Peng, Dong; Wang, Dan

2012-11-01

249

Effect of Capping Front Layer Materials on the Penetration Resistance of Q&T Steel Welded Joints Against 7.62-mm Armor-Piercing Projectile  

NASA Astrophysics Data System (ADS)

In the present investigation, an attempt has been made to study the effect of capping front layers on the ballistic performance of shielded metal arc-welded armor steel joints which were fabricated with a chromium carbide-rich hardfaced middle layer on the buttered/beveled edge. Two different capping front layer materials were chosen for achieving better ballistic performance, namely, low hydrogen ferritic (LHF) and austenitic stainless steel (SS) fillers. On the other hand, the bottom layers are welded with SS filler for both joints. The consequent sandwiched joint served the dual purpose of weld integrity and penetration resistance of the bullet. It is observed that the penetration resistance is due to the high hardness of the hardfacing layer on the one hand and the energy-absorbing capacity of the soft backing SS weld deposits on the other hand. The complementary effect of layers successfully provided resistance to the projectile penetration. On a comparative analysis, the joint fabricated using the LHF filler capping front layer offered superior ballistic performance with respect to depth of penetration. This is mainly due to the presence of acicular ferrite along the bainitic structure in the LHF capping front layer, which caused a shallow hardness gradient along the weld center line.

Balakrishnan, M.; Balasubramanian, V.; Madhusudhan Reddy, G.; Parameswaran, P.

2013-09-01

250

Prediction and comparison of the area of the heat-affected zone for the bead-on-plate and bead-on-joint in submerged arc welding of pipes  

Microsoft Academic Search

The effect of controllable process variables on the heat input and the area of the heat-affected zone (HAZ) for bead-on-plate and bead-on-joint welding were calculated and analyzed using mathematical models developed for the submerged arc welding of pipes (SAW). A comparative study of the area of the heat-effected zone between bead-on-plate and bead-on-joint welding was carried out.This comparative study reveals

V Gunaraj; N Murugan

1999-01-01

251

Microstructure and Mechanical Properties of Pulsed Laser Beam Welded Ti-2Al-1.5Mn Titanium Alloy Joints  

NASA Astrophysics Data System (ADS)

The microstructure and mechanical properties in the pulsed laser beam welded joints of Ti-2Al-1.5Mn titanium alloy thin sheet were investigated in this study. The results show that the original ? + ?-phases and the transformed ? + ?'-phases are found in the partially transformed heat-affected zone (HAZ) together with the remaining ?-phase, and the microhardness gradually enhances in the region as the result of the increase of ?'-phase. The martensitic ?'-phase and the remaining ?-phase are detected in the fully transformed HAZ and the fusion zone (FZ), and the highest microhardness is found in these regions in virtue of the dominant ?'-phase structure. The fine ?'-phase appeared in the FZ results in higher average microhardness at high welding speed. Moreover, similar to the results of microhardness test, the tensile test results mean that the HAZ and FZ are stronger than the base metal (BM). Therefore, pulsed laser beam welding is feasible for joining thin sheet of Ti-2Al-1.5Mn titanium alloy.

Fang, Xiuyang; Liu, Hong; Zhang, Jianxun

2014-06-01

252

Weld joint concepts for on-orbit repair of Space Station Freedom fluid system tube assemblies  

NASA Astrophysics Data System (ADS)

Because Space Station Freedom (SSF) is an independent satellite, not depending upon another spacecraft for power, attitude control, or thermal regulation, it has a variety of tubular, fluid-carrying assemblies on-board. The systems of interest in this analysis provide breathing air (oxygen and nitrogen), a working fluid (two-phase anhydrous ammonia) for thermal control, and a monopropellant (hydrazine) for station reboost. The tube assemblies run both internally and externally with respect to the habitats. They are found in up to 50 ft. continuous lengths constructed of mostly AISI 316L stainless steel tubing, but also including some Inconel 625 nickel-iron and Monel 400 nickel-copper alloy tubing. The outer diameters (OD) of the tubes range from 0.25-1.25 inches, and the wall thickness between 0.028-.095 inches. The system operational pressures range from 377 psi (for the thermal control system) to 3400 psi (for the high pressure oxygen and nitrogen supply lines in the ECLSS). SSF is designed for a fifteen to thirty year mission. It is likely that the tubular assemblies (TA's) will sustain damage or fail during this lifetime such that they require repair or replacement. The nature of the damage will be combinations of punctures, chips, scratches, and creases and may be cosmetic or actually leaking. The causes of these hypothetical problems are postulated to be: (1) faulty or fatigued fluid joints--both QD's and butt-welds; (2) micro-meteoroid impacts; (3) collison with another man-made object; and (4) over-pressure strain or burst (system origin). While the current NASA baseline may be to temporarily patch the lines by clamping metal c-sections over the defect, and then perform high pressure injection of a sealing compound, it is clear that permanent repair of the line(s) is necessary. This permanent repair could be to replace the entire TA in the segment, or perhaps the segment itself, both alternatives being extremely expensive and risky. The former would likely require extensive EVA to release TA clamps and pose great risk to other engineering subsystems, and the latter would require major de-servicing of the Station.

Jolly, Steven D.

1993-11-01

253

A Comparative Analysis of the Impact of Tool Design to Fatigue Behavior of Single-Sided and Double-Sided Welded Butt Joints of EN AW 6082-T6 Alloy  

NASA Astrophysics Data System (ADS)

In this paper, the results of fatigue behavior on friction stir welded joints of aluminum alloy EN AW 6082-T6 are reported. In particular, the study presents the influence of the geometry of a welding tool on fatigue strengths and tensile strengths. The test joints were prepared as single side welded and double side welded by FSW. The welding was performed at various linear welding speeds (224, 560, and 900 mm/min) and one rotational speed of 710 rev./min using three different tool shapes. The results of macro examination and tensile test led to the selection of a single set of tool movement parameters at which the test joints for fatigue test were made. Samples were tested in two states of surface condition, i.e., "as-welded" and with mechanically removed marks left by rotating and moving tool during FSW process. Studies have shown that fatigue behavior of FSW joints depends on the tool shape used in the welding process as well as the surface condition of welded joints and manner of joint production.

Krasnowski, K.; Dymek, S.

2013-12-01

254

Weld-Bead Shaver  

NASA Technical Reports Server (NTRS)

Hand-held power tool shaves excess metal from inside circumference of welded duct. Removes excess metal deposited by penetration of tungsten/inert-gas weld or by spatter from electron-beam weld. Produces smooth transition across joint. Easier to use and not prone to overshaving. Also cuts faster, removing 35 in. (89 cm) of weld bead per hour.

Guirguis, Kamal; Price, Daniel S.

1990-01-01

255

Long-Term Integrity of Waste Package Final Closure for HLW Geological Disposal, (VI) Consistency of the Structural Integrity Evaluation Model for the Weld Joint  

Microsoft Academic Search

Overpack, a container of high-level radioactive waste for Japan's geological disposal program, is required to prevent the sealed vitrified waste from coming into contact with groundwater for 1,000 years. This means that the same duration and function arerequired for the weld joint between the body and lid of the overpack. The authors have initiated studies on a methodology evaluating the

Hidekazu ASANO; Masanori ARITOMI

2010-01-01

256

Microstructures of Inconel 718 alloy subjected to rapid thermal and stress cycle – joint performance and its controlling factors in friction welding of Inconel 718 alloy  

Microsoft Academic Search

The microstructures of an Inconel 718 alloy subjected to rapid thermal and stress cycles have been investigated to explain those observed in the friction welded joint of the alloy. The thermal and stress cycles were simulated with a Gleeble thermal and mechanical simulator. It turned out that the microstructural changes caused by the rapid heating cycle at peak temperatures of

Hongjie Wang; Kenji Ikeuchi; Makoto Takahashi; Akio Ikeda

2009-01-01

257

Automated evaluation of the quality of butt welded joint in magnetographic flaw inspection. II. Examination of the operation efficiency of an algorithm for suppressing the bead signal  

SciTech Connect

A model of a surface dipole is used to examine by numerical modeling the efficiency of the algorithm of suppressing signal of the bead of a butt welded joint in magnetographic flaw inspection. The results show that the defects can be automatically evaluated on the basis of the characteristics of the resultant signal.

Mikhailov, S.P.; Scherbinin, V.E.

1994-12-01

258

Careers in Welding  

NSDL National Science Digital Library

Careers in Welding is a portal jointly produced by the American Welding Society and Weld-Ed, the Nation Center for Welding Education and Training. Here, visitors will find information for educators, students, and welding professionals, in addition to general information about exploring a career in welding. Educators can find teaching tips, curriculum, professional development information, resources and products, events, and networking opportunities. Students can find information about schools with welding programs, scholarships, jobs, and much more. For the welding professional, the site has tips for building a resume, finding a job, and AWS certification information. The site also features videos of technicians and general articles, such as "Why Welding?" and "Welding Fast Facts," that offer information on why to choose a career in welding.

2010-04-15

259

Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel  

NASA Astrophysics Data System (ADS)

The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires.

Mirshekari, G. R.; Saatchi, A.; Kermanpur, A.; Sadrnezhaad, S. K.

2013-12-01

260

Charpy impact test of Ti6Al4V joints diffusion welded at low temperature  

Microsoft Academic Search

The Diffusion Welding (DW) of two or more sheets of Ti-6Al-4V alloy is particularly interesting for aerospace parts manufacturing. In some cases, DW can be carried out together with Superplastic Forming (SPF), because they can share a single facility and the same processing parameters, such as temperature, pressure, time, surface condition and vacuum. The overall manufacturing process is known as

J. M. Gómez de Salazar; A. Ureña; J. G. Carrión

1996-01-01

261

Residual stress evaluation and fatigue life prediction in the welded joint by x-ray diffraction  

NASA Astrophysics Data System (ADS)

In the fossil power plant, the reliability of the components which consist of the many welded parts depends on the quality of welding. The residual stress is occurred by the heat flux of high temperature during weld process. This decreases the mechanical properties as the strength of fatigue and fracture. The residual stress of the welded part in the recently constructed power plants has been the cause of a variety of accidents. The objective of this study is measurement of the residual stress and the full width at half maximum intensity (FWHM) by X-ray diffraction method and to estimate the feasibility of this application for fatigue life assessment of the high-temperature pipeline. The materials used for the study is P92 steel for the use of high temperature pipe on super critical condition. The test results were analyzed by the distributed characteristics of residual stresses and FWHM in x-ray diffraction intensity curve. Also, X-ray diffraction tests using specimens simulated low cycle fatigue damage were performed in order to analyze fatigue properties when fatigue damage conditions become various stages. As a result of X-ray diffraction tests for specimens simulated fatigue damages, we conformed that the ratio of the FWHM due to fatigue damage has linear relationship with fatigue life ratio algebraically. From this relationship, it was suggested that direct expectation of the life consumption rate was feasible.

Yoo, Keun Bong; Hwang, Kwon Tae; Chang, Jung Chel; Kim, Jae Hoon

2009-07-01

262

Effects of laser-weld joint opening size on fatigue strength of Ti-6Al-4V structures with several diameters.  

PubMed

This study was conducted to evaluate the fatigue strength of Ti-6Al-4V laser-welded joints with several diameters and joint openings. Sixty dumbbell rods were machined in Ti-6Al-4V alloy with central diameters of 1·5, 2·0 and 3·5 mm. The specimens were sectioned and then welded using two joint openings (0·0 and 0·6 mm). The combination of variables created six groups, which when added to the intact groups made a total of nine groups (n = 10). Laser welding was executed as follows: 360 V per 8 ms (1·5 and 2·0 mm) and 380 V per 9 ms (3·5 mm) with focus and frequency regulated to zero. The joints were finished, polished and submitted to radiographic examination to be analysed visually for the presence of porosity. The specimens were then subjected to a mechanical cyclic test, and the number of cycles until failure was recorded. The fracture surface was examined with a scanning electron microscope (SEM). The Kruskal-Wallis test and Dunn test (? = 0·05) indicated that the number of cycles required for fracture was lower for all specimens with joint openings of 0·6 mm, and for 3·5-mm-diameter specimens with joint openings of 0·0 mm. The Spearman correlation coefficient (? = 0·05) indicated that there was a negative correlation between the number of cycles and the presence of porosity. So, laser welding of Ti-6Al-4V structures with a thin diameter provides the best conditions for the juxtaposition of parts. Radiographic examination allows for the detection of internal voids in titanium joints. PMID:20678101

Nuñez-Pantoja, J M C; Vaz, L G; Nóbilo, M A A; Henriques, G E P; Mesquita, M F

2011-03-01

263

Infrared Thermography For Welding  

NASA Technical Reports Server (NTRS)

Infrared imaging and image-data-processing system shows temperatures of joint during welding and provides data from which rates of heating and cooling determined. Information used to control welding parameters to ensure reliable joints, in materials which microstructures and associated metallurgical and mechanical properties depend strongly on rates of heating and cooling. Applicable to variety of processes, including tungsten/inert-gas welding; plasma, laser, and resistance welding; cutting; and brazing.

Gilbert, Jeffrey L.; Lucky, Brian D.; Spiegel, Lyle B.; Hudyma, Russell M.

1992-01-01

264

Study of weld offset in longitudinally welded SSME HPFTP inlet  

NASA Technical Reports Server (NTRS)

Welded joints are an essential part of rocket engine structures such as the Space Shuttle Main Engine (SSME) turbopumps. Defects produced in the welding process can be detrimental to weld performance. Recently, review of the SSME high pressure fuel turbopump (HPFTP) titanium inlet X-rays revealed several weld discrepancies such as penetrameter density issues, film processing discrepancies, weld width discrepancies, porosity, lack of fusion, and weld offsets. Currently, the sensitivity of welded structures to defects is of concern. From a fatigue standpoint, weld offset may have a serious effect since local yielding, in general, aggravates cyclic stress effects. Therefore, the weld offset issue is considered in this report. Using the FEM and beamlike plate approximations, parametric studies were conducted to determine the influence of weld offsets and a variation of weld widths in longitudinally welded cylindrical structures with equal wall thicknesses on both sides of the joint. Following the study, some conclusions are derived for the weld offsets.

Min, J. B.; Spanyer, K. S.; Brunair, R. M.

1992-01-01

265

Intelligent Modeling Combining Adaptive Neuro Fuzzy Inference System and Genetic Algorithm for Optimizing Welding Process Parameters  

NASA Astrophysics Data System (ADS)

Modified 9Cr-1Mo ferritic steel is used as a structural material for steam generator components of power plants. Generally, tungsten inert gas (TIG) welding is preferred for welding of these steels in which the depth of penetration achievable during autogenous welding is limited. Therefore, activated flux TIG (A-TIG) welding, a novel welding technique, has been developed in-house to increase the depth of penetration. In modified 9Cr-1Mo steel joints produced by the A-TIG welding process, weld bead width, depth of penetration, and heat-affected zone (HAZ) width play an important role in determining the mechanical properties as well as the performance of the weld joints during service. To obtain the desired weld bead geometry and HAZ width, it becomes important to set the welding process parameters. In this work, adaptative neuro fuzzy inference system is used to develop independent models correlating the welding process parameters like current, voltage, and torch speed with weld bead shape parameters like depth of penetration, bead width, and HAZ width. Then a genetic algorithm is employed to determine the optimum A-TIG welding process parameters to obtain the desired weld bead shape parameters and HAZ width.

Gowtham, K. N.; Vasudevan, M.; Maduraimuthu, V.; Jayakumar, T.

2011-04-01

266

Improving fatigue performance of rail thermite welds  

NASA Astrophysics Data System (ADS)

Rail transport development offers economic and ecological interests. Nevertheless, it requires heavy investments in rolling material and infrastructure. To be competitive, this transportation means must rely on safe and reliable infrastructure, which requires optimization of all implemented techniques and structure. Rail thermite (or aluminothermic) welding is widely used within the railway industry for in-track welding during re-rail and defect replacement. The process provides numerous advantages against other welding technology commonly used. Obviously, future demands on train traffic are heavier axle loads, higher train speeds and increased traffic density. Thus, a new enhanced weld should be developed to prevent accidents due to fracture of welds and to lower maintenance costs. In order to improve such assembly process, a detailed metallurgical study coupled to a thermomechanical modelling of the phenomena involved in the thermite welding process is carried out. Obtained data enables us to develop a new improved thermite weld (type A). This joint is made by modifying the routinely specified procedure (type B) used in a railway rail by a standard gap alumino-thermic weld. Joints of type A and B are tested and compared. Based on experimental temperature measurements, a finite element analysis is used to calculate the thermal residual stresses induced. In the vicinity of the weld, the residual stress patterns depend on the thermal conditions during welding as it also shown by litterature [1, 2]. In parallel, X-Ray diffraction has been used to map the residual stress field that is generated in welded rail of types A and B. Their effect on fatigue crack growth in rail welds is studied. An experimental study based on fatigue tests of rails welded by conventional and improved processes adjudicates on the new advances and results will be shown.

Jezzini-Aouad, M.; Flahaut, P.; Hariri, S.; Winiar, L.

