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1

Performance variability of aluminium hybrid LAP-joints obtained by means of adhesives and ultrasonic welding  

Microsoft Academic Search

This paper presents the first results of the running project HY-LAP (HYbrid LAP-joints) carried out at the Dipartimento di\\u000a Meccanica of the Politecnico di Milano in collaboration with MUSP and the University of Parma. Thin plates of aluminium 6022T4\\u000a have been joined by means of ultrasonic welding, structural adhesives and a combination of them; the applied experimental\\u000a procedures (i.e. specimens

M. Annoni; F. Moroni; V. Mussi

2010-01-01

2

Improving Joint Properties of Friction Welded Joint of High Tensile Steel  

Microsoft Academic Search

This report describes the improvements in the joint properties of friction welded joint of 780MPa class high tensile steel. Welded joint made by a continuous drive friction welding machine, the conventional method, had not obtained 100% joint efficiency despite applying forge pressure. This was due to the softening of the welded interface zone for heat input during braking times. Therefore,

Masaaki Kimura; Masahiro Kusaka; Kenji Seo; Akiyoshi Fuji

2005-01-01

3

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

4

INVESTIGATION TOWARD OBTAINING SIGNIFICANTLY HIGHER MECHANICAL PROPERTIES OF AS-WELDED JOINTS IN HIGH-STRENGTH, HEAT TREATABLE ALUMINUM ALLOYS  

Microsoft Academic Search

Welding techniques, filler metal-parent metal selection, and moderate ; temperature post-weld thermal treatments are described which were employed to ; achieve tensile strengths up to 72,000 pounds per square inch (psi) in welded ; heat treatable aluminum alloy sheet. The aluminum-zinc-magnesium-copper (Al - ; Zn - Mg -Cu) alloys 7075 and 7178 welded Al-Mg or Al-Mg-Zn filler metals gave ;

1961-01-01

5

Testing of explosive welding and welded joints: joint mechanism and properties of explosive welded joints  

Microsoft Academic Search

In this study physical mechanism of explosive welding joint was analysed. The mechanism refers to wavy joint with interpass\\u000a and without one. Plastic strain, viscosity and acoustic waves were applied to explain the problem. The own model of the mechanism\\u000a of oxide removal for the direct joint and test results confirming the bonding mechanism were showed.

Bogumil Wronka

2010-01-01

6

Pyrothermal treatment of welded joints  

SciTech Connect

The results of investigation of the structure and distribution of residual stresses in welded joints in pipes after heat treatment, which includes heating of the surface being treated due to combustion of plates formed from a thermite-type material of pyrotechnic composition, placed around the perimeter of the welded joint, and also an assessment of the level of residual stresses prior to and after pyrotechnic treatment demonstrated the promising nature of the proposed method. 5 refs., 5 figs.

Serikov, S.V.; Idiyatullin, R.S.; Myakushkin, S.N.; Yaufman, V.V.

1992-03-01

7

Explosively Welded Scarf Joint.  

National Technical Information Service (NTIS)

This invention describes a method for producing a modified scarf weld which is not limited due to small gage of the parts to be welded. It uses the simple technique of explosive welding to bond and simultaneously shape sheet material so that an essentiall...

L. J. Bement

1972-01-01

8

Obtaining weld pool vision information during aluminium alloy TIG welding  

Microsoft Academic Search

An image sensing system for the TIG (tungsten inert-gas arc) welding process of aluminium alloy was established. The relationships between the image sensing system and the characteristic of welding current were discussed in detail. Front and back images of the weld pool were obtained with different welding parameters. In order to process the image, the characteristics of an aluminium alloy

J. J. Wang; T. Lin; S. B. Chen

2005-01-01

9

Improving Joint Properties of Friction Welded Joint of High Tensile Steel  

NASA Astrophysics Data System (ADS)

This report describes the improvements in the joint properties of friction welded joint of 780MPa class high tensile steel. Welded joint made by a continuous drive friction welding machine, the conventional method, had not obtained 100% joint efficiency despite applying forge pressure. This was due to the softening of the welded interface zone for heat input during braking times. Therefore, we developed a continuous drive friction welding machine with an electromagnetic clutch to prevent heat input during braking time. We proposed the process as “The Low Heat Input Friction Welding Method (the LHI method).” In this case, the joint had the same tensile strength as the base metal at friction time when the friction torque reached the initial peak torque. That is, the welded joint obtained 100% joint efficiency by using only the friction stage up to the initial peak torque without the forge (upsetting) stage, despite the existence of a slightly softened region adjacent to the welded interface. Furthermore, the softened region was hardly generated when this joint was made by applying forge pressure at the initial peak torque. In conclusion, a welded joint of high tensile steel made by only the friction stage of the LHI method had excellent joint properties. The LHI method has a lot of advantages for joining such materials as super fine grain steel with which conventional fusion welding processes have difficulty.

Kimura, Masaaki; Kusaka, Masahiro; Seo, Kenji; Fuji, Akiyoshi

10

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

11

Inelastic Analysis of a Welded Aluminum Joint.  

National Technical Information Service (NTIS)

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 ...

R. E. Vaughan

1994-01-01

12

Joint tracking and adaptive robotic welding using vision sensing of the weld joint geometry  

SciTech Connect

An approach to the vision-guidance of welding robots and the in-process adjustment of welding conditions is presented. The implementation of a complete vision-guided adaptive robotic welding system is described. The vision-guided adaptive welding system described here has been used to track and weld a wide variety of test and production parts ranging in size from 1.6-mm (1/16-in.) sheet steel to 19.1-mm (3/4-in.) steel plate. Both conventional joint types, including square butt, lap, and V-groove, and special types, such as a multipass square butt submerged arc weld with pre-welded root passes or the axle joints were welded. Various welding procedures, such as GMA welding with a variety of shielding gases and submerged arc welding, have also been used.

Agapakis, J.E.; Katz, J.M.; Koifman, M.; Epstein, G.N.; Friedman, J.M.; Eyring, D.O.; Rutishauser, H.J.

1986-11-01

13

Comparative studies on stresses in weld-bonded, spot-welded and adhesive-bonded joints  

Microsoft Academic Search

A numerical analysis on the distribution of stresses in weld-bonded joints is carried out using a three-dimensional elastoplastic finite-element method. A comparison is made of the stresses distribution in weld-bonded joints, spot-welded joints and adhesive-bonded joints. The results show that the stresses in the lap zone of weld-bonded joints are distributed uniformly, no high-stress zone being found in weld-bonded joints.

Baohua Chang; Yaowu Shi; Shijie Dong

1999-01-01

14

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

15

Improving fatigue strength of welded joints  

NASA Astrophysics Data System (ADS)

One series of fatigue tests was carried out on coverplated bridge girders with small fatigue cracks that had been treated in 1976. The treatment and preconditions were reported in NCHRP Report 206. The Category E' coverplated. beams that were removed from the Yellow Mill Pond Bridge in 1997 had been retrofitted in 1976 by either air hammer peening or GTA remelting the weld toe. Most of the details had small fatigue cracks at the time the retrofit was carried out. No detectable fatigue cracking was observed at the treated coverplate ends after 20 years of service on I-95 and an estimated 56 million truck passages. All beams were tested at a stress range of 69 MPa (10 ksi). Cracks eventually developed from the root of the transverse end welds and propagated through the weld throat and from there into the beam flange via the longitudinal welds. The fatigue resistance of the treated weld toe details was improved to Category C. The one GTA remelted detail that recracked at the weld toe exceeded Category D. The second series of tests was carried out on large scale HPS-485W steel plate girders with as-welded and ultrasonic impact treated (UIT) details. The UIT treatment was applied to the weld toe of transverse stiffeners welded to the web and flanges (Category C details) and to coverplated ends (Category E' details). The as-welded details cracked as expected at their corresponding fatigue resistance. All UIT treated details were improved. The treated transverse stiffeners achieved Category B fatigue resistance. The treated coverplated details achieved Category C. The third series of tests was conducted on large scale HPS-485W steel plate girders with undermatched groove welded details at flange transition. The objectives of using undermatched weld materials compared to the base material is to reduce the potentiality of hydrogen cracking at flange groove welds and to improve the fatigue strength of the welded joints. Fatigue strength of undermatched welded joints was approximately the same as that resulted from conventionally welded joints. The undermatched groove welded joints achieved Category B fatigue resistance.

Takamori, Hiroyuki

16

Selection of optimum welding conditions and evaluation of friction welded joints: Study of optimisation of welding conditions and joint performance in friction welding (2nd Report)  

Microsoft Academic Search

This paper describes the possibility of optimum friction welding conditions being selected through adoption of a joining evaluation equation derived from friction welding behaviour as determined by the response surface method in welding tests of 12 mm dia. SUS304 stainless steel. Through initial analysis of the relationship between the welding behaviour and tensile strength of friction-welded joints in a multiple

K. Ogawa; H. Yamaguchi; G. Kawai; T. Sawai

1998-01-01

17

Weather exposure durability of welded dowel joints  

Microsoft Academic Search

A zigzag pattern of rotationally welded dowels across the interface of a butt joint between two\\u000a wood planks, without any adhesive, was shown to yield joints presenting some resistance to weather exposure,\\u000a although not of exterior grade type.

P. Omrani; H. R. Mansouri; A. Pizzi

2008-01-01

18

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

19

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

20

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

21

Low Distortion Welded Joints for NCSX  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) required precise positioning of the field coils in order to generate suitable magnetic fields. A set of three modular field coils were assembled to form the Half Field-Period Assemblies (HPA). Final assembly of the HPA required a welded shear plate to join individual coils in the nose region due to the geometric limitations and the strength constraints. Each of the modular coil windings was wound on a stainless steel alloy (Stellalloy) casting. The alloy is similar to austenitic 316 stainless steel. During the initial welding trials, severe distortion, of approximately 1/16", was observed in the joint caused by weld shrinkage. The distortion was well outside the requirements of the design. Solutions were attempted through several simultaneous routes. The joint design was modified, welding processes were changed, and specialized heat reduction techniques were utilized. A final joint design was selected to reduce the amount of weld material needed to be deposited, while maintaining adequate penetration and strength. Several welding processes and techniques using Miller Axcess equipment were utilized that significantly reduced heat input. The final assembly of the HPA was successful. Distortion was controlled to 0.012", well within the acceptable design tolerance range of 0.020" over a 3.5 foot length.

M. Denault, M Viola, W. England

2009-02-19

22

Stress corrosion cracking susceptibility of dissimilar stainless steels welded joints  

Microsoft Academic Search

Purpose: The aim of the current study is to reveal the influence of welding conditions on structure and stress corrosion cracking resistance of dissimilar stainless steels butt welded joints. Design\\/methodology\\/approach: Butt joints between duplex 2205 and austenitic 316L steels were performed with the use of submerged arc welding (SAW) method. The plates 15 mm in thickness were welded with heat

J. ?abanowski

23

Friction Stir Knead Welding of steel aluminium butt joints  

Microsoft Academic Search

To develop steel aluminium-tailored hybrids in a butt joint for sheets in a thickness of about 1mm conventional Friction Stir Welding is not feasible due to a high distortion of the welded specimen. Contrary to Friction Stir Welding the tool used for Friction Stir Knead Welding has no pin wherefore higher welding speeds can be realised. Due to the fact

M. Geiger; F. Micari; M. Merklein; L. Fratini; D. Contorno; A. Giera; D. Staud

2008-01-01

24

Method of making an explosively welded scarf joint  

NASA Technical Reports Server (NTRS)

A method is presented for obtaining a bond joint between thin metal members without the addition of a bonding agent. The method yields bond strengths comparable to the parent metal. The method comprises overlapping the materials at the edges and bonding them by explosive welding while also making use of the explosive force to shape the materials into an essentially planar configuration.

Bement, L. J. (inventor)

1974-01-01

25

Ultrasonic quality control methods for spot-welded joints  

Microsoft Academic Search

Spot resistance welding is the most popular method of connecting the steel structures of automotive vehicles. At a time when quality requirements relating to finished goods are higher and higher, welded joints must undergo precise controls in order to assure the highest safety standards possible. Ultrasonic methods enable quick and accurate assessment of any welded joint's quality, and at the

Andrzej Ambroziak; Roman G. Maev; Marcin Korzeniowski; Pawe? Kustro?

2011-01-01

26

The effect of controlled shot peening on fusion welded joints  

Microsoft Academic Search

This work examines the effect of controlled shot peening (CSP) treatment on the fatigue strength of an ASTM A516 grade 70 carbon steel welded joint. Metallurgical modifications, hardness, elemental compositions, and internal discontinuities, such as porosity, inclusions, lack of penetration, and undercut found in treated and untreated fusion welded joints, were characterized. The fatigue results of as-welded and peened skimmed

Nur Azida Che Lah; Aidy Ali; Napsiah Ismail; Lim Poon Chai; Abdul Aziz Mohamed

2010-01-01

27

Guidelines for Improving Welded Joint Toughness at Arctic Temperatures.  

National Technical Information Service (NTIS)

The experimental study recommends means for improving the toughness of welded joints in arctic applications of steel constructions. The microstructural factors characterizing the weld metal and heat-affected-zone toughness at arctic temperatures are ident...

H. Tihekari R. Karppi

1986-01-01

28

78 FR 47486 - Joint Failure on Continuous Welded Rail Track  

Federal Register 2010, 2011, 2012, 2013

...2013-05] Joint Failure on Continuous Welded Rail Track AGENCY: Federal Railroad Administration...reviewing current, internal continuous welded rail (CWR) plans and properly inspecting CWR...Carlo M. Patrick, Staff Director, Rail and Infrastructure Integrity...

2013-08-05

29

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

30

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel  

NASA Astrophysics Data System (ADS)

To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by energy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corrosion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG welding. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints produced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.

Wang, Jing; Lu, Min-xu; Zhang, Lei; Chang, Wei; Xu, Li-ning; Hu, Li-hua

2012-06-01

31

Influence of Welding Parameters on the Tensile Shear Strength of Aluminum Alloy Joint Welded by Resistance Spot Welding  

NASA Astrophysics Data System (ADS)

Aluminum alloy A5052 sheets were welded using the technique of resistance spot welding with cover plates. The effects of welding parameters on the tensile shear strength of the joints were investigated. The results reveal that the technique is feasible to weld aluminum alloy, and that the enhanced electrode force is more effective than the extended down-sloping time for inhibiting pores formation and increasing the strength of the joint.

Qiu, Ranfeng; Zhang, Zhanling; Zhang, Keke; Shi, Hongxin; Ding, Gaojian

2011-04-01

32

Sleeve and cutter simplify disconnecting welded joint in tubing  

NASA Technical Reports Server (NTRS)

To test equipment, welded tubing joints may have to be disconnected and rewelded. To eliminate rewelding, a nonstandard welding sleeve permits the tubing to be welded and then disconnected by a specially designed sleeve cutter. Use of this tool assures that only the sleeve is cut.

Perkins, G. S.

1964-01-01

33

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

34

"Foreign material" to verify root fusion in welded joints  

NASA Technical Reports Server (NTRS)

Foil or thin wire at weld root is used to verify weld penetration. When weld is adequate, material mixes with weld and traces of it diffuse to weld crown. Spectroscopic analysis of samples identifies foreign material and verifies root has fused. Weld roots are usually inaccessible to visual inspection, and X-ray and ultrasonic inspection techniques are not always reliable. Good results are obtained with use of gold/nickel alloy.

Kleint, R. E.

1980-01-01

35

Compact Ignition Tokamak (CIT) vacuum vessel welded joint R and D: FY87 final report  

Microsoft Academic Search

The general purpose of the vacuum vessel welded joint research and development program for FY-87 was to begin the development of both an optimum welded joint design and an analytical method for predicting joint distortion. This work was divided into three subtasks: weld joint tests, to develop automatic welding parameters and producing reliably strong, low distortion joints; material tests, to

T. Hurn; J. Kaae; R. Gallix; F. Puhn

1988-01-01

36

Testing of explosive welding and welded joints. The microstructure of explosive welded joints and their mechanical properties  

Microsoft Academic Search

The present essential models and some theories were applied to explain the wavy phenomenon, microstructure and mechanical\\u000a properties of the characteristic joint area. Two phenomena occurring in the plate collision zone during welding were carefully\\u000a tested. These phenomena were connected with forming the wavy joint surface and the interpass. The available data referring\\u000a to forming the interpass were further developed.

Bogumi? Wronka

2010-01-01

37

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

38

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

39

Residual stress relief in MAG welded joints of dissimilar steels  

Microsoft Academic Search

This paper addresses the relief of residual stress in welded joints between austenitic and non-alloyed ferritic–pearlitic steels. A series of similar and dissimilar steel joints based on the 18G2A (ferritic–pearlitic) and 1H18N10T (austenitic) steels were produced, some of which were stress relieved by annealing and some by mechanical prestressing. For the as-welded and stress relieved test joints the residual stresses

P Sedek; J. Brózda; L. Wang; P. J. Withers

2003-01-01

40

Effect of Spot Welding Parameters on Tensile Properties of Dp600 Steel Sheet Joints  

Microsoft Academic Search

In this study, the electric resistance spot welding process has been applied to dual-phase (DP 600 type) steel sheets.Spot welding parameters namely, electrode form, electrode material and electrode force were stayed constant, and welding current and welding time have been changed to detect the optimum welding parameters for maximum joint strength. The sample welded joints have been carried out as

S. Aktas; U. Ozsarac; S. Aslanlar

2012-01-01

41

Effect of Spot Welding Parameters on Tensile Properties of DP 600 Steel Sheet Joints  

Microsoft Academic Search

In this study, the electric resistance spot welding process has been applied to dual-phase (DP 600 type) steel sheets. Spot welding parameters, namely, electrode form, electrode material, and electrode force were stayed constant, and welding current and welding time have been changed to detect the optimum welding parameters for maximum joint strength. The sample welded joints have been carried out

S. Aktas; U. Ozsarac; S. Aslanlar

2012-01-01

42

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

43

Very low cycle fatigue properties of butt welded joints containing weld defects. Study of acceptable size of defects in girth welds of gas pipelines  

Microsoft Academic Search

This paper describes an investigation of the very low cycle fatigue strength of HT570 steel welded joints containing weld defects to determine the acceptable size of weld defects in girth welds of underground gas pipelines subjected to cyclic ground displacements due to earthquakes. Butt welded joints containing incomplete penetration (IP), blowholes (BH), lack of fusion in theintermedi?ate pass (LF), and

A. Seto; T. Masuda; S. Machida; C. Miki

2000-01-01

44

An inelastic analysis of a welded aluminum joint  

NASA Astrophysics Data System (ADS)

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.

1994-09-01

45

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

46

The interfacial structure of plated copper alloy resistance spot welded joint  

NASA Astrophysics Data System (ADS)

Plated copper alloys are widely used in electron industry. The plating lay caused the farther decreasing of the welding property of copper alloys, whose intrinsic weldability was poor. In this paper, the bronze and brass specimens with nickel-tin double plating layer were joined by resistance spot welding method. The microstructure and peel strength of the joints were investigated. The experiment results show that a sandwich-like structure was obtained in the faying surface after welding, and the nickel plating layer thickness had severe effect on the reliability of the joints.

Wu, Jingwei; Zhai, Guofu; Chen, Qing; Wang, Jianqi; Ren, Gang

2008-09-01

47

Detection of micro-weld joint by magneto-optical imaging  

NASA Astrophysics Data System (ADS)

It is required that the laser beam focus should be controlled to accurately follow the weld joint center during laser butt joint welding; therefore, the weld joint position must be detected automatically in real-time. An approach for detecting the micro-weld joint (weld gap less than 0.1 mm) based on magneto-optical (MO) imaging is investigated during laser butt-joint welding of low carbon steel. Magneto-optical sensor was used to capture the dynamic images of weld joint. Weld MO image gray distribution features were analyzed to extract the transition zone of weld joint. The influences of a different magnetic field intensity and the welding speed on detecting the weld joint position were mainly studied. Under different welding conditions where welding path, weld gap or welding speed varies, it has been found that using magneto-optic imaging technology could effectively detect the position of the micro-weld joint. Different weld joint positions in MO images have been detected with various magnetic field intensities. Experimental results show that the welding speed has little influence on the detection of weld joint position.

Gao, Xiangdong; Liu, Yonghua; You, Deyong

2014-10-01

48

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

49

Microstructure and mechanical properties of the welding joint filled with microalloying 5183 aluminum welding wires  

NASA Astrophysics Data System (ADS)

In this study, 7A52 aluminum alloy sheets of 4 mm in thickness were welded by tungsten inert gas welding using microalloying welding wires containing traces of Zr and Er. The influence of rare earth elements Zr and Er on the microstructure and mechanical properties of the welded joints was analyzed by optical microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, hardness testing, and tensile mechanical properties testing. Systematic analyses indicate that the addition of trace amounts of Er and Zr leads to the formation of fine Al3Er, Al3Zr, and Al3(Zr,Er) phases that favor significant grain refinement in the weld zone. Besides, the tensile strength and hardness of the welded joints were obviously improved with the addition of Er and Zr, as evidenced by the increase in tensile strength and elongation by 40 MPa and 1.4%, respectively, and by the welding coefficient of 73%.

Xu, Zhen; Zhao, Zhi-hao; Wang, Gao-song; Zhang, Chao; Cui, Jian-zhong

2014-06-01

50

Resistance welding of thermoplastic composites skin\\/stringer joints  

Microsoft Academic Search

An experimental investigation of resistance welding of APC-2\\/AS4 PEEK\\/carbon fibre composite using a stainless steel mesh heating element is presented. A special specimen geometry, the skin\\/stringer configuration, was used to represent a typical reinforced aerospace structural joint. The specimens consisted of a flange, representing a stringer or frame, welded onto a skin laminate. The effects of the welding parameters such

M. Dubé; P. Hubert; A. Yousefpour; J. Denault

2007-01-01

51

Improving Fatigue Strength of Welded Joints by Ultrasonic Impact Treatment  

Microsoft Academic Search

Summary Enhancement in fatigue performance of welded joints by Ultrasonic Impact Treatment (UIT) was evaluated with large-scale rolled beam and built-up specimens having yield strength of 345 to 760 MPa. Eighteen rolled-beam specimens having welded details at cover plates and transverse stiffeners and eight built-up specimens having only transverse stiffener details were fatigue tested after treating the weld details by

Sougata ROY

52

Residual Ductivity in Welded Joints Reserve de Ductilite dans les Joints Soudes.  

National Technical Information Service (NTIS)

The measurement of residual ductility and its interpretation for welded joints in a wide range of steels is discussed. Results permit the quantitative evaluation of fracture risk for a welded joint undergoing tensile stress and containing a fault of a giv...

R. Baus W. Chapeau M. Piron

1979-01-01

53

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

54

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

55

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

56

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

57

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

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

Inspection of plastic weld joints with terahertz imaging  

NASA Astrophysics Data System (ADS)

Polymers cover the whole range from commodities to high-tech applications. Plastic products have also gained in importance for construction purposes. This draws the attention to joining techniques like welding. Common evaluation of the weld quality is mostly mechanical and destructive. Existing non-destructive techniques are mostly not entirely reliable or economically inefficient. Here, we demonstrate the potential of terahertz time-domain spectroscopy imaging as a non-destructive testing tool for the inspection of plastic weld joints. High-density polyethylene sheets welded in a lap joint with varying quality serve as samples for terahertz transmission measurements. Imperfections within the weld contact area can clearly be detected by displaying the transmitted intensity in a limited frequency range. Contaminations such as metal or sand are identified since they differ significantly from the polymer in the terahertz image. Furthermore, this new and promising technique is capable of detecting the boundaries of a weld contact area. Aside from revealing a contrast between a proper weld joint and no material connection, the size of an air gap between two plastic sheets can be determined by considering the characteristic frequency-dependent transmission through the structure: The spectral positions of the maxima and minima allow for the calculation of the air layer thickness.

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

2007-06-01

60

Assessment of the fatigue life of aluminium spot-welded and weld-bonded joints  

Microsoft Academic Search

In modern machinery and automobile structures weight reduction and increased durability are the main issues in design. In these applications, lap welded and\\/or bonded joints are widely used; therefore, tools are needed to accurately predict their fatigue life. This paper is concerned with the fatigue strength of single lap joints formed with thin plates of 6082-T6 aluminium alloy using a

A. M. Pereira; J. A. M. Ferreira; F. V. Antunes; P. J. Bártolo

2012-01-01

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

?????????????????????????????????????????????????????????? STRATGHT JOINT BUTT RESISTANCE WELDING OF ALUMINIUM ALLOYS ??????????? ??????????,1 ??????? ???????1 ??? ??????? ????????????1  

Microsoft Academic Search

Straight joint butt resistance welding of aluminium alloys 6063 was prepared by using the variable ac welding machine with various contact forces, current and durations. The joint strength was tested by comparing to the unwelded parent alloy. Results from the study found that all welding parameters were related. From the tensile test on the specimen welded under the contact force

Narin Sirikulrat; Kanokwan Uttarasak

63

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

64

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

65

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

66

Joint strength and behaviour of coated aluminium in laser lap welding of steel sheets  

Microsoft Academic Search

When galvanized steel sheets are closely overlapped and welded by laser lap welding, a large amount of molten metal spatters, resulting in a poor surface appearance of the weld and weakened strength of the welded joint, as compared with that of cold-rolled steel sheets. Whereas in the case of aluminium-coated steel sheets, even when they are closely overlapped and welded

Kenji Saita; Yasunobu Miyazaki

2012-01-01

67

Evaluation of the joint-interface properties of austenitic-stainless steels (AISI 304) joined by friction welding  

Microsoft Academic Search

The aim of this study is to investigate experimentally the micro-structural properties and welding strengths of the joints using austenitic-stainless steel (AISI 304) parts. The experiments were carried out using a beforehand designed and constructed experimental friction welding set-up, constructed as continuous-drive. Firstly, pilot welding experiments under different friction time and friction pressure were carried out to obtain optimum parameters

Mumin Sahin

2007-01-01

68

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

Microsoft Academic Search

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

Masahito Mochizuki; Makoto Hayashi; Toshio Hattori

2000-01-01

69

Details of the electromechanical (E/M) impedance health monitoring of spot-welded structural joints  

NASA Astrophysics Data System (ADS)

Health monitoring of structural joints is a major concern of the engineering community. Among joining techniques, spot- welding play a major role. Spot welding is the traditional method of assembly for steel-based automotive structures, while spot-welding of aluminum is being considered for future vehicular structures. Though spot welding of steel is well researched and understood, the spot-welding of aluminum still poses a considerable challenge. The durability and health monitoring of aluminum spot-welded joint is of major importance. The present paper addresses the use of electro- mechanical method and piezoelectric active sensors for health monitoring spot-welded structural joints.

Giurgiutiu, Victor; Reynolds, Anthony P.; Rogers, Craig A.

1999-06-01

70

Design fatigue strength of TIG-dressed welded joints in high-strength steels subjected to spectrum loading  

Microsoft Academic Search

A large amount of fatigue data from spectrum tests both on AW and post-weld treated welded joints has been obtained during two inter-Nordic projects. These important results will soon gain effect in practical applications through new design specifications furnished by industry. This investigation evaluates the results from TIG-dressed joints and the importance of using steels with higher strength is emphasised.

T Dahle

1998-01-01

71

High cycle fatigue of welded joints: The TCD experience  

Microsoft Academic Search

This paper reports on the use of two methods for the prediction of high cycle fatigue failure in welded joints. The development of these methods – known as the crack modelling method and the theory of critical distances – is described, summarising previously published work on test specimens using steels and aluminium alloys. It is concluded that the methods work

David Taylor; David Hoey

2009-01-01

72

Bucket wheel failure caused by residual stresses in welded joints  

Microsoft Academic Search

Cracks in the welded joints on the bucket wheel (BW) body of the bucket wheel excavator (BWE) SRs 1300 were discovered after merely 1800h of operation. Investigations are carried out in order to detect the causes of cracks occurrence and thus prevent possible heavy damages to the machine.Working stresses in the BW body are defined by using FEM. Methods of

Miodrag Arsi?; Sr?an Bošnjak; Nenad Zrni?; Aleksandar Sedmak; Nebojša Gnjatovi?

