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1

Tube thickness influence in the sheet/tube joint deformation obtained by electrical resistance spot welding  

SciTech Connect

Currently, the automotive industries have been trying to reduce the excessive weight of the vehicles structure, utilizing steel sheets of greater mechanical resistance and smaller thickness, as well as reducing the low carbon steel tubes thickness. The electrical resistance spot welding process has been used in the automotive industry in the sheet joints welding over square section tube, both steels are of low carbon with different chemical compositions, thickness and coatings. During this kind of joint welding it can happen a deformation in the inner part of the tube, with a reduction of the internal height which can compromise the weld quality. So, by means of a comparative analyses of the sheet/sheet joints (with a thickness of 0.95/2.0 mm and 0.95/3.0 mm) and sheet/tube joints (with a thickness of 0.95/2.0 mm and 0.95/3.0 mm) electrical resistance spot welded, it has been possible to observe that the thin wall sheet tube presents a greater deformation, but the biggest fracture axial traction load.

Damasco, A.; Ferreira, I. [Campinas State Univ., Sao Paulo (Brazil). Dept. of Materials; Duboc do Natal, Y. [Companhia Siderurgica Nacional, Volta Redonda, Rio de Janeiro (Brazil)

1996-12-01

2

Light alloys plates welded joints  

Microsoft Academic Search

In the field described by the topics of the title, there are different ways to achieve the joint. One of them is the spot cold pressure welding. First, the paper presents the experimental results regarding the sharing strength test of the spot cold welded joints. The purpose of the research was to analyze different variant of welding, in order to

Valeriu Georgescu; Mihaela Iordachescu; Bogdan Georgescu

3

Flexible Protective Shield For Newly Welded Joints  

NASA Technical Reports Server (NTRS)

Simple device promotes defect-free welds in oxidation-prone metals. Welding torch pulls trailing shield behind to provide protective shield of argon gas over hot weld bead. Guide at front of torch holder feeds welding wire to joint. Shield bent or straightened to fit closely against weld joint.

Dyer, Gerald E.

1988-01-01

4

Microstructure and Properties Analysis of Laser Welding and Laser Weld Bonding Mg to Al Joints  

NASA Astrophysics Data System (ADS)

Laser welding and laser weld bonding (LWB) Mg to Al joints were obtained in different welding parameters. The penetrations and microstructures of these kinds of joints changed with the increasing of pulse laser power density. Both laser welding and LWB Mg to Al joints with the best properties were obtained in conductive welding mode. In laser welding Mg to Al joint, several intermetallics formed at the bottom of the fusion zone, where some cracks were generated. In laser weld bonding Mg to Al joint, the decomposition of the adhesive caused a baffle effect on the diffusion between the Mg and the Al. The intermetallics formed in the middle of the fusion zone, and the thickness of Mg17Al12 layer was approximately 10 to 20 ?m and the Mg2Al3 layer was less than 5 ?m, which influenced the property of the joint less.

Liu, Liming; Wang, Hongyang

2011-04-01

5

Adaptive Robotic Welding Using Preview Vision Sensing of Joint Geometry  

NASA Astrophysics Data System (ADS)

Conventional robotic welding systems can only be used in applications where parts are highly repeatable and well fixtured. In this paper, vision sensing and processing techniques that permit in-process determination of the position and detailed three-dimensional surface geometry of a weld joint are presented. Structured lighting in the form of a cone of laser light and specialized vision processing schemes are used to obtain three-dimensional geometric surface descriptions from a two-dimensional TV image. This geometric description is used to define joint position, surface orientations, and a variety of cross-sectional measurements such as fill volume, preparation angles, gap size, and presence and dimensions of a previously deposited weld bead or tack weld. The visual feedback is then used for real time control of the torch position relative to the weld joint, and for in-process adjustment of welding process parameters such as welding arc voltage, and wire feed rates.

Agapakis, J. E.; Epstein, G. N.; Friedman, J. M.; Katz, J. M.; Koifman, M.

1987-03-01

6

Statistical analysis of optimum friction welding conditions for 6061 aluminium alloy friction-welded joints  

Microsoft Academic Search

Conferring lightweight and good corrosion resistance, aluminium alloy joints are extensively required in the manufacture of various types of electrical and mechanical components. Research data previously obtained by the authors show the efficiency of friction-welded joints, regardless of whether produced from similar or dissimilar materials, to be fairly well scattered under identical sets of friction welding conditions and underline the

R. Tsujino; G. Kawai; H. Ochi; H. Yamaguchi; K. Ogawa; Y. Yamamoto

2005-01-01

7

Polyimide weld bonding for titanium alloy joints  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

8

Some new methods for predicting fatigue in welded joints  

Microsoft Academic Search

This paper is concerned with the prediction of high-cycle fatigue behaviour in welded joints. Recently, we have developed some new approaches for predicting the effects of notches and other stress concentrations which have been successfully applied to solid parts, using stress data obtained from FEA. In the present work we consider the extension of the same theories to cover welded

David Taylor; Niall Barrett; Gabriele Lucano

2002-01-01

9

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

10

Hydrogen damage in friction welded copper joints  

Microsoft Academic Search

The occurrence of hydrogen attack in electrolytic copper and in copper deoxidized with phosphorous, during model heating in oil and in friction welded specimens was investigated. Dissimilar-metal joints, i.e. copper\\/TZM (titanium–zirconium–molybdenum based alloy) joints and copper\\/austenitic steel joints, were subjected to microstructural examinations and tensile strength tests.Microcracks near the weld surface, caused by hydrogen attack, were found to occur in

Andrzej Ambroziak

2010-01-01

11

MECHANICAL RESISTANCE OF SPOT COLD ALUMINIUM WELDED JOINTS  

Microsoft Academic Search

Although the manner of joining the two parts is different in case of one-side welding comparing with both-sides variant, the specialist did not shown if there are differences between the shearing strength of the joints obtained using these techniques (as we know). The case of different thickness joint's shearing strength was not presented in paper by now as too The

Bogdan Georgescu; Octavian Mircea

12

Fatigue behaviour of laser repairing welded joints  

Microsoft Academic Search

This paper presents a fatigue study in Nd-YAG laser surface repairing welded joints in specimens of two base materials used in mould production. The tests were carried out in a servo-hydraulic machine in tension, under constant amplitude loading, with two stress ratios R=0 and R=0.4. Welded specimens were prepared with U notches and filled with laser welding deposits. The fatigue

L. P. Borrego; J. T. B. Pires; J. M. Costa; J. M. Ferreira

2007-01-01

13

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

14

Welding imperfections of submerged arc welded duplex steel joints in aspects of the welding heat input  

Microsoft Academic Search

An influence of the heat input submerged arc welding of duplex steel UNS S31803 on kind and quantity of welded butt joints defects has been determined. Defects were identified by a radiographic method. As a defectiveness rate it was taken the ratio of quantity negative test results RN to complete radiographic test RC. Analysis of welding heat input influence on

J. Nowacki; P. Rybicki

15

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

NASA Technical Reports Server (NTRS)

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

Looney, Alan

1991-01-01

16

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

Microsoft Academic Search

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

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

2012-01-01

17

Residual Stress on Titanium Alloy Welded Joints  

Microsoft Academic Search

Titanium and its alloys presents an elevated strength\\/weight ratio, good mechanical properties also to high temperatures,\\u000a elevated resistance to corrosion and to most part of acids attack. These characteristics makes this material attractive for\\u000a numerous applications. Thanks to recent improvements in welding techniques that allow the realization of high quality welded\\u000a joints, the employ of titanium alloys is spreading in

Caterina Casavola; Carmine Pappalettere

18

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

19

The influence of welding parameters on the joint strength of resistance spot-welded titanium sheets  

Microsoft Academic Search

In this study, commercially pure (CP) titanium sheets (ASTM Grade 2) were welded by resistance spot welding at different welding parameters and under different welding environments. The welded joints were subjected to tensile-shearing tests in order to determine the strength of the welded zones. In addition, hardness and microstructural examinations were carried out in order to examine the influence of

Nizamettin Kahraman

2007-01-01

20

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

21

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

22

Investigation of weld joint detection capabilities of a coaxial weld vision system  

NASA Technical Reports Server (NTRS)

This report describes the second phase of a series of evaluations of a vision-based welding control sensor for the Space shuttle Main Engine Robotic Welding System. The robotic welding system is presently under development at the Marshall Space Flight Center. This evaluation determines the factors influencing the minimum joint gap required for consistent detection of the weld joint.