2010-06-01

267

Dual wire welding torch and method  

DOEpatents

A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

Diez, Fernando Martinez (Peoria, IL); Stump, Kevin S. (Sherman, IL); Ludewig, Howard W. (Groveland, IL); Kilty, Alan L. (Peoria, IL); Robinson, Matthew M. (Peoria, IL); Egland, Keith M. (Peoria, IL)

2009-04-28

268

49 CFR 179.300-9 - Welding.  

Code of Federal Regulations, 2010 CFR

... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks...171.7 of this subchapter). (b) Fusion-welded joints must be in...

2010-10-01

269

Corrosion and mechanical strength of welded joints of downcomers for RBMK reactors  

Microsoft Academic Search

In the process of operation of RBMK reactors damage took place on welded pipings produced from austenitic stainless steel of the type 08X18H10T. The inspection of damaged sections in pipings has shown that in most cases crack-like defects were of corrosion and mechanical character. This paper considers in detail the reasons for the damage appearance and their development for this

B. T. Timofeev; G. P. Karzov; A. A. Gorbakony; Yu. K. Nikolaev

1999-01-01

270

Details of the Electro-Mechanical (E/M) Impedance Health Monitoring of Spot-Welded Structural Joints  

E-print Network

-alloy spot-welded lap shear specimens under fatigue loading to determine a stable pattern of crack1 Details of the Electro-Mechanical (E/M) Impedance Health Monitoring of Spot-Welded Structural, spot- welding play a major role. Spot welding is the traditional method of assembly for steel

Giurgiutiu, Victor

271

Study on microstructures and mechanical properties of laser-arc hybrid welded S355J2W+N steel  

NASA Astrophysics Data System (ADS)

The technology of laser-MAG hybrid welding was used on 16 mm thick plate of weathering steel S355J2W+N. Under the welding parameters used in the experiment, full penetration weld without flaws such as pores, cracks and lack of fusion was obtained by a three-layer and three-pass welding technique. In this study, the outstanding advantages of laser-arc hybrid welding were summarized by comparison with welded joint of traditional MAG welding. The microstructure of hybrid welded joint has also been detailed investigated. Besides, the mechanical property tests were performed according to corresponding European standards. Furthermore, the tensile and impact strength of laser-MAG hybrid welded joint turned out to be almost as good as base metal. Most of the hybrid welded joints had a good bending property, but for some sample, there was a micro-crack with the length of 0.9 mm emerging within the transition region where contraction stress would accumulate and remain, being one of the most vulnerable zones in weld metal. The results show that laser-MAG hybrid welding technology is appropriate for S355J2W+N thick plate welding, in favor of not only improving the product performance, but also lowering the production cost and improving the productivity.

Zhen, Shu; Duan, Zhenzhen; Sun, Daqian; Li, Yexiong; Gao, Dandan; Li, Hongmei

2014-07-01

272

Diffusion welding of SUS304L stainless steel to titanium  

Microsoft Academic Search

The purposes of this study are first to investigate the relationship between the diffusion welding parameters and quality of SUS304L stainless steel\\/titanium diffusion?welded joints, and second to develop a bonding method to obtain sound joints, by vacuum heat treatment for surface control. The equipment used consists of an ultra?high vacuum chamber and surface analysis chamber with Auger device.The strength of

O. O. Hashi; K. El; H. Irie

1996-01-01

273

Installation for ultrasonic quality control of soldered and diffusion welded joints in miniature assemblies  

Microsoft Academic Search

The article describes the operating principle and the design of an automatic ultrasonic device for the quality control of joints in miniature assemblies with inner diameter of 6-30 mm and wall thickness of 1-4 mm. The installation is intended for detecting defects type dry joint, delamination, and pore with 0.3 mm diameter or more. Special features of the design and

A. E. Glagolev; G. F. Gavryushina; G. F. Bortsov; L. V. Myakinkova

1988-01-01

274

Effect of Welding Parameters on the Microstructure and Strength of Friction Stir Weld Joints in Twin Roll Cast EN AW Al-Mn1Cu Plates  

NASA Astrophysics Data System (ADS)

Twin roll cast EN AW Al-Mn1Cu plates were butt welded with the friction stir welding process which employed a non-consumable tool, tilted by 1.5° and 3° with respect to the plate normal, rotated in a clockwise direction at 400 and 800 rpm, while traversing at a fixed rate of 80 mm/min along the weld line. Microstructural observations and microhardness tests were performed on sections perpendicular to the tool traverse direction. Tensile tests were carried out at room temperature on samples cut perpendicular to the weld line. The ultimate tensile strength of the welded EN AW Al-Mn1Cu plates improved with increasing tool rotation speed and decreasing tool tilt angle. This marked improvement in ultimate tensile strength is attributed to the increase in the heat input owing to an increased frictional heat generation. There appears to be a perfect correlation between the ultimate tensile strength and the size of the weld zone. The fracture surfaces of the base plate and the welded plates are distinctly different. The former is dominated by dimples typical of ductile fractures. A vast majority of the intermetallic particles inside the weld zones are too small to generate dimples during a tensile test. The fracture surface of the welded plates is thus characterized by occasional dimples that are elongated in the same direction suggesting a tensile tearing mechanism.

Birol, Yucel; Kasman, Sefika

2013-10-01

275

3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications  

NASA Astrophysics Data System (ADS)

Laser transmission welding is an established single-stage plastic joining process, which enables hermetically sealed joints under the workpiece surface. The process requires joining partners with proper degrees of transmission and absorption to the processing wavelength. For reaching a stable process an in-process quality assurance is very valuable. Current monitoring systems have a limited usage, as no quantitative information of the weld itself is obtained without its destruction. In medical and pharmaceutical applications a weld with leakage is e.g. unacceptable. The main objective of this paper is the presentation of the optical coherence tomography as a tool for the quality assurance in laser transmission welding. This approach enables the measurement of any residual gap, weld geometry, internal pores and leaks. The presented results show that this technique allows even the characterization of welds using joining partners with thicknesses of 2 mm or with glass fiber reinforcement levels of 30% per weight.

Schmitt, Robert; Mallmann, Guilherme; Devrient, Martin; Schmidt, Michael

276

Microstructure Improvement in Weld Metal under the Ultrasonic Application  

SciTech Connect

When considering the operational performance of weldments in the engineering projects, the most important issues to be considered are weld metal mechanical properties, integrity of the welded joint, and weldability 1 . These issues are closely related to the microstructure of the weld metal. A significant amount of research has been carried out to alter the process variables and to use external devices to obtain microstructure control of the weldments. It has been reported that grain refined microstructure not only reduces cracking behavior of alloys including solidification cracking, cold cracking and reheat cracking, 2 - 5 but also improves the mechanical properties of the weld metal, such as toughness, ductility, strength, and fatigue life. 6, 7 Weld pool stirring, 8 arc oscillation, 9, 10 arc pulsation, 11 , and magnetic arc oscillator 12, 13 have been applied to fusion welding to refine the microstructures. This article describes initial experimental results on the use of power ultrasonic vibration to refine the microstructure of weld metals.

Cui, Yan [University of Tennessee, Knoxville (UTK); Xu, Cailu [University of Tennessee, Knoxville (UTK); Han, Qingyou [ORNL

2007-01-01

277

The variable polarity plasma arc welding process: Characteristics and performance  

NASA Technical Reports Server (NTRS)

Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. The power distribution was analyzed for an argon plasma gas flow constituting the fluid in the VPPA Welding Process. The major heat loss at the torch nozzle is convective heat transfer; in the space between the outlet of the nozzle and the workpiece; radiative heat transfer; and in the keyhole in the workpiece, convective heat transfer. The power absorbed at the workpiece produces the molten puddle that solidifies into the weld bead. Crown and root widths, and crown and root heights of the weld bead are predicted. The basis is provided for an algorithm for automatic control of VPPA welding machine parameters to obtain desired weld bead dimensions.

Hung, R. J.; Zhu, G. J.

1991-01-01

278

Automated Variable-Polarity Plasma-Arc Welding  

NASA Technical Reports Server (NTRS)

Variable-polarity plasma-arc methods produces better welds at lower cost than gas-shielded tungsten-arc welding in assemblies. Weld porosity very low and costs of joint preparation, depeaking, inspection, and weld repair minimized.

Numes, A. C., Jr.; Bayless, E. O., Jr.; Jones, S. C., III; Munafo, P.; Munafo, A.; Biddle, A.; Wilson, W.

1984-01-01

279

A study on the control of melting ratio to increase mechanical properties of laser welded joints between AISI 440C and AISI 430F  

NASA Astrophysics Data System (ADS)

Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio.

Romoli, L.; Rashed, C. A. A.; Lovicu, G.; Ishak, R.

2015-05-01

280

Effect of formation and state of interface on joint strength in friction stir spot welding for advanced high strength steel sheets  

NASA Astrophysics Data System (ADS)

The tensile shear strength and cross tension strength of friction stir spot welded joints were evaluated in the cases of lap joints of 270 N/mm2 grade and 980 N/mm2 grade cold rolled steel sheets with respect to the stir zone area, hardness distribution, and interface condition between the sheets. The results suggested that both the tensile shear strength and cross tension strength were based on the stir zone area and its hardness in both grades of steel. The "hook" shape of the interface also affected the joint strength. However, the joining that occurred across the interfaces had a significant influence on the value of the joint strength in the case of the 270 N/mm2 grade steel.

Taniguchi, Koichi; Matsushita, Muneo; Ikeda, Rinsei; Oi, Kenji

2014-08-01

281

Application of YAG Laser TIG Arc Hybrid Welding to Thin AZ31B Magnesium Alloy Sheet  

NASA Astrophysics Data System (ADS)

A magnesium alloy is said to be an ecological material with high ability of recycling and lightweight property. Especially, magnesium alloys are in great demand on account of outstanding material property as a structural material. Under these circumstances, research and development of welding process to join magnesium alloy plates are of great significance for wide industrial application of magnesium. In order to use it as a structure material, the welding technology is very important. TIG arc welding process is the most ordinary process to weld magnesium alloy plates. However, since the heat source by the arc welding process affects the magnesium alloy plates, HAZ of welded joint becomes wide and large distortion often occurs. On the other hand, a laser welding process that has small diameter of heat source seems to be one of the possible means to weld magnesium alloy in view of the qualitative improvement. However, the low boiling point of magnesium generates some weld defects, including porosity and solidification cracking. Furthermore, precise edge preparation is very important in butt-welding by the laser welding process, due to the small laser beam diameter. Laser/arc hybrid welding process that combines the laser beam and the arc is an effective welding process in which these two heat sources influence and assist each other. Using the hybrid welding, a synegistic effect is achievable and the disadvantages of the respective processes can be compensated. In this study, YAG laser/TIG arc hybrid welding of thin magnesium alloy (AZ31B) sheets was investigated. First of all, the effect of the irradiation point and the focal position of laser beam on the quality of a weld were discussed in hybrid welding. Then, it was confirmed that a sound weld bead with sufficient penetration is obtained using appropriate welding conditions. Furthermore, it was made clear that the heat absorption efficiency is improved with the hybrid welding process. Finally, the tensile tests of welded joints were performed, and it was confirmed that they have sufficient mechanical properties. As a result of this study, it is confirmed that, if the appropriate welding conditions are selected, sound welded joints of AZ31B magnesium alloy are obtainable by the YAG laser/TIG arc hybrid welding process.

Kim, Taewon; Kim, Jongcheol; Hasegawa, Yu; Suga, Yasuo

282

Development of Alloy and Superalloy Large Shafts by Friction Welding Process  

NASA Astrophysics Data System (ADS)

The aim of this study is to examine the process parameters of superalloy and alloy steel inertia welding using FE simulation and to evaluate the mechanical properties of a welded joint. FE simulation was carried out to optimize the inertia welding process parameters. Disk of rotor shaft and head of exhaust valve spindle are made by the hot closed die forging. Dissimilar inertia welding for large exhaust valve spindle manufacturing composed of the Nimonic 80 A valve head of 540 mm diameter and the SNCrW valve stem of 115 mm diameter, and for large rotor shaft manufacturing composed of the 310 mm diameter disk and the 140 mm diameter shaft were carried out with optimal process parameter conditions obtained simulation result. Inertia friction welded joint part was joined by inertia friction welder, MTI model 400. Mechanical and metallurgical properties of welded joints were evaluated by using microstructure, tensile, hardness and fatigue tests.

Jeong, H. S.; Cho, J. R.; Choi, S. K.; Oh, J. S.; Kim, E. N.

2010-06-01

283

The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds.  

E-print Network

of laser welds. S. BANNOURa,b * , K. ABDERRAZAKa , S. MATTEIc , J.E. MASSEd , M. AUTRICb , H. MHIRIa, 13617 Aix en Provence, France. Abstract Structure and properties of laser beam welding zone and quality of the Mg/Al weld were studied by metallography, microhardness and optical microscopy. Differences

Paris-Sud XI, Université de

284

Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel  

NASA Astrophysics Data System (ADS)

The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (?) and austenite (?) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the ? phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the ? phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with ? phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

2013-09-01

285

Low-Power Laser/Arc Hybrid Welding Behavior in AZ-Based Mg Alloys  

NASA Astrophysics Data System (ADS)

The low-power laser/arc hybrid welding behaviors of the AZ-based Mg alloys in similar and dissimilar joints are examined in this study in terms of welding parameters, fusion-zone characteristics, mechanical properties, welding temperature fields, and laser-induced arc plasma/plume. Experiments were conducted using a low-power (300 W) pulsed Nd:YAG laser with a gas tungsten welding arc. The results show that the AZ-based Mg alloys can be easily welded by laser/arc hybrid welding process. The introduction of low-power laser beam can stabilize the welding arc even at a high-speed welding, and spattering behavior of laser welding disappeared due to the introduction of welding arc. With the increases of arc power, a higher weld depth can be obtained, and the weld depths for laser and arc acting in combination (laser/arc) are 2 times higher than those of for laser and arc acting separately (laser + arc) in optimal conditions. The postweld tensile strength of Mg alloys could recover ˜80 to 100 pct of the original strength in similar or dissimilar joints. The fatigue strength in laser/arc hybrid welded specimens is equal to that of the unweld base metal.

Liu, L. M.; Song, G.; Zhu, M. L.

2008-07-01

286

The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys  

NASA Astrophysics Data System (ADS)

Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

Güler, Hande

2014-09-01

287

The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys  

NASA Astrophysics Data System (ADS)

Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

Güler, Hande

2014-10-01

288

Extended electrode technique. [gas metal arc welding of metal plates  

NASA Technical Reports Server (NTRS)

The extended electrode technique is a unique welding process which utilizes manual gas-metal-arc (GMAW) semi-automatic equipment and close, square butt joints to effectively produce a weld. The technique takes advantage of the resistance heating of the electode extension to effect the root pass. Weldments as large as 72-X30-X2-inch have been fabricated with this technique under normal shipyard welding conditions. Mechanical properties and explosion bulge tests indicate that satisfactory results are obtained with this process. Potential savings of approximately 50 percent can be achieved in flat welding and repair of heavy structural steel members.

Schaper, V. D.; Pollack, A.

1972-01-01

289

Microstructure and Toughness of Simulated Heat-Affected Zone of Laser Welded Joint for 960 MPa Grade High Strength Steel  

NASA Astrophysics Data System (ADS)

The microstructure and toughness of coarse grain zone (CGZ) and mixed grain zone (MGZ) for laser welded 960 MPa grade high strength steel joints were investigated by thermal simulation with a Gleeble-3500 thermal simulator. The results show that microstructure of the stimulated CGZ mainly consists of uniform interweaved lath martensite, and grain growth is not severe upon increasing the cooling time ( t 8/5). Microstructure of the stimulated MGZ presents strip-like in low peak temperature, and small block martensite is formed on the grain boundary. However, in high peak temperature, the strip-like microstructure disappears and small block martensite presents net-like structure. The lath character for MGZ and CGZ is very obvious under TEM observation, and the average lath thickness of BM, MGZ, and CGZ is 100, 150 and 200 nm, respectively. The impact energy and microhardness of CGZ are higher than MGZ and reduce with increasing the cooling time. The fracture toughness deteriorating drastically for MGZ may be related with the formation of the mixture microstructure, in which the small block martensite is distributed in the shape of a network.

Meng, Wei; Li, Zhuguo; Jiang, Xiaoxia; Huang, Jian; Wu, Yixiong; Katayama, Seiji

2014-10-01

290

Effect of long-term aging on microstructure and local behavior in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint  

SciTech Connect

Evolution of microstructure, micro-hardness and micro-tensile strength behavior was investigated in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint after the artificial aging at 350 °C for 3000 h. After detailed characterization of microstructures in optical microscopy, scanning electron microscopy and transmission electron microscopy, it is revealed that the change of martensite–bainite constituent promotes more homogeneous microstructure distribution. The aging treatment facilitates redistribution of carbon and chromium elements along the welded joint, and the micro-hardness is increased slightly through the welds due to enrichment of carbon. The types of precipitates in the weldment mainly include M{sub 3}C, MC, M{sub 2}C and M{sub 23}C{sub 6}. The carbides in base metal, weld metal and coarse-grained heat-affected zone are prone to change from ellipsoidal to platelet form whereas more uniform spherical carbides are observed in the fine-grained zone. Precipitation and coarsening of M{sub 23}C{sub 6} near the fusion line, and formation of MC and M{sub 2}C, are responsible for the tensile strength decrease and its smooth distribution in the aged heat-affected zone. This implies that the thermal aging can relieve strength mismatch in the weldments. - Highlights: • Microstructure homogeneity improved in HAZ after long-term aging. • Tensile strength decreased in HAZ due to precipitation and coarsening of M{sub 23}C{sub 6}. • Strength mismatch in NiCrMoV steel welds was relieved after aging at 350 °C × 3000 h.