2011-01-01

73

Low cycle fatigue of welded joints: new experimental approach  

Microsoft Academic Search

To take into account the reduced fatigue strength of welded joints, a reduction life factor applied on fatigue curves (Jf value) was introduced into the RCC-MR [Design and Construction Rules for Mechanical Components of FBR Nuclear Islands, AFCEN, 1993], for the design and construction of fast breeder reactors. To better assess this factor, previous work showed that mechanical behavior of

Yazid Madi; Philippe Matheron; Naman Recho; Philippe Mongabure

2004-01-01

74

Analysis of residual stresses and distortions in T-joint fillet welds  

Microsoft Academic Search

T-joint fillet welds are extensively used in ship engineering and bridge structures. Localized heating from the welding process and subsequent rapid cooling induce tensile residual stress near the toe of the T-joint in fillet welds. Welding produces thermal stresses that cause structural distortions, which influence the buckling strength of the welded structures. This study describes the thermal elasto-plastic analysis using

Tso-Liang Teng; Chin-Ping Fung; Peng-Hsiang Chang; Wei-Chun Yang

2001-01-01

75

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

76

Influence of the Strength Mismatch of a Narrow Gap Welded Joint of SA508 on the Plastic ? Factor  

NASA Astrophysics Data System (ADS)

In this article, the influence of the strength mismatch of a narrow gap welded joint of SA508 on the ? factor was evaluated. The ? factor is the principal parameter that determines the plastic portion of the J-integral. The specimens for tensile and hardness tests were collected from piping with narrow gap welding and the stress-strain curve and hardness were obtained from those. From these results, the Ramberg-Osgood (R-O) constant was obtained. Also, the finite element analysis was performed with variations in the strength mismatch and the weld width. The ? factor equation considering the strength mismatch and the weld width of a narrow gap welded joint was suggested.

Koo, J. M.; Huh, Y.; Seok, C. S.

2012-11-01

77

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

78

Thermal analysis for resistance welding of large-scale thermoplastic composite joints  

NASA Astrophysics Data System (ADS)

The need for effective and reliable joining methods continues to grow as the use of thermoplastic composites becomes widespread. It is now possible to join large-scale components with the development of an automated sequential resistance welding process. The thermal history generated by the heating element placed at the interface between adherends determines the quality and performance of the welded joint. This article presents a thermal analysis for the resistance welding of large-scale components that overcomes the limitations of previous models. To simulate welding of the interface, a heat generation term was incorporated that accounts for the Joule heating of graphite fibers in the heating element. A parametric study was conducted to investigate the influence of welding parameters and assess the uniformity of interface temperatures. Components were joined by the resistance welding process to obtain experimental verification. Regions of localized overheating where potential current leakage may occur were identified as a function of process parameters. Insights on promoting more uniform heating for the resistance welding process are discussed.

Holmes, Scott T.; Gillespie, John W., Jr.

1993-06-01

79

Predicting the fatigue strength of small thickness welded joints using the implicit gradient method  

Microsoft Academic Search

This paper discusses the problem of the fatigue behaviour of small thickness welded joints using the implicit gradient method. Welds have been designed using 3D CAD and then subjected to finite element analysis, using the same computational procedure developed in the past for large thickness welded joints. In order to determine the Woehler curves for the various test series described

R. Tovo; P. Livieri

2011-01-01

80

Fatigue Endurance of Welded Joints, Residual Stresses and Fatigue Improvement Treatments  

Microsoft Academic Search

Under certain conditions residual welding stresses greatly effect fatigue performance. Residual tensile stresses re- duce the fatigue life of welded joints in the region of multi-cycle loading by two to three times and more. The effect of tensile residual stresses on the fatigue limit of symmetrically loaded (R= minus 1) welded joints is equal to that of stress concentration factor.

V. I. Trufyakovi; Yu. F. Kudryavtsevi; D. N. Reznik

81

Fatigue Evaluation of Auto-TIG Weld Joints for Heat Exchanger Applications.  

National Technical Information Service (NTIS)

Fatigue tests were performed to compare the dynamic load response of auto-TIG step pulse welds with currently used manual electric arc welds in heat exchanger joint applications. The new auto-TIG weld technique for fabricating the joints, designed by Nava...

J. J. Bethke

1977-01-01

82

Mechanical and Microstructural Characterization of Al5083\\/St12 lap joints made by friction stir welding  

Microsoft Academic Search

Al-5083 and St-12 alloys sheets were friction stir lap welded at various traveland rotation speeds of the welding tool. Microscopic examinations indicate that the joint strength is due to the macroscopic and microscopic mechanical lockings and also atomic diffusion. The reaction zone of the welded joints consists of mixed layers of ultra-fine grains and the intermetallic compounds. The microhardnessand nano

M. Movahedi; A. H. Kokabi; S. M. Seyed Reihani; H. Najafi

2011-01-01

83

Austenitic stainless steel-ferritic steel weld joint failures  

Microsoft Academic Search

The cause of failures of dissimilar-alloy (austenitic or ferritic) joints in superheater and reheater tubes of fossil-fired steam plants was investigated. In the failures of interest, cracks form and propagate in the ferritic steel (usually 2 1\\/4 Cr-1 Mo steel) about 5 to 15 ..mu..m from the fusion lines. The complex microstructure developed at the interface between weld metal and

R. L. Klueh; J. F. King

1982-01-01

84

Mode I failure modeling of friction stir welding joints  

Microsoft Academic Search

This paper analyzes mechanical response by finite element method up to the decohesion failure in fracture mode I for joints\\u000a of friction stir welding (FSW) of an aluminum alloy. It first describes experimental investigations on specimens with FSW\\u000a embedded, subjected to uniform traction and local punch tests used to characterize local elastic and plastic material parameters.\\u000a The heterogeneity of the

Guido Borino; Livan Fratini; Francesco Parrinello

2009-01-01

85

Effect of welding speed on butt joint quality of Ti-6Al-4V alloy welded using a high-power Nd:YAG laser  

NASA Astrophysics Data System (ADS)

Annealed Ti-6Al-4V alloy sheets with 1 and 2 mm thickness are welded using a 4 kW Nd:YAG laser system. The effects of welding speed on surface morphology and shape, welding defects, microstructure, hardness and tensile properties are investigated. Weld joints without or with minor cracks, porosity and shape defects were obtained indicating that high-power Nd:YAG laser welding is a suitable method for Ti-6Al-4V alloy. The fusion zone consists mainly of acicular ?' martensite leading to an increase of approximately 20% in hardness compared with that in the base metal. The heat-affected zone consists of a mixture of ?' martensite and primary ? phases. Significant gradients of microstructures and hardness are obtained over the narrow heat-affected zone. The laser welded joints have similar or slightly higher joint strength but there is a significant decrease in ductility. The loss of ductility is related to the presence of micropores and aluminum oxide inclusions.

Cao, X.; Jahazi, M.

2009-11-01

86

Microstructure and properties of laser micro welded joint of TiNi shape memory alloy  

Microsoft Academic Search

Butt welding of 0.2 mm-thick TiNi shape memory alloy sheet (SMA) was carried out using impulse laser, and tensile strength, fracture morphology, microstructure and phase change behaviour of welded joint were studied. The results show that using impulse laser can realize good butt welding of TiNi SMA sheet, tensile strength of welded joint is 683 MPa, which achieves 97% of

Wei-huai GONG; Yu-hua CHEN; Li-ming KE

2011-01-01

87

Effect of Post-Weld Annealing Treatment on Plastic Deformation of 2024 Friction-Stir-Welded Joints  

NASA Astrophysics Data System (ADS)

Post-weld annealing treatment (PWAT) process was developed to improve the plasticity of friction-stir-welded 2024 aluminum alloy. The effect of the PWAT on plastic deformation behavior and microstructure of the joints were studied using tensile test, the ASAME® automatic strain measuring system, and the electron backscattered diffraction (EBSD). It is found that the elongation of the as-welded joint can be improved by PWAT and increases with the decreasing PWAT temperature. The maximum elongation of the PWAT joints can reach up to 160% of that of the as-welded joint, and the joints exhibit no decrease in the tensile strength. The deformation inhomogeneity of the as-welded joint is significantly improved by large plastic strain occurring in the thermo-mechanically affected zone (TMAZ) when the PWAT temperature is lower than 250°. As the PWAT temperature increases, the deformation in the weld nugget is found to be more beneficial than that in the TMAZ for improving the plasticity of the joint. The high plasticity of the joint is attributed to the presence of the fine-equiaxed grains in the weld nugget during PWAT.

Yuan, S. J.; Hu, Z. L.; Wang, X. S.; Liu, G.; Liu, H. J.

2012-06-01

88

Residual stress in laser welded dissimilar steel tube-to-tube joints  

SciTech Connect

Austenitic-ferritic dissimilar steel joints are widely used in power generation systems. Their utilization has proved to be efficient in terms of satisfactory properties and the economics. These types of joints have usually been produced using conventional welding processes, such as tungsten inert gas (TIG) welding. With the rapid development of high power lasers, laser welding has received considerable attention. Laser welding offers many advantages over conventional welding processes, e.g. low heat input, small heat-affected zone (HAZ), small distortion, and welding in an exact and reproducible manner. Residual stress distribution in laser welds may also differ from those made by conventional welding processes due to its special features. Residual stress, particularly tensile residual stress in the weld, can be very important factor in controlling the quality and service life of the welded structure. The formation of tensile residual stress in the weld may result in the initiation of fatigue cracking, stress corrosion cracking or other types of fractures. It is useful, therefore, to understand the distribution of residual stress in austenitic-ferritic laser welds, and thus evaluate the quality of the joints. Although residual stress distribution in the welded joints has been extensively investigated, little data are available for the residual stress distribution in laser welds. The aim of the work was to examine residual stress distribution along laser welds of dissimilar steel tube-to-tube joints, which were made by both autogeneous welding and welding with filler wire. The results were also compared with the joints made by plasma arc and TIG welding.

Sun, Zheng (Technical Research Centre of Finland, Espoo (Finland). Lab. of Production Engineering)

1993-09-01

89

Study on the dissimilar magnesium alloy and copper lap joint by TIG welding  

Microsoft Academic Search

Dissimilar magnesium alloy and copper were welded by TIG in the form of lap welding. Intermetallic compounds in the interfacial region of the dissimilar joint were observed. It was shown that the intermetallic compounds were the cause of the joint embrittlement. The tensile strength of the joint was about 25MPa. While with the iron plate as interlayer, the embrittleness of

Liu Liming; Wang Shengxi; Zhao Limin

2008-01-01

90

Fatigue crack growth behaviour of A5083 series aluminium alloys and their welded joints  

Microsoft Academic Search

We investigated the difference in fatigue behaviour between the aluminium alloys A5083-O and A5083-H321, which are used as\\u000a structural components in ships and high speed craft. We obtained S–N curves for the base materials and the welded joints made\\u000a of A5083-O. The relationships between the fatigue crack propagation rates and the stress intensity factor ranges ?K, ?K\\u000a eff and ?K

Koji Gotoh; Koji Murakami; Yasuo Noda

91

Structural and mechanical properties of welded joints of reduced activation martensitic steels  

NASA Astrophysics Data System (ADS)

Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program.

Filacchioni, G.; Montanari, R.; Tata, M. E.; Pilloni, L.

2002-12-01

92

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

93

Fabrication of niobium superconducting accelerator cavity by electron beam welded joints  

NASA Astrophysics Data System (ADS)

Fabrication of superconducting cavities has been taken up as a part of the development of accelerator driven sub critical system (ADSS) by Bhabha Atomic Research Centre. Large grain (RRR>99) pure niobium was chosen as the material for the cavity. Niobium,for its application as superconductor requires extremely high quality joints, feasible only by electron beam welding at high vacuum environment. An indigenously developed 100kV, 4kW high vacuum electron beam welding machine has been utilized to carry out the welding operations. Planning of the weld sequences was chalked out. Holding fixtures for the cavity, consists of seven numbers of joints have been fabricated beforehand. A few coupons were welded for optimization of the weld parameters and for inspection of the weld purity by indigenously developed secondary ion mass spectroscopy. The report describes the welding equipment and the stage wise joining operations of the cavity in details and also discusses the qualification testing of the welded cavity.

Saha, T. K.; Mondal, J.; Mittal, K. C.; Bhushan, K. G.; Bapat, A. V.

2012-11-01

94

Estimation of laser hybrid welded joint strength by using genetic algorithm approach  

Microsoft Academic Search

The genetic algorithm approach is extended to the prediction of welding strength of the 6K21-T4 aluminum alloy materials. The welding strength of joint parts can be improved by selecting suitable welding parameters. It is affected by many parameters, such as wire type, shielding gas, laser energy, laser focus, traveling speed, wire feed rate. The model is based on dependence of

Olcay Ersel Canyurt; Hang Rae Kim; Kang Yong Lee

2008-01-01

95

CRITICAL ANALYSIS OF CURRENT CODES ON FATIGUE DESIGN OF WELDED JOINTS  

Microsoft Academic Search

SUMMARY The aim of this paper is focused on the critical analysis of the recommendations, reported in some current codes, for the fatigue strength assessment of welded structures in ship. This paper collects a large amount of experimental data for fatigue assessment of welded joints, which differ for: base material (steel, aluminium alloys), yield stress, welding technique, geometry (i.e. butt,

Giuseppe Chiofalo; Vincenzo Crupi; Eugenio Guglielmino; Letterio Scibilia

96

IMPROVEMENT OF PROPERTIES OF WELDED JOINTS OF CIRCULAR COMPONENTS FOR GAS TURBINE ENGINES  

Microsoft Academic Search

Method of electroslag welding with the combined electrode under ANF-21 flux, resulting in high-quality melting of the edges and satisfactory formation of the welded joint is described. In order to increase the properties of the weld metal, the latter was modified with the ultrafine powder of titanium carbonitride. The results of metallographic examination the zone or failure, the grain size,

E. N. Eremin

97

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

98

Numerical simulation to study the effect of tack welds and root gap on welding deformations and residual stresses of a pipe-flange joint  

Microsoft Academic Search

This paper presents a three dimensional sequentially coupled non-linear transient thermo-mechanical analysis to investigate the effect of tack weld positions and root gap on welding distortions and residual stresses in a pipe-flange joint. Single-pass MIG welding for a single ‘V’ butt-weld joint geometry of a 100mm diameter pipe with compatible weld-neck ANSI flange class # 300 of low carbon steel

M. Abid; M. Siddique

2005-01-01

99

Camera Based Closed Loop Control for Partial Penetration Welding of Overlap Joints  

NASA Astrophysics Data System (ADS)

Welding of overlap joints with partial penetration in automotive applications is a challenging process, since the laser power must be set very precisely to achieve a proper connection between the two joining partners without damaging the backside of the sheet stack. Even minor changes in welding conditions can lead to bad results. To overcome this problem a camera based closed loop control for partial penetration welding of overlap joints was developed. With this closed loop control it is possible to weld such configurations with a stable process result even under changing welding conditions.

Abt, F.; Heider, A.; Weber, R.; Graf, T.; Blug, A.; Carl, D.; Höfler, H.; Nicolosi, L.; Tetzlaff, R.

100

Microstructure and Phase Composition of a Low-Power YAG Laser-MAG Welded Stainless Steel Joint  

NASA Astrophysics Data System (ADS)

This article presents multipass hybrid welding of austenitic stainless steel (ASS) structure by using the low-power Nd:YAG laser-metal active gas (MAG) arc hybrid welding method. The purpose of this work is to investigate and qualify the effects of multipass hybrid welding of ASS structure on the microstructure, phase composition, weld postheat influence, and weld bead (WB) precipitated phase. The results demonstrated that sound welded joints without any solidification and shrinkage defects could be obtained after welding. The top and the bottom portions of the workpieces were joined completely. At room temperature, the microstructures of different regions in WB were different and the WB microstructures were composed of columnar ?-austenite and ?-ferrite phases. The fraction of ?-ferrite decreased from 20% to 10%, and its morphology changed orderly from lath, skeleton, vermicular to reticular with an increase in the number of welding cycles. Because of the influence of postweld heat, the weld metal phase chemistry at 3 mm distance from the top of the WB surface underwent a notable modification that corresponded to an evolution of the partition coefficients toward the parent metal values. This indicated corrosion resistance of the microstructure is equivalent to that of the parent metal.

Huang, R. S.; Kang, L.; Ma, X.

2008-12-01

101

Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints  

NASA Astrophysics Data System (ADS)

This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.

Lakshminarayanan, A. K.; Balasubramanian, V.

2012-04-01

102

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

103

Microstructure characteristics in TIG welded joint of Mg\\/Al dissimilar materials  

Microsoft Academic Search

The microstructure performance of Mg\\/Al TIG welded joint was studied by means of metallography, micro-hardness test and SEM. The test results indicate that the structure close to weld metal is columnar crystals, which grow into the weld metal. The weld metal was mainly composed of dendrite crystal. The micro-hardness near the fusion zone of Mg side is about HM 275–300.

Peng Liu; Yajiang Li; Haoran Geng; Juan Wang

2007-01-01

104

Inertia Radial Friction Welding Joint of Large Size H90 Brass\\/D60 Steel Dissimilar Metals  

Microsoft Academic Search

CT-130 Special Inertia Friction Welding Machine is used to weld a large size (156 mm diameter) of brass\\/steel by radial friction welding. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and Vickers microhardness measurements are used to analyze the welding joint. The results show a refined grain zone near the welding interface at the brass side, which is

Jian Luo; Xiaoming Wang; Dejia Liu; Fei Li; Junfeng Xiang

2012-01-01

105

Inertia Radial Friction Welding Joint of Large Size H90 Brass\\/D60 Steel Dissimilar Metals  

Microsoft Academic Search

CT-130 Special Inertia Friction Welding Machine is used to weld a large size (156 mm diameter) of brass\\/steel by radial friction welding. OM, SEM, EDS and Vickers microhardness measurements are used to analyze the welding joint. The results show a refined grain zone near the welding interface at the brass side, which is closely related to the smaller stacking fault energy

Dejia Liu; Jian Luo; Xiaoming Wang; Fei Li; Junfeng Xiang

2011-01-01

106

Numerical simulation of creep damage for low alloy steel welded joint considering as-welding residual stress  

Microsoft Academic Search

A model to calculate the welding temperature and residual stress was built using finite element code ABAQUS, and a subroutine of creep damage was also developed. Based on the coupling of welding residual stress and creep damage, the welding residual stress and creep damage of a tube made of Cr5Mo steel were simulated. This method can obtain the distributions of

Guodong Zhang; Changyu Zhou; Zhaoxi Wang; Fei Xue; Yanfen Zhao; Lu Zhang; Yan Liu

107

AN EXPERIMENTAL STUDY ON THE EFFECT OF WELDING PARAMETERS ON MECHANICAL AND MICROSTRUCTURAL PROPERTIES OF AA 6082-T6 FRICTION STIR WELDED BUTT JOINTS  

Microsoft Academic Search

The effect of processing parameters on mechanical and microstructural properties of aluminium alloy 6082-T6 Friction stir-welded (FSW) joints were investigated in the present study. Different welded specimens were produced by employing variable rotating speeds and welding speeds. Tensile strength of the produced joints was tested at room temperature and the correlation with process parameter was assessed. Microstructures of various zones

G. Raghu Babu; K. G. K. Murti; G. Ranga Janardhana

108

Characterization of aluminum/steel lap joint by friction stir welding  

NASA Astrophysics Data System (ADS)

The welding of a lap joint of a commercially pure aluminum plate to a low carbon steel plate (i.e., Al plate top, and steel plate bottom) was produced by friction stir welding using various rotations and traveling speeds of the tool to investigate the effects of the welding parameters on the joint strength. The joint strength depended strongly on the depth of the pin tip relative to the steel surface; when the pin depth did not reach the steel surface, the joint failed under low applied loads. Meanwhile, slight penetration of the pin tip to the steel surface significantly increased the joint strength. The joint strength tended to increase with rotationspeed and slightly decrease with the increase in the traveling speed, although the results were quite scattered. The effects of the welding parameters were discussed metallographically based on observations with optical and scanning electron microscopes.

Elrefaey, A.; Gouda, M.; Takahashi, M.; Ikeuchi, K.

2005-02-01

109

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

110

Damage Monitoring of Ultrasonically Welded Aluminum\\/ CFRP-Joints by Electrical Resistance Measurements  

Microsoft Academic Search

Ultrasonic metal welding is well suited to realize aluminum alloy\\/carbon fiber reinforced polymer (CFRP) – joints. Beside monotonic properties the cyclic deformation behavior of ultrasonic welded aluminum\\/CFRP-joints was inves-tigated. Load increase as well as constant amplitude tests were performed with a servohydraulic testing system at a frequency of 5Hz. The joints are realized by temperature induced softening and mechanical replacing

Frank Balle; Stefan Huxhold; Guntram Wagner; Dietmar Eifler

2011-01-01

111

Fatigue behaviour of friction welded medium carbon steel and austenitic stainless steel dissimilar joints  

Microsoft Academic Search

This paper reports the fatigue behaviour of friction welded medium carbon steel–austenitic stainless steel (MCS–ASS) dissimilar joints. Commercial grade medium carbon steel rods of 12mm diameter and AISI 304 grade austenitic stainless steel rods of 12mm diameter were used to fabricate the joints. A constant speed, continuous drive friction welding machine was used to fabricate the joints. Fatigue life of

R. Paventhan; P. R. Lakshminarayanan; V. Balasubramanian

2011-01-01

112

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

113

Integrity of Polymethylmethacrylate (PMMA) Chemically Welded Joints Examined  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center s Capillary Flow Experiments (CFE) program is developing experiment payloads to explore fluid interfaces in microgravity on the International Space Station. The information to be gained from the CFE is relevant to the design of fluid-bearing systems in which capillary forces predominate, for example in the passive positioning of liquids in spacecraft fuel tanks. To achieve the science goals of CFE, Glenn researchers constructed several types of experiment vessels. One type of vessel, known as the interior corner flow (ICF), will be used to determine important transients for low-gravity liquid management in a two-phase system. Each vessel has a cylindrical fluid reservoir connected to each end of the test chamber by internal transport tubes, each with a quarter-turn shutoff valve (see the following photograph). These multipiece vessels are made from polymethylmethacrylate (PMMA) because of its excellent optical properties (i.e., the fluids can be observed easily in the vessel). Because of the complexity of certain vessels, the test chamber had to be manufactured in pieces and welded chemically. Some past experience with adhesive bonded plastic showed that the experiment fluid degraded the adhesive to the point of failure. Therefore, it was necessary to see if the fluid also degraded the chemically welded PMMA joints.

Lerch, Bradley A.; Thesken, John C.; Bunnell, Charles T.; Kurta, Carol E.; Sydenstricker, Mike

2005-01-01

114

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

Microsoft Academic Search

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

Muhammad Abid; Muhammad Siddique

2005-01-01

115

Study on microstructure and mechanical properties of 304 stainless steel joints by TIG, laser and laser -TIG hybrid welding  

NASA Astrophysics Data System (ADS)

This paper investigated the microstructure and mechanical properties of 304 stainless steel joints by tungsten inert gas (TIG) welding, laser welding and laser-TIG hybrid welding. The X-ray diffraction was used to analyze the phase composition, while the microscopy was conducted to study the microstructure characters of joints. Finally, tensile tests were performed and the fracture surfaces were analyzed. The results showed that the joint by laser welding had highest tensile strength and smallest dendrite size in all joints, while the joint by TIG welding had lowest tensile strength, biggest dendrite size. Furthermore, transition zone and heat affected zone can be observed in the joint of TIG welding. The fractograph observation showed that the TIG welding joint existed as cup-cone shaped fracture, while the laser welding and hybrid welding joints existed as pure-shear fracture. The laser welding and hybrid welding are suitable for welding 304 stainless steel owing to their high welding speed and excellent mechanical properties.

Yan, Jun; Gao, Ming; Zeng, Xiaoyan

2010-04-01

116

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

117

Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints  

NASA Astrophysics Data System (ADS)

The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in the heat-affected zone was caused by partial vanishing and tempering of the pre-existing martensite. The extent of softening was much larger in the DP980-welded joints than in the DP600-welded joints. Despite the reduction in ductility, the ultimate tensile strength (UTS) remained almost unchanged, and the yield strength (YS) indeed increased stemming from the appearance of yield point phenomena after welding in the DP600 steel. The DP980-welded joints showed lower YS and UTS than the base metal owing to the appearance of severe soft zone. The YS, UTS, and strain hardening exponent increased slightly with increasing strain rate. While the base metals had multi-stage strain hardening, the welded joints showed only stage III hardening. All the welded joints failed in the soft zone, and the fracture surfaces exhibited characteristic dimple fracture.

Farabi, N.; Chen, D. L.; Zhou, Y.

2012-02-01

118

Characterization of Eurofer-97 TIG-welded joints by FIMEC indentation tests  

NASA Astrophysics Data System (ADS)

Welded joints of 25-mm thick plates of Eurofer-97, produced by a multi-pass GTAW + filler material method, have been investigated before and after different heat treatments to identify the temperature-time combination that gives mechanical properties as close as possible to those of the base material. After NDE (non-destructive examinations), samples were annealed in the temperature range 730-750 °C for 1 and 2 h, microhardness was measured across the joints and FIMEC (flat-top cylinder indenter for mechanical characterization) tests were carried out in the molten zone (MZ), heat affected zone (HAZ) and in the matrix. The FIMEC method allowed determination on a local scale of the yield stress as obtained in standard tensile tests. Mechanical tests were supplemented by optical microscopy observations. The best results were obtained by the treatment at 750 °C for 2 h: original characteristics are substantially recovered in the HAZ but not completely in the MZ.

Montanari, R.; Filacchioni, G.; Riccardi, B.; Tata, M. E.; Costanza, G.

2004-08-01

119

Evaluation of joint interface of friction stir welding between dissimilar metals using HTS-SQUID gradiometer  

Microsoft Academic Search

In this study, we investigated conductive properties of joint interfaces of friction stir welding (FSW) between dissimilar metals, stainless steel SUS304 and aluminum A6063, using a SQUID nondestructive evaluation (NDE) system. With current injection method, the current maps above the FSW specimens jointed under various conditions were measured by a HTS-SQUID gradiometer. The conductivities of the joint interfaces, which were

Y. Mashiko; Y. Hatsukade; T. Yasui; H. Takenaka; Y. Todaka; M. Fukumoto; S. Tanaka

2010-01-01

120

Nondestructive testing of 2017 aluminum copper alloy diffusion welded joints by an automatic ultrasonic system  

SciTech Connect

The quality assurance of diffusion welded joints of 2017 aluminum copper alloys has been performed by ultrasonic nondestructive testing (NDT) at high frequency ranges. An ultrasonic automatic system with a high frequency pulser receiver focused probe (D = 15 MHz) was used to detect and artificial calibrated discontinuity (tungsten wire) with an opening diameter of 25 {micro}m (1 x 10{sup {minus}3} in.), in a scanned area of 0.25 mm{sup 2} (4 x 10{sup 4}in.{sup 2}). By this technique, it was also possible to detect clusters of residual microdiscontinuities and some unwelded zones predicting the state of the welded joints, before their dynamic tensile loading test. The difference between a sound and a rejectable welded joint was made by comparison with an ultrasonic autograph image of a treated sample which was the base material specimen subjected to the same thermal cycle as the welded sample. Furthermore, the reflected echoes of the welded samples, as well as the dynamic stress elongation behavior of loaded samples, were compared to those of a treated base material. The average magnitude of the reflected echoes of the extracted curves, arising from a sound welded joint corresponded to a total average value of 45.6 dB, whereas those of a bad joint were equal to 80.2 dB. Thus, beyond this last value it is concluded that the dynamic mechanical properties of diffusion welded joints become often very weak.