Gangl, K. J.; Weeks, J. L.

1985-01-01

23

Fatigue behaviour of post weld heat treated electron beam welded AA2219 aluminium alloy joints  

Microsoft Academic Search

This paper reports the effect of post weld heat treatment on fatigue behaviour of electron beam welded AA2219 aluminium alloy. An attempt has been made to enhance the fatigue strength of the electron beam welded joints through post weld heat treatment methods such as solution treatment, artificial aging, solution treatment and artificial aging. Electron beam welding machine with 100kV capacity

S. Malarvizhi; K. Raghukandan; N. Viswanathan

2008-01-01

24

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

25

Structure of Fe?Ni?Cr steel weld joints  

Microsoft Academic Search

The properties of a weld joint depend upon the structure of the joint metal and the heat affected zone subjected to thermal influence during welding. In this article together with well-known phenomena accompanying welding (grain growth in the heat affected zone, intergranular slippage, and the stressed condition related to crystallization and rapid cooling) a number of other processes which have

A. G. Bratukhin; S. B. Maslenkov; A. V. Logunov

1993-01-01

26

Effect of welding nugget diameter on the fatigue strength of the resistance spot welded joints of different steel sheets  

Microsoft Academic Search

This paper presents an experimental study on the fatigue strength of resistance spot welded galvanized steel sheets and austenitic stainless steel (AISI 304) sheets. The sheet materials were joined by using resistance spot welding as a lap joint. Material combination and nugget diameter were selected as experimental parameters. The high cycle fatigue tests were performed and S–N curves were obtained

M. Vural; A. Akku?; B. Eryürek

2006-01-01

27

Preweld Joint Tracking System For Weld Path Teaching  

NASA Astrophysics Data System (ADS)

Precision welding of aircraft engine assemblies requires accurate tracking of the weld joint under conditions of positional uncertainty. Real-time laser based joint tracking systems are becoming available but currently cost, accuracy, field-of-view, and applicability to specific joint types, weld processes and robot controllers limit their use. When tracking prior to welding is a feasible alternative to real-time tracking, these issues can be addressed. The software and hardware for such a system is described. The system can track weld joints in two dimensions and offset weld path programs to compensate for assembly and/or fixturing errors. The technique is applicable to both plasma arc welding (PAW) and tungsten inert gas (TIG) welding as the sensor is mounted ahead of the weld torch. The weld path tracking software refines a coarsely taught weld path. To enhance tracking accuracy, reliability and speed, the joint tracking algorithm searches for the joint along a line. Search direction is calculated as the normal to the coarse path trajectory. Search direction is accomplished by rotating a window of the image. A prototype system has been implemented. The system consists of a welding robot, a custom vision system, a CCD camera and fiber optic incandescent lighting. The system has been used to successfully weld production assemblies.

Packer, Scott M.; Pietrzak, Kenneth A.; Skinner, Michael J.; Dunne, Kenneth C.

1990-03-01

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

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

SciTech Connect

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

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

2011-10-15

31

Study on the weld joint of Mg alloy and steel by laser-GTA hybrid welding  

Microsoft Academic Search

A laser-GTA hybrid welding technique was chosen to study the weld of the dissimilar alloys of AZ31B Mg alloy and 304 steel. A lap joint was formed between the two. The weld penetration, which determines the mechanical properties of the welded joints, depends on the laser power. A transition zone formed at the interface of the Mg–Fe during laser-GTA hybrid

L. M. Liu; X. Zhao

2008-01-01

32

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

33

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

34

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

35

Electroslag welding of the longitudinal joints of air cooler chambers  

SciTech Connect

This paper presents a method and equipment for electroslag welding with regulation of the thermal cycle. The method enables one, as the result of external action on the parameters of the welding production cycles, to provide the optimum zonal structural and mechanical uniformity, and consequently, the level of properties of the weld joint which eliminates the expensive normalizing procedure. The welding conditions for chambers of 90G2S and 16GS steels and the cooling parameters are shown. The mechanical properties of weld joints made with the method are presented.

Khakimov, A.N.; Antonov, V.V.; Malyarevskaya, E.K.; Prygaev, A.K.

1986-09-01

36

Low cycle fatigue strength assessment of cruciform welded joints  

Microsoft Academic Search

This paper presents the results of an experimental study on the low cycle fatigue strength of cruciform welded joints. Tests were performed on 22 specimens of three different categories, namely full-penetration, partial-penetration and fillet welded cruciform joints. These tests consisted basically of imposing on each specimen a constant amplitude cyclic displacement history in the plastic range of the material behaviour.

João Ferreira; Carlo A Castiglioni; Luis Calado; M Rosaria Agatino

1998-01-01

37

An investigation of residual stress in welded joints  

E-print Network

. flummery and Conclusions VII. '-. &uggested Procedure for I"uture Investigation 18 o i' VIII. ? . Ppendix IX. Bibliography LIST OP EIGURES Ro. Title Page 1. 'welded Plates snd Gptical Gage Used by Soulton and Martin ~ ~ 6 2. Dr. Rao~s Method... AN INVESTIGATION OF RESIDUAL STRESS IN WELDED JOINTS INTRODUCTION The object of the research reported in this paper was to investigate the magnitude of transverse and longi- tudial residual stress in a welded Joint. These are the stresses in a direction...

Moffat, William Hugh

2012-06-07

38

Neutron irradiation effect on the mechanical properties of type 316L SS welded joints  

NASA Astrophysics Data System (ADS)

In the International Thermonuclear Experimental Reactor design activity, the vacuum vessel (VV) is designed as a double walled structure so that some parts are not qualified by the conventional design standards. JAERI has executed the preparation activity of the new design standards and obtained the technical data to support them. In this study, neutron irradiation effects on the mechanical properties of 316L SS welded joints were investigated. The tensile and Charpy-impact specimens were irradiated at 473 K. The results of post irradiation experiments indicate that sufficient ductility is still maintained for tungsten inert gas (TIG) and electron beam (EB) welded joints; whereas, the impact properties of metal inert gas (MAG) weld metal are extremely poor. Consequently, the soundness of the 316L SS base metal and its TIG and EB welded joints are retained after 0.2-0.5 dpa neutron irradiation. However, it is rather difficult to adopt MAG welding for the fabrication of the VV.

Saito, S.; Fukaya, K.; Ishiyama, S.; Amezawa, H.; Yonekawa, M.; Takada, F.; Kato, Y.; Takeda, T.; Takahashi, H.; Nakahira, M.

2002-12-01

39

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

40

Spot weld arrangement effects on the fatigue behavior of multi-spot welded joints  

Microsoft Academic Search

In the present study, the effects of spot weld arrangements in multi-spot welded joints on the fatigue behavior of the joints\\u000a are studied. Three different four-spot welded joints are considered: one-row four-spot parallel to the loading direction,\\u000a one-row four-spot perpendicular to the loading direction and two-row four-spot weld specimens. The experimental fatigue test\\u000a results reveal that the differences between the

Soran Hassanifard; Mohammad Zehsaz; Firooz Esmaeili

2011-01-01

41

Mechanical behavior study of laser welded joints for DP steel  

NASA Astrophysics Data System (ADS)

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

Yan, Qi

2008-03-01

42

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

43

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

44

Wood joints and laminated wood beams assembled by mechanically-welded wood dowels  

Microsoft Academic Search

Dowel welding by high-speed rotation was used to join two wood blocks and strong joints were obtained. Dowel angle to the surface of the wood blocks to be joined had a marked influence on the mechanical performance of the joint. When the dowel was inserted at 90° to the substrate, the dowel was subjected to and resisted a shear force

J.-F. Bocquet; A. Pizzi; A. Despres; H. R. Mansouri; L. Resch; D. Michel; F. Letort

2007-01-01

45

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

SciTech Connect

This paper describes the application of ultrasonic test method and digital signal analysis techniques for the detection of fine defects of {approx_equal}10 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 weld region and subsequently, testing wa carried out on a number of endcap weld joint suspected to have natural defects which were rejected in the helium leak testing. The results obtained were further validated by destructive metallography, thereby confirming the sensitivity and reliability of the developed test methodology.