Zhu, Ming-Liang, E-mail: mlzhu@ecust.edu.cn; Wang, De-Qiang; Xuan, Fu-Zhen

2014-01-15

291

Fracture evaluation of fusion line cracks in bimetallic welds  

SciTech Connect

There are many locations in nuclear power plants piping systems where carbon steel pipe or components are jointed to stainless steel pipe or components with a bimetallic weld. The objective of the research described in this paper was to assess the accuracy of current fracture analyses for the case of a crack along a carbon steel to austenitic weld fusion line. To achieve th is objective, material property data and data from a large-diameter (i.e., 36-inch) pipe fracture experiment were developed to assess current analytical methods. The bimetallic welds evaluated in this program were bimetallic welds obtained from a canceled Combustion Engineering plant. The welds joined sections of the carbon steel cold-leg piping system to stainless steel safe ends that were to be welded to stainless steel pump housings. The weld procedure involved buttering the carbon steel pipe with Inconel 182 weld metal and then completing the bulk of the weld using a shielded-metal-arc weld (SMAW) process using Inconel 182 weld rod. The major conclusion drawn as a result of these efforts was that the fracture behavior of the bimetallic weld evaluated in this program could be evaluated with reasonable accuracy using the strength and toughness properties of the carbon steel pipe base metal in conjunction with conventional J-estimation schemes. As will be discussed in this paper, this conclusion is only valid for the case where the weld is made using an Inconel weld procedure. If the weld is made using a stainless steel weld procedure, then decarburization at the fusion line may affect the fusion line toughness.

Scott, P.M.; Rudland, D.L.; Francini, R.B.; Marschall, C.; Wilkoswski, G.M. [Battelle, Columbus, OH (United States)

1996-12-01

292

Hydrogen in heavy wall submerged arc weld-joints of 2 1/4 Cr- 1 Mo steel after different soaking treatments  

SciTech Connect

The very important necessity of preventing hydrogen-induced cracks during the welding of 2 1/4 Cr - 1 Mo vessels requires reliable specifications for the dehydrogenation of the welded joints. A real evaluation of the hydrogen risk can only be based on actual figures which have been determined in original joints. For the tests, a 4-3/4 in. (120 mm) thick plate of 2-1/4 Cr - I Mo steel was used. Submerged arc welding was performed with an EB-3 wire and an agglomerated flux which has been used in the past decade for the above application. Immediately after welding, three different dehydrogenation treatments were performed: 2 h at 535{degrees}F (280{degrees}C), 4 h at 660{degrees}F (250{degrees}C), and 1 h at 1150{degrees}F (620{degrees}C). The results show that in all cases, the maximum level of hydrogen was found in the upper half of the joint. Especially interesting are the results of the diffusible hydrogen since its level is directly responsible for the delayed hydrogen cracks. The recommendation gained from the performed investigations is to modify the often-raised requirements of an intermediate stress relieving of highly stressed weldments. Both treatments, 2 h at 535{degrees}F (280{degrees}C) and 4 h at 660{degrees}F (250{degrees}C), result in a diffusible hydrogen content significantly below the critical limit. The application of 4 h at 550{degrees}F (250{degrees}C) even leads to hydrogen contents which are nearly as low as given by an intermediate stress relieving.

Dittrich, S.; Heuser, A.; Grote, G.

1994-12-31

293

Low cycle fatigue behavior of electron beam and friction welded joints of an {alpha}-{beta} titanium alloy  

SciTech Connect

Fusion welds in titanium alloys, with intermediate {beta} stabilizing additions, show poor mechanical properties due to large fusion zone grain size coupled with a brittle plate martensitic microstructure and hydrogen induced microporosity. These problems, associated with fusion welding, have been reported to be overcome by friction welding. The alloy used in this study is a Soviet composition (VT9) of the {alpha}-{beta} class with the nominal chemical composition Ti-6.5Al-3.3Mo-1.6Zr-0.3 Si (in weight percent), intended to be used as discs and blades in compressor stages of gas turbine engine where low cycle fatigue (LCF) loading is experienced. Electron beam welding of the alloy was largely unsuccessful for the reasons described above. Fatigue properties of such welds had large scatter due to the presence of microporosity. A continuous drive friction welding technique was investigated to overcome this problem These welds showed encouraging results in that microporosity, a problem in the electron beam welding, was not observed and the mechanical properties were at par or better than those of the base metal. This paper deals with the study of stress controlled LCF behavior of friction welds and electron beam welds of the {alpha}-{beta} titanium alloy at ambient temperature and the results are compared with those of base metal.

Mohandas, T.; Varma, V.K.; Banerjee, D. [Defence Metallurgical Research Lab., Hyderabad (India)] [Defence Metallurgical Research Lab., Hyderabad (India); Kutumbarao, V.V. [B.H.U., Varanasi (India). Dept. of Metallurgical Engineering] [B.H.U., Varanasi (India). Dept. of Metallurgical Engineering

1996-07-15

294

Algunas consideraciones sobre la contaminación ambiental en la obtención y uso de fundentes para la soldadura automática por arco sumergido Some considerations about the environmental contamination in the fluxes obtaining and use in the submerged arc welding  

Microsoft Academic Search

In the paper a some considerations about the environmental contamination during the obtaining process and use welding fluxes for submerged arc welding process are given. Is appreciated that the processes GMAW, SMAW and FCAW are those more studied regarding the indicative of environmental contamination, but solely related with the affections on the operatives and welders. However, the productive processes of

Facultad de Ingeniería Mecánica; Eriel Pérez Zapico; Carlos R. Gómez Pérez; Rafael Quintana Puchol; Lorenzo Perdomo González

295

Segregation behavior of phosphorus in the heat-affected zone of an A533B/A182 dissimilar weld joint before and after simulated thermal aging  

NASA Astrophysics Data System (ADS)

The segregation behavior of phosphorus (P) in the heat-affected zone (HAZ) of an A533B/A182 dissimilar weld joint before and after step cooling was investigated with atom probe tomography. At grain/packet boundaries, the final P segregation level consisted of non-equilibrium segregation that occurred during cooling after welding and post-weld heat treatment (PWHT) and equilibrium segregation that occurred during step cooling. In both processes, higher P coverage was observed in the coarse-grained and intercritically reheated coarse-grained HAZ than in the fine-grained HAZ and base material. The cooling after welding and PWHT seemed to have a pronounced impact on P segregation in the subsequent aging process. In addition, P segregation also occurred at the precipitate/matrix interfaces of cementite, Mo2C and Al-Si rich precipitates. The evolution of P coverage at these two types of sites suggested increasing risks of embrittlement with an increase in aging time.

Zhai, Ziqing; Miyahara, Yuichi; Abe, Hiroshi; Watanabe, Yutaka

2014-09-01

296

Optimization of laser welding thin-gage galvanized steel via response surface methodology  

NASA Astrophysics Data System (ADS)

The increasing demand of light weight and durability makes thin-gage galvanized steels (<0.6 mm) attractive for future automotive applications. Laser welding, well known for its deep penetration, high speed and small heat affected zone, provides a potential solution for welding thin-gage galvanized steels in automotive industry. In this study, the effect of the laser welding parameters (i.e. laser power, welding speed, gap and focal position) on the weld bead geometry (i.e. weld depth, weld width and surface concave) of 0.4 mm-thick galvanized SAE1004 steel in a lap joint configuration has been investigated by experiments. The process windows of the concerned process parameters were therefore determined. Then, response surface methodology (RSM) was used to develop models to predict the relationship between the processing parameters and the laser weld bead profile and identify the correct and optimal combination of the laser welding input variables to obtain superior weld joint. Under the optimal welding parameters, defect-free weld were produced, and the average aspect ratio increased about 30%, from 0.62 to 0.83.

Zhao, Yangyang; Zhang, Yansong; Hu, Wei; Lai, Xinmin

2012-09-01

297

Design of the friction stir welding tool using the continuum based FEM model  

Microsoft Academic Search

In friction stir welding (FSW), the welding tool geometry plays a fundamental role in obtaining desirable microstructures in the weld and the heat-affected zones, and consequently improving strength and fatigue resistance of the joint. In this paper, a FSW process with varying pin geometries (cylindrical and conical) and advancing speeds is numerically modeled, and a thermo-mechanically coupled, rigid-viscoplastic, fully 3D

G. Buffa; J. Hua; R. Shivpuri; L. Fratini

2006-01-01

298

Friction stir welding of AZ-91 and AM-Lite magnesium alloys  

Microsoft Academic Search

The objective of this paper was to report the results of butt joint quality of friction stir welding (FSW) of samples of alloys of MgAlZn group. Welding has been carried out with the FSW tool of welding speed ranging from 140 to 355 mm\\/min. In the stir zone and the surrounding, neither porosity nor cracks have been obtained. Microhardness in the

Lechos?aw Tuz; Pawe? Ko?odziejczak; Andrzej Kolasa

2011-01-01

299

Development of the weld-braze joining process  

NASA Technical Reports Server (NTRS)

A joining process, designated weld-brazing, was developed which combines resistance spot welding and brazing. Resistance spot welding is used to position and aline the parts, as well as to establish a suitable faying-surface gap for brazing. Fabrication is then completed at elevated temperature by capillary flow of the braze alloy into the joint. The process was used successfully to fabricate Ti-6Al-4V alloy joints by using 3003 aluminum braze alloy and should be applicable to other metal-braze systems. Test results obtained on single-overlap and hat-stiffened panel specimens show that weld-brazed joints were superior in tensile shear, stress rupture, fatigue, and buckling compared with joints fabricated by conventional means. Another attractive feature of the process is that the brazed joint is hermetically sealed by the braze material, which may eliminate many of the sealing problems encountered with riveted or spot welded structures. The relative ease of fabrication associated with the weld-brazing process may make it cost effective over conventional joining techniques.

Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

1973-01-01

300

Double-sided fiber laser beam welding process of T-joints for aluminum aircraft fuselage panels: Filler wire melting behavior, process stability, and their effects on porosity defects  

NASA Astrophysics Data System (ADS)

Aluminum alloy T-joints for aircraft fuselage panels were fabricated by double-sided fiber laser beam welding with filler wire, and the influence of the wire feeding posture on the welding process stability was investigated. A CMOS high speed video system was used to observe the wire melting behavior and the weld pool dynamics in real time during the welding process by using a bandpass red laser with an emission wavelength of 808 nm as backlight source to illuminate the welding zone. The weld porosity defects were analyzed by X-ray radiography. The effects of wire feeding posture on the wire melting behavior, process stability, and porosity defects were investigated. The experimental results indicated that three distinct filler material transfer modes were identified under different wire feeding positions: liquid bridge transfer mode, droplet transfer mode, and spreading transfer mode. The liquid bridge transfer mode could guarantee a stable welding process, and result in the lowest porosity. Compared with wire feeding in the leading direction, the process was not stable and porosity increased when wire feeding in the trailing direction. Increased in the wire feeding angle was disadvantage for pores to escape from the weld molten pool, meanwhile, it made the welding process window smaller due to increasing the centering precision requirement for adjusting the filler wire.

Tao, Wang; Yang, Zhibin; Chen, Yanbin; Li, Liqun; Jiang, Zhenguo; Zhang, Yunlong

2013-11-01

301

Study on the Formation and Characterization of the Intermetallics in Friction Stir Welding of Aluminum Alloy to Coated Steel Sheet Lap Joint  

NASA Astrophysics Data System (ADS)

Multimaterial fabrication such as joining of steel and aluminum is currently prominent in a variety of industries. Friction stir welding is a novel solid-state welding process that causes good joint strength between steel and aluminum. However, the phenomenon contributing significant strength at the interface is not yet clear. In the present study, the interface of the friction stir lap-welded aluminum and coated steel sheet having joint strength maximum (71.4 pct of steel base metal) and minimum, respectively, under two parameter combinations, i.e., 1000 rpm 50 mm min-1 and 500 rpm 100 mm min-1, was exclusively characterized by X-ray diffraction, transmission electron microscopy (TEM), concentration profile, and elemental mapping by electron-probe microanalysis. A TEM-assisted EDS study identifies the morphologies of large size Al13Fe4 and small size Fe3Al-type intermetallic compounds at the interface. The diffusion-induced intermetallic growth (thickness) measured from a backscattered image and concentration profile agreed well with the numerically calculated one. The growth of these two phases at 1000 rpm 50 mm min-1 is attributed to the slower cooling rate (~3.5 K/s) with higher diffusion time (44 seconds) along the interface in comparison to the same for 500 rpm 100 mm min-1 with faster cooling rate (~10 K/s) and less diffusion time (13.6 seconds). The formation of thermodynamically stable and hard intermetallic phase Al13Fe4 at 1000 rpm and travel speed 50 mm min-1 in amounts higher than 500 rpm and a travel speed of 100 mm min-1 results in better joint strength, i.e., 71.4 pct, of the steel base metal.

Das, H.; Ghosh, R. N.; Pal, T. K.

2014-10-01

302

Method for welding beryllium  

DOEpatents

A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon.

Dixon, Raymond D. (Los Alamos, NM); Smith, Frank M. (Espanola, NM); O'Leary, Richard F. (Los Alamos, NM)

1997-01-01

303

Mechanical and structural properties of similar and dissimilar steel joints  

SciTech Connect

The mechanical properties of specimens from similar and dissimilar weld joints were examined. A ferritic steel (St37-2) and an austenitic stainless steel (AISI 304) were joined by the gas tungsten arc weld (GTAW) process using an austenitic filler metal. Mechanical and metallographic properties of the specimens were obtained by means of microhardness testing, tensile testing, bending fatigue testing, and light optical and scanning electron microscopy. The highest microhardness values were recorded on the ferritic-austenitic dissimilar weld joint, whereas the highest tensile strength and bending fatigue life were obtained with the austenitic-austenitic joints. Ferritic and pearlitic structures were observed in the microstructure of the ferritic-ferritic joint. The microstructures of austenitic-austenitic and austenitic-ferritic joints showed small recrystallization grains in addition to the typical austenitic and ferritic structures. Scanning electron microscopy was used to observe the fracture surfaces of the specimens and the origins of the fatigue cracks.

Celik, A.; Alsaran, A.

1999-11-01

304

Virtual restoration of anatomic jaw relationship to obtain a precise 3D model for total joint prosthesis construction for treatment of TMJ ankylosis with open bite.  

PubMed

Temporomandibular joint (TMJ) reconstruction with a TMJ Concepts total joint prosthesis (TMJ Concepts, Ventura, USA) requires a precise 3D model of the jaws in centric occlusion. The authors present a virtual procedure for repositioning the lower jaw in centric occlusion to obtain a precise stereolithographic model for TMJ reconstruction using a custom-made total joint prosthesis in a case of TMJ ankylosis and anterior open bite. PMID:20599355

Zizelmann, C; Bucher, P; Rohner, D; Gellrich, N-C; Kokemueller, H; Hammer, B

2010-10-01

305

Effect of Pin Length on Hook Size and Joint Properties in Friction Stir Lap Welding of 7B04 Aluminum Alloy  

NASA Astrophysics Data System (ADS)

Friction stir lap welding of 7B04 aluminum alloy was conducted in the present paper, and the effect of pin length on hook size and joint properties was investigated in detail. It is found that for each given set of process parameters, the size of hook defect on the advancing side shows an "M" type evolution trend as the pin length is increased. The affecting characteristics of pin length on joint properties are dependent on the heat input levels. When the heat input is low, the fracture strength is firstly increased to a peak value and then shows a decrease. When the heat input is relatively high, the evolution trend of fracture strength tends to exhibit a "W" type with increasing the pin length.

Wang, Min; Zhang, Huijie; Zhang, Jingbao; Zhang, Xiao; Yang, Lei

2014-05-01

306

Reprocessing weld and method  

SciTech Connect

A process is described for improving the fatigue resistance of a small primary structural weld at a joint between structural members of a weldment, the weld having been made with the welding energy input of E[sub 1], the process comprising: applying a reprocessing weld on at least a portion of either one or both toes of the primary structural weld, thereby covering said toe portion, the reprocessing weld containing a filler metal and having a cross-sectional area which is less than the corresponding cross-sectional area of the primary structural weld, the reprocessing weld extending onto the face of the primary structural weld at one side of the toe portion covered and onto the structural member at the other side of the toe portion covered, and the total welding energy input, E[sub 2], used in said reprocessing the primary structural weld being less than the welding energy input E[sub 1] of the primary structural weld.

Killian, M.L.; Lewis, H.E.