Debbouz, O.; Navai, F.

1999-12-01

121

Fatigue failure characterisation of resistance-welded thermoplastic composites skin\\/stringer joints  

Microsoft Academic Search

An experimental investigation characterising the fatigue failure mechanisms of resistance-welded thermoplastic composites skin\\/stringer joints is presented. Unidirectional (UD) and quasi-isotropic adherends were welded using stainless steel meshes as heating elements. The specimen geometry consisted of a flange laminate, representing a stringer, welded onto a skin laminate. In order to avoid current leakage to the electrically conductive adherends, a ceramic-coated heating

M. Dubé; P. Hubert; A. Yousefpour; J. Denault

2009-01-01

122

Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints  

Microsoft Academic Search

This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded\\u000a (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints.\\u000a Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains\\u000a in the base material were changed to fine grains consisting duplex structure

A. K. Lakshminarayanan; V. Balasubramanian

2011-01-01

123

Microstructure of Aluminum/Glass Joint Bonded by Ultrasonic Wire Welding  

NASA Astrophysics Data System (ADS)

An Al/glass joint created by using ultrasonic welding was analyzed by means of multiscale observation techniques. A cross-sectional analysis of the microstructure revealed that a directly joined interface without reaction phases formed at the periphery of a round joined region. The size of Al grains markedly decreased after ultrasonic welding and some subgrains were observed along the interface. The finer Al grains observed around the periphery of the joined interface showed active plastic flow that promoted welding.

Iwamoto, Chihiro

2013-11-01

124

Study on microstructure and mechanical properties of 304 stainless steel joints by TIG, laser and laser TIG hybrid welding  

Microsoft Academic Search

This paper investigated the microstructure and mechanical properties of 304 stainless steel joints by tungsten inert gas (TIG) welding, laser welding and laser-TIG hybrid welding. The X-ray diffraction was used to analyze the phase composition, while the microscopy was conducted to study the microstructure characters of joints. Finally, tensile tests were performed and the fracture surfaces were analyzed. The results

Jun Yan; Ming Gao; Xiaoyan Zeng

2010-01-01

125

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

126

Local strain energy density and fatigue strength of welded joints under uniaxial and multiaxial loading  

Microsoft Academic Search

In the notch stress intensity approach to the fatigue assessment of welded joints, the weld toe is modelled as a sharp V-notch and the local stress distributions in plane problems are given on the basis of the relevant mode I and mode II notch stress intensity factors (N-SIFs). These factors quantify the magnitude of asymptotic stress distribution obeying Williams’ solution.

P. Lazzarin; P. Livieri; F. Berto; M. Zappalorto

2008-01-01

127

Fatigue life improvement of AISI 304L cruciform welded joints by cryogenic treatment  

Microsoft Academic Search

Existing theories and reported practical experience show that cryogenic processing greatly increases abrasion resistance and contact fatigue resistance of some metals and alloys. In the present work, an attempt has been made to investigate the effect of cryogenic treatment on the axial fatigue performance of fillet welded cruciform joints of AISI 304L stainless steel, which failed in the weld metal.

P Johan Singh; B Guha; D. R. G Achar

2003-01-01

128

TEM study of microstructure in explosive welded joints between Zircaloy-4 and stainless steel.  

National Technical Information Service (NTIS)

The microstructure of explosive welded joints between Zircaloy-4 and 18/8 stainless steel has been investigated by transmission electron microscopy (TEM). The metallurgical bonding was achieved by combining effect of diffusion and local melting when the e...

Zhou Hairong Zhou Bangxin

1996-01-01

129

Dissimilar Metal Weld Joints and Their Performance in Nuclear Power Plant and Oil Refinery Conditions.  

National Technical Information Service (NTIS)

The operating experience of major nuclear power plant (NPP) pressure boundary components has recently shown that dissimilar metal weld joints can jeopardize the plant availability and safety because of increased incidences of environment-assisted cracking...

A. Brederholm H. Gripenberg H. Hanninen P. Aaltonen U. Ehrnsten

2006-01-01

130

Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints  

NASA Astrophysics Data System (ADS)

This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone and base metal of the joints. Neutron diffraction results showed residual stresses in the weld are approximately 40% lower than the yield strength of the parent material, with maximum variation occurring in the vertical position of the specimen because of the orientation of electrode clamping forces that produce a non-uniform solidification pattern. In the final section a theoretical continuum modeling framework for 6061-T6 aluminum resistance spot welded joints is presented.

Florea, Radu Stefanel

131

Processing results from ultrasonic quality control of welded joints with a punch-card computer system  

Microsoft Academic Search

The quality control system for welded joints must be regarded as an integral part of any facility automatic control system (FACS), and it enters into the operational-prod uction planning subsystem. The problem of quality control of welded joints can be solved only by widespread application of statistical methods of control and of computer techniques [1-3]. At NIIkhimmash [All-Union Scientific-Resea rch

Yu. T. Len'shin; N. V. Khimchenko

1973-01-01

132

Fatigue strength of friction-welded joints with flash in various carbon steels  

Microsoft Academic Search

The fatigue strength of friction-welded joints with flash sharply decreases with increasing upset pressure. This is previously reported as being due to the stress concentration caused by the flash. This study examines the effect of flash on preventing any decrease in the fatigue strength of friction-welded joints in rotating bending fatigue tests of S15C, S35C, S45C and S55C machine structure

M. Hasegawa; T. Ieda; N. Taki

1997-01-01

133

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

134

A simple estimating method for reduction of welding residual stresses in thick welded joint from stress-relief annealing. Part 2: The characteristics of reduction of welding residual stresses in very thick joints during SR treatment  

Microsoft Academic Search

Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels, etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In the first report, an estimating method was developed for relaxation tests,

K. Nakacho; Y. Ueda

1999-01-01

135

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

136

Prediction of welding distortion and residual stress in a thin plate butt-welded joint  

Microsoft Academic Search

In automotive industry, thin plate parts are commonly used. During assembling process, welding technology is usually employed because of high productivity. Welding distortion often occurs in thin plate welded structures due to relatively low stiffness. The distortion causes problems not only in the assembling process but also in the final product quality. Therefore, prediction and reduction of welding deformation have

Dean Deng; Hidekazu Murakawa

2008-01-01

137

Influences of process parameters on tensile strength of friction stir welded cast A319 aluminium alloy joints  

Microsoft Academic Search

Fusion welding of cast A319 (Al-Si-Cu) alloy will lead to many problems including porosity, micro-fissuring, and hot cracking.\\u000a Friction Stir Welding (FSW) can be used to weld A319 alloy without these defects. In this investigation, an attempt has been\\u000a made to study the effect of FSW process parameters on the tensile strength of A319 alloy welded joints. Joints were made

M. Jayaraman; R. Sivasubramanian; V. Balasubramanian; S. Babu

2009-01-01

138

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

139

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

140

The former of special form current pulses for micro resistance welding  

Microsoft Academic Search

Conditions of obtaining high quality welded joints by micro resistance welding are analyzed. Construction principle of the former of special form current pulses for micro resistance welding is offered. The former provides forming of weld current power pulse in accordance with electrophysic processes in welding contact. Offered pulse former included in experimental welding machine is used for welding details of

Yuriy E. Paerand; Oleksandr F. Bondarenko; Yuliya V. Bondarenko

2009-01-01

141

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

142

Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.  

PubMed

The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint. PMID:20500429

Mroczka, K; Dutkiewicz, J; Pietras, A

2010-03-01

143

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

144

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

145

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

Microsoft Academic Search

Health monitoring of structural joints is a major concern of the engineering community. Among joining techniques, spot- welding play a major role. Spot welding is the traditional method of assembly for steel-based automotive structures, while spot-welding of aluminum is being considered for future vehicular structures. Though spot welding of steel is well researched and understood, the spot-welding of aluminum still

Victor Giurgiutiu; Anthony Reynolds; Craig A. Rogers

146

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

147

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

148

Design of a welded joint for robotic, on-orbit assembly of space trusses  

NASA Technical Reports Server (NTRS)

In the future, some spacecraft will be so large that they must be assembled on-orbit. These spacecraft will be used for such tasks as manned missions to Mars or used as orbiting platforms for monitoring the Earth or observing the universe. Some large spacecraft will probably consist of planar truss structures to which will be attached special purpose, self-contained modules. The modules will most likely be taken to orbit fully outfitted and ready for use in heavy-lift launch vehicles. The truss members will also similarly be taken to orbit, but most unassembled. The truss structures will need to be assembled robotically because of the high costs and risks of extra-vehicular activities. Some missions will involve very large loads. To date, very few structures of any kind have been constructed in space. Two relatively simple trusses were assembled in the Space Shuttle bay in late 1985. Here the development of a design of a welded joint for on-orbit, robotic truss assembly is described. Mechanical joints for this application have been considered previously. Welded joints have the advantage of allowing the truss members to carry fluids for active cooling or other purposes. In addition, welded joints can be made more efficient structurally than mechanical joints. Also, welded joints require little maintenance (will not shake loose), and have no slop which would cause the structure to shudder under load reversal. The disadvantages of welded joints are that a more sophisticated assembly robot is required, weld flaws may be difficult to detect on-orbit, the welding process is hazardous, and welding introduces contamination to the environment. In addition, welded joints provide less structural damping than do mechanical joints. Welding on-orbit was first investigated aboard a Soyuz-6 mission in 1969 and then during a Skylab electron beam welding experiment in 1973. A hand held electron beam welding apparatus is currently being prepared for use on the MIR space station. Presently, Marshall Space Flight Center is evaluating processes appropriate for on-orbit welding. A low gravity environment has been found to have very minor effects on the welding processes appropriate for this application. This is based on tests run on-orbit as well as low gravity environments achieved by flying aircraft in parabolic trajectories. It appears that a modified form of gas tungsten arc welding (GTAW) will be most appropriate for welding together structures on-oribt. The process has been modified to work in a vacuum by providing gas to the arc zone by means of a hollow tungsten electrode with special shielding. A commercial tube welding head has been successfully modified for use on-orbit with a gas leakage rate of approximately 2.5 liters/min. To develop as realistic a joint as possible, a specific truss structure was selected on which to base the design. The structure considered was based on the 120 foot diameter aerobrake tetrahedral truss structure. The truss members were assumed to consist of graphite/epoxy tubes. Also, it was assumed that the nodes were constructed of 2219-T87 aluminum alloy. The magnitude of the member load assumed for design purposes was 100 kips.

Rule, William K.

1992-01-01

149

Influence of the method of welding of AT3 alloy on the weld joint properties and the tendency toward corrosion cracking  

SciTech Connect

The authors investigate the influence of the welding method on the mechanical properties, corrosion resistance, and tendency toward corrosion cracking of weld joints of AT3 alloy produced by mechanized helium arc welding and manual argon arc welding. The specimens were prepared from 22-mm thick hot-rolled plate with a composition (wt. %) of Al 3.5, Cr 0.6, Fe 0.6, Si 0.4, Mo 0.064, Zr 0.3, remainder titanium.

Blashchuk, V.E.; Onoprienko, L.M.; Gorban', V.A.; Trufanov, A.A.

1986-09-01

150

Design of a welded joint for robotic, on-orbit assembly of space trusses  

NASA Technical Reports Server (NTRS)

A preliminary design for a weldable truss joint for on-orbit assembly of large space structures is described. The joint was designed for ease of assembly, for structural efficiency, and to allow passage of fluid (for active cooling or other purposes) along the member through the joint. The truss members were assumed to consist of graphite/epoxy tubes to which were bonded 2219-T87 aluminum alloy end fittings for welding on-orbit to truss nodes of the same alloy. A modified form of gas tungsten arc welding was assumed to be the welding process. The joint was designed to withstand the thermal and structural loading associated with a 120-ft diameter tetrahedral truss intended as an aerobrake for a mission to Mars.

Rule, W. K.; Thomas, F. P.

1992-01-01

151

Effect of Thermal Cycle on the Formation of Intermetallic Compounds in Laser Welding of Aluminum-Steel Overlap Joints  

NASA Astrophysics Data System (ADS)

The intermetallic compound (IMC) (or intermetallic phase layer) has a significant influence on the mechanical properties ofjoints between dissimilar metals obtained by thermal processes such as laser welding. Its formation is basically affected by thermal cycles in the joining or contact zone, where the IMC is formed. Within this study, the influence of the thermal cycle on the formation of the IMC during laser welding of an aluminum-steel (Al99.5-DC01) overlap joint was investigated. The temperature was measured directly by a thermocouple, and the weld seam was analyzed by scanning electron microscope (SEM). The influence of peak temperature, cooling time and the integral of the thermal cycle on the thickness of the IMC was identified and discussed. It was identified that cooling time has the biggest influence on the thickness of the IMC.

Fan, J.; Thomy, C.; Vollertsen, F.

152

Interface microstructure and mechanical properties of laser welding copper-steel dissimilar joint  

NASA Astrophysics Data System (ADS)

Relatively the high reflectivity of copper to CO 2 laser led to the difficulty in joining copper to steel using laser welding. In this paper, a new method was proposed to complete the copper-steel laser butt welding. The scarf joint geometry was used, i.e., the sides of the copper and steel were in obtuse and acute angles, respectively. During the welding process, the laser beam was fixed on the steel side and the dilution ratio of copper to steel was controlled by properly selecting the deviation of the laser beam. The offset of laser beam depended on the scarf angle between the copper and steel, the thickness of plate and the processing parameters used in the laser welding. The microstructure near the interface between Cu plate and the intermixing zone was investigated. Experimental results showed that for the welded joint with high dilution ratio of copper, there was a transition zone with numerous filler particles near the interface. However, if the dilution ratio of copper is low, the transition zone is only generated near the upper side of the interface. At the lower side of the interface, the turbulent bursting behavior in the welding pool led to the penetration of liquid metal into Cu. The welded joint with lower dilution ratio of copper in the fusion zone exhibited higher tensile strength. On the bases of the microstructural evaluation at the interface of the welded joint, a physical model was proposed to describe the formation mechanism of the dissimilar joint with low dilution ratio of copper.

Yao, Chengwu; Xu, Binshi; Zhang, Xiancheng; Huang, Jian; Fu, Jun; Wu, Yixiong

2009-07-01

153

Dual beam Nd:YAG laser welding: influence of lubricants to lap joint welding of steel sheets  

NASA Astrophysics Data System (ADS)

Laser welding is applied in large-volume production since the late eighties and has revolutionized the possibilities of designing and engineering products. Nevertheless, problems appear during application because the operational conditions in industrial environments fluctuate and can influence the welding process negatively. Contaminations, like lubricants and organic solids, are an example of changing conditions in laser beam welding. If a lap joint is welded, these materials have to be removed from the sheets, otherwise pores and surface failures may appear due to keyhole instabilities induced by uncontrolled outgassing. One possibility for solving this problem is the use of two separate laser beams. For producing these two beams several systems are available for all different kind of lasers. A bifocal optic is such a solution for an Nd:YAG laser. By using this system, the laser beam is divided after collimation with a prism. Afterwards the two beams are focussed with a lens to the surface of the sheet and two single spots are produced. If the distance between the two spots is low, one common, elliptical keyhole is created. With this system two different welding strategies are possible. The spots can be oriented parallel or normal to the feed direction. For stabilizing the laser welding of contaminated steel sheets the parallel arrangement is better, because the amount of contamination is nearly the same as in single spot welding but the total volume of the keyhole is greater and so pressure variations due to uncontrolled evaporation of contaminations are lower. In order to prove this theory and to determine the exact effects some investigations were made at the Chair of Manufacturing Technology of the University of Erlangen-Nuremberg. A 4 kW Nd:YAG laser with a beam parameter product of 25 mm*mrad and a focal distance of 200 mm was used to weld two 1 mm DC04 steel sheets together with a lap joint. Between the sheets a deep drawing lubricant, Castrol FST 6, was used to simulate the contaminations. The sheets were welded with mono- and bifocal optic, whereas with bifocal the power distribution between the two beams was varied. After welding, the seams were qualified by analyzing surface defects and mechanical properties. The results of the investigations show that the adoption of a bifocal optic can increase the stability of the welding process. The distribution between the two single spots has an essential influence on the welding result. In order to get a higher penetration and failure free seams, a 30 % to 70 % distribution between the two spots is better. Furthermore the blade angle has another slight impact on the welding result. For monofocus and bifocus a towing angle between the sheets and the beam produces better welding results. Considering these results it can be resumed that the application of a bifocal optic is a possibility to increase the quality and the stability of lap joint welding but the parameter settings for good results can only be varied in a tight tolerance zone.

Geiger, M.; Merklein, M.; Otto, A.; Blankl, A.

2007-05-01

154

Microstructure and Toughness of Ferritic Weld Metal of Hyperbaric Welded Joints.  

National Technical Information Service (NTIS)

In the present work ferritic weld metals of hyperbaric MIG/MAG welds with pressures up to 100 bar were examined. As a result of the pressure, interactions with the shielding gas, the filler metal as well as with the welding parameters had to be expected a...

L. Mueller

1988-01-01

155

Effects of tool rotation and pin diameter on fatigue properties of friction stir welded lap joints  

Microsoft Academic Search

The objective of this study was to determine the effects of the tool pin diameter and tool rotation on the fatigue behaviour\\u000a of friction stir welded (FSW) lap joints. FSW lap joints of AA 5754 aluminium alloy plates were produced by means of a conventional\\u000a semiautomatic milling machine. Consequently, defect free FSW lap joints were produced on alloy plates at

Mustafa Kemal Kulekci; Aydin ?ik; Erdinç Kaluç

2008-01-01

156

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

157

Evaluation of joint interface of friction stir welding between dissimilar metals using HTS-SQUID gradiometer  

NASA Astrophysics Data System (ADS)

In this study, we investigated conductive properties of joint interfaces of friction stir welding (FSW) between dissimilar metals, stainless steel SUS304 and aluminum A6063, using a SQUID nondestructive evaluation (NDE) system. With current injection method, the current maps above the FSW specimens jointed under various conditions were measured by a HTS-SQUID gradiometer. The conductivities of the joint interfaces, which were estimated from the current maps, differed between the joint conditions. By destructive tests using optical microscope, large voids were observed on the joint interfaces with low welding speed that generated excess heating. In case of one specimen, which was welded with welding speed of 500 and 200 mm/min, the conductivity of the former was higher than that of the latter, although the inside voids in the respective regions were not much different. From these results, it is suggested that the current maps were influenced not only by the conductivity of the joint interface but also by inside voids. By hardness test on the SUS boards near the interfaces, only the SUS jointed with 200 mm/min was about half softer than its matrix.

Mashiko, Y.; Hatsukade, Y.; Yasui, T.; Takenaka, H.; Todaka, Y.; Fukumoto, M.; Tanaka, S.

2010-11-01

158

Effect of Activated Flux on the Microstructure, Mechanical Properties, and Residual Stresses of Modified 9Cr-1Mo Steel Weld Joints  

NASA Astrophysics Data System (ADS)

A novel variant of tungsten inert gas (TIG) welding called activated-TIG (A-TIG) welding, which uses a thin layer of activated flux coating applied on the joint area prior to welding, is known to enhance the depth of penetration during autogenous TIG welding and overcomes the limitation associated with TIG welding of modified 9Cr-1Mo steels. Therefore, it is necessary to develop a specific activated flux for enhancing the depth of penetration during autogeneous TIG welding of modified 9Cr-1Mo steel. In the current work, activated flux composition is optimized to achieve 6 mm depth of penetration in single-pass TIG welding at minimum heat input possible. Then square butt weld joints are made for 6-mm-thick and 10-mm-thick plates using the optimized flux. The effect of flux on the microstructure, mechanical properties, and residual stresses of the A-TIG weld joint is studied by comparing it with that of the weld joints made by conventional multipass TIG welding process using matching filler wire. Welded microstructure in the A-TIG weld joint is coarser because of the higher peak temperature in A-TIG welding process compared with that of multipass TIG weld joint made by a conventional TIG welding process. Transverse strength properties of the modified 9Cr-1Mo steel weld produced by A-TIG welding exceeded the minimum specified strength values of the base materials. The average toughness values of A-TIG weld joints are lower compared with that of the base metal and multipass weld joints due to the presence of ?-ferrite and inclusions in the weld metal caused by the flux. Compressive residual stresses are observed in the fusion zone of A-TIG weld joint, whereas tensile residual stresses are observed in the multipass TIG weld joint.

Maduraimuthu, V.; Vasudevan, M.; Muthupandi, V.; Bhaduri, A. K.; Jayakumar, T.

2012-02-01

159

A fatigue design method for spot-welded lap joints  

Microsoft Academic Search

Recently, a new issue in the design of spot-welded structures has been economical predic- tion of a fatigue design criterion without additional fatigue tests. In general, the most typical and traditional method is the use of a ¢P› N f curve. However, since the fatigue data on the curve vary according to welding conditions, materials, geometry and fatigue loading conditions,

Dongho Bae; Ilseon Sohn; Wonseok Jung; Sung-Jin Song

2002-01-01

160

The quality of flash welded joints in mild steel: A study on the effects of welding parameters  

SciTech Connect

This paper discusses the results obtained in a detailed experimental study on the effects of various welding parameters on the quality of flash welded mild steel sheets and plates used for wheel rims. Only welding parameters were varied in the case of sheets, whereas for plates, pre- and postwelding parameters also were varied. The effect of secondary voltage on the steel sheets was also studied. The quality was assessed by metallographic examination, hardness profiles across the weld, macro etch, geometry of flash, and tensile tests. Freedom from defects, smoother hardness profiles with a minimum increase in hardness at the weld, increased flash height and upset slope, and wider heat-affected zone (HAZ) were considered as criteria of acceptable quality. The results indicated that though flashing is the main and important stage of the flash welding (FW) process, pre- and postwelding stages significantly control the quality of welds. Overall, the study indicated the quality of flash welds can be effectively controlled only when a comprehensive study is make taking into account all the stages.

Krishnaraj, N.; Prasad Rao, K.; Ramachandran, E.G. (Indian Inst. of Tech., Madras (India). Dept. of Metallurgical Engineering)

1993-06-01

161

High temperature low-cycle fatigue of friction welded joints - type 304-304 stainless steel and alloy 718-718 nickel base superalloy  

SciTech Connect

This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923 K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

Wakai, T. (Power Reactor and Nuclear Fuel Development Corp., Ibaraki (Japan). Oarai Engineering Center); Sakane, M.; Ohnami, M. (Ritsumeikan Univ., Kyoto (Japan). Dept. of Mechanical Engineering); Okita, K. (Hyogo Prefectural Inst. of Industrial Research, Miki (Japan). Technical Center for Machinery and Metals); Fukuchi, Y. (Hyogo Prefectural Inst. of Industrial Research, Kobe (Japan))

1993-01-01

162

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

163

Prediction of welding distortions and residual stresses in a pipe flange joint using the finite element technique  

Microsoft Academic Search

This paper presents a comparative study of three- and two-dimensional axisymmetric finite element (FE) analyses of a welded pipe–flange joint for residual stresses and deformations in order to identify their merits or demerits. Sequentially coupled thermal stress analysis is performed to simulate single pass metal inert gas welding. Butt weld geometry with a single ‘V’ for a 100 mm nominal

M. Abid; M. Siddique; R. A. Mufti

2005-01-01

164

Residual Stress on Ti6Al4V Hybrid and Laser Welded Joints  

Microsoft Academic Search

\\u000a Ti6Al4V alloy combines mechanical strength, deformability, excellent fatigue and corrosion resistance and high strength to\\u000a weight ratio. Furthermore, the mechanical behavior remains excellent at high temperature. Such characteristics make this material\\u000a attractive for numerous applications (structural, aerospace and naval) because of recent improvements in welding techniques\\u000a (laser, hybrid laser\\/MIG) that allow realizing high quality titanium welded joints. However some problems

C. Casavola; C. Pappalettere; F. Tursi

165

Multi-Response Optimization of Friction-Stir-Welded AA1100 Aluminum Alloy Joints  

Microsoft Academic Search

AA1100 aluminum alloy has gathered wide acceptance in the fabrication of light weight structures. Friction stir welding process\\u000a (FSW) is an emerging solid state joining process in which the material that is being welded does not melt and recast. The\\u000a process and tool parameters of FSW play a major role in deciding the joint characteristics. In this research, the relationships

S. Rajakumar; V. Balasubramanian

2011-01-01

166

Evaluation of fatigue damage at welded tube joint under cyclic pressure using surface hardness measurement  

Microsoft Academic Search

In this paper, fatigue tests were conducted on 1Cr18Ni9Ti stainless steel and its welded joints were subjected to cyclic inner pressure. During the fatigue tests, the HL hardness of base metal (BM), weld metal (WM) and heat affected zone (HAZ) were measured. The results showed that 1Cr18Ni9Ti was a cyclic hardening material and the WM was a cyclic softening material.

Xu Chen; Shuang-Mei Zhao

2005-01-01

167

Optimization of ultrasonic welding parameters for copper to copper joints using design of experiments  

Microsoft Academic Search

Ultrasonic welding is a solid-state joining process that produces joints by the application of high-frequency vibratory energy\\u000a in the work pieces held together under pressure without melting. In electronic and automotive applications, copper wires are\\u000a connected to the equipment (alternator\\/rectifier) by a solid state joining process. For such an application ultrasonic metal\\u000a welding is useful. The dominant problem faced by

Sooriyamoorthy Elangovan; K. Prakasan; V. Jaiganesh

2010-01-01

168

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

169

Experimental study of joint performance in spot friction welding of 6111-T4 aluminium alloy  

Microsoft Academic Search

The effect of process parameters (cycle time, tool speed and axial force) on the specimen temperature measured 2 mm away from the weld in spot friction welding (SFW) of Al 6111-T4 is investigated. The temperatures were correlated to the lap shear load. Results revealed that, to achieve a good joint strength with the maximum lap shear load .2?5 kN, temperatures

S. G. Arul; S. F. Miller; G. H. Kruger; T.-Y. Pan; P. K. Mallick; A. J. Shih

2008-01-01

170

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

171

Fracture Behaviour of Nickel-Titanium Laser Welded Joints  

NASA Astrophysics Data System (ADS)

In this study, the effects of Nd:YAG laser welding on the fracture behavior of Ni-rich nickel-titanium sheets are analyzed by experimental investigations. The welding was carried out in open air conditions by using a special shielding/clamping system to avoid the chemical contamination of the molten zone and the formation of hot cracks. Mechanical tests of standard dog bone-shaped and single edge crack specimens were carried out to measure the stress-strain response and the fracture resistance of both the base and the welded materials. Furthermore, scanning electron microscopy observations of the fracture surfaces were carried out in order to better understand the failure mechanisms. Finally, systematic comparative studies between base and laser-welded materials were carried out.

Maletta, C.; Falvo, A.; Furgiuele, F.; Barbieri, G.; Brandizzi, M.

2009-08-01

172

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2010 CFR

...undesirable conditions such as severe stress concentrations, corrosion or erosion, then: (1) The backing rings shall...Socket welds must not be used where severe erosion or crevice corrosion is expected to occur. Restrictions on the use...

2009-10-01

173

Microstructure of Al–Mg–Si Weld Joints Produced by Pulse TIG Welding  

Microsoft Academic Search

Al–Mg–Si alloys (6000 series) are heat-treatable aluminum alloys and are extensively used in various sectors such as aerospace, automobiles, and general construction. Fabrication of these alloys often requires welding. Pulse TIG offers many advantages over conventional TIG welding as far as control of microstructure is concerned. This research investigated the effect of pulsed TIG welding parameters such as pulse duration,

Rajesh Manti; D. K. Dwivedi

2007-01-01

174

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

2012-05-01

175

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

176

Modeling and analysis of novel laser weld joint designs using optical ray tracing.  

SciTech Connect

Reflection of laser energy presents challenges in material processing that can lead to process inefficiency or process instability. Understanding the fundamentals of non-imaging optics and the reflective propagation of laser energy can allow process and weld joint designs to take advantage of these reflections to enhance process efficiency or mitigate detrimental effects. Optical ray tracing may be used within a 3D computer model to evaluate novel joint and fixture designs for laser welding that take advantage of the reflective propagation of laser energy. This modeling work extends that of previous studies by the author and provides comparison with experimental studies performed on highly reflective metals. Practical examples are discussed.