Subramanian, C.V.; Thavasimuthu, M.; Rajagopalan, C.; Kalyanasundaram, P.; Raj, B. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

1995-11-01

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

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

49

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

50

Residual stresses in welded joints of high-strength steels  

Microsoft Academic Search

By using a “GLEEBLE-3800” complex, we perform the experimental investigations of the dynamics of changes in the yield strength\\u000a of the metal of the heat-affected zone (HAZ) in low-carbon high-strength steels for various rates of cooling of the welded\\u000a joints. The influence of the rate of energy input and thermal welding cycles on the formation of residual stresses in welded

L. Lobanov; V. Poznyakov; V. Pivtorak; O. Mikhodui; V. Orlovs’kyi

2009-01-01

51

LOCAL STRESS APPROACH FOR FATIGUE ASSESSMENT OF WELDED JOINT  

Microsoft Academic Search

Local stress approach can be a strong tool for assessing the fatigue performance of welded joint in steel bridge structures, which is subjected to complicated stress field. This paper surveys the effectiveness and remaining problems of the local stress approaches. Then, this paper examines a method, which utilizes the measured stress, to evaluate fatigue strength of weld root of load

Hiroyuki YOKOTA; Kengo ANAMI

52

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

PubMed Central

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

Liang, Wei; Murakawa, Hidekazu

2014-01-01

53

An inelastic analysis of a welded aluminum joint  

NASA Astrophysics Data System (ADS)

Butt weld joints are most commonly designed into pressure vessels by using weld material properties that are determined from a tensile test. These properties are provided to the stress analyst in the form of a stress vs 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 multiple pass aluminum 2219-T87 butt welds. The weld specimens are analyzed using classical plasticity 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 currently available numerical prediction methods.

Vaughan, Robert E.; Schonberg, William P.

1995-02-01

54

Limit load solution for electron beam welded joints with single edge weld center crack in tension  

NASA Astrophysics Data System (ADS)

Limit loads are widely studied and several limit load solutions are proposed to some typical geometry of weldments. However, there are no limit load solutions exist for the single edge crack weldments in tension (SEC(T)), which is also a typical geometry in fracture analysis. The mis-matching limit load for thick plate with SEC(T) are investigated and the special limit load solutions are proposed based on the available mis-matching limit load solutions and systematic finite element analyses. The real weld configurations are simplified as a strip, and different weld strength mis-matching ratio M, crack depth/width ratio a/ W and weld width 2H are in consideration. As a result, it is found that there exists excellent agreement between the limit load solutions and the FE results for almost all the mis-matching ration M, a/ W and ligament-to-weld width ratio ( W-a)/ H. Moreover, useful recommendations are given for evaluating the limit loads of the EBW structure with SEC(T). For the EBW joints with SEC(T), the mis-matching limit loads can be obtained assuming that the components are wholly made of base metal, when M changing from 1.6 to 0.6. When M decreasing to 0.4, the mis-matching limit loads can be obtained assuming that the components are wholly made of base metal only for large value of ( W-a)/ H. The recommendations may be useful for evaluating the limit loads of the EBW structures with SEC(T). The engineering simplifications are given for assessing the limit loads of electron beam welded structure with SEC(T).

Lu, Wei; Shi, Yaowu; Li, Xiaoyan; Lei, Yongping

2012-05-01

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

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

57

Hydrogen effects in duplex stainless steel welded joints - electrochemical studies  

NASA Astrophysics Data System (ADS)

In this work results on the influence of hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel (DSS) welded joints are described. The results were discussed by taking into account three different areas on the welded joint: weld metal (WM), heat-affected zone (HAZ) and parent metal. The corrosion resistance was qualified with the polarization curves registered in a synthetic sea water. The conclusion is that, hydrogen may seriously deteriorate the passive film stability and corrosion resistance to pitting of 2205 DSS welded joints. The presence of hydrogen in passive films increases corrosion current density and decreases the potential of the film breakdown. It was also found that degree of susceptibility to hydrogen degradation was dependent on the hydrogen charging conditions. WM region has been revealed as the most sensitive to hydrogen action.

Michalska, J.; ?abanowski, J.; ?wiek, J.

2012-05-01

58

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

59

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

Code of Federal Regulations, 2012 CFR

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

2012-10-01

60

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

61

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

Code of Federal Regulations, 2013 CFR

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

2013-10-01

62

Fatigue classification of welded joints in orthotropic steel bridge decks  

Microsoft Academic Search

This dissertation presents the research into fatigue classifications of welded joints in orthotropic steel bridge decks. These classifications are needed to calculate the fatigue life of these joints and should be included in the design codes. For years bridge design was mainly based on static loading. Due to the development of modern light weight steel structures and extremely increasing traffic

M. H. Kolstein

2007-01-01

63

Characterization of Gas Metal Arc Welding welds obtained with new high Cr-Mo ferritic stainless steel filler wires  

E-print Network

1 Characterization of Gas Metal Arc Welding welds obtained with new high Cr-Mo ferritic stainless for homogeneous welding, by Gas Metal Arc Welding (GMAW) process, of a modified AISI 444 ferritic stainless steel Several compositions of metal cored filler wire were manufactured to define the best welding conditions

Paris-Sud XI, Université de

64

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

Microsoft Academic Search

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

Jerzy Nowacki; Pawe? Rybicki

2005-01-01

65

Butt Welding Joint of Aluminum Alloy by Space GHTA Welding Process in Vacuum  

NASA Astrophysics Data System (ADS)

Aluminum alloys have been used widely in constructing various space structures including the International Space Station (ISS) and launch vehicles. For space applications, welding experiments on aluminum alloy were performed using the GHTA (Gas Hollow Tungsten Arc) welding process using a filler wire feeder in a vacuum. We investigated the melting phenomenon of the base metal and filler wire, bead formation, and the effects of wire feed speed on melting characteristics. The melting mechanism in the base metal during the bead on a plate with wire feed was similar to that for the melt run without wire feed. We clarified the effects of wire feed speed on bead sizes and configurations. Furthermore, the butt welded joint welded using the optimum wire feed speed, and the joint tensile strengths were evaluated. The tensile strength of the square butt joint welded by the pulsed DC GHTA welding with wire feed in a vacuum is nearly equal to that of the same joint welded by conventional GTA (Gas Tungsten Arc) welding in air.

Suita, Yoshikazu; Shinike, Shuhei; Ekuni, Tomohide; Terajima, Noboru; Tsukuda, Yoshiyuki; Imagawa, Kichiro

66

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

67

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

68

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

69

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

PubMed

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

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

2001-08-01

70

Interfacial characterization of joint between mild steel and aluminum alloy welded by resistance spot welding  

SciTech Connect

The interfacial characteristics of resistance spot welded steel-aluminum alloy joint have been investigated using electron microscopy. The results reveal that reaction product FeAl{sub 3} is generated in the peripheral region of the weld while a reaction layer consisting of Fe{sub 2}Al{sub 5} adjacent to steel and FeAl{sub 3} adjacent to aluminum alloy forms in the central region of the weld, and that the morphology and thickness of the reaction layer vary with the position at the welding interface.

Qiu Ranfeng, E-mail: xdqrf@yahoo.com.cn [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang, 471003 (China); Henan Key Laboratory of Advanced Non-ferrous Metals, Henan University of Science and Technology, Luoyang 471003 (China); Shi Hongxin; Zhang Keke; Tu Yimin [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang, 471003 (China); Iwamoto, Chihiro; Satonaka, Shinobu [Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto, 860-8555 (Japan)

2010-07-15

71

Cold cracks in welded joints of structural steels  

Microsoft Academic Search

The present survey is devoted to the investigation of a dangerous phenomenon (quite often observed in the process of arc welding)\\u000a of the formation of hydrogen-induced cold cracks in welded joints of structural steels. We briefly analyze the existing models\\u000a of the mechanism of hydrogen embrittlement. It is shown that difficulties in understanding the processes of initiation and\\u000a growth of

I. K. Pokhodnya; V. I. Shvachko

1996-01-01

72

Modeling of welded joints for design against fatigue  

Microsoft Academic Search

Historically, design against fatigue of welded joints is widely based on the nominal stress approach with categorized structural details and appropriate S-N-curves without any need of detailed numerical analysis. Recently, local approaches based on structural and notch stresses are of growing importance for the lifetime assessment of components without post-weld treatment for dominant elastic material behavior in high cycle fatigue

Jürgen Rudolph; Eckart Weiß; Michael Forster

2003-01-01

73

Application of laser peening without coating on steel welded joints  

Microsoft Academic Search

Purpose – Laser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this study is to examine the characteristic at the laser-peened welded zone and the fatigue lives of the welding joints. Design\\/methodology\\/approach – LPwC conditions for 490 MPa grades of structural steels were selected. By using the