1993-08-03

307

The aluminum spot weld  

SciTech Connect

Weld conditions which promote long tip life for aluminum spot welds are not necessarily associated with high weld quality in terms of freedom from defects such as porosity, cracks and expulsion. Schedules which produce good weld nuggets in terms of the peel test and long tip life may not produce a good response in terms of fatigue life. The fatigue life range is optimized by maximizing the weld nugget diameter, i.e., by employing a weld schedule which may lead to expulsion and weld porosity. Weld strength, in both peel and overlap shear configurations, was found to be linearly dependent upon weld diameter. In the peel test, the strength was also dependent upon the base metal thickness, in that for a given thickness, there is a critical diameter for the transition between weld fracture and nugget pull-out. For a given nugget diameter, if pull-out is observed then the strength is greater than if fracture occurs through the weld. In the shear test, the opposite response was observed, the strength for nugget pull-out being less than that for weld shear failure. Weld pull-out was found only for the thinnest base metal thickness tested and the shear load depended only upon the weld diameter over the range of thicknesses tested. Maximum strength in an aluminum spot weld is obtained by maximizing the weld nugget diameter for that thickness of material.

Thornton, P.H.; Krause, A.R.; Davies, R.G. [Ford Motor Co., Dearborn, MI (United States). Scientific Lab.

1996-03-01

308

Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications  

NASA Technical Reports Server (NTRS)

Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading the way for future circumferential weld implementation.

Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

2003-01-01

309

Microstructures of friction stir weld joints between an aluminium-base metal matrix composite and a monolithic aluminium alloy  

Microsoft Academic Search

Microstructures in friction stir welds between monolithic AA2024 and AA2014 reinforced with 20 vol% particulate Al2O3 reveal that the narrowest layers of each material are about 0.1 mm thick. Thus, each material retains its identity in the weld zone and convoluted macrointerfaces can be identified between material domains. When the harder material is on the advancing side of the tool

John A. Wert

2003-01-01

310

Fatigue Performance of Advanced High-Strength Steels (AHSS) GMAW Joints  

SciTech Connect

The fatigue performance of gas metal arc welding (GMAW) joints of advanced high strength steels (AHSS) are compared and analyzed. The steel studied included a number of different grades of AHSS and baseline mild steels: DP600, DP780, DP980, M130, M220, solution annealed boron steel, fully hardened boron steels, HSLA690 and DR210 (a mild steel). Fatigue testing was conducted under a number of nominal stress ranges to obtain the S/N curves of the weld joints. A two-phase analytical model is developed to predict the fatigue performance of AHSS welds. It was found that there are appreciable differences in the fatigue S/N curves among different AHSS joints made using the same welding practices, suggesting that the local microstructure in the weld toe and root region plays non-negligible role in the fatigue performance of AHSS welds. Changes in weld parameters can influence the joint characteristics which in turn influence fatigue life of the weld joints, particularly of those of higher strength AHSS. The analytical model is capable of reasonably predicting the fatigue performance of welds made with various steel grades in this study.

Feng, Zhili [ORNL; Sang, Yan [AET Integration, Inc; Jiang, Cindy [AET Integration, Inc; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel

2009-01-01

311

46 CFR 154.650 - Cargo tank and process pressure vessel welding.  

Code of Federal Regulations, 2012 CFR

... (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration type, except for small penetrations...

2012-10-01

312

46 CFR 154.650 - Cargo tank and process pressure vessel welding.  

Code of Federal Regulations, 2010 CFR

... (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration type, except for small penetrations...

2010-10-01

313

46 CFR 154.650 - Cargo tank and process pressure vessel welding.  

Code of Federal Regulations, 2013 CFR

... (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration type, except for small penetrations...

2013-10-01

314

46 CFR 154.650 - Cargo tank and process pressure vessel welding.  

Code of Federal Regulations, 2011 CFR

... (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration type, except for small penetrations...

2011-10-01

315

46 CFR 154.650 - Cargo tank and process pressure vessel welding.  

... (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration type, except for small penetrations...

2014-10-01

316

Prediction of Weld Penetration in FCAW of HSLA steel using Artificial Neural Networks  

SciTech Connect

Flux-cored arc welding (FCAW) is a semiautomatic or automatic arc welding process that requires a continuously-fed consumable tubular electrode containing a flux. The main FCAW process parameters affecting the depth of penetration are welding current, arc voltage, nozzle-to-work distance, torch angle and welding speed. Shallow depth of penetration may contribute to failure of a welded structure since penetration determines the stress-carrying capacity of a welded joint. To avoid such occurrences; the welding process parameters influencing the weld penetration must be properly selected to obtain an acceptable weld penetration and hence a high quality joint. Artificial neural networks (ANN), also called neural networks (NN), are computational models used to express complex non-linear relationships between input and output data. In this paper, artificial neural network (ANN) method is used to predict the effects of welding current, arc voltage, nozzle-to-work distance, torch angle and welding speed on weld penetration depth in gas shielded FCAW of a grade of high strength low alloy steel. 32 experimental runs were carried out using the bead-on-plate welding technique. Weld penetrations were measured and on the basis of these 32 sets of experimental data, a feed-forward back-propagation neural network was created. 28 sets of the experiments were used as the training data and the remaining 4 sets were used for the testing phase of the network. The ANN has one hidden layer with eight neurons and is trained after 840 iterations. The comparison between the experimental results and ANN results showed that the trained network could predict the effects of the FCAW process parameters on weld penetration adequately.

Asl, Y. Dadgar; Mostafa, N. B.; Panahizadeh, V. R. [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Seyedkashi, S. M. H. [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

2011-01-17

317

Enhanced diffusion welding  

NASA Technical Reports Server (NTRS)

Surfaces of unrecrystallized alloys are sanded and polished. This is followed by a two-step welding process by which the strength of the parent metal is retained at the weld joint. The first step forces the surfaces into intimate contact at a temperature where the metal still has good ductility. The second step causes diffusion, recrystallization, and grain growth across the original weld interface.

Holko, K. H.; Moore, T. J. (inventors)

1973-01-01

318

Microstructures and Mechanical Properties of Laser Penetration Welding Joint With/Without Ni-Foil in an Overlap Steel-on-Aluminum Configuration  

NASA Astrophysics Data System (ADS)

The microstructures and mechanical properties of laser penetration welding joints with/without Ni-foil in an overlap steel-on-aluminum configuration were investigated. The interfacial structure between fusion zone and aluminum alloy without Ni-foil consists of FeAl/FeAl3. After the Ni-foil is added, the interfacial structure transforms into Ni1.1Al0.9/FeAl3, and the molten pool of aluminum alloy is expanded, which leads to the formation of the NiAl3 between Ni-foil and the molten pool. A banded structure composed of ?(Fe, Ni)Al appears whether the joints are made with/without Ni-foil over the reaction zone. It was found that the Ni-foil enhanced tensile property of the joint, expanded usable processing parameters, and decreased microhardness of the intermetallic compounds. The enhancement of mechanical properties is attributed to the improvement of the toughness of the joint made by Ni-foil.

Chen, Shuhai; Huang, Jihua; Ma, Ke; Zhao, Xingke; Vivek, Anupam

2014-06-01

319

Weld-bonded titanium structures  

NASA Technical Reports Server (NTRS)

Structurally stronger titanium articles are produced by a weld-bonding technique comprising fastening at least two plates of titanium together using spotwelding and curing an adhesive interspersed between the spot-weld nuggets. This weld-bonding may be employed to form lap joints or to stiffen titanium metal plates.

Vaughan, R. W.; Creedon, J. F. (inventors)

1976-01-01

320

APPLICATION OF WELDING TECHNOLOGIES FOR JOINING OF Mg ALLOYS: MICROSTRUCTURE AND MECHANICAL PROPERTIES  

Microsoft Academic Search

Five welding technologies were investigated as possible solutions to the challenge of joining Mg alloys: Gas Tungsten Arc Welding, Electron Beam Welding, Magnetic Pulse Welding, Laser Assisted Friction Stir Welding and Resistance Spot Welding. The main influencing parameters have been analyzed, using the joint strength and microstructure to evaluate the welding processes. The advantages and difficulties for each technique are

Adin Stern; Abraham Munitz; Gabriel Kohn

321

Diffusion weld test fixture  

Microsoft Academic Search

A weld joint test fixture for testing the strength of a weld joining several members forming a test specimen is provided. The fixture includes a base which supports the test specimen and an attachment for applying a testing force to the test specimen while the test specimen is supported by the base. The fixture further includes holding elements attached to

Wendell C. Maciejewski; Kurt J. Janecek; George J. Kavarnos; Elizabeth A. McLaughlin

1995-01-01

322

Diffusion weld test fixture  

Microsoft Academic Search

A weld joint test fixture for testing the strength of a weld joining several members forming a test specimen is provided. The fixture includes a base which supports the test specimen and an attachment for applying a testing force to the test specimen while the test specimen is supported by the base. The fixture further includes holding elements attached to

Wendell Maciejewski; Roger Tyron; George Kavarnos; Elizabeth McLaughlin; Kurt Janecek

1994-01-01

323

Gas Shielding Technology for Welding and Brazing  

NASA Technical Reports Server (NTRS)

Welding is a common method that allows two metallic materials to be joined together with high structural integrity. When joints need to be leak-tight, light-weight, or free of contaminant-trapping seams or surface asperities, welding tends to be specified. There are many welding techniques, each with its own advantages and disadvantages. Some of these techniques include Forge Welding, Gas Tungsten Arc Welding, Friction Stir Welding, and Laser Beam Welding to name a few. Whichever technique is used, the objective is a structural joint that meets the requirements of a particular component or assembly. A key practice in producing quality welds is the use of shielding gas. This article discusses various weld techniques, quality of the welds, and importance of shielding gas in each of those techniques. Metallic bonds, or joints, are produced when metals are put into intimate contact. In the solid-state "blacksmith welding" process, now called Forge Welding (FOW), the site to be joined is pounded into intimate contact. The surfaces to be joined usually need to be heated to make it easier to deform the metal. The surfaces are sprinkled with a flux to melt surface oxides and given a concave shape so that surface contamination can be squeezed out of the joint as the surfaces are pounded together; otherwise the surface contamination would be trapped in the joint and would weaken the weld. In solid-state welding processes surface oxides or other contamination are typically squeezed out of the joint in "flash."

Nunes, Arthur J.; Gradl, Paul R.

2012-01-01

324

Environmentally-assisted cracking behaviour in the transition region of an Alloy182/SA 508 Cl.2 dissimilar metal weld joint in simulated boiling water reactor normal water chemistry environment  

NASA Astrophysics Data System (ADS)

The stress corrosion cracking (SCC) and corrosion fatigue behaviour perpendicular and parallel to the fusion line in the transition region between the Alloy 182 Nickel-base weld metal and the adjacent SA 508 Cl.2 low-alloy reactor pressure vessel (RPV) steel of a simulated dissimilar metal weld joint was investigated under boiling water reactor normal water chemistry conditions. A special emphasis was placed to the question whether a fast growing interdendritic SCC crack in the highly susceptible Alloy 182 weld metal can easily cross the fusion line and significantly propagate into the adjacent low-alloy RPV steel. Cessation of interdendritic SCC crack growth was observed in high-purity or sulphate-containing oxygenated water under constant or periodical partial unloading conditions for those parts of the crack front, which reached the fusion line. In chloride containing water, on the other hand, the interdendritic SCC crack in the Alloy 182 weld metal very easily crossed the fusion line and further propagated with a very high rate as a transgranular crack into the heat-affected zone and base metal of the adjacent low-alloy steel. The observed SCC cracking behaviour at the interface correlates excellently with the field experience of such dissimilar metal weld joints, where SCC cracking was usually confined to the Alloy 182 weld metal.

Seifert, H. P.; Ritter, S.; Shoji, T.; Peng, Q. J.; Takeda, Y.; Lu, Z. P.

2008-08-01

325

Effects of residual stress, weld toe notch and weld defects on fatigue of welded steel structures  

Microsoft Academic Search

In studying the fatigue behavior of fillet welded railroad tank car shell structures, the effects of welding residual stress, weld toe notch, and weld defects on the fatigue of fillet welded A515 steel specimens were evaluated. Both hole-drilling and sectioning measurement techniques were used to obtain residual stress information. Pad-on-plate weld specimens were designed to simulate the tank car structure

Wenyu Shen

1992-01-01

326

Clamp and Gas Nozzle for TIG Welding  

NASA Technical Reports Server (NTRS)

Tool that combines clamp with gas nozzle is aid to tungsten/inert-gas (TIG) welding in hard-to-reach spots. Tool holds work to be welded while directing a stream of argon gas at weld joint, providing an oxygen-free environment for tungsten-arc welding.

Gue, G. B.; Goller, H. L.

1982-01-01

327

New explosive seam welding concepts  

NASA Technical Reports Server (NTRS)

Recently developed techniques provide totally-confined linear explosive seam welding and produce scarf joint with linear explosive seam welding. Linear ribbon explosives are utilized in making narrow, continuous, airtight joints in variety of aluminum alloys, titanium, copper, brass, and stainless steel.

Bement, L. J.

1973-01-01

328

The application of the fusion method of thermit welding to small diameter tubing: An analysis of joint geometry.  

E-print Network

' or butt welding, the slag is poured into the mold before the metal. It covers the iron surface in a thin layer that is at once chilled and adheres to the metal. This coating of slag serves as a distributor of the heat of the thermit steel to the iron... by working (g:zs3). Thermit weld metal can be regarded as having physical properties closely approaching those of forged steel (l3:2S3). In summary, the thermit process. . . . . . has been used in almost every industry (I:17-2D). Llhile the plastic...

Glynn, Thomas Michael

2012-06-07

329

Parametric study in weld mismatch of longitudinally welded SSME HPFTP inlet  

NASA Technical Reports Server (NTRS)

Welded joints are an essential part of pressure vessels such as the Space Shuttle Main Engine (SSME) Turbopumps. Defects produced in the welding process can be detrimental to weld performance. Recently, review of the SSME high pressure fuel turbopump (HPFTP) titanium inlet x rays revealed several weld discrepancies such as penetrameter density issues, film processing discrepancies, weld width discrepancies, porosity, lack of fusion, and weld offsets. Currently, the sensitivity of welded structures to defects is of concern. From a fatigue standpoint, weld offset may have a serious effect since local yielding, in general, aggravates cyclic stress effects. Therefore, the weld offset issue is considered. Using the finite element method and mathematical formulations, parametric studies were conducted to determine the influence of weld offsets and a variation of weld widths in longitudinally welded cylindrical structures with equal wall thickness on both sides of the joint. From the study, the finite element results and theoretical solutions are presented.

Min, J. B.; Spanyer, K. L.; Brunair, R. M.

1991-01-01

330

Determining The Weld Quality In Extrusion Welding  

NASA Astrophysics Data System (ADS)

An overview is first given over various methods applied for testing of the bond strength across the extrusion weld obtained in hollow extruded profiles of light metals. A new innovative technique for measurement of weld quality has been developed and the mechanical characteristic of the method is then described. An application of the technique is finally presented where a contaminant film is observed to flow into the extrusion weld so that extrusion weld quality becomes lowered due to the presence of the film. The reduction of the weld quality in this case is quantified by the new technique.

Valberg, Henry; Melkild, Tony; Kandis, Janis

2011-05-01

331

Measures for ensuring reliable operation of the welded joint connecting the reactor coolant circuit's header to the shell of a steam generator used at a VVER-1000 reactor-based nuclear power station  

NASA Astrophysics Data System (ADS)

Problems that arose around the weld joint connecting the reactor coolant circuit's header to the steam generator shell during operation of steam generators at nuclear power stations equipped with VVER-1000 reactors are considered. Works on studying the defects occurred in the header's metal are described, and ways for preventing their development are determined.

Kharchenko, S. A.; Trunov, N. B.; Korotaev, N. F.; Lyakishev, S. L.

2011-03-01

332

Development of an intelligent system for cooling rate and fill control in GMAW. [Gas Metal Arc Welding (GMAW)  

SciTech Connect

A control strategy for gas metal arc welding (GMAW) is developed in which the welding system detects certain existing conditions and adjusts the process in accordance to pre-specified rules. This strategy is used to control the reinforcement and weld bead centerline cooling rate during welding. Relationships between heat and mass transfer rates to the base metal and the required electrode speed and welding speed for specific open circuit voltages are taught to a artificial neural network. Control rules are programmed into a fuzzy logic system. TRADITOINAL CONTROL OF THE GMAW PROCESS is based on the use of explicit welding procedures detailing allowable parameter ranges on a pass by pass basis for a given weld. The present work is an exploration of a completely different approach to welding control. In this work the objectives are to produce welds having desired weld bead reinforcements while maintaining the weld bead centerline cooling rate at preselected values. The need for this specific control is related to fabrication requirements for specific types of pressure vessels. The control strategy involves measuring weld joint transverse cross-sectional area ahead of the welding torch and the weld bead centerline cooling rate behind the weld pool, both by means of video (2), calculating the required process parameters necessary to obtain the needed heat and mass transfer rates (in appropriate dimensions) by means of an artificial neural network, and controlling the heat transfer rate by means of a fuzzy logic controller (3). The result is a welding machine that senses the welding conditions and responds to those conditions on the basis of logical rules, as opposed to producing a weld based on a specific procedure.