Milewski, J. O. (John O.)

2002-01-01

177

Mechanical Behavior and Low-Cycle Shear Fatigue Life of the Pure Ni Laser-Welded Joints in Optoelectronics Packaging  

Microsoft Academic Search

The aim of this study is to characterize the behaviors of laser-welded joint between pure nickel (Ni200) weld clip and Kovar base metal under various mechanical loadings, i.e. shear and fatigue in shear. A Nd:YAG laser source with 1064 nm was used to weld a Ni200 piece onto a Kovar substrate by single weld spot. These samples were then subjected

C. W. Tan; Y. C. Chan; N. W. Leung; H. D. Liu

2008-01-01

178

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

179

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

180

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

181

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

2014-03-01

182

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

183

A simple estimating method for reduction of welding residual stresses in thick welded joint from stress-relief annealing. Part 2: The characteristics of reduction of welding residual stresses in very thick joints during SR treatment  

SciTech Connect

Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels, etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In the first report, an estimating method was developed for relaxation tests, in uniaxial stress state, at changing and constant temperatures because the stress relaxation phenomenon is considerably similar to that observed in the SR treatment of a joint. In this report, the stresses relaxed by SR treatment in a very thick welded joint are analyzed accurately by the finite element method based on thermal elastic-plastic-creep theory. The characteristics of the changes of the welding residual stresses in multiaxial stress state are studied in detail for further development of the estimating method to SR treatment of a very thick welded joint, of which the stress state and boundary condition are very complex.

Nakacho, K.; Ueda, Y. [Osaka Univ., Ibaraki, Osaka (Japan). Joining and Welding Research Inst.

1999-02-01

184

Empleo de diagramas especificos AVG derivados en Computadora para la realizacion del control ultrasonico. (Ultrasonic Control of welded joints by using specific PC generated AVG diagrams).  

National Technical Information Service (NTIS)

This paper describes an algoritm easy to be implemented in a modern personnel computer (PC), which can be used to obtain the specific AVG diagrams required during the ultrasonic control of welded joints by the AVG method. The algoritm is illustrated by me...

S. Rondon Torriente N. J. Galeano Alvarez T. Frometas Castillo J. J. Gonzalez Mastrapa

1996-01-01

185

Columnar jointing in non-welded Cerro Galan ignimbrite: Paycuqui, Argentina  

NASA Astrophysics Data System (ADS)

Well-developed columnar joint sets are thought to occur most commonly in moderately to densely welded facies of ignimbrites. Columnar joints in welded deposits form when sintering between juvenile grains provides sufficient cohesion to allow thermal volume contraction to be accommodated in brittle fracture. However, well- developed columnar joints can also form in unwelded deposits, where cohesion is produced by high temperature devitrification of the deposit. Such is the case at Paycuqui, Argentina, in the Cerro Galan ignimbrite. The Cerro Galan ignimbrite is a very large volume rhyodacitic pyroclastic flow deposit (>1000 km3), which erupted ~2.3 Ma. At the Paycuqui locality, 29 km west of the caldera margin, the flow is valley-confined and is over 30 m thick. The deposit is massive, pumice-poor, lithic-poor, crystal-rich, and contains well-developed joint sets in the upper 15m. Remant magnetization analyses of incorporated lithics indicate high temperature emplacement. However, welding deformation and sintering textures are absent. Instead, textural differences between the nonjointed base and the jointed top of the ignimbrite are coincident with devitrification variations, inluding dominant cryptocrystalline sanidine and crystobalite that increase in abundance upwards in the section. The presence of a 1mm wide, more devitrified zone along columnar joint faces constrains the timing of high temperature devitrification. Devitrification must have begun prior to brittle fracture and continued after joints had formed. The morphology of joints at Paycuqui differs from well-described joint sets elsewhere. The average diameter of polygons is 0.75 m. Intersecting columnar joint surfaces at Paycuqui form polygons with fewer sides (mean of 4.5 sides) than on many lava flows or than predicted in models. These polygonal patterns vary within the flow due to the presence of vertical, rose-shaped, and radiating joints. Such complexities may result from fumarolic vapor rise.

Wright, H. M.; Cas, R.; Lesti, C.; Viramonte, J.; Folkes, C.; Porreca, M.

2007-12-01

186

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

187

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

188

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

189

A comparative study of the mechanical properties of 6061-T6 GMA welds obtained by the indirect electric arc (IEA) and the modified indirect electric arc (MIEA)  

Microsoft Academic Search

Plates of a 6061-T6 aluminium alloy with 12.7mm in thickness were welded with the gas metal arc welding process (GMAW) using three different joint designs; a single V groove butt joint, the indirect electric arc (IEA) joint and the modified indirect electric arc joint (MIEA). The later is a modification of the IEA joint which requires preheating of the plates

R. R. Ambriz; G. Barrera; R. García; V. H. López

2009-01-01

190

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

191

Recent developments in local concepts of fatigue assessment of welded joints  

Microsoft Academic Search

Several lately proposed modifications or variants of the structural stress or strain concepts, of the notch stress or strain concepts (also termed ‘local stress or strain concepts’) and of the fracture mechanics concepts of fatigue assessment of welded joints are reviewed, whereas the wider context is presented in a recently republished and actualised standard work. The structural stress concepts described

D. Radaj; C. M. Sonsino; W. Fricke

2009-01-01

192

Microstructure and bonding strength of impact-welded aluminium–stainless steel joints  

Microsoft Academic Search

An aluminium projectile was impact-welded on a stainless steel target using a nitrogen gas gun at an impact velocity over 250 m s?1. Effects of surface roughness of the impact face of the target on the bonding area and the strength of the bonding area were examined. The microstructure and element distribution in the joint were analyzed and the experimental

Hidefumi Date; Shin Kobayakawa; Masaaki Naka

1999-01-01

193

Evaluation of Fatigue Properties of Copper-Nickel, Silver-Brazed, and Socket-Welded Joints.  

National Technical Information Service (NTIS)

The objective of the research effort was an evaluation of the fatigue behavior of socket-joined, copper-nickel piping. Specific areas of investigation were: evaluation of the fatigue behavior of 2- and 4-inch-diameter silver-brazed and welded socket joint...

D. C. Martin H. Mindlin M. S. Healy R. P. Meister W. S. Hyler

1965-01-01

194

Ultrasonic test procedure for evaluating fuel clad endcap weld joints of PHWRs  

Microsoft Academic Search

This paper describes the application of ultrasonic test method and digital signal analysis techniques for the detection of fine defects of â10 percent of wall thickness in resistance welded endcap-clad tube joints of fuel elements used in pressurized heavy water reactors (PHWRs). Standardization of test methodology was carried out using reference defects made on inner an outer surface of the

C. V. Subramanian; M. Thavasimuthu; C. Rajagopalan; P. Kalyanasundaram; B. Raj

1995-01-01

195

Finite element analysis of welded hollow spherical joints interpenetrated by circular steel pipe  

Microsoft Academic Search

In large-scale grid structure, the load bearing capacity of welded hollow spherical can be increased effectively by transfixing main steel pipe through the hollow spherical, and now this method has been applied in engineering. In order to investigate the change laws of the capacity of spherical interpenetrated by main steel pipe, and explore the calculation method of spherical joint, ANSYS

Kun Qian; Meng Guo; Tian Xia

2012-01-01

196

Mechanical properties of laser-pressure-welded joint between dissimilar galvannealed steel and pure aluminium  

Microsoft Academic Search

Dissimilar metal joints of Zn-coated Galvannealed steel (GA steel) and commercially available pure aluminium (A1050) sheets were produced by changing the laser power and the roller pressure by the laser pressure welding method. By this method, the YAG laser beam was irradiated into a flare groove made by these dissimilar metal sheets. In addition, the laser beam was scanned at

Koji Nishimoto; Tomoki Harano; Yoshihiro Okumoto; Ken Atagi; Hiroo Fujii; Seiji Katayama

2009-01-01

197

Residual Stress Evaluation of AA2024-T3 Friction Stir Welded Joints  

Microsoft Academic Search

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

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

2007-01-01

198

Collapse load for a crack in a plate with a mismatched welded joint  

Microsoft Academic Search

The accuracy of flaw assessment techniques for welded joints is directly related to the accurate estimate of the yield collapse load. A careful finite element limit analysis can provide a very good and reliable assessment of the collapse load. Unfortunately, such an analysis is normally time-consuming and requires a substantial effort in order to validate the finite element calculations. In

Andrei Kotousov; Mohd Fairuz Mohmed Jaffar

2006-01-01

199

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

Microsoft Academic Search

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

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

2011-01-01

200

About the Stress Distribution in Electric Resistance Welding Joints in Thin Sheet Metals.  

National Technical Information Service (NTIS)

On three models made from Trolon the edge stresses are determined by means of the photoelastic method for simplified conditions of resistance-welded joints of overlapped sheet metals of equal thickness. The stress maxima have been found at the edge of the...

F. Bollenrath

1964-01-01

201

Numerical simulation analysis on insulating joint's welding based on the finite element  

Microsoft Academic Search

Insulating joint is the important equipment of cathodic protection in the system of pipeline and it is succedaneum of insulating flange. This paper researcher systemically discusses the finite element theory, and has a 3D dynamic simulation towards the temperature field and stress field generated during the process of welding combining with the numerical calculation method. According to analytical result, the

ChangQing Cai; XinTong Tang; Zhuo Zhang; Gao Wang

2010-01-01

202

Failure of weld joints between carbon steel pipe and 304 stainless steel elbows  

Microsoft Academic Search

A number of weld joints between carbon steel (CS) pipe and type 304 stainless steel (SS) elbows constituting a gas piping system of a petrochemical unit developed cracks after a relatively short period of usage, resulting in leakage. The gas flowing through the pipe, was hydrogen rich at a temperature of 45 °C and a pressure of 16 kg\\/cm2. Light

Anwar Ul-Hamid; Hani M. Tawancy; Nureddin M. Abbas

2005-01-01

203

Rehabilitation of Welded Joints by Ultrasonic Impact Treatment (UIT)  

Microsoft Academic Search

Due to the increasing traffic and life loading fatigue becomes of high relevance in order to maintain the integrity of existing steel bridge structures. Poor construction details which used to be regarded as less important when applied e.g. to road bridges are nowadays often the starting point of fatigue cracks. Repair and strengthening of welded details are thus of great

Hans-Peter GÜNTHER; Ulrike KUHLMANN; André DÜRR

204

Microstructure and Properties of TIG/FSW Welded Joints of a New Al-Zn-Mg-Sc-Zr Alloy  

NASA Astrophysics Data System (ADS)

A new Al-Zn-Mg-Sc-Zr alloy with low Sc content was welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques. The microstructure and properties of those two welded joints were investigated by property tests and microstructural observations. The results show that the new Al-Zn-Mg-Sc-Zr alloy has desirable welding property. The ultimate tensile strength and welding coefficient of the TIG joint reach 405 MPa and 76.7%, respectively, and in FSW joint those property values reach 490 MPa and 92.6%, respectively. The studied base metal has a deformed fibrous subgrains structure, many nano-scaled Al3(Sc,Zr) particles, and very fine aging precipitates. In the TIG joint, the fusion zone consists of coarsened dendritic grains and the heat-affected zone (HAZ) has fibrous micro-scaled subgrains. The FSW welded joint is characterized by a weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. Due to plastic deformation around the rotating pin and anti-recrystallized effectiveness of Al3(Sc,Zr) particles, the weld nugget zone has a very fine subgrain structure. The TMAZ experiences some dissolution of aging precipitates. Coarsening of aging precipitates was observed in the HAZ. The better mechanical properties of the FSW joint are derived from a fine subgrain structure and homogeneous chemical compositions.

Lei, Xuefeng; Deng, Ying; Peng, Yongyi; Yin, Zhimin; Xu, Guofu

2013-09-01

205

CHEMICAL AND STRUCTURAL CHANGES FOR BIMETALLIC MATERIALS OBTAINED BY THE WELDING PROCESS  

Microsoft Academic Search

This paper presents the transformations which take place during the obtaining process of bimetallic materials. As a plating process was used the welding. The added material was a bronze with aluminum complex alloyed with iron, nickel. The based material was the steel. EDAX analyses and microstructures analyses were done in order to explain the metallurgical processes which take place during

Felicia Bratu

206

Radiographic inspection of porosity in Ti-6Al-4V laser-welded joints.  

PubMed

Widely used in dentistry, Ti-6Al-4V alloy is difficult to cast and solder, as it frequently exhibits pores inside the structure. This study was conducted to evaluate the effect of joint openings and diameters of laser-welded joints executed in Ti-6Al-4V structures on the presence of pores as checked by radiographic procedures. Sixty dumbbell rods with central diameters of 1.5, 2.0 and 3.5 mm were created from Ti-6Al-4V-wrought bars. Specimens were sectioned and welded using two joint openings (0.0 and 0.6 mm). The combination of variables created six groups (n = 10). Laser welding was executed using 360V/8ms (1.5 and 2.0 mm) and 380V/9ms (3.5 mm), with the focus and frequency set to zero. The joints were finished, polished and submitted to radiographic examination. The radiographs were visually examined for the presence of pores in the joints, qualitatively. The percentage of radiographic presence of pores was calculated without counting pores per joint. Data were analyzed using a chi-square test (? = 0.05). For the 1.5-mm specimens, the incidence of pore presence was significantly higher (p = 0.0001) when using 0.6-mm joint openings (40%) compared to 0.0-mm openings (0%). For the 2.0-mm specimens, there was no significant difference between groups (p = 0.2008). However, for the 3.5-mm specimens, the incidence of pore presence was lower (p = 0.0061) for 0.6-mm openings (50%) compared to 0.0-mm openings (70%). Therefore, laser welding of Ti-6Al-4V structures with thin diameters provides the best condition for the juxtaposition of the parts. PMID:21359490

Nuñez-Pantoja, Juliana Maria Costa; Takahashi, Jessica Mie Ferreira Koyama; Nóbilo, Mauro Antônio de Arruda; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz

2011-01-01

207

T-joints of Ti alloys with hybrid laser-MIG welding: macro-graphic and micro-hardness analyses  

NASA Astrophysics Data System (ADS)

Titanium alloys are characterized by high mechanical properties and elevated corrosion resistance. The combination of laser welding with MIG/GMAW has proven to improve beneficial effects of both processes (keyhole, gap-bridging ability) while limiting their drawbacks (high thermal gradient, low mechanical resistance) In this paper, the hybrid Laser-GMAW welding of Ti-6Al-4V 3-mm thick sheets is investigated using a specific designed trailing shield. The joint geometry was the double fillet welded T-joint. Bead morphologies, microstructures and mechanical properties (micro-hardness) of welds were evaluated and compared to those achieved for the base metals.

Spina, R.; Sorgente, D.; Palumbo, G.; Scintilla, L. D.; Brandizzi, M.; Satriano, A. A.; Tricarico, L.

2012-02-01

208

Missed joint induced by thermoelectric magnetic field in electron-beam welding dissimilar metals—Experiment and scale analysis  

NASA Astrophysics Data System (ADS)

A missed joint, resulting from an induced thermoelectric magnetism in welding dissimilar metals with a high-intensity electron beam, is experimentally and analytically investigated. Election-beam welding is a very useful process for joining a wide range of dissimilar metals, which may be difficult or impossible to weld by other techniques. Certain combinations of materials, unfortunately, readily give rise to a missed-joint defect because of thermoelectric-magnetic deflection of the beam. Combinations of dissimilar metals chosen for this study are low-carbon steel and type 304 stainless steel, low-carbon steel and Ni-Cu alloy, and type 304 stainless steel and Ni-Cu alloy. The experimental results find agreement with a previous study showing that the electron beam deflects toward the metal with a larger Seebeck coefficient (denoted by metal 1). A general and algebraic expression for predicting deflection angle as a function of dimensionless beam power, accelerating voltage-to-Seebeck electromotive force (EMF) parameter, Peclet and Prandtl numbers, and electrical conductivity ratio between metals 1 and 2 has been derived from a scale analysis for the first time. The predicted results agree well with experimental data obtained from the literature, this work, and three-dimensional theoretical prediction.

Wei, P. S.; Wen, Chih-Wei

2002-10-01

209

Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel  

NASA Astrophysics Data System (ADS)

This work describes the results of an investigation on a dissimilar weld joint comprising a boiler-grade low alloy steel and duplex stainless steel (DSS). Welds produced by shielded metal arc-welding with two different electrodes (an austenitic and a duplex grade) were examined for their microstructural features and properties. The welds were found to have overmatching mechanical properties. Although the general corrosion resistance of the weld metals was good, their pitting resistance was found to be inferior when compared with the DSS base material.

Srinivasan, P. Bala; Muthupandi, V.; Sivan, V.; Srinivasan, P. Bala; Dietzel, W.

2006-12-01

210

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

211

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

212

Structure of the transition zone and its influence on the strength of copper-tantalum joint (Explosion welding)  

NASA Astrophysics Data System (ADS)

The joint of copper and tantalum, metals without mutual solubility, formed by explosion welding is studied. The mechanism of the influence of mutual solubility on the structure of the transition zone is established. It is demonstrated that the interface contains heterogeneities, and their role in the strength of the materials joint is revealed. A microheterogeneous structure of the joint zones is detected.

Greenberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Elkina, O. A.; Patselov, A. M.; Antonova, O. V.; Inozemtsev, A. V.; Salishchev, G. A.; Kozhevnikov, V. E.

2012-10-01

213

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

214

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

215

Evaluation of Bending Strength in Friction Welded Alumina/mild Steel Joints by Applying Factorial Technique  

NASA Astrophysics Data System (ADS)

Joining of metal with ceramics has become significant in many applications, because they combine properties like ductility with high hardness and wear resistance. By friction welding technique, alumina can be joined to mild steel with AA1100 sheet of 1mm thickness as interlayer. In the present work, investigation of the effect of friction time on interlayer thickness reduction and bending strength is carried out by factorial design. By using ANOVA, a statistical tool, regression modeling is done. The regression model predicts the bending strength of welded ceramic/metal joints accurately with ± 2% deviation from the experimental values.

Jesudoss Hynes, N. Rajesh; Nagaraj, P.; Vivek Prabhu, M.

216

Effect of Zinc Coatings on Joint Properties and Interfacial Reactions in Aluminum to Steel Ultrasonic Spot Welding  

NASA Astrophysics Data System (ADS)

Dissimilar joining of aluminum to steel sheet in multimaterial automotive structures is an important potential application of ultrasonic spot welding (USW). Here, the weldability of different zinc-coated steels with aluminum is discussed, using a 2.5-kW USW welder. Results show that soft hot-dipped zinc (DX56-Z)-coated steel results in better weld performance than hard (galv-annealed) zinc coatings (DX53-ZF). For Al to hard galv-annealed-coated steel welds, lap shear strengths reached a maximum of ~80% of the strength of an Al-Al joint after a 1.0 s welding time. In comparison, welds between Al6111-T4 and hot dipped soft zinc-coated steel took longer to achieve the same maximum strength, but nearly matched the Al-Al joint properties. The reasons for these different behaviors are discussed in terms of the interfacial reactions between the weld members.

Haddadi, F.; Strong, D.; Prangnell, P. B.

2012-03-01

217

Local fatigue strength parameters for welded joints based on strain energy density with inclusion of small-size notches  

Microsoft Academic Search

A fatigue strength parameter for (seam-)welded joints is presented which is based on the averaged elastic strain energy density (SED) criterion applied to full circle and semicircular ‘control volumes’, the latter centred by the expected crack path. The parameter is applicable both at weld toes and weld roots, at least in the medium-cycle and high-cycle fatigue range where elastic conditions

D. Radaj; F. Berto; P. Lazzarin

2009-01-01

218

A comparison between FSW and TIG welding techniques: modifications of microstructure and pitting corrosion resistance in AA 2024-T3 butt joints  

Microsoft Academic Search

An experimental investigation has been carried out, in present paper, on microstructure and corrosion resistance of weld butt joints of AA 2024-T3. Two different welding processes have been considered: a conventional tungsten inert gas (TIG) process and an innovative solid state welding process known as friction stir welding (FSW). Micro-hardness measurements allow pointing out a general decay of mechanical properties

A. Squillace; A. De Fenzo; G. Giorleo; F. Bellucci

2004-01-01

219

Characterization of mechanical properties in AISI 1040 parts welded by friction welding  

Microsoft Academic Search

This study deals with the importance of welding in manufacturing methods. There are various welding methods that have been developed to obtain suitable joints in various applications. However, friction welding, which is an alternative manufacturing method, is one of the methods that has been widely used for many years. In the present study, an experimental friction welding set-up, which is

Mumin Sahin; H. Erol Akata; Turgut Gulmez

2007-01-01

220

Predicting tensile strength, hardness and corrosion rate of friction stir welded AA6061-T 6 aluminium alloy joints  

Microsoft Academic Search

AA6061-T6 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. The friction stir welding (FSW) process and tool parameters play major role in deciding the joint characteristics. In this research, the tensile strength and hardness along with the corrosion rate of friction-stir-butt welded joints of AA6061-T6

S. Rajakumar; C. Muralidharan; V. Balasubramanian

2011-01-01

221

Effects of heat treatments on mechanical properties of Fe\\/Al explosion-welded structural transition joints  

Microsoft Academic Search

The aluminum\\/steel structural transition joints are widely used in shipbuilding industry due to the advantages of joining these two materials with important weight savings while exploiting their best properties. The research objective is the evaluation of process feasibility to laser weld structural transition joints to overcome manufacturing limitations of traditional TIG\\/MIG welding. This study presents results achieved during as-simulated laser

L. Tricarico; R. Spina; D. Sorgente; M. Brandizzi

2009-01-01

222

Dissimilar material lap joints by friction stir welding of steel and titanium sheets: Process modeling  

NASA Astrophysics Data System (ADS)

In the paper a continuum based FEM model for Friction Stir Welding of different material lap joint made out of thin stainless steel and titanium sheets is proposed. The simulation campaign was made out using the 3D Lagrangian implicit code DEFORM{trade mark, serif} by means of a rigid-visco-plastic approach. The model, already set up and tuned for FSW process of similar materials and geometrical configurations takes into account the different mechanical and thermal behavior of the two materials and the microstructural evolution of the considered titanium alloy in the same joint. Additionally, it is able to predict temperature, phase, strain and strain rate distributions and evolution at the varying of the main process variables. The phase evolution models take into account only the main phases called Alpha, Beta and Alpha+Baeta so that, at the end of the simulation, the complete phase distribution in the welded zone.

Buffa, Gianluca; Ducato, Antonino; Fratini, Livan

2013-05-01

223

Electron-microscopic examination of the transition zone of aluminum-tantalum bimetallic joints (explosion welding)  

NASA Astrophysics Data System (ADS)

A study of the structure of an aluminum-tantalum joint and a comparison of this structure with the structures of iron-silver and copper-tantalum joints have revealed the following processes of the interpenetration of the materials that occur during explosion welding: the formation of protrusions, the injection of particles of one material into the other, and the formation of zones of local melting. Regardless of the mutual solubility of the metals being welded, two types of fragmentation occur, i.e., (1) a granulating fragmentation (GF), which includes the formation, explosion-governed (EG) dispersion, and partial consolidation of particles, and (2) the fragmentation that is usually observed during severe plastic deformation. It is important that this traditional fragmentation is not accompanied by the formation and EG dispersion of particles. This feature allows one to easily distinguish these types of fragmentation (traditional and GF fragmentation).

Volkova, A. Yu.; Greenberg, B. A.; Ivanov, M. A.; Elkina, O. A.; Inozemtsev, A. V.; Plotnikov, A. V.; Patselov, A. M.; Kozhevnikov, V. E.

2014-04-01

224

Hydrogen permeability over the joint weld of the steel parts of fusion reactor with magnet confinement of plasma  

NASA Astrophysics Data System (ADS)

Hydrogen and its isotopes diffusion and permeability over the laser joint weld of low-activation 10Cr9WVA ferritic steels have been studied. Welding of steel sheets were produced with the help of Russian gas laser TL-5M type ( l=10.6 mm, P=2.5 kW) in He atmosphere with the rate of 66 mm/s. Hydrogen diffusion over the joint welds was detected by the conventional method of electrical resistance measurement. By this way, the kinetics of resistance changes during hydrogenation of specimens engraved from weld metal, neighboring zone of thermal effect as well as basic metal have been determined. Coefficients of hydrogen diffusion were measured in the temperature range from 773 to 1073 K. So, for 10Cr9WVA steel at 873 K it was established that the hydrogen diffusion coefficient in the weld metal is approximately 10 times higher than in the basic metal, and three times higher than that in the zone of thermal effect. Hydrogen permeability over the joint weld specimens was measured by the Dines-Barrer method on the volummetric setup. It was established that the hydrogen flux over the laser joint weld is significantly (up to two orders) more than that over the basic metal. Using the data on the hydrogen permeability and diffusion coefficient, the hydrogen solubility in the weld metal was estimated, which is several ten times higher than that in the basic metal of the steel investigated. As a result, it was concluded that welding the steel parts of the first wall of thermonuclear reactors with magnet confinement of plasma is undesirable due to possible tritium leaking into the environment. A possible way of decreasing the joint welds hydrogen permeability, including application of protective impermeable for hydrogen coatings, is considered.

Fedorov, V. V.; Dyomina, E. V.; Zasadny, T. M.; Ivanov, L. I.; Prusakova, M. D.; Vinogradova, N. A.; Zabelin, A. M.

2002-12-01

225

Residual Stress Evaluation of AA2024-T3 Friction Stir Welded Joints  

Microsoft Academic Search

The main aim of this study was to evaluate the residual stress field in friction stir welded joints of 2024-T3 aluminum alloy\\u000a plates using the slitting method. This is based on the fact that when a cut, simulating a growing crack, is incrementally\\u000a introduced into a part, residual stresses are relieved on the slot surfaces created, causing the part to

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

2007-01-01

226

The degradation of dissimilar explosively welded joints due to thermal ageing  

Microsoft Academic Search

The effect of thermal ageing on the microstructure and shear strength properties of an explosively welded dissimilar joint has been investigated using compositional analysis and a novel shear testing technique. Ageing temperatures of 1000°C and 115°C were used up to 4000h, and in each case Al was found to diffuse from the ODM751 to the CR39W, and Ni diffused in

S. D. Norris

1998-01-01

227

Laser Shock Processing influence on local properties and overall tensile behavior of friction stir welded joints  

Microsoft Academic Search

Based on laser beam intensities above 109W\\/cm2 with pulse energy of several Joules and duration of nanoseconds, Laser Shock Processing (LSP) is capable of inducing a surface compressive residual stress field. The paper presents experimental results showing the ability of LSP to improve the mechanical strength and cracking resistance of AA2024-T351 friction stir welded (FSW) joints. After introducing the FSW

Mihaela Iordachescu; Andrés Valiente; Luis Caballero; Danut Iordachescu; José Luis Ocaña; Juan Antonio Porro

228

Uniaxial Tensile and Simple Shear Behavior of Resistance Spot-Welded Dual-Phase Steel Joints  

NASA Astrophysics Data System (ADS)

Small test coupons were machined from single spot welds in a dual-phase steel (DP600) to investigate deformation and failure of weld joints in both tension and shear. Quasi-static ( ifmmodeexpandafterdotelseexpandafter\\.fi{\\upvarepsilon } ˜ 10^{{ - 4}} 1/{text{s}} ) testing was conducted in a miniature tensile stage with a custom image acquisition system. Strain accumulation in each weld was analyzed where fracture occurred, which was typically outside the fusion zone. A few shear test coupons that failed in the fusion zone were found to have the same spheroidal defects noted in previous work, and thus, severely limited weld strength and ductility. A novel strain mapping method based upon digital image correlation was employed to generate two-dimensional deformation maps, from which local stress-strain curves to failure were computed. As an important first step toward incorporation of material models into weld simulations, a preliminary finite element analysis of a tension test successfully reproduced the experimental results with material models for the base, heat-affected, and fusion zone materials generated from prior work.