Yoshihiro Sakino; Yuji Sano; You-Chul Kim

2011-01-01

74

Artificial neural network modeling of weld joint strength prediction of a pulsed metal inert gas welding process using arc signals  

Microsoft Academic Search

This paper addresses the weld joint strength monitoring in pulsed metal inert gas welding (PMIGW) process. Response surface methodology is applied to perform welding experiments. A multilayer neural network model has been developed to predict the ultimate tensile stress (UTS) of welded plates. Six process parameters, namely pulse voltage, back-ground voltage, pulse duration, pulse frequency, wire feed rate and the

Sukhomay Pal; Surjya K. Pal; Arun K. Samantaray

2008-01-01

75

Characterization on strength and toughness of welded joint for Q550 steel  

Microsoft Academic Search

.  Q550 high strength steel was welded using gas shielded arc welding and three different welding wires without pre- or post-heat\\u000a treatments. The paper investigates the influence of welding wire on the microstructure, tensile strength and impact toughness\\u000a of Q550 steel weld joints. Results showed that the microstructure of the weld metal of joints produced using ER50-6 wire was\\u000a a mixture

JIANG QINGLEI; LI YAJIANG; WANG JUAN; ZHANG LEI

76

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

77

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

78

Analysis of martensite transformation behaviour in welded joints of low transformation-temperature materials  

Microsoft Academic Search

In order to improve fatigue strength in welded joints, low transformation-temperature welding wire has been developed in which residual tensile stress can be reduced. In application of the low transformation-temperature welding wire, the prevention of cold cracking without preheating in high strength steel welded joints is expected and examined from the control of residual tensile stress. However, it is expected

Junji Yamamoto; Susumu Meguro; Yoshiki Muramatsu; Naoya Hayakawa; Kazuo Hiraoka

2009-01-01

79

Pitting corrosion on weld joints offshore structure jackets  

SciTech Connect

During underwater inspection, pitting corrosion was observed on various weld joints of offshore structure jackets. For this purpose, during underwater inspection surveys cathodic protection potentials were measured at different locations on the jackets. The position and condition of anodes were also examined. Pitting and galvanic corrosion studies and cathodic protection experiments were carried out in synthetic sea water and in 3.5% NaCl solution. Field exposure studies were also carried out. The present paper describes the investigations carried out to determine reasons for pitting corrosion on weld joints and remedial measures.

Anto, P.F. [Oil and Natural Gas Corp. Ltd., Panvel (India). Inst. of Engineering and Ocean Technology

1999-11-01

80

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

Microsoft Academic Search

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

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

2002-01-01

81

Research on fatigue behavior evaluation and fatigue fracture mechanisms of cruciform welded joints  

Microsoft Academic Search

The applications of infrared thermographic method and the relationship between the microstructures and mechanical properties of materials were reviewed. Experimental tests, using the thermographic method, have been carried out in order to evaluate the fatigue behavior of cruciform welded joints subjected to a high mean stress. A good agreement was achieved between the predicted values and those obtained by the

J. L. Fan; X. L. Guo; C. W. Wu; Y. G. Zhao

2011-01-01

82

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

E-print Network

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

Paris-Sud XI, Université de

83

Friction welding of dissimilar metal joints with intermediate layers  

Microsoft Academic Search

Purpose: Metals such as titanium, vanadium, zirconium, niobium, molybdenum and also tantalum and tungsten must be protected at elevated temperatures from the effects of oxygen, nitrogen and hydrogen. For this reason, it is of interest, both from the innovative and practical points of view, to investigate the possibility of using the process of friction welding to produce joints in these

A. Ambroziak; M. Korzeniowski; P. Kustro?

84

Pitting corrosion on weld joints of offshore structure jackets  

SciTech Connect

During underwater inspection, pitting corrosion was observed on weld joints of offshore structure jackets. A detailed investigation was carried out to find the cause of the pitting. Pitting and galvanic corrosion studies and cathodic protection experiments were carried out in synthetic seawater and in 3.5% sodium chloride (NaCl) solution. Field exposure studies also were carried out. Remedial measures are described.

Anto, P.F.

2000-04-01

85

Faults in cold reheat steam pipe welded joints  

Microsoft Academic Search

An analysis of the effects of thermal expansion on steam pipes in thermal power plants is presented. Steam quality, steam conditions and reduced and allowable stresses from internal pressures in the pipes are given. The analysis conducted on the pipe metal and on the welded joints showed that the quality of the metal did not appear to cause the failures.

Kryuchko

1982-01-01

86

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

87

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

88

Embrittlement of welded joints in austenitic steel  

Microsoft Academic Search

1.The nonuniformity of the structure of 1Kh14N14V2M steel lowers its working characteristics. Prolonged operation under superhigh parameters induces the decomposition of the ?-solid solution.2.During use, a ferromagnetic phase is precipitated in the preweld zone. A very thin layer of the base metal near the boundary with the weld seam is strengthened much more as compared to those layers situated at

M. A. Krishtal; É. G. Titenskii; T. A. Sirenko

1966-01-01

89

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

90

Control system architecture for robotic welding of tubular joints  

SciTech Connect

This paper presents the architecture of a geometry model and sensor based control system for robotic welding of tubular joints. The functional architecture of the system is described with the main emphasis on the overall mode of operation of the system. Furthermore, it is described how measurements of the physical seam profile are used to update a reference geometry model, and how welding control variables are generated based on the updated reference geometry. Finally, it is illustrated how the use of a reference geometry can improve the flexibility and robustness of the system.

Madsen, O.; Holm, H.; Lauridsen, J.K. [Aalborg Univ. (Denmark)

1996-12-31

91

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

92

Effects of welding speed, energy input and heat source distribution on temperature variations in butt joint welding  

Microsoft Academic Search

In this paper, a moving heat source model based on Goldak's double-ellipsoid heat flux distribution is presented. A C++ programme was developed in order to implement heat inputs into finite element thermal simulation of the plate butt joint welding. The transient temperature distributions and temperature variations of the welded plates during welding were predicted and the fusion zone and heat

D. Gery; H. Long; P. Maropoulos

2005-01-01

93

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

ERIC Educational Resources Information Center

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

Espy, John

94

Effects of weld microstructure on static and impact performance of resistance spot welded joints in advanced high strength steels  

Microsoft Academic Search

Evaluating the impact performance of resistance spot welded joints in advanced high strength steels (AHSS) is critical for their continued integration into the automotive architecture. The effect of strain rate on the joint strength and failure mode is an important consideration in the design of welded structures. Recent results suggest that the failure mode is dependent upon the strength, chemistry,

M. I. Khan; M. L. Kuntz; Y. Zhou

2008-01-01

95

Experimental investigation on laser beam welding of martensitic stainless steels in a constrained overlap joint configuration  

Microsoft Academic Search

This paper presents experimental investigation of laser beam welding of martensitic stainless steels in a constrained overlap configuration. Experimental studies were focused on the effects of laser power, welding speed and fiber diameter on bead geometry and mechanical properties of the weld. Metallurgical study of a selected welded joint was done only to show various microstructures typically formed at different

M. M. A. Khan; L. Romoli; M. Fiaschi; F. Sarri; G. Dini

2010-01-01

96

Low-cycle fatigue of welded joints of alloy AMg5  

Microsoft Academic Search

The authors study the low-cycle fatigue of welded joints of aluminum alloy AMg5 in order to determine the cyclic strength coefficient of welded seams. Tests were carried out on cylindrical specimens of the parent metal, welded specimens, and models of welded vessels. The average values of mechanical properties of the specimens and the parent metal are shown. It is shown

R. V. Modestova; V. A. Borisenko; I. N. Parfenova; S. V. Stepanov; A. A. Kholodilo; A. N. Kuzyukova; A. F. Basanets

1986-01-01

97

Electroslag welding of the circular joints of large apparatus with localized normalizing with gas heating  

Microsoft Academic Search

With a width of heavy rolled plate of about 2 m the primary volume of welding work is the welding of circular joints. Multipass automatic welding under flux of metal of significant thickness has a low rate of productivity and is accompanied by the formation of various defects such as slag inclusions, poor penetration, and cracks in the weld metal.