Einerson, C.J.; Smartt, H.B.; Johnson, J.A.; Taylor, P.L. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Moore, K.L. (Idaho State Univ., Pocatello, ID (United States))

1992-01-01

333

Crustal structure of the Iberian Peninsula and Morocco obtained by joint inversion of seismic and gravity data  

NASA Astrophysics Data System (ADS)

We present a model of the three-dimensional shear wave velocity structure underneath the Iberian Peninsula and Moroco obtained by joint inversion of surface-wave dispersion measurements and gravity observations. Surface-wave dispersion measurements are sensitive to smooth lateral variations of shear-wave velocities; gravity measurements provide information on shallow, broad-wavenumber and and deep, long-wavenumber density variations. We use an empirical relationship between density and seismic velocities to allow the single, joint inversion of both datasets. By combining these two independent types of observations we obtain a self-consistent three-dimensional shear-velocity-density model with increased resolution of shallow structures. The dispersion dataset consists of high-resolution group and phase velocity maps of Rayleigh waves at periods from 6 to 35 s. These maps were obtained from cross-correlations of seismic ambient noise between stations from temporary broadband experiments in the region (IberArray, PICASSO) complemented with stations from permanent regional networks. Gravity observations are extracted from the global gravity model derived from the GRACE satellite mission as well as gravity anomaly maps provided by the Spanish Instituto Geográfico Nacional (IGN) and other regional studies. Preliminary results show the main structural elements of the Iberian crust, including the Iberian Massif, Alpine orogens (Pyrenees, Betics) and major sedimentary basins (Gulf of Cadiz, Valencia Trough, Guadalquivir and Ebro). The Pyrenees and the Iberian Chain are imaged as relatively high velocities, in contrast with the Betic Cordillera, which is characterized by low velocities. The most prominent low velocity anomalies in the Iberian Peninsula are related to the Guadalquivir basin, the flysch units of the Campo de Gibraltar, and the sediments of the Gulf of Cadiz. Other smaller features such as the Ronda Peridotite and West Alboran basin are also well imaged. This high-resolution model will not only help improve the understanding of the geodynamic evolution of the westernmost Mediterranean but also serve as starting model for time-consuming full 3D waveform inversions.

Villaseñor, A.; Maceira, M.; Gallart, J.; Topo-Iberia Working Group

2012-04-01

334

Apparatus for welding blades to rotors  

NASA Technical Reports Server (NTRS)

Using magnetic force upset welding to form T-joints between dissimilar thickness parts. This type of resistance welding is used to join compressor and turbine parts thereby reducing the weight and cost of a jet engine.

Holko, K. H.; Moore, T. J. (inventors)

1973-01-01

335

General Mechanical Repair. Welding. Volume 2. Teacher's Guide.  

ERIC Educational Resources Information Center

Five units on welding are presented in this teacher's guide. The units are the following: introduction to oxyacetylene welding, oxyacetylene welding positions and applications, use of the cutting torch, introduction to shielded metal arc welding, and welding joints and positions. Each instructional unit generally contains eight components:…

East Texas State Univ., Commerce. Occupational Curriculum Lab.

336

Effect of Welding Speed and Defocusing Distance on the Quality of Laser Welded Ti-6Al-4V  

E-print Network

Effect of Welding Speed and Defocusing Distance on the Quality of Laser Welded Ti-6Al-4V A:YAG laser, Laser welding, Ti-6Al-4V alloy Abstract In this study, the weldability of 5.1-mm thick Ti-6Al-4V at various welding speeds and defocusing distances. The joint quality was characterized in terms of weld

Medraj, Mamoun

337

Evaluation of GTA tube welding techniques  

SciTech Connect

In this study, various tube weld joint designs are evaluated for use with manual welding techniques and automatic tube welding heads. Manual welds were made with three joint types: square butt with no filler metal addition, square butt with manual filler wire addition, and square butt with tube weld fittings designed for use with automatic tube welding heads. Automatic welding was conducted using procedures for three joint types: square butt with no filler wire addition, square butt with type ''C'' tube weld fittings, and square butt with type ''P'' tube weld fittings. While tube welds of good quality can be made without using automatic welding equipment, the welder must be highly skilled and practiced. Automatic tube welding equipment drastically reduces the level of skill required of the welding operator. Further skill reductions can be made when tube weld fittings designed for use with automatic equipment are used. The fittings provide a means for accurate positioning of the tube ends. In the case of the type ''P'' fitting, mechanized welding heads are automatically positioned by a special locating rib on the fitting. Fittings also simplify manual welding procedures with the tube end alignment feature. This is particulary advantageous in limited access situations where visibility is restricted.

Marburger, S.J.

1986-10-01

338

Microstructural Characterizations with EDAX Analysis of Dissimilar Friction Stir Welds  

NASA Astrophysics Data System (ADS)

This paper reports the microstructural characteristics of dissimilar friction stir welds with AA7075T651 and AA6061T651. Dissimilar friction stir welds between AA7075T651 and AA6061T651 were produced by varying the rotational speeds between 800 and 1,000 rpm and the welding speeds between 90 and 110 mm/min. The welds were characterized through optical microscope and scanning electron microscope (SEM). Three different tool profiles (taper cylindrical threaded, taper square threaded and simple square) were used for this investigation and in that taper cylindrical threaded tool with process parameters 900 rpm and 100 mm/min were found to have maximum tensile strength of 205 MPa for the dissimilar butt joints. The SEM with energy-dispersive X-ray spectroscopy analysis reveals the metallurgical bonding achieved at the joint interfaces of the welds produced. The good mixing of both the materials joined was obtained at lower welding and higher rotational speed while the tunnel defect was found to be common in the welds produced irrespective of the tool pin profiles and process parameters due to insufficient axial load with 0° tilt angle.

Ravikumar, S.; Rao, V. S.

2013-10-01

339

Welding and properties of welds of TMCP-steel  

SciTech Connect

Thermomechanical control process (TMCP) of steel includes a multiplicity of processing schedules of combined thermal and mechanical working treatments that have been developed to optimize the resulting microstructure and mechanical properties of various steel grades. Weld metal properties of multipass submerged arc welded (SAW) TMCP steel joints were investigated in order to study the influences of different welding wires and heat inputs. Weld metal characterization consisted of tensile, Charpy-V Notch (CVN) and hardness testing, and microstructural examination. Cross-weld tensile specimens were tested principally to examine whether HAZ softening, which might have occurred, causes failure in this region. The tests verified that by using the right welding wire; it is possible to achieve weld joint which fulfills the strength requirements and gives satisfactory toughness at low temperatures.

Brederholm, A.T.; Kotamies, J.M.N.; Haenninen, H. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Engineering Materials

1995-12-31

340

Welding of 316L Austenitic Stainless Steel with Activated Tungsten Inert Gas Process  

NASA Astrophysics Data System (ADS)

The use of activating flux in TIG welding process is one of the most notable techniques which are developed recently. This technique, known as A-TIG welding, increases the penetration depth and improves the productivity of the TIG welding. In the present study, four oxide fluxes (SiO2, TiO2, Cr2O3, and CaO) were used to investigate the effect of activating flux on the depth/width ratio and mechanical property of 316L austenitic stainless steel. The effect of coating density of activating flux on the weld pool shape and oxygen content in the weld after the welding process was studied systematically. Experimental results indicated that the maximum depth/width ratio of stainless steel activated TIG weld was obtained when the coating density was 2.6, 1.3, 2, and 7.8 mg/cm2 for SiO2, TiO2, Cr2O3, and CaO, respectively. The certain range of oxygen content dissolved in the weld, led to a significant increase in the penetration capability of TIG welds. TIG welding with active fluxes can increase the delta-ferrite content and improves the mechanical strength of the welded joint.

Ahmadi, E.; Ebrahimi, A. R.

2014-12-01

341

The influence of salt fog exposure on the fatigue performance of Alclad 6xxx aluminum alloys laser beam welded joints  

Microsoft Academic Search

Laser welding is increasingly used for the fabrication of lightweight and cost-effective integral stiffened panels in modern\\u000a civil aircraft. As these structures age in service, the issue of the effect of corrosion on their damage tolerance requires\\u000a attention. In this work, laboratory data on the influence of salt fog corrosion on the fatigue behavior of cladded 6156 T4\\u000a aluminum alloy

A. T. Kermanidis; A. D. Zervaki; G. N. Haidemenopoulos; Sp. G. Pantelakis

2010-01-01

342

Predictive permeability model of faults in crystalline rocks; verification by joint hydraulic factor (JH) obtained from water pressure tests  

NASA Astrophysics Data System (ADS)

In the present study, a new model is proposed to predict the permeability per fracture in the fault zones by a new parameter named joint hydraulic factor (JH). JH is obtained from Water Pressure Test (WPT) and modified by the degree of fracturing. The results of JH correspond with quantitative fault zone descriptions, qualitative fracture, and fault rock properties. In this respect, a case study was done based on the data collected from Seyahoo dam site located in the east of Iran to provide the permeability prediction model of fault zone structures. Datasets including scan-lines, drill cores, and water pressure tests in the terrain of Andesite and Basalt rocks were used to analyse the variability of in-site relative permeability of a range from fault zones to host rocks. The rock mass joint permeability quality, therefore, is defined by the JH. JH data analysis showed that the background sub-zone had commonly <3 Lu (less of 5 ×10-5 m 3/s) per fracture, whereas the fault core had permeability characteristics nearly as low as the outer damage zone, represented by 8 Lu (1.3 ×10-4 m 3/s) per fracture, with occasional peaks towards 12 Lu (2 ×10-4 m 3/s) per fracture. The maximum JH value belongs to the inner damage zone, marginal to the fault core, with 14-22 Lu (2.3 ×10-4-3.6 ×10-4 m 3/s) per fracture, locally exceeding 25 Lu (4.1 ×10-4 m 3/s) per fracture. This gives a proportional relationship for JH approximately 1:4:2 between the fault core, inner damage zone, and outer damage zone of extensional fault zones in crystalline rocks. The results of the verification exercise revealed that the new approach would be efficient and that the JH parameter is a reliable scale for the fracture permeability change. It can be concluded that using short duration hydraulic tests (WPTs) and fracture frequency (FF) to calculate the JH parameter provides a possibility to describe a complex situation and compare, discuss, and weigh the hydraulic quality to make predictions as to the permeability models and permeation amounts of different zone structures.

Barani, Hamidreza Rostami; Lashkaripour, Gholamreza; Ghafoori, Mohammad

2014-08-01

343

Use of DL-EPR Test to Assess Sensitization Resistance of AISI 409M Grade Ferritic Stainless Steel Joints  

NASA Astrophysics Data System (ADS)

The susceptibility of 409M grade ferritic stainless steels to sensitization due to welding was investigated. Joints were fabricated by gas tungsten arc welding, friction stir welding, laser beam welding, and electron beam welding processes. Double loop electrochemical potentiokinetic reactivation test was carried out for determining the degree of sensitization of welded joints. The experimental result reveals that, the friction stir welded joint is less prone to sensitization, when compared to the other joints.

Lakshminarayanan, A. K.; Balasubramanian, V.

2013-08-01

344

Fatigue of welded components  

SciTech Connect

Fatigue cracks in engineering structures typically initiate from discontinuities associated with weld joints. Such discontinuities can be volumetric or planar in nature and, in either case, elevate local stresses sufficiently so as to drastically reduce weld joint fatigue strength. In addition, the weld geometry itself can induce stress concentrations higher than those associated with the weld discontinuities. For instance, one of the most fatigue sensitive weld details is a fillet weld termination oriented perpendicular to the applied cyclic stress field. In this case, fatigue cracking initiates from the toe of the fillet weld and propagates through the adjacent base metal in a rather rapid fashion. Although the applied service stresses may be within Code design allowables for ``fatigue rated`` components, welded and bolted connections can sufficiently elevate local stresses to initiate and propagate cracks. Since most fatigue failures occur at weldments, it is reasonable to expect that modern design codes would incorporate the effects of weldments on fatigue life. This paper examines the parameters which most affect the fatigue performance of weldments and the manner in which various codes address fatigue.

Barsom, J.M. [United States Steel, Pittsburgh, PA (United States); Vecchio, R.S. [Lucius Pitkin, Inc., New York, NY (United States)

1995-12-01

345

Homopolar welding development and economics  

SciTech Connect

Homopolar welding (HPW) is a single-shot solid-state resistance forge welding process that is under development as a single-station pipe welding method. Weld quality issues have been addressed by a Joint Industry Program and the process economics favor commercial use. Fielding of a HPW system is dependent on process tooling design, the speed of the process, and the economics of the process. The HPW weld speed of three seconds makes weld advance times of 12 to 20 minutes possible and will result in a large reduction in overall pipeline construction costs. In addition, HPW is an inherently controllable process, so the weld power pulse will be tailorable to meet a variety of weld and material requirements.

Pappas, J.A.; Harville, M.W.; Weldon, J.M. [Parker Kinetic Designs, Inc., Austin, TX (United States); Carnes, R.W.; Hudson, R.S.; Nichols, S.P. [Univ. of Texas, Austin, TX (United States). Center for Electromechanics

1996-09-01

346

Shimmed electron beam welding process  

DOEpatents

A modified electron beam welding process effects welding of joints between superalloy materials by inserting a weldable shim in the joint and heating the superalloy materials with an electron beam. The process insures a full penetration of joints with a consistent percentage of filler material and thereby improves fatigue life of the joint by three to four times as compared with the prior art. The process also allows variable shim thickness and joint fit-up gaps to provide increased flexibility for manufacturing when joining complex airfoil structures and the like.

Feng, Ganjiang (Clifton Park, NY); Nowak, Daniel Anthony (Alplaus, NY); Murphy, John Thomas (Niskayuna, NY)

2002-01-01

347

A New Perspective on Fatigue Performance of Advanced High- Strength Steels (AHSS) GMAW Joints  

SciTech Connect

Weld fatigue performance is a critical aspect for application of advanced high-strength steels (AHSS) in automotive body structures. A comparative study has been conducted to evaluate the fatigue life of AHSS welds. The material studied included seven AHSS of various strength levels - DP 600, DP 780, DP 980, M130, M220, solution annealed boron and fully hardened boron steels. Two conventional steels, HSLA 590 and DR 210, were also included for baseline comparison. Lap fillet welds were made on 2-mm nominal thick sheets by the gas metal arc welding process (GMAW). Fatigue test was conducted under a number of stress levels to obtain the S/N curves of the weld joints. It was found that, unlike in the static and impact loading conditions, the fatigue performance of AHSS is not influenced by the HAZ softening in AHSS. There are appreciable differences in the fatigue lives among different AHSS. Changes in weld parameters can influence the fatigue life of the weld joints, particularly of these of higher strength AHSS. A model is developed to predict the fatigue performance of AHSS welds. The validity of the model is benchmarked with the experimental results. This model is capable to capture the effects of weld geometry and weld microstructure and strength on the fatigue performance experimentally observed. The theoretical basis and application of the newly developed fatigue modeling methodology will be discussed.

Feng, Zhili [ORNL; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel; Jiang, Cindy [AET Integration, Inc; Sang, Yan [AET Integration, Inc

2008-01-01

348

Aircraft and ground vehicle friction correlation test results obtained under winter runway conditions during joint FAA/NASA Runway Friction Program  

NASA Technical Reports Server (NTRS)

Aircraft and ground vehicle friction data collected during the Joint FAA/NASA Runway Friction Program under winter runway conditions are discussed and test results are summarized. The relationship between the different ground vehicle friction measurements obtained on compacted snow- and ice-covered conditions is defined together with the correlation to aircraft tire friction performance under similar runway conditions.

Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

1988-01-01

349

Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy  

PubMed Central

The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr. PMID:19088892

Watanabe, Ikuya; Wallace, Cameron

2008-01-01

350

Weld braze technique  

DOEpatents

High-strength metal joints are formed by a combined weld-braze technique. A hollow cylindrical metal member is forced into an undersized counterbore in another metal member with a suitable braze metal disposed along the bottom of the counterbore. Force and current applied to the members in an evacuated chamber results in the concurrent formation of the weld along the sides of the counterbore and a braze along the bottom of the counterbore in one continuous operation.

Kanne, Jr., William R. (Aiken, SC); Kelker, Jr., John W. (North Augusta, SC); Alexander, Robert J. (Aiken, SC)

1982-01-01

351

Effect of proof testing on the flaw growth characteristics of 304 stainless steel. [crack propagation in welded joints  

NASA Technical Reports Server (NTRS)

The effects of proof overload frequency and magnitude on the cyclic crack growth rates of 304 stainless steel weldments were investigated. The welding procedure employed was typical of those used on over-the-road cryogenic vessels. Tests were conducted at room temperature with an overload ratio of 1.50 to determine the effect of overload frequency. Effect of overload magnitude was determined from tests where a room temperature overload was applied between blocks of 1000 cycles applied at 78 K (-320 F). The cyclic stress level used in all tests was typical of the nominal membrane stress generally encountered in full scale vessels. Test results indicate that judicious selection of proof overload frequency and magnitude can reduce crack growth rates for cyclic stress levels.

Finger, R. W.