Tao, Hong; Tong, Wei; Hector, Louis G.; Zavattieri, Pablo D.

2008-08-01

229

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

230

Characterizations of 21-4N to 4Cr9Si2 stainless steel dissimilar joint bonded by electric-resistance-heat-aided friction welding  

Microsoft Academic Search

A new welding process, electric-resistance-heat-aided friction welding (ERHAFW), was introduced in this study. To further improve the joint quality and energy-saving, electric resistance welding was combined with the conventional continuous-drive friction welding. 21-4N (austenitic stainless steel) and 4Cr9Si2 (martensitic stainless steel) valve steel rods of 4mm diameter were used as base metals. The results show that electric-resistance-heat-aided friction welding can

Wen-Ya Li; Min Yu; Jinglong Li; Guifeng Zhang; Shiyuan Wang

2009-01-01

231

Electrical, Corrosion, and Mechanical Properties of Aluminum-Copper Joints Produced by Explosive Welding  

NASA Astrophysics Data System (ADS)

This study investigates the microstructure, electrical, corrosion, and mechanical properties of plate-shaped aluminum-copper couple produced using the explosive welding method. Mechanical tests, including hardness, tensile, tensile-shear, and impact test, concluded that the Al-Cu bimetal had an acceptable joint resistance. In this study, local intermetallic regions formed on the interface of the joint of the aluminum-copper bimetal, produced using the explosive welding technique. However, the formed intermetallic regions had no significant effect on the mechanical properties of the joint, except for increasing its hardness. According to electrical conductivity tests, the Al-Cu bimetal had an average electrical conductivity in comparison to the electrical conductivity of aluminum and copper, which were the original materials forming the joint. According to the results of electro-chemical corrosion test, during which galvanic corrosion formed, the Al side of the Al-Cu bimetal was more anodic due to its high electronegativity; as a result, it was exposed to more corrosion in comparison to the copper side.

Acarer, Mustafa

2012-11-01

232

Weld line detection and process control for welding automation  

NASA Astrophysics Data System (ADS)

Welding has been widely used as a process to join metallic parts. But because of hazardous working conditions, workers tend to avoid this task. Techniques to achieve the automation are the recognition of joint line and process control. A CCD (charge coupled device) camera with a laser stripe was applied to enhance the automatic weld seam tracking in GMAW (gas metal arc welding). The adaptive Hough transformation having an on-line processing ability was used to extract laser stripes and to obtain specific weld points. The three-dimensional information obtained from the vision system made it possible to generate the weld torch path and to obtain information such as the width and depth of the weld line. In this study, a neural network based on the generalized delta rule algorithm was adapted to control the process of GMAW, such as welding speed, arc voltage and wire feeding speed. The width and depth of the weld joint have been selected as neurons in the input layer of the neural-network algorithm. The input variables, the width and depth of the weld joint, are determined by image information. The voltage, weld speed and wire feed rate are represented as the neurons in the output layer. The results of the neural-network learning applied to the welding are as follows: learning ratio 0.5, momentum ratio 0.7, the number of hidden layers 2 and the number of hidden units 8. They have significant influence on the weld quality.

Yang, Sang-Min; Cho, Man-Ho; Lee, Ho-Young; Cho, Taik-Dong

2007-03-01

233

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

234

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

235

Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints  

NASA Astrophysics Data System (ADS)

Aging treatment and various heat input conditions were adopted to investigate the microstructural evolution and mechanical properties of TIG welded 6061-T6 alloy joints by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone (HAZ) increases and grains in the fusion zone (FZ) coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175°C for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

Peng, Dong; Shen, Jun; Tang, Qin; Wu, Cui-ping; Zhou, Yan-bing

2013-03-01

236

The effect of joint design and volume fraction on friction welding properties of A360\\/SiC(p) composites  

Microsoft Academic Search

This research uses a rotation friction welding system with 360Al and 360Al\\/5v-%-10v-% (v-% = volume fraction percent) SiC particulate composites utilizing both identical and different materials and two joint designs. In joint design 1, one side is a lead angle and the other is a plane. In joint design 2, both sides are planes. From the experiment, it was noted

C. B. Lin; C. K. Mu; W. W. Wu; C. H. Hung

1999-01-01

237

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

238

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

NASA Technical Reports Server (NTRS)

A variation of cold welding is described 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.

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

1978-01-01

239

A Comparison of Creep Rupture Strength of Ferritic/Austenitic Dissimilar Weld Joints of Different Grades of Cr-Mo Ferritic Steels  

NASA Astrophysics Data System (ADS)

Evaluations of creep rupture properties of dissimilar weld joints of 2.25Cr-1Mo, 9Cr-1Mo, and 9Cr-1MoVNb steels with Alloy 800 at 823 K were carried out. The joints were fabricated by a fusion welding process employing an INCONEL 182 weld electrode. All the joints displayed lower creep rupture strength than their respective ferritic steel base metals, and the strength reduction was greater in the 2.25Cr-1Mo steel joint and less in the 9Cr-1Mo steel joint. Failure location in the joints was found to shift from the ferritic steel base metal to the intercritical region of the heat-affected zone (HAZ) of the ferritic steel (type IV cracking) with the decrease in stress. At still lower stresses, the failure in the joints occurred at the ferritic/austenitic weld interface. The stress-life variation of the joints showed two-slope behavior and the slope change coincided with the occurrence of ferritic/austenitic weld interface cracking. Preferential creep cavitation in the soft intercritical HAZ induced type IV failure, whereas creep cavitation at the interfacial particles induced ferritic/austenitic weld interface cracking. Micromechanisms of the type IV failure and the ferritic/austenitic interface cracking in the dissimilar weld joint of the ferritic steels and relative cracking susceptibility of the joints are discussed based on microstructural investigation, mechanical testing, and finite element analysis (FEA) of the stress state across the joint.

Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, Sunil; Mathew, M. D.

2012-04-01

240

National Shipbuilding Research Program, 1990 Ship Production Symposium, Paper No. 5B-2: Shipboard Aluminum/Steel Welded Transition Joints Evaluation and Improvements.  

National Technical Information Service (NTIS)

Aluminum to steel explosion welded transition joints are used to attach aluminum superstructures to steel hulls. Transition joint bond separation sometimes occurs during ship construction. Ingalls Shipbuilding conducted a long term study to determine caus...

E. Gaines J. Banker

1990-01-01

241

A simple estimating method for reduction of welding residual stresses in thick welded joint from stress-relief annealing. Part 1: Development of the analytical method for relaxation tests and its applicability  

SciTech Connect

Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In this first report, an estimating method is developed for relaxation tests, in uniaxial stress state, at changing and constant temperatures because the stress relaxation phenomenon is very similar to that observed in the SR treatment of a joint. Using the various relations between stress and strains in the relaxation tests, estimating equations are formulated in order to simply calculate the change of the stress. The results obtained by applying the equations are compared with the highly accurate analytical result based on the finite element method. Both results show such a good coincidence that the appropriateness of the adopted method is confirmed. In the next report, this method is extended to SR treatment of a very thick welded joint, of which the stress state and boundary condition are very complex.

Nakacho, K.; Ueda, Y. [Osaka Univ., Ibaraki, Osaka (Japan). Joint and Welding Research Inst.

1996-08-01

242

Azides and nitrides in joints welded by laser using N2 as covering gas  

NASA Astrophysics Data System (ADS)

A large amount of metals and alloys are successfully penetration welded by pulsed or cw laser. The laser welding process requires a gas flow (covering gas) to ensure adequate protection of the melt against atmospheric oxidation. The gas can be supplied in a variety of ways but in many cases the coaxial gas-laser geometry is used. This work is concerned with technological and structural investigations (using SEM and A.E.S. microanalysis) aimed at identifying any particular differences in the welds obtained using N2 instead of He as the covering gas. The investigations conducted on INCONEL 600 and stainless steel appear to provide conclusive evidence that N2 may be readily used as an alternative to He. Very recent works have studied some peculiarities (blanketing, transmission, and process efficiency) of N2 as a covering gas, when used in 2 kW CO2 laser welding. The influence of the covering gas in welding two stainless steels (AISI 304 and 430) and of a nickel alloy (INCONEL 600) using a 2 kW CO2 laser is examined.

Daurelio, Giuseppe; Dionoro, G.; Memola Capece Minutolo, F.; Panagopoulos, C.

1993-05-01

243

Effects of a double sided heating method and its controlling parameters: Development of a residual stress control method for butt-welded pipe joints (1st Report)  

Microsoft Academic Search

This paper describes a new stress improvement method to reduce tensile residual stress on the inner and outer surfaces near butt-welded pipe joints. Its procedure is as follows. An annular region on both sides of the weld line is heated from the outside at the same time to generate a temperature differential between the weld line and region being heated.

M. Nayama; N. Sakamoto; G. Takano; K. Murase; N. Akitomo

1997-01-01

244

Effect of parameters of the butt pressure welding process on the strength and ductile properties of polyvinylidene fluoride – PVDF – tubular joints  

Microsoft Academic Search

The method most often used for permanent joining of thermoplastic elements is that of butt pressure welding. So far, the investigations carried out at Instytut Spawalnictwa (The Welding Institute) have been focussed on the assessment of the quality of joints made in basic grades of thermoplastics, such as polyethylene (PE), and polypropylene (PP) by the fusion and pressure welding processes,

S. Dziuba

2003-01-01

245

Prediction of residual stresses and distortions due to laser beam welding of butt joints in pressure vessels  

Microsoft Academic Search

A two-level three-dimensional Finite Element (FE) model has been developed to predict keyhole formation and thermo-mechanical response during Laser Beam Welding (LBW) of steel and aluminium pressure vessel or pipe butt-joints. A very detailed and localized (level-1) non-linear three-dimensional transient thermal model is initially developed, which simulates the mechanisms of keyhole formation, calculates the temperature distribution in the local weld

G. A. Moraitis; G. N. Labeas

2009-01-01

246

Dynamic behaviors of 0Cr18Ni10Ti stainless steel welded joints at elevated temperatures and high strain rates  

Microsoft Academic Search

Dynamic mechanical behaviors of the base metal (BM) and the weld metal (WM) for the welded joints of an austenitic stainless steel, 0Cr18Ni10Ti, are studied at loading rates ranging from 200 to 3800s?1 and temperatures from 25 to 600°C using a modified Hopkinson pressure bar system. We focus on the effects of strain, strain rate and temperature on the flow

Z. Xu; Y. Li

2009-01-01

247

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

Microsoft Academic Search

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

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

2010-01-01

248

First samples of Ti and Nb tubes explosion welding joint with stainless steel for ILC 1.8 K cryomodule  

NASA Astrophysics Data System (ADS)

The world first samples of Ti and Nb tubes joint with stainless steel ones by an explosion welding by the JINR-VNIIEF-FNAL-INFN cooperation were manufactured in the frame of ILC R&D programe. An applying methods of relaxation of residual tensions (after explosion and electron beam welding), macro- and microanalyses of welding seam and cryogenic tests of the samples produced manifest the achievement of high mechanic strength (?250 MPa/share) of welding seam, solidity and leak absence on 10-10 l atm/s level at 1.8 K. The explosion welding technology and methods introducing to industrial manufacturing of the 4-th generation of cryomodule of TESLA TYPE DESIGN can exclude the Ti—communications, connect the Nb—cavity with stainless steel vessel and reduce significantly the accelerator cost.

Sabirov, B. M.; Budagov, J. A.; Shirkov, G. D.

2013-07-01

249

Computer integrated vision and neural network technologies for intelligent automatic laser butt joint welding  

Microsoft Academic Search

This paper discusses the integrated application of computer vision and neural technologies on laser welding to make welding processes more intelligent and automatic. Computer vision was employed to inspect a welding gap, to measure the welding gap size, and to trace the welding path for laser beam alignment. The NC code for the welding path was generated, and then the

Jeng-ywan Jeng; Tzuoh-fei Mau; Sh Yeu-ming Leu

2000-01-01

250

Introductory fatigue tests on welded joints in high strength steel and aluminium improved by various methods including ultrasonic impact treatment (UIT)  

Microsoft Academic Search

This paper summarizes fatigue test on high strength steel specimens in the as-welded condition and specimens treated by ultrasonic impact treatment, TIG dressing and a combination of TIG dressing and ultrasonic impact treatment. Single lap joint specimens in 6 mm aluminium plate material were tested in the as-welded, hammer peened, needle peened and ground condition. Aluminium joints with longitudinal stiffeners

NORWEGIAN DELEGATION; P. J. Haagensen; E. S. Statnikov; L. Lopez-Martinez

251

Mechanical Properties of Shielded Metal Arc (SMA) and Submerged Arc (SA) Welded Joints for Quenched and Tempered High Strength Steel N-A-XTRA-70.  

National Technical Information Service (NTIS)

Hardness, tensile and Charpy-V testing, and fracture mechanics results of shielded metal arc and submerged arc welded joints for quenched and tempered high-strength steel N-A-XTRA-70 (Ste 690) are given. Results for joints welded with Ni-Cr-Mo alloyed fil...

M. Vilpas H. Tihekari R. Karppi

1985-01-01

252

Welding Metals by Friction.  

National Technical Information Service (NTIS)

Contents: Features of friction welding; Mechanism of formation of a welded joint in solid phase; Basic information from the friction theory; Heat liberation during friction welding; Basic parameters and recommended regimes in friction welding process; Fri...

V. I. Vill

1972-01-01

253

The effect of process parameters and tool geometry on mechanical properties of friction stir welded aluminum butt joints  

Microsoft Academic Search

In Friction Stir Welding (FSW), process parameters and tool geometry play a fundamental role in obtaining desirable mechanical\\u000a properties and microstructures in the welded zone. The results of experimental activity on friction stir welding of aluminum\\u000a alloys, focused on the above mentioned aspects, are reported in the present paper. The experimental campaign was performed\\u000a on sheets 5 mm thick of

G. D’Urso; E. Ceretti; C. Giardini; G. Maccarini

2009-01-01

254

Study on the Microstructures and Tensile Behaviors of Friction Stir Welded T-joints for AA6061-T4 Alloys  

NASA Astrophysics Data System (ADS)

Friction stir welding (FSW) of T-joints with 3 mm thickness for AA6061-T4 sheets has been performed, and the influences of process parameters on the microstructures, defects, hardness profiles, and tensile strength were discussed specifically. It is found that the macrostructures and microstructures are similar in different process parameters, and the microstructure features in the skin welds have the same patterns as that of butt-joints. The unique microstructures of T-joints are the two fillet zones. Two lower hardness zones in the skin and one lower hardness zone in the stringer are found. Additionally, the tensile properties of T-welded joints are examined along the skin and the stringer plane directions. Results show that the tensile strength is in the range of 170-180 MPa for all the specimens along the skin direction, and the specimens fail in the heat affected zone (HAZ). In the stringer direction, the larger tunnel defects (DA) (the DA is greater than 0.1 mm2) would reduce the ultimate tensile strength of the T-joints and cause the joints to fracture at the bonding interface. The smaller tunnel defects (the DA is less than 0.015 mm2) and the zigzag lines have no pronounced effect on the failed location. In the stringer direction, tensile efficiencies of T-joints could be 83% of the base material (BM) when ?/v = 1541/218 r/mm is applied.

Zhou, G.; Yang, X. Q.; Cui, L.; Zhang, Z. H.; Xu, X. D.

2012-10-01

255

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.

256

PALS determination of defect density within friction stir welded joints of aluminium alloys  

Microsoft Academic Search

Positron annihilation spectroscopy is employed to investigate the density of defects in samples of aluminium alloys (2017 A and 6013) welded using the Friction Stir Welding method. The vacancy and dislocation densities were determined at the weld junction as a function of various parameters and conditions: Travel and rotational speed of welding tool, cooling of the surface of the welded

J. Kansy; K. Mroczka; J. Dutkiewicz

2011-01-01

257

LWRHU GTA Weld Development  

SciTech Connect

Nineteen LWRHU Development Welds have been made. Welds WD-1 through WD-4 were made early in the program to obtain preliminary joint design data. Welds WD-5 through WD-10 were made with the vertical leg of the shim located toward the closure end cap. A decision was made to locate the shim with the vertical leg on the fuel side of the capsule; therefore, the data obtained on the above capsule welds will not be included in this report. A tantalum pellet machined to the configuration of the fuel pellet was placed inside each development capsule. O.D. shrinkage measurements were taken across the stand-off ring nearest the weld. A small increase in capsule length resulted from the weld bead on the end of the capsule.

Burgan, C.E.

1979-12-13

258

Characterisation of dissimilar joints in laser welding of steel–kovar, copper–steel and copper–aluminium  

Microsoft Academic Search

Joining of dissimilar materials is one of the challenging tasks facing modern manufacturers. Dissimilar joining technologies find applications in many sectors including microelectronics, medical, optoelectronics and microsystems. The tiny geometry of the joints and the different optical and thermal properties of the materials makes laser welding one of the most suitable production methods. This paper presents the results of an

T. A. Mai; A. C. Spowage

2004-01-01

259

C-ring stress corrosion test for Inconel 600 and Inconel 690 sleeve joint welded by Nd:YAG laser  

Microsoft Academic Search

C-ring stress corrosion test for Inconel 600 and Inconel 690 sleeve joint welded by Nd:YAG laser were carried out to evaluate the applicability of the technique in the repair of heat exchanger tube of nuclear power plant. Corrosion test were carried out mainly in caustic solution. The applied stresses range between 207 and 414 MPa at 348 °C and the

Jae-Do Kim; Ju-Hong Moon

2004-01-01

260

Mechanical characterization of spot friction stir welded joints in aluminum alloys by combined experimental\\/numerical approaches  

Microsoft Academic Search

This is part II of a two part paper summarizing material characteristics of Spot Friction Stir Welded (SFW) lap joints in aluminum alloy 6111 at the macromechanical and micromechanical levels. In this paper, modal vibration testing and static flexure testing at the macromechanical level combined with numerical finite element models have been used to indirectly determine the elastic moduli of

Srinivasa D. Thoppul; Ronald F. Gibson

2009-01-01

261

Creep rupture properties of trial welded joints of a Ni-Cr-W superalloy in air environment.  

National Technical Information Service (NTIS)

The item to be solved in order to put the Ni-Cr-W superalloy to practical use is development of filler metal. Therefore, creep properties of trial welded joints were estimated. Filler metals whose susceptibility to cracking in the weldments was lowered by...

Y. Kurata H. Tsuji H. Nakajima T. Saito T. Takatsu

1997-01-01

262

Studies of the Fatigue Behavior of Butt-Welded Joints in HY-80 and HY-100 Steels.  

National Technical Information Service (NTIS)

The results of axial fatigue tests of transverse butt welded joints in HY-80 steel containing internal defects are reported. The tests were conducted on 3/4 in. and 1-1/2 in. thick material under stress cycles of zero-to-tension and complete reversal. The...

W. H. Munse W. H. Bruckner A. J. Hartmann J. B. Radziminski R. W. Hinton

1964-01-01

263

Re-weldability of neutron-irradiated stainless steels studied by multi-pass TIG welding  

Microsoft Academic Search

Weldability of neutron-irradiated stainless steel (SS) has been studied by multi-pass bead-on-plate and build-up tungsten inert gas (TIG) welding, simulating the repair-welding of reactor components. Specimens were submerged arc welding (SAW) joint of Type 304 SS containing 0.5 appm helium (1.8 appm in the SAW weld metal). Sound welding could be obtained by one- to three-pass welding on the plates

K. Nakata; M. Oishi; M. Koshiishi; T. Hashimoto; H. Anzai; Y. Saito; W. Kono

2002-01-01

264

A Fatigue Life Prediction Model of Welded Joints under Combined Cyclic Loading  

NASA Astrophysics Data System (ADS)

A practical and robust methodology is developed to evaluate the fatigue life in seam welded joints when subjected to combined cyclic loading. The fatigue analysis was conducted in virtual environment. The FE stress results from each loading were imported to fatigue code FE-Fatigue and combined to perform the fatigue life prediction using the S x N (stress x life) method. The measurement or modelling of the residual stresses resulting from the welded process is not part of this work. However, the thermal and metallurgical effects, such as distortions and residual stresses, were considered indirectly through fatigue curves corrections in the samples investigated. A tube-plate specimen was submitted to combined cyclic loading (bending and torsion) with constant amplitude. The virtual durability analysis result was calibrated based on these laboratory tests and design codes such as BS7608 and Eurocode 3. The feasibility and application of the proposed numerical-experimental methodology and contributions for the technical development are discussed. Major challenges associated with this modelling and improvement proposals are finally presented.

Goes, Keurrie C.; Camarao, Arnaldo F.; Pereira, Marcos Venicius S.; Ferreira Batalha, Gilmar

2011-01-01

265

Investigation of the fatigue behaviour of the welded joints treated by TIG dressing and ultrasonic peening under variable-amplitude load  

Microsoft Academic Search

Weld toe treatment by ultrasonic peening (IIW.Doc.XIII-1817-00; J. Mech. Strength 21(1999)289; Welding World (3\\/4)(2001); Welding World (37)(1996)72) or TIG dressing (Trans. Jpn. Welded Soc. 17(2)(1986)3; Int. J. Fatigue 21(6)(1999)587; Metal Construction 19(2)(1984)143; Int. J. Fatigue 20(9)(1998)677) improves the fatigue performance of welded joints and structures significantly. This has been verified by many constant amplitude fatigue tests. However, there is the

Lixing Huo; Dongpo Wang; Yufeng Zhang

2005-01-01

266

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

267

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. 34 figs.

Milewski, J.O.; Sklar, E.

1998-06-02

268

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

269

Joint characteristics and dissimilar materials joining of pure-Al\\/5083 by friction stir welding  

Microsoft Academic Search

Friction stir welding (FSW), developed in 1991 by The Welding Institute, UK is a joining process which overthrew welding concepts which existed at the time; its application has been progressed not only for soft alloys including aluminium, but also, in recent years, for steel. Sato and others carried out friction stir welding on 1080-O and 5083-O materials and investigated variations

M. Katoh; K. Nishio; T. Yamaguchi; M. Uemura; S. Oohara

2005-01-01

270

Performance of strength mis-match welded joints: comparison of experimental and numerical results.  

National Technical Information Service (NTIS)

Two 70 mm thick 316L austenitic plates have been butt-welded using a TIG welding process. The weld metal yield strength is more than twice the base metal yield strength. From this overmatched weld, 25 mm thick Compact Tension (CT), Single Edge Notched Ben...

P. Hornet C. Eripret M. Kocak E. Junghans

1997-01-01

271

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

Microsoft Academic Search

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

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

2009-01-01

272

A simple estimating method for reduction of welding residual stresses in thick welded joint from stress-relief annealing. Part 1: Development of the analytical method for relaxation tests and its applicability  

Microsoft Academic Search

Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In this first report, an estimating method is developed for relaxation tests,

K. Nakacho; Y. Ueda

1996-01-01

273

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

274

Analysis of Formation and Interfacial WC Dissolution Behavior of WC-Co/Invar Laser-TIG Welded Joints  

NASA Astrophysics Data System (ADS)

During the valve fabrication, hard metal is welded to stainless steel or invar alloy for sealing purposes because of its good heat resistance operating at 500 °C. However, WC (tungsten carbide) dissolution in weld pool softens the hard metal and decreases mechanical properties near the hard metal/weld interface. In order to analyze the WC dissolution in welded joint, joining of hard metal and invar alloy was carried out using laser-tungsten inert gas hybrid welding method. Microstructures of the weld region, chemical composition were investigated using optical microscope, scanning electron microscopy, and EDAX, respectively. Mechanical properties such as microhardness and four-point bend strength test were performed. Larger and smaller WC dissolution and WC dissolution through transition layer based on thermo-dynamics were discussed. The results thus indicate that WC dissolution led to cellular microstructure, columnar crystal, and transition layer under the effect of laser beam and tungsten arc. WC dissolution was affected by metal ions Fe+, Ni+, Co+ exchange in W-M-C system, and WC grain growth was driven by forces caused by laser beam and tungsten arc in larger WC, smaller WC, and liquid Fe, Ni systems.

Xu, P. Q.; Ren, J. W.; Zhang, P. L.; Gong, H. Y.; Yang, S. L.

2013-02-01

275

Effect of welding processes on tensile properties of AA6061 aluminium alloy joints  

Microsoft Academic Search

The present investigation is aimed at to study the effect of welding processes such as GTAW, GMAW and FSW on mechanical properties\\u000a of AA6061 aluminium alloy. The preferred welding processes of these alloys are frequently gas tungsten arc welding (GTAW)\\u000a and gas metal arc welding (GMAW) due to their comparatively easier applicability and better economy. In this alloy, the weld

A. K. Lakshminarayanan; V. Balasubramanian; K. Elangovan

2009-01-01

276

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

277

Fatigue behaviour of AISI 304 steel to AISI 4340 steel welded by friction welding  

Microsoft Academic Search

In the presented study, The weldability of AISI 304 austenitic stainless steel to AISI 4340 steel joined by friction welding\\u000a in different rotational speeds and fatigue behaviour of friction-welded samples were investigated. Tension tests were applied\\u000a to welded parts to obtain the strength of the joints. The welding zones were examined by scanning electron microscopy (SEM)\\u000a and analyzed by energy

A. Hasçalik; E. Ünal; N. Özdemir

2006-01-01

278

Interfacial microstructure and mechanical properties of aluminium–zinc-coated steel joints made by a modified metal inert gas welding–brazing process  

Microsoft Academic Search

The microstructure and properties of aluminium–zinc coated steel lap joints made by a modified metal inert gas CMT welding–brazing process was investigated. It was found that the nature and the thickness of the high-hardness intermetallic compound layer which formed at the interface between the steel and the weld metal during the welding process varied with the heat inputs. From the

H. T. Zhang; J. C. Feng; P. He; H. Hackl

2007-01-01

279

Australian Standard Methods for the Radiographic Examination of Fusion Welded Butt Joints in Steel (Metrication and Revision of as B164-1965).  

National Technical Information Service (NTIS)

This standard sets out methods for the radiographic examination of fusion welded joints in steel by the use of X-rays or gamma rays. Methods described are based on procedures in which the film lies parallel and adjacent to one surface of the weld and the ...

1975-01-01

280

Accuracy of the Modified Wöhler Curve Method applied along with the r ref = 1 mm concept in estimating lifetime of welded joints subjected to multiaxial fatigue loading  

Microsoft Academic Search

In the present paper the accuracy of the Modified Wöhler Curve Method (MWCM) in estimating fatigue lifetime of welded joints subjected to multiaxial fatigue loading is investigated when this bi-parametrical critical plane approach is applied in conjunction with the reference radius concept. In more detail, local liner-elastic stress fields in the vicinity of weld toes are suggested as being determined

L. Susmel; C. M. Sonsino; R. Tovo

2011-01-01

281

Examination of irradiated 304L stainless steel to 6061-T6 aluminum inertia welded transition joints after irradiation in a spallation neutron  

SciTech Connect

The Savannah River Technology Center (SRTC) designed and fabricated tritium target/blanket assemblies which were irradiated for six months at the Los Alamos Neutron Science Center (LANSCE). Cooling water was supplied to the assemblies through 1 inch diameter 304L Stainless Steel (SS) tubing. To attach the 304L SS tubing to the modules a 304L SS to 6061-T6 Aluminum (Al) inertia welded transition joint was used. These SS/Al inertia weld transition joints simulate expected transition joints in the Accelerator Production of Tritium (APT) Target/Blanket where as many as a thousand SS/Al weld transition joints will be used. Materials compatibility between the 304L SS and the 6061-T6 Al in the spallation neutron environment is a major concern as well as the corrosion associated with the cooling water flowing through the piping. The irradiated inertia weld examination will be discussed.