A. M. Makara; I. V. Novikov; A. S. Iskra; A. E. Erinov; V. A. Sokora; I. N. Medrish; I. K. Drankovskii; V. A. Rumyantsev

1975-01-01

98

Mechanical properties evolution during post-welding-heat treatments of double-lap Friction Stir Welded joints  

Microsoft Academic Search

The present study focuses on double-lap Friction Stir Welded (FSW) joints in 2024T3 and 7075T6 aluminium alloys subjected to several post-welding-heat treatments at warm (typical aging) and high temperature (solution range) followed by room temperature deformation (tensile tests). The effect of post-welding-heat treatments on the microstructure and mechanical properties of double lap FSW joints were investigated. Polarized Optical Microscopy (POM)

E. Cerri; P. Leo

2011-01-01

99

Tendency of weld joints in titanium alloys toward delayed cracking  

Microsoft Academic Search

Conclusions 1.The main reason for the tendency of weld joints in titanium alloys toward delayed cracking is the creased hydrogen content.2.High-strength titanium alloys as well as titanium alloys of medium and low strength with an increased amount of nitrogen and oxygen are more likely to form cracks because of lower ductility, all other things being equal.3.The most dangerous point for

A. S. Mikhaylov; V. S. Krylov

1962-01-01

100

The joint-limits and singularity avoidance in robotic welding  

Microsoft Academic Search

Purpose – The aim of this paper is to develop a redundancy-resolution (RR) algorithm to optimize the joint space trajectory of the six-rotation-axis industrial robot as performing arc-welding tasks. Design\\/methodology\\/approach – The rotation of the tool around its symmetry axis is clearly irrelevant to the view of the task to be accomplished besides some exceptional situations. When performed with a

Liguo Huo; Luc Baron

2008-01-01

101

Structure and properties of welded joints from various titanium alloys  

Microsoft Academic Search

Metallographic, x-ray diffraction, x-ray microspectral and hardness testing techniques have been used to examine the changes in the structure, phase composition, microhardness and the distribution of alloying elements in the parent metal and in the heat affected zone and in the seams of welded joints formed from various titanium alloys (VT6-OT4, VT6-VT20, VT23-OT4, VT23-VT6, VT23-VT19 and VT23-VT32) in the post

A. A. Popov; A. G. Illarionov; M. A. Khorev; N. A. Drozdova

1992-01-01

102

INVESTIGATION OF THE FATIGUE STRENGTH OF THE WELDED JOINTS TREATED BY TIG DRESSING  

E-print Network

The fatigue fracture of structural details subjected to cyclic loads mostly occurs at a critical cross section with stress concentration. The welded joint is particularly dangerous location because of sinergetic harmful effects of stress concentration, tensile residual stresses, deffects, microstructural heterogeneity. Because of these reasons many methods for improving the fatigue resistance of welded joints are developed. Significant increase in fatigue strength and fatigue life was proved and could be attributed to improving weld toe profile, the material microstructure, removing deffects at the weld toe and modifying the original residual stress field. One of the most useful methods to improve fatigue behaviour of welded joints is TIG dressing. The magnitude of the improvement in fatigue performance depends on base material strength, type of welded joint and type of loading. Improvements of the fatigue behaviour of the welded joints in low-carbon structural steel treated by TIG dressing is considered in this paper.

Zoran D. Perovi?

103

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

104

Correlation Between Tensile Strength and Hardness of Electron Beam Welded TC4-DT Joints  

NASA Astrophysics Data System (ADS)

Correlation between tensile strength and hardness for damage-tolerant Ti-6Al-4V (TC4-DT) alloy and its electron beam welded joints was investigated. Yield strength (YS), ultimate tensile strength (UTS) and strain hardening coefficient of base metal and weld metal were obtained using uniaxial tensile tests. Microhardness of the base metal, heat affected zone, and weld metal was measured. Then, the linear correlations among the yield strength, tensile strength, and hardness were proposed. Moreover, correlation between strain hardening coefficient and the ratio of YS to UTS (YS/UTS) was established. The results indicate that microhardness can be used to predict the YS and UTS of the TC4-DT welded joint successfully. In addition, the strain hardening coefficient can be predicted by the YS/UTS. The prediction of strength and strain hardening coefficient is in agreement with the experiments. The correlations are applicable and valuable for the strength prediction of narrow welded fusion zone and heat affected zone based on the microhardness measurement.

Lu, Wei; Shi, Yaowu; Li, Xiaoyan; Lei, Yongping

2013-06-01

105

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

106

Some characteristics of friction welded joints between particulate alumina composite material and 6061 aluminium alloy  

Microsoft Academic Search

Friction welded joints were made with 6061 aluminium alloy and aluminium alloy composite material (MMC) containing 16.1% vol. dispersed particulate alumina and the structures and mechanical properties of these joints were examined.For a short friction time the heat affected zone of a joint was formed almost parallel to the weld interface; however, with increasing friction time it became shaped like

K. Katoh; H. Tokisue

1997-01-01

107

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

Microsoft Academic Search

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

Keshav Prasad; D. K. Dwivedi

2008-01-01

108

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

109

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

110

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

NASA Astrophysics Data System (ADS)

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

Scintilla, Leonardo Daniele; Tricarico, Luigi

2013-02-01

111

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

SciTech Connect

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

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

2012-11-15

112

Effect of Autogenous Arc Welding Processes on Tensile and Impact Properties of Ferritic Stainless Steel Joints  

Microsoft Academic Search

The effect of autogeneous arc welding processes on tensile and impact properties of ferritic stainless steel conformed to AISI 409M grade is studied. Rolled plates of 4 mm thickness have been used as the base material for preparing single pass butt welded joints. Tensile and impact properties, microhardness, microstructure, and fracture surface morphology of continuous current gas tungsten arc welding

AK Lakshminarayanan; K Shanmugam; V Balasubramanian

2009-01-01

113

Modeling and validation of multiple joint reflections for ultra- narrow gap laser welding  

SciTech Connect

The effects of multiple internal reflections within a laser weld joint as a function of joint geometry and processing conditions have been characterized. A computer model utilizing optical ray tracing is used to predict the reflective propagation of laser beam energy focused into the narrow gap of a metal joint for the purpose of predicting the location of melting and coalescence which form the weld. The model allows quantitative analysis of the effects of changes to joint geometry, laser design, materials and processing variables. This analysis method is proposed as a way to enhance process efficiency and design laser welds which display deep penetration and high depth to width aspect ratios, reduced occurrence of defects and enhanced melting. Of particular interest to laser welding is the enhancement of energy coupling to highly reflective materials. The weld joint is designed to act as an optical element which propagates and concentrates the laser energy deep within the joint to be welded. Experimentation has shown that it is possible to produce welds using multiple passes to achieve deep penetration and high depth to width aspect ratios without the use of filler material. The enhanced laser melting and welding of aluminum has been demonstrated. Optimization through modeling and experimental validation has resulted in the development of a laser welding process variant we refer to as Ultra-Narrow Gap Laser Welding.

Milewski, J.; Keel, G. [Los Alamos National Lab., NM (United States); Sklar, E. [Opticad Corp., Santa Fe, New Mexico (United States)

1995-12-01

114

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

115

Fracture toughness of partially welded joints of SUS316 in high magnetic field at 4K  

SciTech Connect

Two kinds of partially welded austenitic stainless steel joints were prepared using SUS 316, 75 mm thick. One joint was fabricated using tungsten inert gas welding and metal arc gas welding, and the other was electron beam welded. Compact tension specimens for fracture toughness tests were machined out from these welded plates in the thickness direction. The fracture toughness tests of these specimens with natural cracks were carried out in 0, 8, and 14 T fields at 4 K. The test results show that there is no strong effect of the high magnetic field on the fracture toughness of these joints, and the electron beam welded joints give a very low toughness in any case because of the complicated natural crack front shape.

Nishimura, A.; Yamamoto, J.; Motojima, O. [National Institute for Fusion Science, Toki, Gifu (Japan)] [and others

1997-06-01

116

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

117

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

118

Researches on the failure modes under tensile forces of the Resistance Spot Welding (RSW) joints  

NASA Astrophysics Data System (ADS)

Resistance spot welding (RSW) is one of the most used methods of joining sheet metals. The RSW process is based on Joule Lenz effect, of the electric current passing trough the (similar or dissimilar ) joining metal sheets positioned between the two contact electrodes. At welding process , some important changes occurs in metallurgical and mechanical properties of the welded areas and heat affected zones (HAZ) . The purpose of this work is to highlight the influences of joint materials and welding parameters on the tensile strength and on the failure mode of the joints. By using constant pressure (force) of the electrodes and different values of current and welding time, three types of materials were welded . The welding samples have been subjected to tensileshear tests and the surfaces of failures were analyzed by scanning electron microscopy (SEM) Some recommendations referring the electing of the optimum welding parameters were formulated..