1974-01-01

352

CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS  

SciTech Connect

Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions, defect characteristics and weld residual strains were examined by optical metallography, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Industry-supplied mock-up welds were characterized including alloy 52 and 152 weldments, alloy 52M overlay and inlay welds, and an alloy 52 overlay. II. WELDMENTS II.A. Alloy 52 and 152 Weld Mockups The alloy 52 and 152 weld mockups were fabricated by MHI for the Kewaunee reactor and were obtained from the EPRI NDE Center. The mockups were U-groove welds joining two plates of 304SS as shown in Figure 1. Alloy 152 butter (heat 307380) was placed on the U-groove surface for both mockups by shielded metal arc welding (SMAW). For the alloy 152 weld mockup, the alloy 152 fill (heat 307380) was also applied using SMAW while for the alloy 52 weld mockup, the alloy 52 fill (heat NX2686JK) was applied using gas tungsten arc welding (GTAW). Welding parameters for the fill materials were substantially different with the alloy 152 SMAW having a deposition speed of 4-25 cm/min with a current of 95-145 A and the alloy 52 GTAW having a deposition speed of 4-10 cm/min with a current of 150-300 A. One prominent feature in these mockup welds is the presence of a crack starting at the 304SS butt joint at the bottom of the U-groove and extending up into the weld. It appears that the 304SS plate on either side of the butt joint acted as an anchor for the weld resulting in a stress rise across the slit that drove crack formation and extension up into the fill weld. As will be shown in the next section, the extent of the cracking around this stress riser was much greater in the MHI 52 weld mockup.

Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

2009-08-27

353

49 CFR 213.119 - Continuous welded rail (CWR); plan contents.  

Code of Federal Regulations, 2012 CFR

...shall either, within 60 days— (i) Weld the joint; (ii) Install a joint with...the track owner shall either— (i) Weld the joint; (ii) Replace the broken...adjust the anchors and, within 30 days, weld the joint; (iii) Replace the...

2012-10-01

354

49 CFR 213.119 - Continuous welded rail (CWR); plan contents.  

Code of Federal Regulations, 2013 CFR

...shall either, within 60 days— (i) Weld the joint; (ii) Install a joint with...the track owner shall either— (i) Weld the joint; (ii) Replace the broken...adjust the anchors and, within 30 days, weld the joint; (iii) Replace the...

2013-10-01

355

Method for welding beryllium  

DOEpatents

A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon. 9 figs.

Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

1997-04-01

356

Method for welding beryllium  

SciTech Connect

A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon. Beryllium parts made using this method can be used as structural components in aircraft, satellites and space applications.

Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

1995-12-31

357

Research on key influence factors of laser overlap welding of automobile body galvanized steel  

NASA Astrophysics Data System (ADS)

In views of structure characteristics of the auto-body parts, the influences of the beam incident angle and joint gap on the performance of laser overlap welded joints were investigated. The experimental results indicate that there were the critical values of beam incident angle and joint gap during laser overlap welding of galvanized steel. The thickness of sheet and the width of joint had a certain influence on the critical beam incident angle and the limit joint gap. With regard to thicker sheet, the limit joint gap can increase appropriately, but the critical beam incident angle should not be too big. With narrow weld width, the laser beam incident angle can increase appropriately, but the joint gap should not be bigger. Additionally, the critical beam incident angle and the limit joint gap were varied with the thickness of the upper sheet. The tensile-shear tests show that the maximum tensile-shear strength of the joint can be obtained with an optimized beam incident angle and joint gap.

Chen, Genyu; Mei, Lifang; Zhang, Mingjun; Zhang, Yi; Wang, Zujian

2013-02-01

358

Submerged arc fillet welds between mild steel and stainless steel  

SciTech Connect

Submerged arc fillet welds between mild steel and Type 304 stainless steel, made with ER309L wire, may contain no ferrite and be at risk of hot cracking, or they may be sufficiently diluted that they transform to martensite with both hot cracking risk and low ductility. This situation is most prevalent when direct current electrode positive (DCEP) polarity is used and when the flange is the mild steel part of the T-joint. A flux that adds chromium to the weld can somewhat alleviate this tendency. Direct current electrode negative (DCEN) polarity greatly reduces this tendency by limiting dilution. Fillet weld compositions and dilutions are obtained for a number of welding conditions and fluxes.

Kotecki, D.J.; Rajan, V.B. [Lincoln Electric Co., Cleveland, OH (United States)

1997-02-01

359

The influence of laser welding parameters on the microstructure and mechanical property of the as-jointed NiTi alloy wires  

E-print Network

The influence of laser welding parameters on the microstructure and mechanical property of the as September 2007; accepted 27 November 2007 Available online 4 December 2007 Abstract The Nd:YAG laser welding.%Ni) which had the same diameter of 1 mm. The wires were welded with different parameters, including impulse

Zheng, Yufeng

360

Thermal stir welding apparatus  

NASA Technical Reports Server (NTRS)

A welding method and apparatus are provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

Ding, R. Jeffrey (Inventor)

2011-01-01

361

Thermal stir welding process  

NASA Technical Reports Server (NTRS)

A welding method is provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

Ding, R. Jeffrey (Inventor)

2012-01-01

362

Microstructure change in the interface of co2 laser welded zirconium alloys  

NASA Astrophysics Data System (ADS)

Welding is a joining procedure that offers some benefits over mechanical fasteners such as weight reduction and absence of notches induced by machining operations. CO2 laser beam welding with a continuous wave is a high energy density and low heat input process. The result of this is a small heat-affected zone (HAZ), which cools very rapidly with very little distortion, and a high depth-to-width ratio for the Welding is a necessary process during fabricating fuel rods and fuel assemblies with Zircaloy-4 cladding, and electron beam welding is one of the commonly- used method. In this work, the joining of zirconium alloys was attempted by laser beam welding. A 2 kW CO2 laser is used and the joints are obtained from similar materials, which are plates of Zircaloy-4 (2 mm thick). A series of zirconium alloys were welded and investigated in a tow-fold approach: (1) process optimisation: the laser processing parameters are optimized to obtain welds with minimum defects, and (2) material characterisation: weld microstructures were evaluated. The microstructure and the phases present in the resolidified zone of the laser -welded specimens were analyzed by optical and scanning electron microscopy, X-ray diffraction, and also by the realization of micro hardness diagrams. A particular attention was made to study the correlation between surface structure and mechanical behaviour.

Boutarek, N.; Azzougui, B.; Saidi, D.; Neggache, M.

2009-11-01

363

Numerical Simulation on Joining of Ceramics with Metal by Friction Welding Technique  

NASA Astrophysics Data System (ADS)

The joining of ceramic and metals can be done by different techniques such as ultrasonic joining, brazing, transient liquid phase diffusion bonding, and friction welding. Friction Welding is a solid state joining process that generates heat through mechanical friction between a moving workpiece and a stationary component. In this article, numerical simulation on thermal analysis of friction welded ceramic/metal joint has been carried out by using Finite Element Analysis (FEA) software. The finite element analysis helps in better understanding of the friction welding process of joining ceramics with metals and it is important to calculate temperature and stress fields during the welding process. Based on the obtained temperature distribution the graphs were plotted between the lengths of the joint corresponding to the temperatures. To increase the wettability, aluminium sheet was used as an interlayer. Hence, numerical simulation of friction welding process is done by varying the interlayer sheet thickness. Transient thermal analysis had been carried out for each cases and temperature distribution was studied. From the simulation studies, it is found that the increase in interlayer thickness reduces the heat affected zone and eventually improves the joint efficiency of alumina/aluminum alloy joints.

Jesudoss Hynes, N. Rajesh; Nagaraj, P.; Basil, S. Joshua

364

Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint  

NASA Astrophysics Data System (ADS)

To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

2014-10-01

365

Selection of Processes for Welding Steel Rails  

E-print Network

...._ _) Selection of Processes for Welding Steel Rails by N.S. Tsai* and T.W. Eagar* ABSTRACT 421 The advantages and limitations ofseveral conventional and prospective rail welding processes are reviewed with emphasis on the heat input rate, on joint preparation, on post weld grinding and on resultant metallurgical

Eagar, Thomas W.

366

Welds chilled by liquid coolant manifold  

NASA Technical Reports Server (NTRS)

Liquid coolant chill tool provides uniform cooling to materials adjacent to weld areas on long or contoured butt welds. This tool incorporates a manifold that clamps to the weld joint by vacuum and circulates liquid in direct contact with adjacent material.

Odor, M. E.; Whiffen, E. E.

1966-01-01

367

49 CFR 179.220-10 - Welding.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Welding. 179.220-10 Section 179.220-10...DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion...see § 171.7 of this subchapter). Welding procedures, welders, and...

2011-10-01

368

Quick Check Of Butt-Weld Alignment  

NASA Technical Reports Server (NTRS)

Proposed tool measures alignments of plates before butt-welded. Provides nearly instantaneous check on alignment, thereby facilitating repetitive measurements along length of weld joint. Reduces risk of contamination of weld from dirty measuring tools. Middle photodetector indicates acceptable alignment when position of transmitter fiber preciously matches that of center receiver fiber. If plates offset, other photodetectors signal misalignment.

Smith, Matthew A.

1990-01-01

369

Pulsed-Current Welding Of Nickel-Based Alloy  

NASA Technical Reports Server (NTRS)

Joints as strong (or stronger than) joints made with constant current. Report based on study of pulsed-current versus constant-current gas/tungsten arc welding of butt joints between panels of nickel-based alloy 718. In pulsed-current welding, arc current alternated between high and low value. Enables greater control of freezing and depth of penetration of weld puddle at given heat input. Thicker sections joined. Readily incorporated into automated welding system, with resultant greater uniformity and reproducibility of welds than attained in manual welding.

Gamwell, W. R.; Kurgan, C.; Malone, T. W.

1993-01-01

370

Improved microstructure and mechanical properties in gas tungsten arc welded aluminum joints by using graphene nanosheets/aluminum composite filler wires.  

PubMed

In the present study, different amounts of graphene nanosheets (GNSs) were added to the 4043 aluminum alloy powders by using the mechanical alloying method to produce the composite filler wires. With each of the produced composite filler wires, one all-weld metal coupon was welded using the gas tungsten arc (GTA) welding process. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. As the amount of GNSs in the composition of filler wire is increased, the microstructure of weld metal was changed from the dendritic structure to fine equiaxed grains. Furthermore, the tensile strength and microhardness of weld metal was improved, and is attributed to the augmented nucleation and retarded growth. From the results, it was seen that the GNSs/Al composite filler wire can be used to improve the microstructure and mechanical properties of GTA weld metals of aluminum and its alloys. PMID:24981209

Fattahi, M; Gholami, A R; Eynalvandpour, A; Ahmadi, E; Fattahi, Y; Akhavan, S

2014-09-01

371

Properties of friction welds between 9Cr-ODS martensitic and ferritic martensitic steels  

NASA Astrophysics Data System (ADS)

Friction welding of oxide-dispersion-strengthened-steel (ODS) and ferritic-martensitic 11Cr-0.5Mo-2W, V, Nb steel (PNC-FMS) was examined to investigate the feasibility of the welding of this alloy combination. Forge pressure was varied in the welding test to investigate the effect on the soundness of the weld joint. Post-weld heat treatment was necessary for the weld joint because of quench hardening in the heat-affected zone in the as-welded condition. The welds were cross-sectioned and examined to determine their metallurgical structure, hardness and tensile strength. Since the heat treatment produced a softened zone near the weld interface, the furnace-cooling rate was investigated to determine the rate at which the softening did not occur. The weld joints were cold-rolled and the soundness of the weld interface was determined by tensile testing the cold-rolled weld joints.

Uwaba, Tomoyuki; Ukai, Shigeharu; Nakai, Tatsuyoshi; Fujiwara, Masayuki

2007-08-01

372

46 CFR 154.182 - Contiguous hull structure: Production weld test.  

Code of Federal Regulations, 2011 CFR

... Contiguous hull structure: Production weld test. 154.182 Section 154.182... Contiguous hull structure: Production weld test. If a portion of the contiguous...structure must pass the following production weld tests in the position that the joint...

2011-10-01

373

46 CFR 154.182 - Contiguous hull structure: Production weld test.  

Code of Federal Regulations, 2010 CFR

... Contiguous hull structure: Production weld test. 154.182 Section 154.182... Contiguous hull structure: Production weld test. If a portion of the contiguous...structure must pass the following production weld tests in the position that the joint...

2010-10-01

374

46 CFR 154.182 - Contiguous hull structure: Production weld test.  

Code of Federal Regulations, 2012 CFR

... Contiguous hull structure: Production weld test. 154.182 Section 154.182... Contiguous hull structure: Production weld test. If a portion of the contiguous...structure must pass the following production weld tests in the position that the joint...

2012-10-01

375

46 CFR 154.182 - Contiguous hull structure: Production weld test.  

Code of Federal Regulations, 2013 CFR

... Contiguous hull structure: Production weld test. 154.182 Section 154.182... Contiguous hull structure: Production weld test. If a portion of the contiguous...structure must pass the following production weld tests in the position that the joint...

2013-10-01

376

46 CFR 154.182 - Contiguous hull structure: Production weld test.  

... Contiguous hull structure: Production weld test. 154.182 Section 154.182... Contiguous hull structure: Production weld test. If a portion of the contiguous...structure must pass the following production weld tests in the position that the joint...

2014-10-01

377

JANUARY 1989 V' PUBLISHED BY THE AMERICAN WELDING SOCIETY TO ADVANCE  

E-print Network

by Professor T. Kuwana (Tohoku University) Technical Committee on Fatigue Strength of Welded Joints ChairedA JANUARY 1989 V' PUBLISHED BY THE AMERICAN WELDING SOCIETY TO ADVANCE THE SCIENCE, TECHNOLOGY AND APPLICAliON OF WELDING ...I

Eagar, Thomas W.

378

Polyimide adhesives for weld-bonding titanium  

NASA Technical Reports Server (NTRS)

Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system and a new adhesive system, CP/CFA, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219K (-65 F) to 561K (550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of weld-bonding for fabricating stringer stiffened skin panels.

Vaughan, R. W.; Sheppard, C. H.; Baucom, R.

1976-01-01

379

Oil-Ash Corrosion Resistance of Dissimilar T22/T91 Welded Joint of Super Heater Tubes  

NASA Astrophysics Data System (ADS)

The studies on the high temperature corrosion of the dissimilar metal weldment are necessary for longer service of the weldments in corrosive medium. This paper reports the performance of microstructurally different regions, namely heat-affected zone (HAZ), weld metal (WM), and base metal (BM) of dissimilar metal weldment of T22/T91 in the molten salt (Na2SO4-60%V2O5) environment under cyclic studies. The T22 HAZ, WM, and T91 HAZ were observed to oxidize at higher rates and develop more scale thickness than other regions in the weldment. Microstructures and elemental analysis indicate lesser availability of Cr in T22 HAZ and T91 HAZ due to formation of Cr-rich phases, which ultimately causes the difference in oxidation behavior of different regions. The presence of chromium carbides and intermetallics in un-oxidized T22 HAZ region and martensitic structure with the presence of delta ferrites in un-oxidized T91 HAZ region was observed to be the major cause behind the weak corrosion resistance of the respective HAZs. The higher oxidation rate of T22 HAZ may be attributed to the absence of protective scale of Cr2O3 and presence of Fe3O4 phases. Similarly higher oxidation rate of T91 HAZ region can be attributed to lesser availability of Cr due to the propensity of development of delta ferrite in martensitic structure.

Mittal, Rutash; Sidhu, Buta Singh

2014-12-01

380

Friction Stir Spot Welding of DP780 Carbon Steel  

SciTech Connect

Friction stir spot welds were made in uncoated and galvannealed DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1 to 10 s. Increasing tool rotation speed from 800 to 1600 rev min{sup -1} increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap shear strengths exceeding 10 {center_dot} 3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

Santella, Michael L [ORNL; Hovanski, Yuri [ORNL; Frederick, David Alan [ORNL; Grant, Glenn J [ORNL; Dahl, Michael E [ORNL

2010-01-01

381

Weld defect formation in FSWed coppers  

NASA Astrophysics Data System (ADS)

This work was undertaken to explore the formation of weld defects in FSWed copper metals via both numerical and experimental approaches. The 4 mm-thick copper sheets were friction stir welded at a tool rotational speed of 710 rpm and tool translational speed of 40 mm/min. Microstructural evaluations were performed on the welded specimens. Also a 3D arbitrary Lagrangian Eulerian numerical model was developed to obtain temperature and material velocity profiles. To this aim, DEFORM-3D was implemented for developing the numerical simulation. Numerical results for temperature values showed good agreement with the recorded experimental data. They also suggest that on the advancing side (AS) of the trailing side, the pin velocity has the minimum amount (zero), and this is the main reason for the formation of tunneling cavity. Experimental results show that a force is created between the reminder of material at the joint and the rim of AS. This force causes a prong of surface material from the AS rim to penetrate into lower parts of weld. It seems that the inadequate pressure (low values of the plunge depth), inadequate surface materials, and the trapped air are the main causes for the formation of the weld defects.