Dunn, K.A.

2000-04-28

282

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

283

In-service damage to heat-exchange tubes and welded joints in steam generators of power-generating units of nuclear power plants with WWER-1000  

Microsoft Academic Search

We analyze the results of investigations of the in-service defects of heat-exchange tubes of steam generators of WWER reactors\\u000a and the metal of pipelines and welded joints. The specific features of damage to heat exchangers and welded joints of the\\u000a collectors with branch pipes of the bodies steam generators are analyzed. The causes of degradation of materials of the secondary

I. M. Neklyudov; V. M. Azhazha; L. S. Ozhigov; A. S. Mitrofanov

2008-01-01

284

fatigue assessment of welded joints in AlMg 4.5Mn aluminium alloy (AA 5083) by local approaches  

Microsoft Academic Search

Three different local stress approaches, the stress averaging approach, the highly stressed volume approach and the crack propagation approach were applied to the fatigue assessment of welded joints in AlMg 4.5 Mn aluminium alloy (AA 5083) with different stress concentrations and plate thicknesses. These approaches rendered strength or life estimates with acceptable accuracy in the high-cycle fatigue range (N ?

C. M. Sonsino; D. Radaj; U. Brandt; H. P. Lehrke

1999-01-01

285

Microstructure and mechanical property of the fusion boundary region in an Alloy 182-low alloy steel dissimilar weld joint  

Microsoft Academic Search

Characterizations of the microstructure and mechanical property of the fusion boundary region of an Alloy 182-A533B low alloy\\u000a steel (LAS) dissimilar weld joint were conducted. The existence of type-II boundary that parallels to the fusion boundary\\u000a in the dilution zone (DZ) of Alloy 182 within a distance of about 50 ?m was observed. The chemical composition transition\\u000a was found in

J. Hou; Q. J. Peng; Y. Takeda; J. Kuniya; T. Shoji; J. Q. Wang; E.-H. Han; W. Ke

2010-01-01

286

Investigation of fatigue-induced socket-welded joint failures for small-bore piping used in power plants  

Microsoft Academic Search

Nuclear power plants typically experience two or three high-cycle fatigue failures of stainless steel socketwelded connections\\u000a in small bore piping during each plant-year of operation. This paper discusses fatigue-induced failure in socket-welded joints\\u000a and the strategy Texas Utilities Electric Company (TU Electric) has implemented in response to these failures. High-cycle\\u000a fatigue is invisible to proven commercial nondestructive evaluation (NDE) methods

Daniel N. Hopkins; Daniel J. Benac

2001-01-01

287

Effect of prior microstructure on microstructure and mechanical properties of modified 9Cr–1Mo steel weld joints  

Microsoft Academic Search

Strength of modified 9Cr–lMo steel, which is used in the normalized and tempered condition, increases with increase in solutionising temperature with a corresponding reduction in percentage elongation. There is an increase in the prior-austenite grain size with increase in solutionising temperature. The heat-affected zone (HAZ) of the weld joints prepared from this material that has been subjected to solutionising at

C. R. Das; S. K. Albert; A. K. Bhaduri; G. Srinivasan; B. S. Murty

2008-01-01

288

Effect of rotation speed on temperature field and axial shortening of inertia friction welded GH4169 joints by numerical simulation  

Microsoft Academic Search

A 2D finite element model was established for inertia friction welding of GH4169 nickel-base superalloy based on the ABAQUS\\u000a environment. The remeshing and map solution techniques were adopted to solve the problem of element distortion. The effect\\u000a of rotation speed on the temperature field and axial shortening of joints was investigated. The results show that the interface\\u000a temperature increases rapidly

Liang Chen; Wen-Ya Li; Jing-long Li

2011-01-01

289

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

290

Stress corrosion cracking susceptibility of friction stir welded AA7075–AA6056 dissimilar joint  

Microsoft Academic Search

Two aluminium alloys, AA7075 and AA6056, were friction stir welded, with the AA7075 alloy placed on the advancing side of the welding tool. Microstructural observations revealed the development of a recrystallised fine-grained weld nugget, with two different grain sizes, resulting from the two different base materials. Slow strain rate tensile (SSRT) tests in air have shown that the weld nugget

P. Bala Srinivasan; W. Dietzel; R. Zettler; J. F. dos Santos; V. Sivan

2005-01-01

291

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

292

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

2014-05-01

293

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

294

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

295

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

296

Microstructural development at weld interface between Zr-based glassy alloy and stainless steel by resistance microwelding  

NASA Astrophysics Data System (ADS)

Zr-based bulk metallic glasses are expected to be welded to conventional structural alloys. Dissimilar welding of metallic glasses to stainless steel was carried out by resistance microwelding. The metallurgical analysis of the weld interface revealed the welding mechanism. A thin reaction layer was formed between the two liquid materials. The melting of stainless steel should be limited to obtain sound joints.

Fukumoto, S.; Minami, M.; Soeda, A.; Matsushima, M.; Takahashi, M.; Yokoyama, Y.; Fujimoto, K.

2012-08-01

297

Surface preparation is key to girth weld coating performance. [Corrosion resistive coatings on welded joints in pipeline construction  

Microsoft Academic Search

Test evaluations show that girth weld coatings, regardless of the type of coating, provides better performance when applied over an ideally prepared surface. Primary coating for most new pipe lines is applied in a coating plant under detailed specifications and controlled conditions. Typically, surface preparation, preheat, application, and other important parameters are well controlled and the coating is, of course,

1994-01-01

298

The effect of joint design and volume fraction on friction welding properties of A360/SiC(p) composites  

SciTech Connect

This research uses a rotation friction welding system with 360Al and 360Al/5v-%-10v-% (v-% = volume fraction percent) SiC particulate composites utilizing both identical and different materials and two joint designs. In joint design 1, one side is a lead angle and the other is a plane. In joint design 2, both sides are planes. From the experiment, it was noted that using joint design 1 achieved better joint strength. The joint strength is best with 360Al-360Al and worst with 360Al/10v-%-360Al/10v-% SiC particulate composites. 360Al-360Al has a ductile fracture with dimples, while the 360Al/10v-%-360Al/10v-% SiC particulate composite has a low-ductile fracture. The 360Al/10v-%-360Al/10v-% SiC particulate composites are fractured in the Zpl zone, while the others are fractured in the interface between the Zpl zone and the Zpd zone. For the joint systems using different materials, the fracture is in the interface between the Zpl zone and Zpd zone, where the quantity of SiC particulate is higher. In the heat-affected zone (HAZ) for identical materials, the Zpl hardness value is smaller than Zud; for the different materials, the hardness in Zpl is half of the two Zud hardness total values.

Lin, C.B.; Mu, C.K.; Wu, W.W.; Hung, C.H. [Tamkang Univ. (Taiwan, Province of China). Dept. of Mechanical Engineering

1999-03-01

299

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

300

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

301

Effect of welding speed on mechanical strength of friction welded joint of YSZ–alumina composite and 6061 aluminum alloy  

Microsoft Academic Search

Successful application of ceramics in many devices and structures requires some type of ceramic metal joining. All applications require a high-strength metal–ceramic bond. Even successful joint formation does not guarantee mechanical soundness of the joint. The inherent differences in physical properties between the ceramic and the metal make it extremely difficult to find an effective joining process that maintains the

M. B. Uday; M. N. Ahmad Fauzi; H. Zuhailawati; A. B. Ismail

2011-01-01

302

Features of misoriented structures in a copper-copper bilayer plate obtained by explosive welding  

NASA Astrophysics Data System (ADS)

Structures induced by deformation in the narrow zone of a contact between two copper plates that is prepared by explosive welding are systematically investigated at the micro-, meso-, and macrolevels. Plastic jets, regions of metal plastic flow anomalous localization, are discovered in areas adjacent to the contact surface. The defect structure of the plastic jets is examined by transmission electron microscopy and electron backscatter diffraction. It is shown that at the mesolevel the plastic jets are regions with a heavily fragmented structure. The statistics of the fragment distribution over misorientations and transverse sizes is studied.

Rybin, V. V.; Ushanova, E. A.; Zolotorevskii, N. Yu.

2013-09-01

303

PALS determination of defect density within friction stir welded joints of aluminium alloys  

NASA Astrophysics Data System (ADS)

Positron annihilation spectroscopy is employed to investigate the density of defects in samples of aluminium alloys (2017 A and 6013) welded using the Friction Stir Welding method. The vacancy and dislocation densities were determined at the weld junction as a function of various parameters and conditions: Travel and rotational speed of welding tool, cooling of the surface of the welded material and the compositions of the welded alloys. The 3-state trapping model used in the computer analysis allowed to separate a vacancy component from a component related to dislocations. The determined lifetime of positron trapped by dislocation was much shorter than its experimental values referred to in literature, however, it is closer to the theoretical predictions.

Kansy, J.; Mroczka, K.; Dutkiewicz, J.

2011-01-01

304

A study of structure and mechanical properties of welded joints in polyethylene pipes  

Microsoft Academic Search

The structure and the mechanical properties of a butt weld in a polyethylene pipe were examined and contrasted to non-welded PE pipe. X-ray diffraction, differential scanning calorimeter and fourier transform infra red spectrometer measurements revealed details of axial amorphous and crystal orientation in the original pipe. Contrary to expectations considering the squeeze flow nature of butt-welding, formation of randomly oriented

K. Leskovics; M. Kollár; P. Bárczy

2006-01-01

305

Cracking of the mixing chamber caused by sigma phase precipitation in austenitic steel welded joints  

Microsoft Academic Search

In the air mixing chamber of the chipboard production line, made of austenitic X15CrNiSi20-12 steel, cracks have been found, which were located in the fillet welds connecting the suspension ring with the chamber shell and also in the butt welds of the suspension ring. The failure investigation covered temperature measurement of the suspension ring, chemical analysis of welds and parent

J. Brózda; J. Madej

2008-01-01

306

The Effect of Alloying Elements on the Shear Strength of the Lap Joint of AZ31B Magnesium Alloy to Q235 Steel by Hybrid Laser-TIG Welding Technique  

NASA Astrophysics Data System (ADS)

Welding between AZ31B Mg alloy and Q235 mild steel was examined in this study. The effects of welding parameters were first investigated on the penetration depth into the steel and the shear strength of the joints. The optimum parameters and the maximum shear strength were obtained. Based on these parameters, alloying elements in the form of interlayers were added into the joints, and the shear strength was improved as high as 98 pct of the AZ31B Mg alloy. Microstructures of the joints were inspected with a scanning electron microscope and an electron probe micro-analyzer. Two bonding modes were proposed, and their effects on the joint shear strength were discussed. It is suggested that the bonding changed from nonmetallurgical to "semimetallurgical" mode with the addition of the interlayers, which contributed to the enhancement of the shear strength. Micro-hardness profiles were measured in the fusion zone of the joints, and their influence on the joint strength was also discussed. Intermediate phases that distributed uniformly in the fusion zone strengthened the microstructures, and thus, the shear strength was elevated. An empirical trend for Cu and Ni interlayer selection was proposed.

Liu, Liming; Qi, Xiaodong; Zhang, Zhaodong

2012-06-01

307

Predicting the geometry and location of defects in adhesive and spot-welded lap joints using steady-state thermographic techniques  

NASA Astrophysics Data System (ADS)

Development of nondestructive evaluation (NDE) methods for spot-welded and adhesive-bonded sheet metal joints is essential for widespread use of lightweight materials and new construction techniques in automotive applications. An important objective of research in progress is development of NDE methods to identify and characterize critical flaws in welded and adhesive-bonded joints. We used steady-state heat- flow and thermographic imaging techniques to test welded and adhesive-bonded lap joints in steel and aluminum samples and in adhesive-bonded composite panels and to identify defective spot welds. The resulting surface-temperature maps or thermograms were used to detect voids and areas where the adhesive was not bonded. To better characterize defects in welds and adhesive layers, algorithms have been developed to post process temperature data, producing more accurate definition of the geometry and location of defects than in previous images. Classic heat-transfer theory was used to calculate the heat-flux equilibrium for each individual pixel on the thermograms. Convective and radiative surface heat- transfer coefficients were applied to compensate for the heat exchange between the sample and the environment. This post processing permits us to determine the locations of spot welds and the sizes of the weld nuggets in welded joints, and to clearly image voids in adhesive layers between joints. The effectiveness of the image-processing algorithms was investigated using data from laboratory experiments on test specimens with flaws of known size and location. In addition, the images of the defects produced with the new method were compared to results of two-dimensional heat transfer simulations through the same samples. The simulations were also used to determine boundary conditions for post-processing of images.

Turler, Daniel; Orlando, Ernest

1999-03-01

308

Determination of near surface residual stresses on welded joints using ultrasonic methods  

Microsoft Academic Search

Ultrasonic velocity measurements are used to determine residual stresses induced by welding processes. A welded stainless steel pipe and aluminium alloy plate are analysed in their near surface residual stress distribution by using subsurface longitudinal waves and Rayleigh waves. The experimental procedure is presented: measurement of time of flight, calibration of the acoustoelastic effect, methods for residual stress measurements. The

E. Tanala; G. Bourse; M. Fremiot; J. F. De Belleval

1995-01-01

309

Mechanisms of joint and microstructure formation in high power ultrasonic spot welding 6111 aluminium automotive sheet  

Microsoft Academic Search

Resistance spot welding (RSW) is difficult to apply to aluminium automotive alloys. High power ultrasonic spot welding (HP-USW) is a new alternative method which is extremely efficient, using ?2% of the energy of RSW. However, to date there have been few studies of the mechanisms of bond formation and the material interactions that take place with this process. Here, we

D. Bakavos; P. B. Prangnell

2010-01-01

310

Distortion and residual stresses in laser beam weld shaft-hub joints  

Microsoft Academic Search

In laser beam welding, a serious challenge is to control the distortion during the process. Understanding the whole process chain in view of different distortion potentials applied in each processing step provides the ability to control the distortion of the welded components. Every manufacturing step induces residual stresses in the component which can be released by the heat of the

F. Buschenhenke; M. Hofmann; T. Seefeld; F. Vollertsen

2010-01-01

311

Effect of fatigue loading and residual stress on microscopic deformation mechanisms in a spot welded joint  

Microsoft Academic Search

The microstructure evolution in as welded and post-heated residual stress relived spot welded steel sheets during fatigue testing has been studied. The relationship between microstructure evolution and residual stress during fatigue loading has been considered. It has been found that under high fatigue load, dislocation density in spot nugget edge is much higher than that in nugget center area, which

Xin Long; Sanjeev K. Khanna; Lawrence F. Allard

2007-01-01

312

Tensile behavior of dissimilar friction stir welded joints of aluminium alloys  

Microsoft Academic Search

The heat treatable aluminium alloy AA2024 is used extensively in the aircraft industry because of its high strength to weight ratio and good ductility. The non-heat treatable aluminium alloy AA5083 possesses medium strength and high ductility and used typically in structural applications, marine, and automotive industries. When compared to fusion welding processes, friction stir welding (FSW) process is an emerging

N. Shanmuga Sundaram; N. Murugan

2010-01-01

313

A Microstructural Study of Friction Stir Welded Joints of Carbon Steels  

Microsoft Academic Search

Friction Stir Welding (FSW) is an emerging technology that has made significant inroads in the joining of aluminum alloys in the aerospace industry. To explore the potential advantages in joining carbon steels by FSW, the present study focuses on microstructure characterization of friction stir welded API grade X80 and L80 steels using SEM, TEM and SIMS. The study focuses on

A. Ozekcin; H. W. Jin; J. Y. Koo; N. V. Bangaru; R. Ayer; G. Vaughn; R. Steel; S. Packer

2004-01-01

314

Friction stir welding of lap joints: Influence of process parameters on the metallurgical and mechanical properties  

Microsoft Academic Search

Aluminum alloys are widely used in the aircraft industries even if such materials present lower ductility with respect to steels, anisotropy phenomena and, more important, they are often “difficult” to be welded or even “non-weldable”. In the last years the friction stir welding process (FSW) was proposed and applied in order to get good mechanical and technological performances of the

G. Buffa; G. Campanile; L. Fratini; A. Prisco

2009-01-01

315

Examination of copper\\/stainless steel joints formed by explosive welding  

Microsoft Academic Search

In this study, bonding ability of copper and steel with explosion welding was investigated using different ratios of explosive and different stand-off distance. Experimental studies showed out that, copper and stainless steel could be bonded with a good quality of bonding properties with explosion welding. In the bonding interface, intermetallics were not formed. It was observed that, when explosive ratio

Ahmet Durgutlu; Behçet Gülenç; Fehim Findik

2005-01-01

316

Acoustic determination of cracks in welded joints. [by resonant structural vibration measurements  

NASA Technical Reports Server (NTRS)

The acoustic analysis method permits detection of any cracks that might take place and their manner of propagation. The study deals with the cracks produced in experiments to determine the welding technology for a welded gray cast iron workpiece by using piezoelectric transducers to determine vibration acceleration.

Baltanoiu, M.; Criciotoiu, E.

1974-01-01

317

Study of friction welding of polyethylene pipes  

Microsoft Academic Search

This paper describes an investigation of the effects of the friction welding conditions on the joining phenomena and tensile strength of welded joints produced from polyethylene gas supply pipes in tests conducted on a metal brake-type friction welding machine. The results obtained may be summarised as follows:1. The friction pressure strongly affects the initial torque and total loss (burn-off) in

M. Hasegawa; T. Asada; Y. Ozawa; N. Taki

1998-01-01

318

Effect of pre- and post-weld heat treatment on metallurgical and tensile properties of Inconel 718 alloy butt joints welded using 4 kW Nd:YAG laser  

Microsoft Academic Search

The effects of pre- and post-weld heat treatments on the butt joint quality of 3.18-mm thick Inconel 718 alloy were studied\\u000a using a 4 kW continuous wave Nd:YAG laser system and 0.89-mm filler wire with the composition of the parent metal. Two pre-weld\\u000a conditions, i.e., solution treated, or solution treated and aged, were investigated. The welds were then characterized in\\u000a the

X. Cao; B. Rivaux; M. Jahazi; J. Cuddy; A. Birur

2009-01-01

319

Estimation of the Efficiency of Methods Aimed at Increasing the Fatigue Resistance of Welded Joints under Impact Loading at Low Temperatures  

Microsoft Academic Search

We analyze the experimental data on the influence of various types of hardening treatment (mechanical removal of reinforcement of the weld, argon-arc treatment, blasting, and ultrasonic surface cold working) on the fatigue resistance of welded joints of low-alloy steels under harmonic and impact loads at room and low (–60°C) temperatures. It is shown that the level of fatigue resistance increases

V. A. Degtyarev; B. S. Shul'ginov

2000-01-01

320

Fatigue strength improvement of 5083 H11 Al-alloy T-welded joints by shot peening: experimental characterization and predictive approach  

Microsoft Academic Search

Shot peening improvement of high cycle fatigue (HCF) behavior of metal inert gas (MIG) welded T-joints made from 5083 H11 Al-alloy plates using 5183 Al-alloy welding wires was evaluated by means of four-point bending fatigue tests. The enhancement of the fatigue limits at 2×106 cycles were 135 and 59% for the stress ratios R1=0.1 and R2=0.5, respectively. The properties of

N. Sidhom; A. Laamouri; R. Fathallah; C. Braham; H. P. Lieurade

2005-01-01

321

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

322

Polishing-assisted galvanic corrosion in the dissimilar friction stir welded joint of AZ31 magnesium alloy to 2024 aluminum alloy  

SciTech Connect

Galvanic corrosion of a dissimilar friction stir welded 2024-T3 Al/AZ31B-H24 Mg joint prepared using a water-based and a non-water-based polishing solution was characterized. Microstructure and the distribution of chemical elements were analyzed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The stir zone polished using water-based solution was observed to be much more susceptible to galvanic corrosion attack than that obtained using non-water-based polishing solution. The location of corrosion attack was observed in the narrow regions of AZ31 Mg alloy adjacent to Al2024 regions in the stir zone. The occurrence of galvanic corrosion was due to the formation of Mg/Al galvanic couples with a small ratio of anode-to-cathode surface area. The corrosion product was primarily the porous magnesium hydroxide with characteristic microcracks and exhibited a low microhardness value.

Liu, C. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)], E-mail: dchen@ryerson.ca; Bhole, S. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Cao, X.; Jahazi, M. [Aerospace Manufacturing Technology Centre, Institute For Aerospace Research, National Research Council Canada, 5145 Decelles Avenue, Montreal, Quebec H3T 2B2 (Canada)

2009-05-15

323

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

324

Numerical Analysis of Joint Temperature Evolution During Friction Stir Welding Based on Sticking Contact  

NASA Astrophysics Data System (ADS)

A three-dimensional numerical model for friction stir welding was developed by using the ABAQUS software based on a fully sticking friction. The temperature measurement was performed to validate the reliability of the model. The simulated thermal histories are in good agreement with the experiments. Simulated results show that the rotation speed has no influence on the time to reach the peak temperature in the workpiece, while the welding speed has significant effect on the time to reach the peak temperature at points away from the plunging center. The value of this peak temperature also changes somewhat. Moreover, the peak temperature in the workpiece tends to reach a quasi-steady state at the beginning of the moving stage; but the temperature at some distance away from the weld does not reach the quasi-steady state during the welding.

Li, Wenya; Zhang, Zhihan; Li, Jinglong; Chao, Y. J.

2012-09-01

325

Strength of Rewelded Inconel 718: Repeated repair welds do not affect joint strength.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. Inconel 718, the nickel-based alloy used extensively for high-temperature structural service, can be welded repeatedly without detriment to its strength. Tests show ...

1983-01-01

326

Effects of porosity on weld-joint tensile strength of aluminum alloys  

NASA Technical Reports Server (NTRS)

Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

Lovoy, C. V.

1974-01-01

327

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

2014-04-01

328

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

329

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

330

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

NASA Technical Reports Server (NTRS)

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.

1993-01-01

331

Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model  

Microsoft Academic Search

AA6061 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being

K. Elangovan; V. Balasubramanian; S. Babu

2009-01-01

332

Properties of Friction Stir Welded Joints: A Review of the Literature  

Microsoft Academic Search

The solid-state process of friction stir welding (FSW) was invented in 1991 by TWI (1), and its emergence as a commercial joining technique is partly due to the ease with which the more difficult-to-weld high strength aluminium alloys can be joined. Whilst the process was developed initially for aluminium alloys, over the past decade the number of materials found to

D. Harris; A. F. Norman

333

Optimizing the laser-welded butt joints of medium carbon steel using RSM  

Microsoft Academic Search

The optimization capabilities in design-expert software were used to optimize the keyhole parameters (i.e. maximize penetration (P), and minimize the heat input, width of welded zone (W) and width of heat-affected zone (WHAZ)) in CW CO2 laser butt-welding of medium carbon steel. The previous developed mathematical models to predict the keyhole parameters in terms of the process factors, namely laser

K. Y. Benyounis; A. G. Olabi; M. S. J. Hashmi

2005-01-01

334

Fatigue design of welded joints from the wrought magnesium alloy AZ31 by the local stress concept with the fictitious notch radii of r f = 1.0 and 0.05 mm  

Microsoft Academic Search

Investigations were carried out with three different types of MIG- and TIG-welded joints of the magnesium alloy AZ31(ISO-MgAl3Zn1): fully or partially penetrated butt welds, transversal stiffeners. The evaluation of the results showed that the local stress concept using the fictitious notch radius of rf=1.0 mm can be applied to magnesium welded joints from plates with thicknesses t?5 mm independently of

Ö. Karakas; C. Morgenstern; C. M. Sonsino

2008-01-01

335

Microstructure development in Nd:YAG laser welding of AISI 304 and Inconel 600  

Microsoft Academic Search

In this work, the morphology of solidification of the weld zone (WZ) was studied in a joint formed from dissimilar materials, composed of austenitic AISI 304 stainless steel and Inconel 600 nickel alloy, welded with an Nd:YAG-pulsed laser. The laser beam and optical system parameters were selected with a view to obtain a weld with total penetration and good surface

Maurício David M. das Neves; André Lotto; José Roberto Berretta; Wagner de Rossi; Nilson Dias V. Júnior

2010-01-01

336

Multi-response optimization of CO 2 laser-welding process of austenitic stainless steel  

Microsoft Academic Search

Recently, laser welding of austenitic stainless steel has received great attention in industry. This is due to its widespread application in petroleum refinement stations, power plants, the pharmaceutical industry and also in households. Therefore, mechanical properties should be controlled to obtain good welded joints. The welding process should be optimized by the proper mathematical models. In this research, the tensile

K. Y. Benyounis; A. G. Olabi; M. S. J. Hashmi

2008-01-01

337

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

338

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

339

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

340

Studies on A-TIG welding of Low Activation Ferritic/Martensitic (LAFM) steel  

NASA Astrophysics Data System (ADS)

Low Activation Ferritic-Martensitic steels (LAFM) are chosen as the candidate material for structural components in fusion reactors. The structural components are generally fabricated by welding processes. Activated Tungsten Inert Gas (A-TIG) welding is an emerging process for welding of thicker components. In the present work, attempt was made to develop A-TIG welding technology for LAFM steel plates of 10 mm thick. Activated flux was developed for LAFM steel by carrying out various bead-on-plate TIG welds without flux and with flux. The optimum flux was identified as one which gave maximum depth of penetration at minimum heat input values. With the optimized flux composition, LAFM steel plate of 10 mm thickness was welded in square butt weld joint configuration using double side welding technique. Optical and Scanning Electron Microscopy was used for characterizing the microstructures. Microhardness measurements were made across the weld cross section for as welded and post weld heat treated samples. Tensile and impact toughness properties were determined. The mechanical properties values obtained in A-TIG weld joint were comparable to that obtained in weld joints of LAFM steel made by Electron beam welding process.

Vasantharaja, P.; Vasudevan, M.

2012-02-01

341

Macro\\/micro mechanical level characterization of friction stir welded joints in aluminum alloys using combined experimental\\/numerical approaches  

Microsoft Academic Search

Friction stir welding (FSW) is a solid state joining process having key benefits such as low energy consumption, greater environmental friendliness and increased versatility, when compared with the conventional welding processes such as gas metal arc welding or tungsten inert-gas welding. The FSW process has been used successfully to weld high strength aluminum alloys that are used in the aerospace

Srinivasa Deshikan Thoppul

2008-01-01

342

Effect of the Surface State of Steel on the Microstructure and Mechanical Properties of Dissimilar Metal Lap Joints of Aluminum and Steel by Friction Stir Welding  

Microsoft Academic Search

Friction stir lap joints of AC4C Al alloy (top sheet) and steel (zinc-coated steel, brushed finish steel, and mirror finish\\u000a steel) were produced when the friction stir welding tool did not touch the lower steel surface. For zinc coat steel, the strength\\u000a of joints could reach 97.7 pct of that of steel; for brushed finish steel, the strength was 63.2 pct of

Y. C. Chen; K. Nakata

2008-01-01

343

Three different ways of using the Modified Wöhler Curve Method to perform the multiaxial fatigue assessment of steel and aluminium welded joints  

Microsoft Academic Search

The present paper reviews the different procedures to be followed to use the Modified Wöhler Curve Method (MWCM) to estimate fatigue lifetime of steel and aluminium welded joints subjected to multiaxial cyclic loading. In more detail, the MWCM is a conventional critical plane approach which postulates that fatigue damage reaches its maximum value on the plane experiencing the maximum shear

Luca Susmel

2009-01-01

344

Effect of Segregation of Secondary Phase Particles and "S" Line on Tensile Fracture Behavior of Friction Stir-Welded 2024Al-T351 Joints  

NASA Astrophysics Data System (ADS)

A 5-mm-thick 2024Al-T351 plate was friction stir welded (FSWed) at welding speeds of 100, 200, and 400 mm min-1 with a constant rotation rate of 800 rpm, and the microstructure and tensile fracture behavior of the joints were investigated in detail. FSW resulted in the redistribution of secondary phase particles along the recrystallized grain boundaries at the nugget zone (NZ), forming linear segregation bands consisting of secondary phase particles. The segregation bands, mainly present in the shoulder-driven zone, were believed to result from periodic material flow, with the average band spacing on the longitudinal and horizontal cross sections equal to the tool advancement per revolution. At a low welding speed of 100 mm min-1, in spite of the highest density of segregation bands, the FSWed 2024Al-T351 joint fractured along the low hardness zone (LHZ) of the heat-affected zone because of large hardness gap between NZ and LHZ. Increasing the welding speed to 200 and 400 mm min-1 reduced both the hardness gap between NZ and LHZ and the density of segregation bands. In this case, the segregation bands played a role, resulting in unusual fracture of the joints along the segregation bands. The "S" line originated from the oxide film on the initial butting surfaces and did not affect the fracture behavior of the FSWed 2024Al-T351 joints.