Chirileanu, Marius; Georgiana, Nistoroschi; Axinte, Eugen

2013-03-01

119

Cracking of Welded Joints of Cast and Deformed Titanium Alloy VT5  

Microsoft Academic Search

The macro- and microstructure and microhardness of welded joints of titanium alloy VT5 are investigated. Fracture surfaces are studied and fractional analysis of hydrogen in cast metals is performed. Suggestions are put forward as to the causes and mechanisms of formation of cracks in a weld joint of a forging and a casting from alloy VT5. Places of crack initiation

A. M. Polyanskii; V. M. Polyanskii

2004-01-01

120

A parametric fracture mechanics study of welded joints with toe cracks and lack of penetration  

Microsoft Academic Search

The existing design rules give quite general guidelines to the fatigue assessment of different types of welded joints. The goal of this investigation was to give designers some tools, which would allow more precise assessment of the effect of dimensional variations on the fatigue strength. Therefore the fatigue behaviour of 12 common types of welded joints has been studied parametrically.

Timo Nykänen; Xiaoyan Li; Timo Björk; Gary Marquis

2005-01-01

121

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

NASA Astrophysics Data System (ADS)

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

Hongo, Hiromichi; Tabuchi, Masaaki; Watanabe, Takashi

2012-04-01

122

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

123

Fatigue behavior of welded joint spray fused by nickel-base alloy powder  

Microsoft Academic Search

Modification of spray fusing (MSF), which is a new method, was used to improve the fatigue strength of welded joints. Cruciform welded joint of Q235B steel was processed by MSF with nickel-base alloy powder of Ni60A and Ni25A. The bonding layer between coating and weld was studied by optical microscopy, scanning electron microscopy (SEM) and energy spectrum analysis. The results

Xiaohui Zhao; Dongpo Wang; Caiyan Deng

2011-01-01

124

STUDYING THE QUALITY OF RESISTANCE SPOT WELDING JOINTS USING BAYESIAN NETWORKS  

Microsoft Academic Search

Resistance spot welding is used to join two or more metal sheets together, and the technique is used widely in the automotive industry, for example. Furthermore, other metal-to-metal connections, such as wire-to-wire joints in the electronics industry, are accomplished by resistance spot welding. Application-specific measures, such as the diameter of the welding spot, define the quality of the joint. By

Perttu Laurinen; Heli Junno; Lauri Tuovinen; Juha Röning

125

A study on mechanical and microstructure characteristics of the STS304L butt joints using hybrid CO 2 laser-gas metal arc welding  

Microsoft Academic Search

In order to examine mechanical characteristics of the stainless steel (STS304L) hybrid welded butt joints, two-dimensional thermal elasto-plastic analysis has been carried out. To this end, a 2D simulation model has been developed considering hybrid welding features. Based on thermal history data obtained from this heat source model, the residual stress distribution in weld metal (WM), heat affected zone (HAZ)

Hee Seon Bang; Han Sur Bang; You Chul Kim; Ik Hyun Oh

2011-01-01

126

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

Microsoft Academic Search

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

N. Krishnaraj; K. Prasad Rao; E. G. Ramachandran

1993-01-01

127

Fracture resistance of Nd:YAG laser-welded cast titanium joints with various clinical thicknesses and welding pulse energies.  

PubMed

The purpose of this study was to evaluate the fracture resistance of Nd:YAG laser-welded cast titanium (Ti) joints with various clinical thicknesses and welding pulse energies. A four-point bending test was used to assess the effects of various specimen thicknesses (1-3 mm) and welding pulse energies (11-24 J) on the fracture resistance of Nd:YAG laser-welded Ti dental joints. Fracture resistance was evaluated in terms of the ratio of the number of fractured specimens to the number of tested specimens. As for the fracture frequencies, they were compared using the Cochran-Mantel-Haenszel test. Morphology of the fractured Ti joints was observed using a scanning electron microscope. Results showed that decreasing the specimen thickness and/or increasing the welding pulse energy, i.e., increasing the welded area percentage, resulted in an increase in the fracture resistance of the Ti joint. Where fracture occurred, the fracture site would be at the center of the weld metal. PMID:17694746

Lin, Mau-Chin; Lin, Sheng-Chieh; Wang, Yu-Tsai; Hu, Suh-Woan; Lee, Tzu-Hsin; Chen, Li-Kai; Huang, Her-Hsiung

2007-05-01

128

Application of BP neural network in welding joint data processing  

Microsoft Academic Search

This article gathered the welding current, welding voltage and column displacement moves parameters of the U71Mn rail welding process orthogonal test, and extracted the quality characteristic quantities of luminous time ratio, energy input, weld period and cremation quantity before accelerating preceding to input to the BP neural network forecast model to research the welding process research to the U71Mn rail.

Liu Yuan-peng; Wen Zhen-hua

2011-01-01

129

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

130

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

131

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

132

46 CFR 56.30-5 - Welded joints.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

133

Corrosion fracture resistance of welded joints in 16GMYuCh steel  

SciTech Connect

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

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

1986-01-01

134

Welding of TZM molybdenum alloy  

Microsoft Academic Search

Molybdenum and TZM alloy are not too difficult to form or weld if the proper procedures are employed. Consistently good welds can be obtained by controlling the area of heating by ensuring full penetration of the welded pieces and by reducing the stresses. A large percentage of the problems incurred in welding TZM can be corrected by good weld joint

Hanks

1970-01-01

135

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

136

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

SciTech Connect

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

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

2010-06-22

137

Numerical and Experimental Evaluation on the Residual Stresses of Welded Joints  

NASA Astrophysics Data System (ADS)

Wings for the defense industry such as fighters, missiles, and rockets should show no deformation or damage on the structure. The structures of existing wings had holes for weight reduction. The plates and frames were fixed with rivets or screws, which limited the weight reduction possible. In this study, an improvement was made in jointing methods through EB welding and laser welding. Welding strength was measured through tension testing. In addition, finite element analysis was performed for the welding process so as to deduce the optimum welding condition.

Huh, Sun Chul; Park, Wonjo; Yang, Haesug; Jung, Haeyoung; Kim, Chuyoung

138

Imperfections in friction stir welded zones and their precision non-destructive testing. Studies on characteristics of friction stir welded joints in structural thin aluminium alloys  

Microsoft Academic Search

The purpose of this study is to investigate various characteristics of thin aluminium alloy structural plate joints welded by the friction stir welding (FSW) process. A number of reports have been published concerning these characteristics. Most of these reports concern joints made by the relevant company's unique procedures using selected parent materials; consequently, the joints were made under restricted specified

S. Iwaki; T. Okada; N. Eguchi; S. Tanaka; K. Namba; N. Oiwa

2006-01-01

139

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

140

Cold-pressure-welded joints in large multifilamentary Nb--Ti superconductors  

Microsoft Academic Search

A number of mechanical and electrical measurements were made on joints in typical conductors for the proposed mirror fusion test facility (MFTF) and high field test facility (HFTF). For such measurements, a commercially available cold-pressure-welding machine was used. For joints in the MFTF conductor, which has a large proportion of superconductor, joint strength approached conductor strength. For the HFTF conductor,

D. N. Cornish; D. W. Deis; J. P. Zbasnik

1977-01-01

141

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

NASA Astrophysics Data System (ADS)

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

Unt, Anna; Poutiainen, Ilkka; Salminen, Antti

142

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

145

Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints  

NASA Astrophysics Data System (ADS)

The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.

Lakshminarayanan, A. K.; Shanmugam, K.; Balasubramanian, V.