Gheisari, Yousof; Pashazadeh, Hamed; Teimournezhad, Jamal; Masoumi, Abolfazl

2014-06-01

382

Effects of friction stir welding on microstructure of 7075 aluminum  

Microsoft Academic Search

Friction stir welding is a relatively new technique developed by The Welding Institute (TWI) for the joining of aluminum alloys. The technique, based on friction heating at the faying surfaces of two pieces to be joined, results in a joint created by interface deformation, heat, and solid-state diffusion. In evaluating friction stir welding, critical issues (beyond a sound joint) include

C. G. Rhodes; M. W. Mahoney; W. H. Bingel; R. A. Spurling; C. C. Bampton

1997-01-01

383

Laser welding of bone: Successful in vitro experiments  

SciTech Connect

A method for ``welding`` bones is being developed. Tensile joint strengths of chicken bones welded in vitro have exceeded one kilogram. Welding was performed with either a Nd:YAG (1064 nm) or a diode laser (820 nm). Light was delivered with an optical fiber held a few millimeters from the bone surface. A solder was developed to assist in the welding process.

Mourant, J.R.; Anderson, G.D.; Bigio, I.J.; Johnson, T.M.

1994-02-01

384

Friction stir welding of carbon steels  

Microsoft Academic Search

In order to determine the effect of the carbon content and the transformation on the mechanical properties and microstructures of the FSW carbon steel joints, three types of carbon steels with different carbon contents (IF steel, S12C, S35C) were friction stir welded under various welding conditions. Compared with IF steel, the microstructures and mechanical properties of the carbon steel joints

Hidetoshi Fujii; Ling Cui; Nobuhiro Tsuji; Masakatsu Maeda; Kazuhiro Nakata; Kiyoshi Nogi

2006-01-01

385

Laser transmission welding of ABS: Effect of CNTs concentration and process parameters on material integrity and weld formation  

NASA Astrophysics Data System (ADS)

This paper reports a study of the laser transmission welding of polymeric joints composed by two ABS (acrylonitrile/butadiene/styrene) sheets, one transparent (natural ABS) and the other absorbent (filled by different percentages of carbon nanotubes (CNTs)). The objective of this work is to analyze the effect of process parameters and CNTs concentrations on weld formation and mechanical resistance of the weld joints.

Rodríguez-Vidal, E.; Quintana, I.; Gadea, C.

2014-04-01

386

Welding arc plasma physics  

NASA Technical Reports Server (NTRS)

The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

Cain, Bruce L.

1990-01-01

387

49 CFR 179.400-11 - Welding.  

Code of Federal Regulations, 2012 CFR

...circumferential closing joints in the cylindrical portion of the outer jacket, each joint of an inner tank and the outer jacket must be a fusion double welded butt joint. (b) The closure for openings and the circumferential closing joints in the cylindrical...

2012-10-01

388

49 CFR 179.400-11 - Welding.  

Code of Federal Regulations, 2013 CFR

...circumferential closing joints in the cylindrical portion of the outer jacket, each joint of an inner tank and the outer jacket must be a fusion double welded butt joint. (b) The closure for openings and the circumferential closing joints in the cylindrical...

2013-10-01

389

49 CFR 179.400-11 - Welding.  

Code of Federal Regulations, 2011 CFR

...circumferential closing joints in the cylindrical portion of the outer jacket, each joint of an inner tank and the outer jacket must be a fusion double welded butt joint. (b) The closure for openings and the circumferential closing joints in the cylindrical...

2011-10-01

390

Welding Research  

NASA Technical Reports Server (NTRS)

Welding fabrication and welding processes were studied. The following research projects are reported: (1) welding fabrication; (2) residual stresses and distortion in structural weldments in high strength steels; (3) improvement of reliability of welding by in process sensing and control (development of smart welding machines for girth welding of pipes); (4) development of fully automated and integrated welding systems for marine applications; (5) advancement of welding technology; (6) research on metal working by high power laser (7) flux development; (8) heat and fluid flow; (9) mechanical properties developments.

1982-01-01

391

Spot-Welding Gun With Adjustable Pneumatic Spring  

NASA Technical Reports Server (NTRS)

Proposed spot-welding gun equipped with pneumatic spring, which could be bellows or piston and cylinder, exerts force independent of position along stroke. Applies accurate controlled force to joint welded, without precise positioning at critical position within stroke.

Burley, Richard K.

1990-01-01

392

Fatique Resistant, Energy Efficient Welding Program, Final Technical Report  

SciTech Connect

The program scope was to affect the heat input and the resultant weld bead geometry by synchronizing robotic weave cycles with desired pulsed waveform shapes to develop process parameters relationships and optimized pulsed gas metal arc welding processes for welding fatique-critical structures of steel, high strength steel, and aluminum. Quality would be addressed by developing intelligent methods of weld measurement that accurately predict weld bead geometry from process information. This program was severely underfunded, and eventually terminated. The scope was redirected to investigate tandem narrow groove welding of steel butt joints during the one year of partial funding. A torch was designed and configured to perform a design of experiments of steel butt weld joints that validated the feasability of the process. An initial cost model estimated a 60% cost savings over conventional groove welding by eliminating the joint preparation and reducing the weld volume needed.

Egland, Keith; Ludewig, Howard

2006-05-25

393

Weld width indicates weld strength  

NASA Technical Reports Server (NTRS)

Width of butt weld in 2219-T87 aluminum has been found to be more reliable indicator of weld strength than more traditional parameters of power input and cooling rate. Yield stress and ultimate tensile strength tend to decrease with weld size. This conclusion supports view of many professional welders who give priority to weld geometry over welding energy or cooling rate as indicator of weld quality.

Nunes, A. C. J.; Novak, H. L.; Mcllwain, M. C.

1982-01-01

394

Welding of titanium alloy by Disk laser  

NASA Astrophysics Data System (ADS)

The following article describes results of investigations on influence of laser welding parameters on the weld shape, quality and mechanical properties of 2.0 mm thick butt joints of titanium alloy Ti6Al4V (Grade 5 according to ASTM B265) welded with a new generation disk laser TRUMPF TRUDISK 3302, emitting at 1030 nm, with maximum output power 3300 W at circular laser beam spot, characterized by laser beam divergence 8.0 mm•mrad. The test butt joints of Ti6Al4V titanium alloy sheets were prepared as single square groove (I-type joint) and one-side laser welded without an additional material, at a flat position, using a specially designed system for shielding gas (purity 99.999%). The investigations at the initial stage were focused on detailed analysis of influence of the basic laser welding parameters such as laser power and welding speed on the shape and quality of single bead produced during bead-on-plate welding. Then the optimal parameters were chosen for laser welding of 2.0 mm thick butt joints of the titanium alloy Ti6Al4V. Edges of the titanium alloy sheets were melted in argon atmosphere by the laser beam focused on the top surface of butt joints. The test welded joints were investigated by visual inspection, metallographic examinations, hardness and micro-hardness measurements and mechanical tests such as tensile tests and bending tests. It was found that the welding mode is a keyhole welding and providing high quality of joints requires a special techniques and conditions of laser welding, as well as special gas shielding nozzles is required.

Lisiecki, Aleksander

2013-01-01

395

FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY  

SciTech Connect

Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

2007-01-09

396

Fiber laser welding of nickel based superalloy Inconel 625  

NASA Astrophysics Data System (ADS)

The paper describes the application of single mode high power fiber laser (HPFL) for the welding of nickel based superalloy Inconel 625. Butt joints of Inconel 625 sheets 0,8 mm thick were laser welded without an additional material. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The quality and mechanical properties of the joints were determined by means of tensile and bending tests, and micro hardness tests, and also metallographic examinations. The results showed that a proper selection of laser welding parameters provides non-porous, fully-penetrated welds with the aspect ratio up to 2.0. The minimum heat input required to achieve full penetration butt welded joints with no defect was found to be 6 J/mm. The yield strength and ultimate tensile strength of the joints are essentially equivalent to that for the base material.

Janicki, Damian M.

2013-01-01

397

Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.  

PubMed

The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks. PMID:23858281

Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

2012-06-01

398

Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy  

NASA Technical Reports Server (NTRS)

Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds [1]. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. [1] In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

Talia, George E.

1996-01-01

399

Diode laser welding of aluminum to steel  

SciTech Connect

Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica [University of Rome Tor Vergata, Department of Mechanical Engineering, Via del Politecnico 1, 00133 Rome (Italy)

2011-05-04

400

Welding I.  

ERIC Educational Resources Information Center

Instructional objectives and performance requirements are outlined in this course guide for Welding I, a performance-based course offered at the Community College of Allegheny County to introduce students to shielded arc welding procedures involving stringer beads, butt welds, and lap welds. After introductory material outlining course objectives,…

Allegheny County Community Coll., Pittsburgh, PA.

401

Welding IV.  

ERIC Educational Resources Information Center

Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

Allegheny County Community Coll., Pittsburgh, PA.

402

Analysis Method of Friction Torque and Weld Interface Temperature during Friction Process of Steel Friction Welding  

NASA Astrophysics Data System (ADS)

This paper describes an analysis method of the friction torque and weld interface temperature during the friction process for steel friction welding. The joining mechanism model of the friction welding for the wear and seizure stages was constructed from the actual joining phenomena that were obtained by the experiment. The non-steady two-dimensional heat transfer analysis for the friction process was carried out by calculation with FEM code ANSYS. The contact pressure, heat generation quantity, and friction torque during the wear stage were calculated using the coefficient of friction, which was considered as the constant value. The thermal stress was included in the contact pressure. On the other hand, those values during the seizure stage were calculated by introducing the coefficient of seizure, which depended on the seizure temperature. The relationship between the seizure temperature and the relative speed at the weld interface in the seizure stage was determined using the experimental results. In addition, the contact pressure and heat generation quantity, which depended on the relative speed of the weld interface, were solved by taking the friction pressure, the relative speed and the yield strength of the base material into the computational conditions. The calculated friction torque and weld interface temperatures of a low carbon steel joint were equal to the experimental results when friction pressures were 30 and 90 MPa, friction speed was 27.5 s-1, and weld interface diameter was 12 mm. The calculation results of the initial peak torque and the elapsed time for initial peak torque were also equal to the experimental results under the same conditions. Furthermore, the calculation results of the initial peak torque and the elapsed time for initial peak torque at various friction pressures were equal to the experimental results.

Kimura, Masaaki; Inoue, Haruo; Kusaka, Masahiro; Kaizu, Koichi; Fuji, Akiyoshi

403

Half-transient liquid phase diffusion welding: An approach for diffusion welding of SiC p \\/A356 with Cu interlayer  

Microsoft Academic Search

Aluminum matrix composite SiCp\\/A356 was welded by half-transient liquid Phase diffusion welding (HTLPDW) with a Cu interlayer. The effects of welding parameters\\u000a and interlayer thickness on the properties of the welded joint were investigated, and the optimal welding parameters were\\u000a subsequently put forward. The relationship between the tensile strength of the joint and the microstructure was studied by\\u000a analyzing the

Meng Hua; Wei Guo; Hang Wai Law; John Kin Lim Ho

2008-01-01

404

Weldability aspects in the design and fabrication of aluminium structures subjected to fatigue loads. Part 1: Effect of welding on the structural integrity of joint types designed for repairing aluminium ship sections  

NASA Astrophysics Data System (ADS)

The Laboratory of Production Engineering and the Metals Laboratory of the Technical Research Center of Finland (VTT) have participated in a Nordic research project entitled 'New methods for joining of aluminium'. The results from Finnish work of the project will be presented in a report to be published in two parts. Part 1 of the report will evaluate the effects of welding on the structural integrity of some joint types primarily designed for repairing ship sections and sea crafts made from 6xxx (AlSiMg) series alloys.

Nevasmaa, P.; Peltonen, J.; Kuitunen, R.; Rahka, K.

1993-05-01

405

Welding, Bonding and Fastening, 1984  

NASA Technical Reports Server (NTRS)

A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

Buckley, J. D. (editor); Stein, B. A. (editor)

1985-01-01

406

Diode laser welding of high yield steel  

NASA Astrophysics Data System (ADS)

The following article describes results of investigations on influence of laser welding parameters on the weld shape, quality and mechanical properties of 2.5 mm thick butt joints of thermo-mechanically rolled, high yield strength steel for cold forming S420MC (according to EN 10149 - 3 and 060XLK according to ASTM) welded with high power diode laser HPDL ROFIN SINAR DL 020 with rectangular laser beam spot and 2.2 kW output power, and 808 nm wavelength. The investigations at the initial stage were focused on detailed analysis of influence of the basic laser welding parameters such as laser power and welding speed on the shape and quality of single bead produced during bead-on-plate welding. Then the optimal parameters were chosen for laser welding of 2.5 mm thick butt joints of the thermo-mechanically rolled, high yield strength steel sheets for cold forming S420MC. The test joints were prepared as single square groove and one-side laser welded without an additional material, at a flat position. Edges of steel sheets were melted in argon atmosphere by the laser beam focused on the top joint surface. The test welded joints were investigated by visual inspection, metallographic examinations, mechanical tests such as tensile tests and bending tests. It was found that the high power diode laser may be applied successfully for one-side welding of the S420MC steel butt joints. Additionally it was found that in the optimal range of laser welding parameters the high quality joint were produced.

Lisiecki, Aleksander

2013-01-01

407

Welding Penetration Control of Fixed Pipe in TIG Welding Using Fuzzy Inference System  

NASA Astrophysics Data System (ADS)

This paper presents a study on welding penetration control of fixed pipe in Tungsten Inert Gas (TIG) welding using fuzzy inference system. The welding penetration control is essential to the production quality welds with a specified geometry. For pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small diameter pipes progresses. Having welded pipe in fixed position, obviously, the excessive arc current yields burn through of metals; in contrary, insufficient arc current produces imperfect welding. In order to avoid these errors and to obtain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used a charge-coupled device (CCD) camera to monitor backside image of molten pool. The captured image was processed to recognize the edge of molten pool by image processing algorithm. Simulation of welding control using fuzzy inference system was constructed to simulate the welding control process. The simulation result shows that fuzzy controller was suitable for controlling the welding speed and appropriate to be implemented into the welding system. A series of experiments was conducted to evaluate the performance of the fuzzy controller. The experimental results show the effectiveness of the control system that is confirmed by sound welds.

Baskoro, Ario Sunar; Kabutomori, Masashi; Suga, Yasuo

408

Laser Welding and Syncristallization Techniques Comparison: In Vitro Study  

PubMed Central

Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd?:?YAG laser device (Fotona Fidelis III, ? = 1064?nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd?:?YAG laser welding (group A = 12 samples), chair-side Nd?:?YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56?N for group A, 896.41 ± 120.84?N for group B, and 283.58 ± 84.98?N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd?:?YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

Fornaini, C.; Merigo, E.; Vescovi, P.; Meleti, M.; Nammour, S.

2012-01-01

409

Laser welding and syncristallization techniques comparison: in vitro study.  

PubMed

Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd?:?YAG laser device (Fotona Fidelis III, ? = 1064?nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd?:?YAG laser welding (group A = 12 samples), chair-side Nd?:?YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56?N for group A, 896.41 ± 120.84?N for group B, and 283.58 ± 84.98?N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd?:?YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

Fornaini, C; Merigo, E; Vescovi, P; Meleti, M; Nammour, S

2012-01-01

410

Effect of interface microstructure on the bond strength of the diffusion welded joints between titanium and stainless steel  

SciTech Connect

Diffusion bonding between commercially pure titanium and 304 stainless steel was carried out at a temperature of 950 deg. C for 30-120 min under uniaxial load in a vacuum. The diffusion bonds were characterized by optical and scanning electron microscopy. The diffusion zone contained different reaction bands and their chemical composition was determined using energy dispersive X-ray spectroscopy. The concentration of chemical species indicated the presence of {sigma}, {lambda}, {chi}, FeTi, {beta}-Ti and Fe{sub 2}Ti{sub 4}O phases in the reaction zone and their existence was confirmed by X-ray diffraction. A maximum bond strength of {approx}71% of that of titanium along with 5.8% ductility were obtained for the diffusion couple processed for 30 min due to formation of finer size intermetallics. A rise in joining time increases void generation and growth of intermetallic compounds, which are responsible for a drastic fall in the strength value.

Ghosh, M. [Department of Metallurgy, Bengal Engineering College, Deemed University, Howrah-711103, West Bengal (India)]. E-mail: ghosh_mnk@yahoo.com; Chatterjee, S. [Department of Metallurgy, Bengal Engineering College, Deemed University, Howrah-711103, West Bengal (India)]. E-mail: schatterjee46@yahoo.com

2005-05-15

411

Microstructural analysis of solar cell welds  

NASA Astrophysics Data System (ADS)

Parallel-gap resistance welding of silicon solar cells with copper interconnects results in complex microstructural variations that depend on the welding variables. At relatively low heat input solid-state welds are produced. At medium heat the Ag-Cu eutectic forms resulting in a braze joint. High heat produces a fusion weld with complete melting of the silver layer on the silicon solar cell. If the silicon is also melted, cracking occurs in the silicon cell below the weld nugget. These determinations were made using light microscopy, microprobe, and scanning electron microscopy analyses.

Moore, T. J.; Watson, G. K.; Baraona, C. R.