Zhang, Z.; Xiao, B. L.; Ma, Z. Y.

2013-09-01

345

Mechanical Properties of SMA- and SA-Welded Joints for Quenched and Tempered High-Strength Steel N-A-XTRA 70.  

National Technical Information Service (NTIS)

The report gives the test results of mechanical properties of shielded metal arc (SMAW) and submerged arc (SAW) welded joints for quenched and tempered high-strength steel N-A-XTRA 70 (StE 690). The testing procedure comprised conventional hardness, tensi...

M. Vilpas H. Tihekari R. Karppi

1985-01-01

346

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

347

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

348

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

349

Fatigue of Iron Base Alloys HY-80 Steel Cast Tees Butt Welded to Rolled Section Single and Double Weld Joint Design.  

National Technical Information Service (NTIS)

The average fatigue life of 1 5/8 in. thick cast tee butt welded to rolled plate is approximately the same as that of cast plate butt welded to rolled plate and rolled plate butt welded to rolled plate. At 80,000 psi nominal stress range the fatigue life ...

1964-01-01

350

Effect of Shoulder Size on Weld Properties of Dissimilar Metal Friction Stir Welds  

NASA Astrophysics Data System (ADS)

This article reports a research study that shows the effect of shoulder diameter size on the resulting weld properties of dissimilar friction stir welds between 5754 aluminum alloy (AA) and C11000 copper (Cu). Welds were produced using three different shoulder diameter tools: 15, 18, and 25 mm by varying the rotational speed between 600 and 1200 rpm and the traverse speed between 50 and 300 mm/min to achieve the best result. Each parameter combination was chosen to represent different heat input conditions (low, intermediates and high). The welds were characterized through microstructural evaluation, tensile testing, microhardness measurements, x-ray diffraction analysis, and electrical resistivity. Microstructural evaluation of the welds revealed that the welds produced consisted of all the friction stir welding (FSW) microstructure zones with organized flow lines comprising mixture layers of aluminum (Al) and copper (Cu) at the Stir Zones. The average Ultimate Tensile Strength (UTS) of the welds considered ranged from 178 to 208 MPa. Higher Vickers microhardness values were measured at the joint interfaces of all the welds because of the presence of intermetallic compounds in these regions. The x-ray diffraction analysis revealed the presence of Al4Cu9 and Al2Cu intermetallics at the interfacial regions, and low electrical resistivities were obtained at the joint interfaces. An optimized parameter setting for FSW of Al and Cu was obtained at the weld produced at 950 rpm and 50 mm/min with the 18-mm shoulder diameter tool.

Akinlabi, E. T.

2012-07-01

351

Joining Porous and Compact Titanium by Laser Welding and Plastic Deformation  

Microsoft Academic Search

Joining porous elements (40-45% porosity) prepared by compaction and sintering of titanium powder (PTKh2-1) with compact titanium (VT1-0 and VT-6) by laser welding and plastic deformation is studied. Welding is accomplished by a pulsed-periodic laser Nd:YAG (? = 1.06 µm). It is shown that prior mechanical treatment of porous surfaces improves welded joint quality. A joint may be obtained without

Vadim V. Savich; L. P. Pilinevich; M. V. Tumilovich; N. K. Tolochko

2003-01-01

352

Effect of the Surface State of Steel on the Microstructure and Mechanical Properties of Dissimilar Metal Lap Joints of Aluminum and Steel by Friction Stir Welding  

NASA Astrophysics Data System (ADS)

Friction stir lap joints of AC4C Al alloy (top sheet) and steel (zinc-coated steel, brushed finish steel, and mirror finish steel) were produced when the friction stir welding tool did not touch the lower steel surface. For zinc coat steel, the strength of joints could reach 97.7 pct of that of steel; for brushed finish steel, the strength was 63.2 pct of that of steel; for mirror finish steel, Al alloy and steel could not be welded. The effect of the surface state of steel on the microstructure and mechanical properties of dissimilar metal friction stir lap joints of AC4C Al alloy and steel was discussed.

Chen, Y. C.; Nakata, K.

2008-08-01

353

Multicell-type transistor converter with combined control for micro resistance welding  

Microsoft Academic Search

Micro resistance welding is effective way to reliably join small-scale parts in electronics industry and instrument- making. High quality welded joints are obtained by accurate regulation of welding current with transistor converter module which is one of the most important sub-systems in micro resis- tance welding machine. Multicell-type transistor converter with combined control, represented in the paper, provides high accu-

Yuriy E. Paerand; Oleksandr F. Bondarenko; Iuliia V. Bondarenko

2011-01-01

354

The use of the J V parameter in welded joints: Stress analysis and fatigue assessment  

Microsoft Academic Search

This paper investigates the use of the JV parameter, a path-independent integral, for the evaluation of the elastic local stress parameters in welded details and for the estimation of their fatigue life.First, the stress intensity factors (SIF) of an embedded crack lying along the bisector of a sharp V-notch is calculated by means of the JV without modelling the crack

Paolo Livieri; Roberto Tovo

2009-01-01

355

Analysis of the Creep Behavior of P92 Steel Welded Joint  

Microsoft Academic Search

Different regions of heat-affected zone (HAZ) were simulated by heat treatment to investigate the mechanisms of the Type IV\\u000a fracture of P92 (9Cr-2W) steel weldments. Creep deformation of simulated HAZ specimens with uniform microstructures was investigated\\u000a and compared with those of the base metal (BM) and the weld metal (WM) specimens. The results show that the creep strain rate\\u000a of

Junchao An; Hongyang Jing; Guangchun Xiao; Lei Zhao; Lianyong Xu

356

Influence of Machine Setting and Wood Parameters on Crack Formation in Scots Pine Joints Produced by Linear Friction Welding  

Microsoft Academic Search

Previous investigations on linear welded woods have shown that the connections are not sufficiently resistant to water for use in outdoor conditions. Therefore, they are utilized mainly for non-structural use, with only short time exposure to varying humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood or sapwood on crack formation in the

Mojgan Vaziri; Owe Lindgren; Antonio Pizzi

2012-01-01

357

Quantitative ultrasonic testing of acoustically anisotropic materials with verification on austenitic and dissimilar weld joints  

NASA Astrophysics Data System (ADS)

Austenitic stainless steel materials are widely used in a variety of industry sectors. In particular, the material is qualified to meet the design criteria of high quality in safety related applications. For example, the primary loop of the most of the nuclear power plants in the world, due to high durability and corrosion resistance, is made of this material. Certain operating conditions may cause a range of changes in the integrity of the component, and therefore require nondestructive testing at reasonable intervals. These in-service inspections are often performed using ultrasonic techniques, in particular when cracking is of specific concern. However, the coarse, dendritic grain structure of the weld material, formed during the welding process, is extreme and unpredictably anisotropic. Such structure is no longer direction-independent to the ultrasonic wave propagation; therefore, the ultrasonic beam deflects and redirects and the wave front becomes distorted. Thus, the use of conventional ultrasonic testing techniques using fixed beam angles is very limited and the application of ultrasonic Phased Array techniques becomes desirable. The "Sampling Phased Array" technique, invented and developed by Fraunhofer IZFP, allows the acquisition of time signals (A-scans) for each individual transducer element of the array along with fast image reconstruction techniques based on synthetic focusing algorithms. The reconstruction considers the sound propagation from each image pixel to the individual sensor element. For anisotropic media, where the sound beam is deflected and the sound path is not known a-priori, a novel phase adjustment technique called "Reverse Phase Matching" is implemented. By taking into account the anisotropy and inhomogeneity of the weld structure, a ray tracing algorithm for modeling the acoustic wave propagation and calculating the sound propagation time is applied. This technique can be utilized for 2D and 3D real time image reconstruction. The "Gradient Constant Descent Method" (GECDM), an iterative algorithm, is implemented, which is essential for examination of inhomogeneous anisotropic media having unknown properties (elastic constants). The Sampling Phased Array technique with Reverse Phase Matching extended by GECDM-technique determines unknown elastic constants and provides reliable and efficient quantitative flaw detection in the austenitic welds. The validation of ray-tracing algorithm and GECDM-method is performed by number of experiments on test specimens with artificial as well as natural material flaws. A mechanized system for ultrasonic testing of stainless steel and dissimilar welds is developed. The system works on both conventional and Sampling Phased Array techniques. The new frontend ultrasonic unit with optical data link allows the 3D visualization of the inspection results in real time.

Boller, C.; Pudovikov, S.; Bulavinov, A.

2012-05-01

358

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

359

Study of the Fatigue Behavior of Welded Joints, Cross Stressed Etude du Comportement a la Fatigue de Joints Soudes Sollicites selon le Travers Court.  

National Technical Information Service (NTIS)

Fatigue tests were carried out on welded steel specimens. The influence of inclusions in the welded specimens on fatigue resistance was studied. Results show that inclusions influence fatigue behavior only when they provoke damage before fatigue testing. ...

F. Maltrud

1980-01-01

360

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

361

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

362

Friction-stir welding of AA 2198 butt joints: mechanical characterization of the process and of the welds through DOE analysis  

Microsoft Academic Search

In this study, rolled plates of AA 2198 T3 aluminium alloy are friction-stir welded in butt configuration varying two fundamental\\u000a process parameters: rotational and welding speeds. Two sets of empirical models based on regression analysis are developed.\\u000a The first one predicts the stationary values of the in-plane and downwards forging welding forces in dependence of the process\\u000a parameters under investigation.

Ciro Bitondo; Umberto Prisco; Antonino Squilace; Pasquale Buonadonna; Gennaro Dionoro

2011-01-01

363

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

364

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

365

Joint sampling programme--verification of data obtained in environmental monitoring.  

PubMed

The objective of the Environmental Radiological Monitoring Control programme carried out by the Institute of Radiation Protection and Dosimetry (IRD) in Brazil is to verify the licensee's compliance with the requirements for environmental monitoring of Brazilian facilities. The Joint Sampling Programme (JSP) is just one part of the control programme. In order to verify that the data reported by the licensees is representative and legitimate, this programme verifies sampling procedures, accuracy and precision of the data and the changes in the environmental conditions. This paper discusses the main findings of this programme that allowed IRD to optimize its available resources to control the monitoring of the eight facilities in Brazil. PMID:18502139

Lauria, D C; Martins, N S F; Vasconcellos, M L H; Zenaro, R; Peres, S S; Pires do Rio, M A

2008-11-01

366

Local mechanical properties of Alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320C  

SciTech Connect

This paper presents the variations of local mechanical and microstructural properties in dissimilar metal weld joints consisting of the SA508 Gr.1a ferritic steel, Alloy 82/182 filler metal, and F316 austenitic stainless steel. Flat or round tensile specimens and transmission electron microscopy disks were taken from the base metals, welds, and heat-affected zones (HAZ) of the joints and tested at room temperature (RT) and/or at 320 C. The tensile test results indicated that the mechanical property was relatively uniform within each material zone, but varied considerably between different zones. Further, significant variations were observed both in the austenitic HAZ of F316 SS and in the ferritic HAZ of SA508 Gr.1a. The yield stress (YS) of the weld metal was under-matched with respect to the HAZs of SA508 Gr.1a and F316 SS by 0.78 to 0.92, although the YS was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1 at both test temperatures. The plastic instability stress also varied considerably in the weld joints, with minimum values occurring in the SA508 Gr.1a base metal at RT and in the HAZ of F316 SS at 320 C, suggesting that the probability of ductile failure caused by a unstable deformation at the Alloy 82/182 buttering layer is low. Within the HAZ of SA508 Gr.1a, the gradient of the YS and ultimate tensile strength (UTS) was significant, primarily because of the different microstructures produced by the phase transformation during the welding process. The increment of YS was unexpectedly high in the HAZ of F316 SS, which was explained by the strain hardening induced by a strain mismatch between the weldment and the base metal. This was confirmed by the transmission electron micrographs showing high dislocation density in the HAZ.

Byun, Thak Sang [ORNL; Kim, Jin Weon [ORNL

2009-01-01

367

Behaviour of welded aluminium T-stub joints under monotonic loading  

Microsoft Academic Search

This paper deals with the behaviour of aluminium alloy T-stub joints subjected to monotonic tensile loads. In particular, a numerical model developed by means of the non linear code ABAQUS has been accurately calibrated on the basis of previous experimental test results related to 26 specimens, characterised by different geometry and connection type. In particular, four different geometries (by varying

G. De Matteis; M. Brescia; A. Formisano; F. M. Mazzolani

2009-01-01

368

Infrared thermography for inspecting the adhesion integrity of plastic welded joints  

Microsoft Academic Search

This work aim at developing a non-destructive tool for the evaluation of bonded plastic joints. The paper examines infrared thermographic transmission and reflection mode imaging and validates the feasibility of the thermal NDT approach for this application. Results demonstrate good estimation performance for adhesion integrity, uniformity and bond strength using a transmission mode application of infrared thermography. In addition, results

M. Omar; M. Hassan; K. Donohue; K. Saito; R. Alloo

2006-01-01

369

Residual Stress Estimation of Welded Tubular K-joints under Fatigue Loads  

Microsoft Academic Search

In tubular joints, the hot spot stress concept is used to characterize the stress field at potential fatigue crack locations. The combination of determining stresses using the hot spot concept, with a reduction factor on fatigue strength is however not a satisfactory solution. In this paper, an overview of a on-going research project in which the overall phenomenon, including geometrical

C. Acevedo; A. Nussbaumer

370

Microstructure and stress corrosion cracking of the fusion boundary region in an alloy 182-A533B low alloy steel dissimilar weld joint  

Microsoft Academic Search

Stress corrosion cracking (SCC) in the fusion boundary (FB) region of an Alloy 182-A533B low alloy steel (LAS) dissimilar weld joint in high temperature water doped with sulfate was studied following a microstructure characterization of the FB region. The microstructure characterization suggested the type-II and type-I boundaries in the dilution zone (DZ) adjacent to the FB had lower resistance to

Juan Hou; Qunjia Peng; Yoichi Takeda; Jiro Kuniya; Tetsuo Shoji

2010-01-01

371

Local mechanical properties of Alloy 82\\/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320 °C  

Microsoft Academic Search

The distributions of mechanical and microstructural properties were investigated for the dissimilar metal weld joints between SA508 Gr.1a ferritic steel and F316 austenitic stainless steel with Alloy 82\\/182 filler metal using small-size tensile specimens. The material properties varied significantly in different zones while those were relatively uniform within each material. In particular, significant gradient of the mechanical properties were observed

Jin Weon Kim; Kyoungsoo Lee; Jong Sung Kim; Thak Sang Byun

2009-01-01

372

Polishing-assisted galvanic corrosion in the dissimilar friction stir welded joint of AZ31 magnesium alloy to 2024 aluminum alloy  

Microsoft Academic Search

Galvanic corrosion of a dissimilar friction stir welded 2024-T3 Al\\/AZ31B-H24 Mg joint prepared using a water-based and a non-water-based polishing solution was characterized. Microstructure and the distribution of chemical elements were analyzed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The stir zone polished using water-based solution was observed to be much more susceptible to galvanic corrosion

C. Liu; D. L. Chen; S. Bhole; X. Cao; M. Jahazi

2009-01-01

373

Study of residual stress reduction in welded joints using phase transformation behaviour of welding material. Studies on numerical simulation of temperature, microstructure, and thermal stress histories during welding and their application to welded structures (2 report)  

Microsoft Academic Search

The residual stress generated in welded structures is well-known to exert a strong influence on features such as brittle fracture, buckling, stress corrosion cracking, fatigue, etc. It is therefore important to develop appropriate measures for evaluation of the residual stress distribution at structural locations requiring prevention of deformation or fracture and for suitable reduction of residual stress in response to

M. Mochizuki; S. Matsushima; M. Toyoda; Y. Morikage; T. Kubo

2005-01-01

374

Summary of Results of Tests Made by Aluminum Research Laboratories of Spot-welded Joints and Structural Elements  

NASA Technical Reports Server (NTRS)

Available information concerning spot welding as a means of joining aluminum-alloy parts has been summarized and comparisons have been made of the relative merits of spot-welded and riveted aluminum-alloy structural elements. The results indicated that spot welding was as satisfactory as riveting insofar as resistance to static loads is concerned. Spot welds showed slightly lower resistance to impact loads but definitely lower resistance to repeated loads than rivets.

HARTMANN E C; Stickley, G W

1942-01-01

375

A transient finite element simulation of the temperature and bead profiles of T-joint laser welds  

Microsoft Academic Search

Laser welding is a high power density welding technology, which has the capability of focusing the beam power to a very small spot diameter. Its characteristics such as high precision and low and concentrated heat input, helps in minimizing the micro-structural modifications, residual stresses and distortions on the welded specimens. In this study, finite element method (FEM) is adopted for

N. Siva Shanmugam; G. Buvanashekaran; K. Sankaranarayanasamy; S. Ramesh Kumar

2010-01-01

376

Low cycle fatigue behavior of electron beam and friction welded joints of an α-β titanium alloy  

Microsoft Academic Search

Fusion welds in titanium alloys, with intermediate β 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

T. Mohandas; V. K. Varma; D. Banerjee; V. V. Kutumbarao

1996-01-01

377

Optimal Design of Friction Stir Welding Process to Improve Tensile Force of the Joint of A6005 Extrusion  

Microsoft Academic Search

An aluminum alloy is widely used in various fields of industries such as aerospace, shipbuilding, automotive, and railway vehicles, and gas metal Arc Welding (GMAW) technique has been applied to make the aluminum products. Recently, friction stir welding (FSW) method was developed and known to have many benefits compared to the classical GMAW technique. In this study, three important welding

Weon-kyong Kim; Byeong-choon Goo; Si-tae Won

2010-01-01

378

Comparison of RSM with ANN in predicting tensile strength of friction stir welded AA7039 aluminium alloy joints  

Microsoft Academic Search

Friction stir welding(FSW) is an innovative solid state joining technique and has been employed in aerospace, rail, automotive and marine industries for joining aluminium, magnesium, zinc and copper alloys. The FSW process parameters such as tool rotational speed, welding speed, axial force, play a major role in deciding the weld quality. Two methods, response surface methodology and artificial neural network

A. K. LAKSHMINARAYANAN; V. BALASUBRAMANIAN

2009-01-01

379

The influence of some factors on steel\\/steel bonding quality on there characteristics of explosive welding joints  

Microsoft Academic Search

Explosive welding is a solid state process in which controlled explosive detonations force two or more metals together at high pressures. The resultant arrangement is joined with a high quality metallurgical bond. The aim of this study was to investigate of strength of explosive welding metals which had same chemical compositions. In this study, it was taken different welding interfaces

M. Acarer; B. Gülenç; F. Findik

2004-01-01

380

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

381

Friction welding.  

NASA Technical Reports Server (NTRS)

Results of an exploratory study of the structure and properties of friction welds in Udimet 700 (U-700) and TD-nickel (TD-Ni) bar materials, as well as dissimilar U-700/TD-Ni friction welds. Butt welds were prepared by friction welding 12.7-mm-diam U-700 bars and TD-Ni bars. Specimens for elevated temperature tensile and stress rupture testing were machined after a postweld heat treatment. Friction welding of U-700 shows great potential because the welds were found to be as strong as the parent metal in stress rupture and tensile tests at 760 and 980 C. In addition, the weld line was not detectable by metallographic examination after postheating. Friction welds in TD-Ni or between U-700 and TD-Ni were extremely weak at elevated temperatures. The TD-Ni friction welds could support only 9% as much stress as the base metal for 10-hour stress rupture life at 1090 C. The U-700/TD-Ni weld could sustain only 15% as much stress as the TD-Ni parent metal for a 10-hour stress rupture life at 930 C. Thus friction welding is not a suitable joining method for obtaining high-strength TD-Ni or U-700/TD-Ni weldments.

Moore, T. J.

1972-01-01

382

Method of Laser Welding.  

National Technical Information Service (NTIS)

A method of welding two HY-steel members to produce a weld joint having improved impact toughness. The surface to be welded are first machined, roto-blasted and cleaned with acetone. Then, an inset of Inconel 600 is provided and cleaned with acetone. Next...

D. W. Moon E. A. Metzbower

1983-01-01

383

A Study of the Effect of Tool Pin Profiles on Tensile Strength of Welded Joints Produced Using Friction Stir Welding Process  

Microsoft Academic Search

Friction Stir Welding (FSW) has evolved into a process focused on joining of arc-weldable (5xxx and 6xxx) and which are difficult to weld (2xxx and 7xxx) aluminium alloys. The method described in this paper for the prediction of tensile properties and optimization can eliminate the need for performing experiments on the basis of conventional trial and error method. The present

C. N. Suresha; B. M. Rajaprakash; Sarala Upadhya

2011-01-01

384

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

385

Torch kit for welding in difficult areas  

NASA Technical Reports Server (NTRS)

Miniature tungsten inert gas welding torch, used with variously formed interchangeable soft copper tubing extensions, provides inexpensive, accurate welding capability for inaccessible joints. Kit effectively welds stainless steel tubing 0.089 cm thick. Other applications are cited.

Stein, J. A.

1971-01-01

386

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

387

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

388

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

389

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

390

Process Optimization for Friction-Stir-Welded Martensitic Steel  

NASA Astrophysics Data System (ADS)

Advanced high-strength M190 steel sheets were joined by friction-stir welding under different tool rotational and traversing speeds. The optical microstructure of the joints exhibited complete martensite and partial martensite at the weld nugget depending on the cooling rate during welding. The first heat-affected zone outside of the weld nugget revealed ferrite-pearlite phase aggregate, and the second heat-affected zone showed a tempered martensitic structure. The interplay of process variables in terms of peak temperature and cooling rate was studied to observe their effect on joint efficiency under shear testing. The peak hardness at weld nugget was close to the parent alloy at an intermediate cooling rate of 294 to 313 K/s. The lowest hardness was observed at the first heat-affected zone for all welded joints. Joint efficiency was dependent on relative quantity of ferrite-pearlite at first heat-affected zone. In that respect, the intermediate temperature to the tune of ~1193 K to 1273 K (~920 °C to 1000 °C) at the weld nugget was found to be beneficial for obtaining an adequate quantity of pearlite at the first heat-affected zone to provide joint efficiency of more than 50 pct of that of parent alloy.

Ghosh, M.; Kumar, K.; Mishra, R. S.

2012-06-01

391

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

392

Capillary flow weld-bonding  

NASA Technical Reports Server (NTRS)

The invention of a weld-bonding technique for titanium plates was described. This involves fastening at least two plates of titanium together using spot-welding and applying a bead of adhesive along the edge of the resistance spot-welded joint which upon heating, flows and fills the separation between the joint components.

Vaughan, R. W.; Jones, R. J. (inventors)

1976-01-01

393

Internal-bore-welding of 2 1\\/4 Cr1 Mo steel tube-to-tubesheet joints  

Microsoft Academic Search

In order to avoid the disadvantages of the conventional face-side tube-to-tubesheet weld, the steam generators for the Clinch River Breeder Reactor Plant (a power-producing demonstration LMFBR) will be built using a relatively new technique known as internal-bore-welding (IBW). In IBW the tube does not pass through the tubesheet but rather is welded to a short stub machined on the tube

A. J. Moorhead; G. M. Slaughter

1976-01-01

394

A new method for explosive welding of Al\\/ZrO 2 joint using regulated underwater shock wave  

Microsoft Academic Search

Thin aluminium plate was welded onto a zirconia ceramic by the use of a newly developed explosive welding technique. A 0.1 mm-thick aluminium plate was accelerated about 800 m s?1 by regulated underwater shock wave and collided with a zirconia plate at a certain collision angle under moderate conditions for explosive welding. The use of a stainless steel cover plate

K Hokamoto; M Fujita; H Shimokawa; H Okugawa

1999-01-01

395

Local mechanical properties of Alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320 °C  

NASA Astrophysics Data System (ADS)

The distributions of mechanical and microstructural properties were investigated for the dissimilar metal weld joints between SA508 Gr.1a ferritic steel and F316 austenitic stainless steel with Alloy 82/182 filler metal using small-size tensile specimens. The material properties varied significantly in different zones while those were relatively uniform within each material. In particular, significant gradient of the mechanical properties were observed near the both heat-affected zones (HAZs) of F316 SS and SA508 Gr.1a. Thus, the yield stress (YS) was under-matched with respect to the both HAZs, although, the YS of the weld metal was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1a at both test temperatures. The plastic instability stress also varied considerably across the weld joints, with minimum values occurring in the SA508 Gr.1a base metal at RT and in the HAZ of F316 SS at 320 °C. The transmission electron micrographs showed that the strengthening in the HAZ of F316 SS was attributed to the strain hardening, induced by a strain mismatch between the weldment and the base metal, which was evidenced by high dislocation density in the HAZ of F316 SS.

Kim, Jin Weon; Lee, Kyoungsoo; Kim, Jong Sung; Byun, Thak Sang

2009-02-01

396

Assessment of the fatigue behaviour of welded aluminium joints under multiaxial spectrum loading by a critical plane approach  

Microsoft Academic Search

Multiaxial stress states occur in many welded constructions like chemical plants, railway carriages and frames of trucks. Depending on the loading mode, those stresses can have constant and changing principal stress directions. For welded fine grained steel, research results show a severe loss of fatigue life for changing principal stress directions simulated by out-of-phase bending and torsion compared to constant

M. Kueppers; C. M. Sonsino

2006-01-01

397

Mechanical strength evaluation for Nd-YAG laser and electric resistance spot weld (ERSW) joint under multiaxial loading  

Microsoft Academic Search

This work presents a comparison between laser weld (LBW) and electric resistance spot weld (ERSW) processes used for assemblies of components in a body-in-white (BIW) at a world class automotive industry. It is carried out by evaluating the mechanical strength modeled both by experimental and numerical methods. An “Arcan” multiaxial test was designed and manufactured in order to enable 0°,

Haroldo Akira Kavamura; Gilmar Ferreira Batalha

2008-01-01

398

Effect of current pulses on the temperature distribution and microstructure in TIG tantalum welds  

NASA Astrophysics Data System (ADS)

The welding process employed for bonding metals by melting and solidification produces a joint which is generally inhomogeneous. The micro structure of the fused zone and its adjacent heat affected zone, HAZ, is usually different from the microstructure of the parent metal, obtained by mechanical working or heat treatment. The fused zone is usually composed of coarse columnar grains characteristic of as-cast structures. If the parent metal was originally cold-worked, recrystallization will occur in the HAZ, producing a coarse grained structure. As a result of the effect of the microstructure on the mechanical properties of the weld, the obtained joint may be weaker than the rest of the structure which was not affected by the heat of the welding. Although in some cases it is possible to improve the properties of the weld by post-welding heat treatment, different methods are tried in order to improve the microstructure directly during the welding process.

Grill, A.