2009-10-01

146

Geometrically nonlinear behaviour or spot welded joints in tensile and compressive shear loading  

Microsoft Academic Search

The geometrically nonlinear behaviour of spot welded joints including buckling and gap closure and its influence on local stress parameters at the weld spot edge (structural stresses, notch stress or fatigue notch factor, stress intensity factors) are determined by a large displacement analysis of the tensile shear specimen subjected to tensile and compressive loading. The local parameters mentioned are considered

D. Radaj; S. Zhang

1995-01-01

147

HIGH CYCLE FATIGUE BEHAVIOUR OF WELDED JOINTS BASED ON NOTCH STRESS INTENSITY FACTORS  

Microsoft Academic Search

The present paper summarises the application of NSIF approach to stress analysis and high cycle fatigue assessment of welded joints. This approach is based on linear elastic stress analysis of the open sharp corner defined at the weld toe; in that corner the NSIFs evaluate the intensity of the stress singularity similarly to the evaluation of the stress field ahead

B. Atzori; P. Lazzarin; R. Tovo

148

The influence of the cog geometriy on the resistance of cold-welded joints  

Microsoft Academic Search

Cold welding on cogged surfaces can be realized by pressing a smooth aluminum component on the cogged surface of a more rigid component. Focus is to be laid on the deformation of the plastic component. Welded joints have been made from a combination of aluminum and copper, brass, carbon steel, stainless steel with a deformation rate of over 20%, value

Bogdan Georgescu; Emil Constantin

149

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

150

Experimental evaluation of stress concentration factor of welded steel bridge T-joints  

Microsoft Academic Search

This paper describes an experimental study on determining the stress concentration factor (SCF) and its stochastic characteristics for a typical welded steel bridge T-joint. A full-scale segment model, which holds the same profile with a railway beam section of the suspension Tsing Ma Bridge (TMB) in geometric dimension and material property as well as in weld details, is fabricated and

X. W. Ye; Y. Q. Ni; J. M. Ko

151

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

152

Effect of cracked weld joint and yield strength dissimilarity on crack tip stress triaxiality  

Microsoft Academic Search

This paper is concerned with an elasto-plastic analysis of a weld joint containing a central crack in the weld material (WM) whose yield strength may differ from that of the base material (BM). Stress triaxiality along the path of expected crack extension is found to be influenced not only by the applied tensile load level and crack length relative to

J. Q. Fu; Y. W. Shi

1996-01-01

153

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

Microsoft Academic Search

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

C. Casavola; C. Pappalettere; F. Tattoli

2009-01-01

154

Estimated accuracy of classification of defects detected in welded joints by radiographic tests  

Microsoft Academic Search

Over the last two decades, there has been a considerably increase in the number of publications of research projects for the detection and classification of welding defects in radiographs using image processing and pattern recognition tools. All these research projects aim to set up an automatic or semi-automatic classification system for weld joint defects detected by the radiographic method. A

Romeu R. da Silva; Marcio H. S. Siqueira; Marcos Paulo Vieira de Souza; João M. A. Rebello; Luiz P. Calôba

2005-01-01

155

Microstructures and mechanical properties of resistance spot welded magnesium alloy joints  

Microsoft Academic Search

The resistance spot welded magnesium alloy joints consist mainly of weld nugget and heat-affected zone (HAZ). The nugget contains two different structures, the cellular-dendritic structure at the edge of the nugget and the equiaxed dendritic structure in the center of the nugget. The structure transition is attributed to the changes of solidification conditions. In HAZ, the grain boundary melting occurred

D. Q. Sun; B. Lang; D. X. Sun; J. B. Li

2007-01-01

156

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

157

Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints  

Microsoft Academic Search

The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue\\u000a crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm\\u000a thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were\\u000a prepared to evaluate

A. K. Lakshminarayanan; K. Shanmugam; V. Balasubramanian

2009-01-01

158

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

159

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

160

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

NASA Astrophysics Data System (ADS)

AA1100 aluminum alloy has gathered wide acceptance in the fabrication of light weight structures. Friction stir welding process (FSW) is an emerging solid state joining process in which the material that is being welded does not melt and recast. The process and tool parameters of FSW play a major role in deciding the joint characteristics. In this research, the relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder diameter, pin diameter, and tool hardness) and the responses (tensile strength, hardness, and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified for AA1100 aluminum alloy and reported here.

Rajakumar, S.; Balasubramanian, V.

2012-06-01

161

The influence of reaction layer on the strength of aluminum\\/steel joint welded by resistance spot welding  

Microsoft Academic Search

We investigated the influence of interfacial reaction layer on the strength of resistance spot welded aluminum\\/steel joint by analyzing fracture surface and observing interfacial structure. The results revealed that the interfacial strength was approximately 6.509 MPa in the case that the reaction layer thickness exceeds 1.5 µm.

Ranfeng Qiu; Chihiro Iwamoto; Shinobu Satonaka

2009-01-01

162

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

163

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

164

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

165

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

166

Effect of weld metal properties on fatigue crack growth behaviour of gas tungsten arc welded AISI 409M grade ferritic stainless steel joints  

Microsoft Academic Search

The effect of filler metals such as austenitic stainless steel, ferritic stainless steel and duplex stainless steel on fatigue crack growth behaviour of the gas tungsten arc welded ferritic stainless steel joints was investigated. Rolled plates of 4mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Centre cracked tensile (CCT) specimens were prepared to

K. Shanmugam; A. K. Lakshminarayanan; V. Balasubramanian

2009-01-01

167

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

168

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

SciTech Connect

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

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

1994-09-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

170

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

NASA Astrophysics Data System (ADS)

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.

1992-10-01

171

Repair welding process of friction stir welding groove defect  

Microsoft Academic Search

The groove defect formed in the friction stir welding dramatically deteriorates weld appearances and mechanical properties of the joints owing to its larger size and penetration. Therefore, the friction stir repair welding was utilized to remove such a groove defect, and the focus was placed on the mechanical properties and microstructural characteristics of the repair joints so as to obtain

Hui-jie LIU; Hui-jie ZHANG

2009-01-01

172

The properties of cold-welded joints between multifilamentary Nb3Sn wires  

Microsoft Academic Search

The experimental results on the cold-welded joints between multifilamentary Nb3Sn wires were reported. The joint was made before the heat treatment of the wire. The resistance of the joint was measured to be about 10-12 ohm. The microstructure of it was observed and photographed by SEM. The resistance and the microstructure were compared and analysed. Based on the microstructure, the

J. D. Li; L. Z. Lin; S. Han; H. M. Wen

1994-01-01

173

Some considerations about fatigue failure in milled butt-welded joints affected by residual stress  

Microsoft Academic Search

Many factors are involved in determining the fatigue strength of welded joints. It is, however, very difficult to consider\\u000a their relative importance. The aim of this paper is to isolate the effect of residual stress from other factors, establishing\\u000a a relation between the amount of residual stress and fatigue life. A geometrical notch due to the weld bead is removed

M. De Giorgi; V. Dattoma; R. Nobile

2010-01-01

174

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

175

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

176

Creep damage in welded joints of a Ni-base heat-resistant alloy Hastelloy XR  

Microsoft Academic Search

The relationship between creep rupture lives and cavitation damage is examined in a welded Ni-base alloy, Hastelloy XR, in an impure He gas at 1123–1273 K. The rupture lives of the welded joints are almost the same as those of the base metal at lower temperatures of 1123–1173 K, whereas the former lives become shorter than the latter ones at

Tatsuhiko Tanabe; Yuji Kurata; Isao Mutoh; Hirokazu Tsuji; Keijiro Hiraga; Masami Shindo

1997-01-01

177

Static and impact crack properties of a high-strength steel welded joint  

Microsoft Academic Search

In order to gain the benefits of weldable high-strength steels in pressurized equipment applications, satisfactory toughness and crack properties of the welded joint, both in the weld metal and the heat-affected –zone (HAZ), are required. Experimental investigations of toughness and crack resistance parameters through static and impact tests of a high-strength, low-alloy steel (HSLA) with a nominal yield strength of

M. Zrilic; V. Grabulov; Z. Burzic; M. Arsic; S. Sedmak

2007-01-01

178

Statistical analysis of the results of tests of weld joints of petroleum apparatus made by electroslag welding with control of the thermal cycles  

SciTech Connect

Electroslag welding with control of the thermal cycles provides weld joints with the required mechanical properties, reduces the labor requirements and saves on costs. A statistical analysis of the results of sample compounds of weld joints of apparatus from specified sources derives strength indices, and the mechanical test results are treated by the methods of mathematical statistics with the use of a computer. It is found that electroslag welding can be used in the production of apparatus of 20K, 20 YuCh, 09G2S, and 16GS steels.

Khakimov, A.N.; Agafonov, V.V.; Efimenko, L.A.; Zakharov, V.A.