412

Laser Welding in Space  

NASA Technical Reports Server (NTRS)

Solidification type welding process experiments in conditions of microgravity were performed. The role of convection in such phenomena was examined and convective effects in the small volumes obtained in the laser weld zone were observed. Heat transfer within the weld was affected by acceleration level as indicated by the resulting microstructure changes in low gravity. All experiments were performed such that both high and low gravity welds occurred along the same weld beam, allowing the effects of gravity alone to be examined. Results indicate that laser welding in a space environment is feasible and can be safely performed IVA or EVA. Development of the hardware to perform the experiment in a Hitchhiker-g platform is recomended as the next step. This experiment provides NASA with a capable technology for welding needs in space. The resources required to perform this experiment aboard a Shuttle Hitchhiker-pallet are assessed. Over the four year period 1991 to 1994, it is recommended that the task will require 13.6 manyears and $914,900. In addition to demonstrating the technology and ferreting out the problems encountered, it is suggested that NASA will also have a useful laser materials processing facility for working with both the scientific and the engineering aspects of materials processing in space. Several concepts are also included for long-term optimization of available solar power through solar pumping solid state lasers directly for welding power.

Workman, Gary L.; Kaukler, William F.

1989-01-01

413

Damage Tolerance Assessment of Friction Pull Plug Welds  

NASA Technical Reports Server (NTRS)

Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

McGill, Preston; Burkholder, Jonathan

2012-01-01

414

Advanced Welding Concepts  

NASA Technical Reports Server (NTRS)

Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

Ding, Robert J.

2010-01-01

415

Differences between Laser and Arc Welding of HSS Steels  

NASA Astrophysics Data System (ADS)

Conventional welding processes often fail to provide adequate joints in high strength steels with multiphase microstructures. One of the promising techniques is laser beam welding: working without filler metal and with sufficient capacity for automotive and transportation industry (where the amount of AHSS steels increases each year, as well as the length of laser welds). The paper compares microstructures and properties of HSS (high strength steel) joints made by MAG (Metal Active Gas) and laser welding. The effects of main welding parameters (heat input, welding speed and others) are studied on multiphase TRIP 900 steel tubes and martensitic sheets DOCOL 1200, advanced materials for seat frames and other automotive components. Whereas the strength of conventional welds is significantly impaired, laser welding leaves strength of the base material nearly unaffected. As the nature of fracture changes during loading and depending on the welding method, failure mechanisms upon cross tension tests have been studied as well.

N?me?ek, Stanislav; Mužík, Tomáš; Míšek, Michal

416

Specific wave interface and its formation during magnetic pulse welding  

NASA Astrophysics Data System (ADS)

A specific wave interface and its formation mechanism in an Al-Fe joint prepared by magnetic pulse welding method are investigated. Specific waves appear occasionally at the interfaces of joints, and the height of the wave peak coincides with the width of the transition zone formed by the enormous force. This work reveals that the specific wave interface is caused by high speed shearing at a certain angle. This shearing process can be classified using Stokes' Theorem, and the Navier-Stokes equation is employed to predict the height of the wave peak to obtain the width of the transition zone.

Cui, Junjia; Sun, Guangyong; Li, Guangyao; Xu, Zhidan; Chu, Paul K.

2014-12-01

417

A Study on the Welding Characteristics of Tailor Welded Blank Metal Sheets Using GTAW and Laser Welding  

NASA Astrophysics Data System (ADS)

In this study, a computational and experimental effort was carried out to qualitatively understand the weld pool shape, distortion and residual stress for continuous laser welding and manual pulsed gas metal arc welding. For all the welding simulations given in this dissertation, a welding specific finite element package, SYSWELD, is used. This research focuses on the welding behavior observed in light-weight metal structures known as the tailor-welded blanks, TWBs. They are a combination of two or more metal sheets with different thickness and/or different materials that are welded together in a single plane prior to forming, e.g., stamping. They made from the low carbon steel. As laser welding experiment results show, the weld pool shape at the top and bottom surface, is strongly influenced by surface tension, giving it a characteristic hourglass shape. In order to simulate the hourglass shape, a new volumetric heat source model was developed to predict the transient temperature profile and weld pool shape, including the effect of surface tension. Tailor welded blanks with different thicknesses were examined in the laser welding process. All major physical phenomena such as thermal conduction, heat radiation and convection heat losses are taken into account in the model development as well as temperature-dependant thermal and mechanical material properties. The model is validated for the case of butt joint welding of cold rolled steel sheets. The results of the numerical simulations provide temperature distributions representing the shape of the molten pool, distortion and residual stress with varying laser beam power and welding speed. It is demonstrated that the finite element simulation results are in good agreement with the experiment results. This includes the weld pool shape and sheet metal distortion. While there is no experimental data to compare directly with residual stress results, the distorted shape provides an indirect measure of the welding residual stresses. The welding details such as clamping, butt joint configuration, material, sample thickness are similar for both the laser welding process and the manual pulsed GTAW process. Also as same metallurgical investigation, the weld pool shape displays wider full penetration without the effect of surface tension. The double ellipsoid volumetric heat source is applied in the finite element simulation to determine the temperature distribution, distortion and residual stress. The simulation results are compared with the experimental results and show good agreement. In addition, the results from the laser welding process are compared to the equivalent results from the GTAW process in the order to better understand the fundamental differences between these two welding processes.

Thasanaraphan, Pornsak

418

Effect of welding process on fatigue crack growth behaviour of austenitic stainless steel welds in a low alloy (Q & T) steel  

Microsoft Academic Search

Fatigue crack growth behaviour from a lack of penetration (LOP) defect in austenitic stainless steel weld metals of cruciform joints made of a low alloy high strength (Q & T) steel has been studied to understand the effect of two welding processes, namely, shielded metal arc welding (SMAW) and flux cored arc welding (FCAW). Fatigue crack growth studies were carried

E. J. Rao; B. Guha; G. Malakondaiah; V. M. Radhakrishnan

1997-01-01

419

Welding Technician  

ERIC Educational Resources Information Center

About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

Smith, Ken

2009-01-01

420

Welding Introduction  

NSDL National Science Digital Library

The Materials Education Resource Center has provided this module to help students learn the basics of metal welding, including techniques. Students will learn the vocabulary used in welding and see examples of welding processes. This PDF document includes a step by step procedure for the learning module as well as links to supporting videos and online reference tools.

Stoebe, Thomas G.

2012-09-24

421

Magnetic pulse welding in plane geometry  

NASA Astrophysics Data System (ADS)

The results of a study of the feasibility of magnetic pulse welding of flat conductors are given. Various inductor circuits and sheet configurations are investigated experimentally. An optimized inductor circuit for accelerating flat conductors by a magnetic field is presented and the necessary diagnostic equipment is developed. Results of experiments on the acceleration of flat conductors and production of aluminum-aluminum and aluminum-steel welded joints are presented. The characteristics of the welds are investigated.

Kazeev, M. N.; Koidan, V. S.; Kozlov, V. F.; Tolstov, Yu. S.

2013-11-01

422

Reliability of welded structures containing fatigue cracks  

Microsoft Academic Search

This study investigates the reliability of a cracked fillet welded T-joint typically found in offshore structures. A formulation for the aspect ratio (a\\/c) of a propagating semi-elliptical fatigue crack located at the toe of the weld is developed using Newman and Raju`s stress intensity factor for a cracked flat plate in conjunction with a weld magnification factor. The reliability in

D. Lanning; M.-H. H. Shen

1996-01-01

423

SmartWeld working session for the GTS4  

SciTech Connect

Results from SmartWeld`s first working session involving in-progress designs is presented. The Welding Advisor component of SmartWeld was thoroughly exercised, evaluated all eleven welds of the selected part. The Welding Advisor is an expert system implemented with object-oriented techniques for knowledge representation. With two welding engineers in attendance, the recommendations of the Welding Advisor were thoroughly examined and critiqued for accuracy and for areas of improvement throughout the working session. The Weld Schedule Database component of SmartWeld was also exercised. It is a historical archive of proven, successful weld schedules that can be intelligently searched using the current context of SmartWeld`s problem solving state. On all eleven welds, the experts agreed that Welding Advisor recommended the most risk free options. As a result of the Advisor`s recommendation, six welds agreed completely with the experts, two welds had their joint geometry modified for production, and three welds were not modified but extra care was exercised during welding. 25 figs., 3 tabs.

Kleban, S. [Sandia National Labs., Albuquerque, NM (United States); Hicken, K.; Ng, R. [Sandia National Labs., Livermore, CA (United States); Fricke, B. [Allied Signal Kansas City Division, MO (United States)

1997-08-01

424

Integration of NASA-sponsored studies on aluminum welding  

NASA Technical Reports Server (NTRS)

The results are presented of numerous studies relating to aluminum alloy welding. The subjects covered include: (1) effects of porosity on weld joint performance, (2) sources of porosity, (3) weld thermal effects, (4) residual stresses and distortion, and (5) manufacturing process system control.

Masubuchi, K.

1972-01-01

425

49 CFR 179.100-9 - Welding.  

Code of Federal Regulations, 2011 CFR

...Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2011-10-01

426

49 CFR 179.200-10 - Welding.  

Code of Federal Regulations, 2013 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2013-10-01

427

49 CFR 179.200-10 - Welding.  

Code of Federal Regulations, 2011 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2011-10-01

428

49 CFR 179.200-10 - Welding.  

Code of Federal Regulations, 2010 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2010-10-01

429

49 CFR 179.100-9 - Welding.  

Code of Federal Regulations, 2012 CFR

...Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2012-10-01

430

49 CFR 179.220-10 - Welding.  

Code of Federal Regulations, 2013 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion welded in compliance with AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of this subchapter)....

2013-10-01

431

49 CFR 179.220-10 - Welding.  

Code of Federal Regulations, 2010 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion welded in compliance with AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of this subchapter)....

2010-10-01

432

49 CFR 179.220-10 - Welding.  

Code of Federal Regulations, 2012 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion welded in compliance with AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of this subchapter)....

2012-10-01

433

49 CFR 179.200-10 - Welding.  

Code of Federal Regulations, 2012 CFR

...for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2012-10-01

434

49 CFR 179.100-9 - Welding.  

Code of Federal Regulations, 2013 CFR

...Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2013-10-01

435

49 CFR 179.100-9 - Welding.  

Code of Federal Regulations, 2010 CFR

...Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded in compliance with the requirements of AAR Specifications for Tank Cars, appendix W (IBR, see § 171.7 of...

2010-10-01

436

Rounding And Aligning Tubes For Butt Welding  

NASA Technical Reports Server (NTRS)

Easy-to-use tool helps to ensure solid, reliable joint. Tool similar to automobile-tailpipe expander corrects out-of-roundness in tubes before butt-welded and holds tubes in position during welding. Two tubes rounded and aligned with each other by expansion shoes. After use, shoes retracted so tool withdrawn, even through tube narrower than its mate.

Burley, Richard H.; Burow, Glenn H.

1990-01-01

437

Effect of Repair Welding on Electrochemical Corrosion and Stress Corrosion Cracking Behavior of TIG Welded AA2219 Aluminum Alloy in 3.5 Wt Pct NaCl Solution  

NASA Astrophysics Data System (ADS)

The stress corrosion cracking (SCC) behavior of AA2219 aluminum alloy in the as-welded (AW) and repair-welded (RW) conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using the slow strain rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both BM and welded joints. The results show that the ductility ratio ( ? NaCl/( ? air)) of the BM was close to one (0.97) and reduced to 0.9 for the AW joint. This value further reduced to 0.77 after carrying out one repair welding operation. However, the RW specimen exhibited higher ductility than the single-weld specimens even in 3.5 wt pct NaCl solution. SSRT results obtained using pre-exposed samples followed by post-test metallographic observations clearly showed localized pitting corrosion along the partially melted zone (PMZ), signifying that the reduction in ductility ratio of both the AW and RW joints was more due to mechanical overload failure, caused by the localized corrosion and a consequent reduction in specimen thickness, than due to SCC. Also, the RW joint exhibited higher ductility than the AW joint both in air and the environment, although SCC index (SI) for the former is lower than that of the latter. Fractographic examination of the failed samples, in general, revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy. Microstructural examination and polarization tests further demonstrate grain boundary melting along the PMZ, and that provided the necessary electrochemical condition for the preferential cracking on that zone of the weldment.

Venugopal, A.; Sreekumar, K.; Raja, V. S.

2010-12-01

438

Parametric Studies Of Weld Quality Of Tungsten Inert Gas Arc Welding Of Stainless Steel  

SciTech Connect

Effect of current and gas flow rate on quality of weld in tungsten inter gas arc welding of austenitic stainless steel has been studied in the present work through experiments and analyses. Butt welded joints have been made by using several levels of current and gas flow rate. The quality of the weld has been evaluated in terms of ultimate and breaking strengths of the welded specimens. The observed data have been interpreted, discussed and analyzed by using Grey--Taguchi methodology. Optimum parametric setting has been predicted and validated as well.

Kumar Pal, Pradip; Nandi, Goutam; Ghosh, Nabendu [Mechanical Engineering Department, Jadavpur University, Kolkata-700032 (India)

2011-01-17

439

Effect of Weld Tool Geometry on Friction Stir Welded AA2219-T87 Properties  

NASA Technical Reports Server (NTRS)

In this study, flat panels of AA2219-T87 were friction stir welded (FSWed) using weld tools with tapered pins The three pin geometries of the weld tools included: 0 (straight cylinder), 30 , and 60 angles on the frustum. For each weld tool geometry, the FSW process parameters were optimized to eliminate defects. A constant heat input was maintained while varying the process parameters of spindle rpm and travel speed. This provided a constant heat input for each FSW weld panel while altering the hot working conditions imparted to the workpiece. The resulting mechanical properties were evaluated from tensile test results of the FSW joint.

Querin, Joseph A.; Schneider, Judy A.

2008-01-01

440

Weld geometry strength effect in 2219-T87 aluminum  

NASA Technical Reports Server (NTRS)

A theory of the effect of geometry on the mechanical properties of a butt weld joint is worked out based upon the soft interlayer weld model. Tensile tests of 45 TIG butt welds and 6 EB beads-on-plate in 1/4-in. 2219-T87 aluminum plate made under a wide range of heat sink and power input conditions are analyzed using this theory. The analysis indicates that purely geometrical effects dominate in determining variations in weld joint strength with heat sink and power input. Variations in weld dimensions with cooling rate are significant as well as with power input. Weld size is suggested as a better indicator of the condition of a weld joint than energy input.

Nunes, A. C., Jr.; Novak, H. L.; Mcilwain, M. C.

1981-01-01

441

Friction Stir Welding of Tapered Thickness Welds Using an Adjustable Pin Tool  

NASA Technical Reports Server (NTRS)

Friction stir welding (FSW) can be used for joining weld lands that vary in thickness along the length of the weld. An adjustable pin tool mechanism can be used to accomplish this in a single-pass, full-penetration weld by providing for precise changes in the pin length relative to the shoulder face during the weld process. The difficulty with this approach is in accurately adjusting the pin length to provide a consistent penetration ligament throughout the weld. The weld technique, control system, and instrumentation must account for mechanical and thermal compliances of the tooling system to conduct tapered welds successfully. In this study, a combination of static and in-situ measurements, as well as active control, is used to locate the pin accurately and maintain the desired penetration ligament. Frictional forces at the pin/shoulder interface were a source of error that affected accurate pin position. A traditional FSW pin tool design that requires a lead angle was used to join butt weld configurations that included both constant thickness and tapered sections. The pitch axis of the tooling was fixed throughout the weld; therefore, the effective lead angle in the tapered sections was restricted to within the tolerances allowed by the pin tool design. The sensitivity of the FSW process to factors such as thickness offset, joint gap, centerline offset, and taper transition offset were also studied. The joint gap and the thickness offset demonstrated the most adverse affects on the weld quality. Two separate tooling configurations were used to conduct tapered thickness welds successfully. The weld configurations included sections in which the thickness decreased along the weld, as well as sections in which the thickness increased along the weld. The data presented here include weld metallography, strength data, and process load data.

Adams, Glynn; Venable, Richard; Lawless, Kirby

2003-01-01

442

HIGH TEMPERATURE CREEP PROPERTIES AND MICROSTRUCTURAL EXAMINATIONS OF P92 WELDS  

E-print Network

1 HIGH TEMPERATURE CREEP PROPERTIES AND MICROSTRUCTURAL EXAMINATIONS OF P92 WELDS Kalck Charlotte1: charlotte.kalck@cea.fr Abstract The present study deals with the creep properties of welded joints made of P surfaces and the microstructural examination of welded joints prior to and after creep tests allow

Paris-Sud XI, Université de

443

Matrix penetration in the bulk:In uence of humidity: Morphological analysis of wood welding  

E-print Network

Matrix penetration in the bulk:In uence of humidity: Morphological analysis of wood welding.pichelin@b .ch Context: Wood can be welded using linear vibration welding tech- niques similar to the ones in plastic and metal industry[1] . Wood welding allows bonding strength similar to glued joints. However, due

Dalang, Robert C.

444

Elements of arc welding  

SciTech Connect

This paper looks at the following arc welding techniques: (1) shielded metal-arc welding; (2) submerged-arc welding; (3) gas metal-arc welding; (4) flux-cored arc welding; (5) electrogas welding; (6) gas tungsten-arc