1981-03-01

399

Laser ultrasonics for defect detection and residual stress measurement of friction stir welds  

Microsoft Academic Search

The laser-ultrasonic technique is investigated for defect detection and sizing as well as for residual stress measurement in welds obtained by friction stir welding (FSW). When combined with the Fourier domain synthetic aperture focusing technique, very good performances are achieved for detecting lack of penetration in butt joints, the detection limit coinciding with the conditions of reduced mechanical properties. Also,

Daniel Lévesque; Laurent Dubourg; Alain Blouin

2011-01-01

400

Modeling of plasma and thermo-fluid transport in hybrid welding  

NASA Astrophysics Data System (ADS)

Hybrid welding combines a laser beam and electrical arc in order to join metals within a single pass at welding speeds on the order of 1 m min -1. Neither autonomous laser nor arc welding can achieve the weld geometry obtained from hybrid welding for the same process parameters. Depending upon the process parameters, hybrid weld depth and width can each be on the order of 5 mm. The ability to produce a wide weld bead increases gap tolerance for square joints which can reduce machining costs and joint fitting difficulty. The weld geometry and fast welding speed of hybrid welding make it a good choice for application in ship, pipeline, and aerospace welding. Heat transfer and fluid flow influence weld metal mixing, cooling rates, and weld bead geometry. Cooling rate affects weld microstructure and subsequent weld mechanical properties. Fluid flow and heat transfer in the liquid weld pool are affected by laser and arc energy absorption. The laser and arc generate plasmas which can influence arc and laser energy absorption. Metal vapors introduced from the keyhole, a vapor filled cavity formed near the laser focal point, influence arc plasma light emission and energy absorption. However, hybrid welding plasma properties near the opening of the keyhole are not known nor is the influence of arc power and heat source separation understood. A sound understanding of these processes is important to consistently achieving sound weldments. By varying process parameters during welding, it is possible to better understand their influence on temperature profiles, weld metal mixing, cooling rates, and plasma properties. The current literature has shown that important process parameters for hybrid welding include: arc power, laser power, and heat source separation distance. However, their influence on weld temperatures, fluid flow, cooling rates, and plasma properties are not well understood. Modeling has shown to be a successful means of better understanding the influence of processes parameters on heat transfer, fluid flow, and plasma characteristics for arc and laser welding. However, numerical modeling of laser/GTA hybrid welding is just beginning. Arc and laser welding plasmas have been previously analyzed successfully using optical emission spectroscopy in order to better understand arc and laser plasma properties as a function of plasma radius. Variation of hybrid welding plasma properties with radial distance is not known. Since plasma properties can affect arc and laser energy absorption and weld integrity, a better understanding of the change in hybrid welding plasma properties as a function of plasma radius is important and necessary. Material composition influences welding plasma properties, arc and laser energy absorption, heat transfer, and fluid flow. The presence of surface active elements such as oxygen and sulfur can affect weld pool fluid flow and bead geometry depending upon the significance of heat transfer by convection. Easily vaporized and ionized alloying elements can influence arc plasma characteristics and arc energy absorption. The effects of surface active elements on heat transfer and fluid flow are well understood in the case of arc and conduction mode laser welding. However, the influence of surface active elements on heat transfer and fluid flow during keyhole mode laser welding and laser/arc hybrid welding are not well known. Modeling has been used to successfully analyze the influence of surface active elements during arc and conduction mode laser welding in the past and offers promise in the case of laser/arc hybrid welding. A critical review of the literature revealed several important areas for further research and unanswered questions. (1) The understanding of heat transfer and fluid flow during hybrid welding is still beginning and further research is necessary. (2) Why hybrid welding weld bead width is greater than that of laser or arc welding is not well understood. (3) The influence of arc power and heat source separation distance on cooling rates during hybrid welding are not known. (4) Convect

Ribic, Brandon D.

401

Direct welding with arc discharging to joint quart optical fiber to multicomponent glass mold lens (small factor fiber collimator with new push-pull welding method)  

NASA Astrophysics Data System (ADS)

In this paper, a new direct splicing method called push-pull welding is described. Direct coupling based on direct fusion splicing, which makes an optical fiber joining a multicomponent glass lens, gives not only a high optical performance but also high reliability and easy alignment.

Koishi, Musubu; Nishizawa, Koichi; Kawai, Shigeru

2011-03-01

402

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

403

Laser Beam Welding of Nitride Steel Components  

NASA Astrophysics Data System (ADS)

Laser beam welding is a joining technique that has many advantages over conventional GMAW welding, such as low heat input, short cycle time as well as good cosmetic welds. Laser beam welding has been widely used for welding powertrain components in automotive industry. When welding nitride steel components, however, laser beam welding faces a great challenge. The difficulty lies in the fact that the nitride layer in the joint releases the nitrogen into the weld pool, resulting in a porous weld. This research presents an industrial ready solution to prevent the nitrogen from forming gas bubbles in the weld.

Gu, Hongping; Yin, Guobin; Shulkin, Boris

404

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

405

Thermomechanical treatments of Sc and Mg-modified Al–Cu alloy welds  

Microsoft Academic Search

High-strength heat-treatable aluminum alloy AA2219 finds application in aerospace industries. Though it has good weldability,\\u000a with alternating current–tungsten inert gas welding, the joint efficiency obtained is only 40%, particularly in thicker plates.\\u000a In the present study, an attempt has been made to improve the weld metal properties by modifying the chemistry of fusion zone\\u000a and post-weld thermo-mechanical treatments. Fillers were

S. R. Koteswara Rao; B. Kamsala Devi; K. Sreenivasa Rao; K. Prasad Rao

2009-01-01

406

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

407

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  

Microsoft Academic Search

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

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

2008-01-01

408

Weld bonding of titanium with polyimide adhesives  

NASA Technical Reports Server (NTRS)

A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.

Vaughan, R. W.; Sheppard, C. H.; Orell, M. K.

1975-01-01

409

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

410

Observation of Joining Phenomena in Friction Stage and Improving Friction Welding Method  

NASA Astrophysics Data System (ADS)

This report describes the observation result of joining phenomena in the friction stage, and an improvement of the conventional friction welding method with similar materials. The materials used were carbon steels and a brake type (direct drive) friction welding machine was used for joining. As the improving friction welding method, relative speed was instantaneously rendered to zero at the end of each friction time. The wear of both surfaces started at periphery portion (outer surface) of the joint and moved to center portion (center axis). Seizure and joining began at center portion and then extended toward periphery portion. The friction torque reached to initial peak torque when the welded interface was joined completely and upsetting of both base metals started. It was determined that friction welded joints with 100% joint efficiency and good bend ductility could be obtained by using only the friction stage up to initial peak torque and without the need for the forging (upsetting) stage. As a conclusion, friction welded joints made without using the forging stage has the same mechanical properties as those welded by the conventional friction welding process including that stage. The friction welding method without forging stage has the advantages of less burn-off (axial shortening) and less burr.

Kimura, Masaaki; Seo, Kenji; Kusaka, Masahiro; Fuji, Akiyoshi

411

Residual Stresses Measurements by Means of X Ray Diffraction on Electron Beam Welded Joints and Laser Hardened Surfaces.  

National Technical Information Service (NTIS)

X ray diffraction techniques are applied to the evaluation of residual stresses induced by two metallurgical processes: electron beam welding (EBW) and laser surface hardening (LSH) on low alloy steel of aeronautical interest. This technique is shown to b...

G. P. Mor R. Pezzoni

1989-01-01

412

Effect of Initial Microstructure on the Microstructural Evolution and Joint Efficiency of a WE43 Alloy During Friction Stir Welding.  

National Technical Information Service (NTIS)

The initial microstructure plays an important role in determining the spatial and temporal evolution of the microstructure during friction stir welding (FSW). The overall kinetics of microstructural evolution is location sensitive and the effect of the pr...

B. Davis K. J. Doherty R. DeLorme R. S. Mishra S. Palanivel

2013-01-01

413

Contribution of precipitate on migrated grain boundaries to ductility-dip cracking in Alloy 625 weld joints  

Microsoft Academic Search

We investigated the crack properties in Alloy 625 weld metals and their characteristics using experimentally designed filler\\u000a wires fabricated by varying the niobium and manganese contents in the flux with the shield metal arc welding (SMAW) process.\\u000a The fast diffusivity of niobium on the migrated grain boundary (MGB) under strong restraint tensile stress, which was induced\\u000a by the hardened matrix

Dong Jin Lee; Youn Soo Kim; Yong Taek Shin; Eon Chan Jeon; Sang Hwa Lee; Hyo-Jong Lee; Sung Keun Lee; Jun Hee Lee; Hae Woo Lee

2010-01-01

414

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

415

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

416

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

417

Thermal analysis of friction welding process in relation to the welding of YSZ-alumina composite and 6061 aluminum alloy  

NASA Astrophysics Data System (ADS)

The objective of this work is to establish an analytical data for heat generation by friction welding, based on different parameters of the contact condition between two dissimilar materials. The ceramic composite of Al2O3-YSZ and 6061 Al alloy, which is the example of joining materials by friction welding was used in the experiments. Alumina rods containing 0, 25 and 50 wt% yttria stabilized zirconia were produced by slip casting in Plaster of Paris molds and subsequently sintered at 1600 °C. The diameter of both the ceramic and metal rods was 16 mm. Rotational speeds for friction welding were between 630 and 2500 rpm. As a result, different data was evaluated for obtaining joint properties and operating conditions, and obtained results are useful in modeling the welding process and reliability joint under various conditions.

Uday, M. B.; Fauzi, M. N. Ahmad; Zuhailawati, H.; Ismail, A. B.

2012-08-01

418

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

419

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

420

Some studies on temperature profiles in AISI 304 stainless steel sheet during laser beam welding using FE simulation  

Microsoft Academic Search

The investigation of transient temperature profiles of a weld joint produced by the laser welding process is presented. A\\u000a three-dimensional finite element model is developed using a commercial finite element code ANSYS in order to obtain the behavior\\u000a of temperature field and molten pool shape during the welding process. A three-dimensional conical Gaussian heat source is\\u000a employed as a heat

N. Siva Shanmugam; G. Buvanashekaran; K. Sankaranarayanasamy; K. Manonmani

2009-01-01

421

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

422

Comparison of creep crack growth rate in heat affected zone of welded joint for 9%Cr ferritic heat resistant steel based on C ?, d ?\\/d t, K and Q ? parameters  

Microsoft Academic Search

Creep crack growth behavior is very sensitive to the materials’ micro-structures such as the heat affected zone of a weld joint. This is a main issue to be clarified for 9%Cr ferritic heat resistant steel for their application in structural components. In this paper, high temperature creep crack growth tests were conducted on CT specimens with cracks in the heat

R. Sugiura; A YOKOBORIJR; M. Tabuchi; T. Yokobori

2007-01-01

423

Role of water chemistry and microstructure in stress corrosion cracking in the fusion boundary region of an Alloy 182-A533B low alloy steel dissimilar weld joint in high temperature water  

Microsoft Academic Search

Stress corrosion cracking (SCC) in the fusion boundary (FB) region of an Alloy 182-low alloy steel (LAS) dissimilar weld joint in 288°C water was investigated by experiments and finite element simulation. Creviced bent beam and crack growth rate (CGR) experiments showed that, while the FB was a barrier to SCC growth, further crack growth into LAS was activated by a

Qunjia Peng; He Xue; Juan Hou; Kazuhiko Sakaguchi; Yoichi Takeda; Jiro Kuniya; Tetsuo Shoji

2011-01-01

424

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

425

NDT (Non-Destructive Testing) of Electron Beam Welded Joints (Micro-Focus and Real Time X-Ray).  

National Technical Information Service (NTIS)

The introduction of electron beam welding (EBW) into the aero engine industry in the early 1960's has presented many new problems for non-destructive testing (NDT). Highlighted among these are the following particular problems: (1) accessibility the use o...

R. G. Taylor

1986-01-01

426

The joint properties of dissimilar formed Al alloys by friction stir welding according to the fixed location of materials  

Microsoft Academic Search

The mechanical properties of the weld mainly depended on the materials fixed at the retreating side because the microstructure of the stir zone was mainly composed of the materials fixed at the retreating side. The onion ring pattern was observed like lamellar structure stacked by each material in turn.

Won-Bae Lee; Yun-Mo Yeon; Seung-Boo Jung

2003-01-01

427

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

428

Fatigue design of complex welded structures  

Microsoft Academic Search

This paper is concerned with the design of complex welded structures subjected to fatigue loadings. In the last years it has been developed a new approach for predicting the high cycle fatigue behaviour of welded joints, based on the Notch-Stress Intensity Factors of the uncracked geometries, which have been successfully applied to welded joints of different geometries using an analytical

B. Atzori; P. Lazzarin; G. Meneghetti; M. Ricotta

2009-01-01

429

Joint Variability of Airborne Passive Microwave and Ground-based Radar Observations Obtained in the TRMM Kwajalein Experiment  

NASA Astrophysics Data System (ADS)

The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) held July-September 1999 in the west Pacific was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. The majority of the precipitation was from mixed-phase clouds. Coordinated data sets were obtained from aircraft and ground-based sensors including passive microwave measurements by the Advanced Microwave Precipitation Radiometer (AMPR) instrument on the NASA DC-8 aircraft and S-band volumetric radar data by the KPOL radar. The AMPR and KPOL data sets were processed to yield a set of 25,049 matching observations at ~ 2 km x 2 km horizontal spatial resolution and within 6 min. The TRMM satellite Microwave Imager (TMI) has a similar set of channels to AMPR but coarser spatial resolution (19 GHz: 35 km, 85 GHz: 7.7 km). During KWAJEX, the 0 deg C level height was nearly constant at ~ 4800 m. Hence, two potential sources of uncertainty in relating passive microwave brightness temperatures (Tbs) to surface precipitation, inhomogeneous beam filling and variations in depth of the rain layer are much smaller sources of error in the KWAJEX data set than for TMI. TRMM was originally designed to yield monthly rainfall estimates over 5 deg x 5 deg grid boxes. The use of these data to yield instantaneous rainrate products at smaller spatial scales is more sensitive to the detailed characteristics of the joint distributions of passive microwave Tbs versus rain rate. KWAJEX data sets reveal poor correlations, very wide scatter, and weak modes in these distributions. The spread of emission Tb values for a given rain-layer reflectivity (e.g., 75 K at 30 dBZ for 19 GHz) is similar or larger within convective compared to stratiform precipitation regions. This result implies that the enhancement in emission Tbs associated with partially melted ice particles can occur whether the particles are concentrated within a thin layer in stratiform regions or are more dispersed in the column in convective regions. There is little information in either ice-layer radar reflectivity or scattering (85 GHz) Tbs on the underlying quantitative surface rain rates at the spatial scale examined.

Yuter, S. E.; Kingsmill, D. E.

2007-12-01

430

Magnetic Deflection Of Welding Electron Beam  

NASA Technical Reports Server (NTRS)

Electron-beam welds inside small metal parts produced with aid of magnetic deflector. Beam redirected so it strikes workpiece at effective angle. Weld joint positioned to where heavy microfissure concentration removed when subsequent machining required, increasing likelihood of removing any weld defects located in face side of electron-beam weld.

Malinzak, R. Michael; Booth, Gary N.

1991-01-01

431

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

432

Neutron techniques for developing engineering welding methods  

Microsoft Academic Search

This paper examines important technical issues pertaining to the methodological limitations of the welding techniques currently in use, with particular consideration given to welding mathematical modelling procedures. The recent progress achieved with high nano-technologies suggests the application of similar approaches to conventional mechanics and materials science, with particular reference to welding processes. Recent studies on welded joints have highlighted the

M. Rogante

2011-01-01

433

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

434

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

435

The effects of casting and forging processes on joint properties in friction-welded AISI 1050 and AISI 304 steels  

Microsoft Academic Search

The aim of the present study was to investigate the effects of investment casting and forging process on the microstructure\\u000a and mechanical properties of friction weldments, AISI 1050–AISI 304. A continuous-drive friction welding device with the automatic\\u000a control ability of friction time and forging pressure was designed and constructed. Factorial design of experiments was performed\\u000a to join investment cast AISI

Tolga Y. Sunay; Mumin Sahin; Sabri Altintas

2009-01-01

436

Evaluation of the inhomogeneity of the joint metal in mechanized welding of steels with an aluminum coating  

Microsoft Academic Search

In the experiments 5-mm thick 500  350 mm plates with a 150-180 um thick aluminum coating on one side faced by the electric arc method with AD-I wire were used. The fusion of the plates was done on the side of the faced layer with full fusion in a flux-copper backing, which is practically similar to welding of a

O. I. Steklov; M. A. Sycheva; N. P. Karmazinov

1989-01-01

437

Explosive Welding for Remote Applications  

NASA Technical Reports Server (NTRS)

Explosive seam welding produces up to 100-percent joint strength. Ribbon explosive activated by remote energy source produces metallurgically sound joint. Success of technique verified for joints between like metals and joints between two different metals. Applications include structural assembly in toxic atmospheres and in radioactive or otherwise hazardous environments.

Bement, L. J.

1985-01-01

438

Fast, Nonspattering Inert-Gas Welding  

NASA Technical Reports Server (NTRS)

Proposed welding technique combines best features of metal (other than tungsten)/inert-gas welding, plasma arc welding, and tungsten/inert-gas welding. Advantages include: wire fed to weld joint preheated, therefore fed at high speed without spattering; high-frequency energy does not have to be supplied to workpiece to initiate welding; size of arc gap not critical, power-supply control circuit adjusts voltage across gap to compensate for changes; only low gas-flow rate needed; welding electrode replaced easily as prefabricated assembly; external wire-feeding manipulator not needed; and welding process relatively forgiving of operator error.

Gilbert, Jeffrey L.

1991-01-01

439

Microstructural Evolution of Inconel 625 and Inconel 686CPT Weld Metal for Clad Carbon Steel Linepipe Joints: A Comparator Study - The Effect of Iron Dilution on the Elemental Segregation of Alloying Elements in Nickel Based Filler Metals  

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

2014-04-01

440

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

441

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

442

Effect of Different Chromium Additions on the Microstructure and Mechanical Properties of Multipass Weld Joint of Duplex Stainless Steel  

NASA Astrophysics Data System (ADS)

The correlation between the mechanical properties and ferrite volume fraction (approximately 40, 50, and 60 Ferrite Number [FN]) in duplex stainless steel weld metals were investigated by changing the Cr content in filler wires with a flux-cored arc-welding (FCAW) process. The interpass temperature was thoroughly maintained under a maximum of 423 K (150 °C), and the heat input was also sustained at a level under 15 KJ/cm in order to minimize defects. The microstructure examination demonstrated that the ?-ferrite volume fraction in the deposited metals increased as the Cr/Ni equivalent ratio increased, and consequently, chromium nitride (Cr2N) precipitation was prone to occur in the ferrite domains due to low solubility of nitrogen in this phase. Thus, more dislocations are pinned by the precipitates, thereby lowering the mobility of the dislocations. Not only can this lead to the strength improvement, but also it can accentuate embrittlement of the weld metal at subzero temperature. Additionally, the solid-solution strengthening by an increase of Cr and Mo content in austenite phase depending on the reduction of austenite proportion also made an impact on the increase of the tensile and yield strength. On the other hand, the impact test (at 293 K, 223 K, and 173 K [20 °C, -50 °C, and -100 °C]) showed that the specimen containing about 40 to 50 FN had the best result. The absorbed energy of about 40 to 50 J sufficiently satisfied the requirements for industrial applications at 223 K (-50 °C), while the ductile-to-brittle transition behavior exhibited in weldment containing 60 FN. As the test temperature decreased under 223 K (-50 °C), a narrow and deep dimple was transformed into a wide and shallow dimple, and a significant portion of the fracture surface was occupied by a flat cleavage facet with river patterns.

Kang, Dong Hoon; Lee, Hae Woo

2012-12-01

443

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

444

Re-weldability of neutron-irradiated stainless steels studied by multi-pass TIG welding  

NASA Astrophysics Data System (ADS)

Weldability of neutron-irradiated stainless steel (SS) has been studied by multi-pass bead-on-plate and build-up tungsten inert gas (TIG) welding, simulating the repair-welding of reactor components. Specimens were submerged arc welding (SAW) joint of Type 304 SS containing 0.5 appm helium (1.8 appm in the SAW weld metal). Sound welding could be obtained by one- to three-pass welding on the plates at weld heat inputs less than 1 MJ/m in the irradiated 304 SS base metal. In the case of the build-up welding of a groove, no visible defects appeared in the specimen at a heat input as low as 0.4 MJ/m. However, build-up welding at a high heat input of 1 MJ/m was prone to weld cracking, owing to the formation of helium bubbles on grain boundaries of the base metal or dendrite boundaries of pre-existing SAW weld metal, in the area within 0.6 mm from the fusion line.

Nakata, K.; Oishi, M.; Koshiishi, M.; Hashimoto, T.; Anzai, H.; Saito, Y.; Kono, W.

2002-12-01

445

A phenomenological model for anisotropic creep in a multipass weld metal  

Microsoft Academic Search

Creep strength of welded joints can be estimated by continuum damage mechanics. In this case constitutive equations are required for different constituents of the welded joint: the weld metal, the heat-affected zone, and the parent material. The objective of this paper is to model the anisotropic creep behavior in a weld metal produced by multipass welding. To explain the origins

K. Naumenko; H. Altenbach

2005-01-01

446

Welding experiments of aluminium pipe by space GHTA welding in aircraft-borne simulated space environment  

Microsoft Academic Search

The gas hollow tungsten arc (GHTA) welding experiments on aluminum pipe were carried out in a simulated space environment using an aircraft. A vacuum chamber and welding machine for GHTA welding test were placed in the cabin of the aircraft and the 10 G gravity environment was produced by a parabolic flight of the aircraft. The square butt welding joints with

Yoshikazu Suita; Masahiro Ohara; Hiroki Sogawa; Kazunori Matsushita; Shinichiro Shobako; Noboru Terajima; Yoshiyuki Tsukuda; Koichi Masubuchi; Shoji Yamauchi

2009-01-01

447

Welding of Duplex Stainless Steel Composite Plate: Influence on Microstructural Development  

Microsoft Academic Search

In the present study, the duplex stainless steel (DSS) composite plate (SAF2205\\/16MnR) was welded by shielded metal arc welding, and the appropriate joint design and welding procedure were carried out. After welding, the mechanical behaviors and microstructure of welded joint were analyzed by using SEM and TEM. Results show that the tensile strength of welded joint satisfied the requirement, and

Shao-Gang Wang; Gui-Ping Dong; Qi-Hui Ma

2009-01-01

448

Resistance welding graphite-fiber composites  

NASA Technical Reports Server (NTRS)

High-strength joints are welded in seconds in carbon-reinfored thermoplastic beams. Resistance-welding electrode applies heat and pressure to joint and is spring-loaded to follow softening material to maintain contact; it also holds parts together for cooling and hardening. Both transverse and longitudinal configurations can be welded. Adhesive bonding and encapsulation are more time consuming methods and introduce additional material into joint, while ultrasonic heating can damage graphite fibers in composite.

Lamoureux, R. T.

1980-01-01

449

Parameter Study of the Corrosion Behaviour of Welding Joints Combining Various Austenitic Stainless Steels in Boiling 65% Nitric Acid (Huey-Test).  

National Technical Information Service (NTIS)

As part of the corrosion testing of numerous austenitic CrNi-steels as appropriate materials for nuclear reprocessing purposes welding samples, made of various matrix and welding filler materials, have been subjected to corrosion testing under ASTM Standa...

M. Schneider R. Kraft

1985-01-01

450

Prediction of weld strength and seam width for laser transmission welding of thermoplastic using response surface methodology  

NASA Astrophysics Data System (ADS)

In the present work, a study is made to investigate the effects of process parameters, namely, laser power, welding speed, size of the laser beam and clamp pressure, on the lap-shear strength and weld-seam width for laser transmission welding of acrylic (polymethyl methacrylate), using a diode laser system. Response surface methodology (RSM) is employed to develop mathematical relationships between the welding process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired weld quality. In addition, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Design-Expert v7 is used to establish the design matrix and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA) method to check their adequacy. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses adequately within the limits of welding parameters being used.

Acherjee, Bappa; Misra, Dipten; Bose, Dipankar; Venkadeshwaran, K.

2009-11-01

451

EXPERIMENTAL STUDY ON THE EFFECT OF ROTATIONAL SPEED AND TOOL PIN PROFILE ON AA2024 ALUMINIUM FRICTION STIR WELDED BUTT JOINTS  

Microsoft Academic Search

Friction stir welding (FSW) is a novel solid state welding process for joining metallic alloys and has been employed in several industries such as aerospace and automotive for joining aluminium, magnesium and copper alloys. The various parameters such as rotational speed, longitudinal speed, axial force and attack angle play vital roles in FSW process in order to analyse the weld

P. Bahemmat; A. Rahbari; M. Haghpanahi; M. K. Besharati

452

Better welds for launch vehicles  

NASA Technical Reports Server (NTRS)

The use and benefits of automated variable polarity plasma arc (VPPA) welding of Al joints are described. The entire welding system, including welding head manipulator, weld-wire feed, torch, and power supply are computer controlled. The importance of proper torch dynamics and the control of argon gas flow through the plasma orifice are discussed. The use of arc-voltage control, the improvements in system monitoring, and the reduction or elimination of electromagnetic interferences are examined. VPPA welding is applicable to joining Space Shuttle components, and an example of its use on an External Tank of the Shuttle is presented.

Schwinghamer, Robert J.

1987-01-01

453

Creep rupture strength of activated-TIG welded 316L(N) stainless steel  

NASA Astrophysics Data System (ADS)

316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower ?-ferrite content, alignment of columnar grain with ?-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K. S.; Mathew, M. D.; Bhaduri, A. K.

2011-06-01

454

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

455

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.

Watanabe, Ikuya; Wallace, Cameron

2008-01-01

456

Effects of Different Filler Metals on the Mechanical Behaviors of GTA Welded AA7A52(T6)  

NASA Astrophysics Data System (ADS)

ER4043, ER5356, and AA7A52 on behalf of the Al-Si, Al-Mg, and Al-Zn-Mg-based welding material, respectively, were chosen as the filler metal to weld AA7A52(T6) plates by GTAW. The variance in mechanical performances of the joints caused by the various filler materials was investigated with reference to the SEM and EDS test results for the weld seam and the fracture surface. Failure was found in the seam for all the welded joints. With regard to the joint obtained with ER4043 welding wire, the total elongation was limited by the brittle intergranular compound Mg2Si of which Mg was introduced by convection mass transfer. As for the other two welds, the content ratio of Zn and Mg was found to play the dominant role in deciding the mechanical properties of the intergranular Mg-Zn compounds which were responsible for the tensile behavior of the joints. The content ratio (wt.%) of beyond 2:1 gave birth to the strengthening phase MgZn2 leading to a ductile fracture. Cr in the seam obtained with AA7A52 filler metal was found to enhance the strength of the joint through isolated particles.

Shu, Fengyuan; Lv, Yaohui; Liu, Yuxin; Lin, Jianjun; Sun, Zhe; Xu, Binshi; He, Peng

2014-04-01

457

Effects of Different Filler Metals on the Mechanical Behaviors of GTA Welded AA7A52(T6)  

NASA Astrophysics Data System (ADS)

ER4043, ER5356, and AA7A52 on behalf of the Al-Si, Al-Mg, and Al-Zn-Mg-based welding material, respectively, were chosen as the filler metal to weld AA7A52(T6) plates by GTAW. The variance in mechanical performances of the joints caused by the various filler materials was investigated with reference to the SEM and EDS test results for the weld seam and the fracture surface. Failure was found in the seam for all the welded joints. With regard to the joint obtained with ER4043 welding wire, the total elongation was limited by the brittle intergranular compound Mg2Si of which Mg was introduced by convection mass transfer. As for the other two welds, the content ratio of Zn and Mg was found to play the dominant role in deciding the mechanical properties of the intergranular Mg-Zn compounds which were responsible for the tensile behavior of the joints. The content ratio (wt.%) of beyond 2:1 gave birth to the strengthening phase MgZn2 leading to a ductile fracture. Cr in the seam obtained with AA7A52 filler metal was found to enhance the strength of the joint through isolated particles.

Shu, Fengyuan; Lv, Yaohui; Liu, Yuxin; Lin, Jianjun; Sun, Zhe; Xu, Binshi; He, Peng

2014-06-01