1984-01-01

179

Real-time monitoring of laser welding of galvanized high strength steel in lap joint configuration  

NASA Astrophysics Data System (ADS)

Two different cases regarding the zinc coating at the lap joint faying surface are selected for studying the influence of zinc vapor on the keyhole dynamics of the weld pool and the final welding quality. One case has the zinc coating fully removed at the faying surface; while the other case retains the zinc coating on the faying surface. It is found that removal of the zinc coating at the faying surface produces a significantly better weld quality as exemplified by a lack of spatters whereas intense spatters are present when the zinc coating is present at the faying surface. Spectroscopy is used to detect the optical spectra emitted from a laser generated plasma plume during the laser welding of galvanized high strength DP980 steel in a lap-joint configuration. A correlation between the electron temperature and defects within the weld bead is identified by using the Boltzmann plot method. The laser weld pool keyhole dynamic behavior affected by a high-pressure zinc vapor generated at the faying surface of galvanized steel lap-joint is monitored in real-time by a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source.

Kong, Fanrong; Ma, Junjie; Carlson, Blair; Kovacevic, Radovan

2012-10-01

180

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

182

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

NASA Astrophysics Data System (ADS)

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

Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

2014-09-01

183

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

NASA Astrophysics Data System (ADS)

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

Tabuchi, Masaaki; Hongo, Hiromichi; Abe, Fujio

2014-10-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

185

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

186

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

187

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

188

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

189

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

190

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

191

Effect of Welding Processes on Tensile and Impact Properties, Hardness and Microstructure of AISI 409M Ferritic Stainless Joints Fabricated by Duplex Stainless Steel Filler Metal  

Microsoft Academic Search

The effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade is studied. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties,

AK Lakshminarayanan; K Shanmugam; V Balasubramanian

2009-01-01

192

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

USGS Publications Warehouse

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

Prostka, Harold J.

1977-01-01

193

Deformation limit and ultimate strength of welded T-joints in cold-formed RHS sections  

Microsoft Academic Search

This paper describes the deformation limit and ultimate strength of welded T-joints in cold-formed RHS sections. Both web buckling failure mode and chord flange failure mode are investigated. The strength at a certain deformation (chord flange indentation) limit can be regarded as the ultimate strength of a T-joint. The deformation limit mainly depends on the ratio ? (=b1\\/bo). Based on

Xiao-Ling Zhao

2000-01-01

194

Effects of electron beam local post-weld heat-treatment on the microstructure and properties of 30CrMnSiNi2A steel welded joints  

Microsoft Academic Search

To improve the microstructure and properties of electron beam welded joints, vacuum or furnace whole post-weld heat-treatment (FWPWHT) should usually be carried out. Electron beam local post-weld heat-treatment (EBLPWHT) is a quite new heat-treatment procedure that provides the advantages of high precision, flexibility and efficiency, energy saving, and higher productivity. In this paper, the microstructure, mechanical properties, fracture toughness and

F. R. Chen; L. X. Huo; Y. F. Zhang; L. Zhang; F. J. Liu; G. Chen

2002-01-01

195

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

PubMed Central

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

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

2013-01-01

196

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

197

Evaluation of fatigue crack propagation in spot welded joints by stiffness measurements  

Microsoft Academic Search

Resistance spot welded joints made of two advanced high strength steels (AHSS) and one high strength steel (HSS) were examined. In the high cycle fatigue regime tests were realised for one loading condition, and the load and the displacement were measured. From the load and displacement range, the stiffness was calculated and in situ normalised to its value after 1000

H. Gaul; G. Weber; M. Rethmeier

2011-01-01

198

The effect of seismic loading on the fatigue strength of welded joints  

Microsoft Academic Search

Earthquakes sometimes damage steel structures. Structures which are not seriously damaged are still used after earthquakes but their fatigue strength may have been reduced by the large cyclic loadings imposed by the earthquakes. In order to clarify the effect of seismic loading on the fatigue strength of welded joints, high cycle fatigue and variable amplitude fatigue tests after a number

Y. Kondo; K. Okuya

2007-01-01

199

Installation for fatigue testing of materials and their welded joints under high-cycle impact loading  

Microsoft Academic Search

We present a description of an installation designed for the determination of the characteristics of impact fatigue of alloys\\u000a and their welded joints according to the results of testing of large-sized specimens in the entire range of the load ratio\\u000a 0?R<1.

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

1998-01-01

200

The cold resistance of weld joints of several construction steels after impulse loading  

Microsoft Academic Search

Experimental studies have been carried out on the effects of explosion treatment on a number of strength characteristics and the brittle-ductile transition point found in weld joints made of two tube steels. The choosen regime of explosion treatment did not significantly change the values of these characteristics. However, by changing the investigated strength and deformation characteristics, it has been shown

G. N. Nadezhdin; S. N. Smirnova; Yu. I. Fadeenko

1992-01-01

201

Fatigue assessment of welded joints using critical distance and other methods  

Microsoft Academic Search

This paper describes an investigation into four different methods for predicting high-cycle fatigue behaviour in welded joints. Two of these methods (the crack modelling method and the notch stress intensity factor) are based on modifications of linear elastic fracture mechanics. The other two are methods to which we give the general name critical distance methods (CDM). The direct CDM approach

G. Crupi; V. Crupi; E. Guglielmino; D. Taylor

2005-01-01

202

Intergranular corrosion of welded joints of austenitic stainless steels studied by using an electrochemical minicell  

Microsoft Academic Search

An intergranular corrosion study of welded joints of austenitic stainless steels (AISI 304 and 316L) has been addressed. A specific small-scale electrochemical cell (minicell) has been used. Four different weldment zones have been studied. The electrochemical methods applied were the electrochemical potentiokinetic reactivation test and electrochemical potentiokinetic reactivation double loop test. These techniques showed that the HAZ was the most

C. Garcia; M. P. de Tiedra; Y. Blanco; O. Martin; F. Martin

2008-01-01

203

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

NASA Astrophysics Data System (ADS)

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

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

204

Selected Welding Techniques, Part 2.  

National Technical Information Service (NTIS)

Partial contents: CONVENTIONAL WELD JOINTS VERSUS BUTT JOINTS IN 1- INCH ALUMINUM PLATE, SPECIAL WELD JOINT PREPARATION, UPSET METAL EDGES FOR INCREASED WELD JOINT STRENGTH, OUT-OF-POSITION WELDING OF HEAVY GAGE ALUMINUM ALLOY IN SPACE VEHICLE APPLICATION...

1964-01-01

205

Fracture Toughness of Friction Stir-Welded Lap Joints of Aluminum Alloys  

NASA Astrophysics Data System (ADS)

The aim of this study is to determine the fracture toughness of friction stir-welded (FSW) lap joints of aluminum alloys. FSW lap joints of AA 2014 and AA 6063 aluminum alloy plates were performed on a conventional semiautomatic milling machine. FSW lap joints were produced on alloy plates. Fracture toughness of FSW lap joints were calculated from the results of tensile shearing tests. New empirical equations were developed for fracture toughness and energy release rate based on the relation between the hardness and fracture toughness values. Fracture toughness of FSW lap joints increases exponentially as the hardness reduces. The results of the experiments showed that the amount of Si content in Al alloys affects the fracture toughness of the FSW lap joints.

Kulekci, M. Kemal; Sevim, Ibrahim; Esme, Ugur

2012-07-01

206

Resistance welding of thermosetting composite\\/thermoplastic composite joints  

Microsoft Academic Search

An investigation of the resistance welding between carbon fibre (CF)-reinforced polyetherimide (PEI) and CF-reinforced epoxy laminates is presented. A three-dimensional transient finite element model (FEM) featuring heat transfer, consolidation and thermal degradation was used for simulating the process. A hybrid interlayer made of a glass fibre (GF) fabric essentially impregnated with PEI on one side and with epoxy resin on

C. Ageorges; L. Ye

2001-01-01

207

On the Critical Technological Issues of Friction Stir Welding T-Joints of Dissimilar Aluminum Alloys  

NASA Astrophysics Data System (ADS)

In this article, friction stir welded T-joints of innovative dissimilar aluminum alloys have been produced and tested with the aim to investigate the feasibility of using this joining technique, in this configuration, in the aerospace field with the final aim to save weight. The introduction of both this new welding technique and innovative alloys, such as AA 2198 and AA 6056, could allow making lighter and stronger structures. Some experiments, carried out previously, have shown that the fixturing device, the tool geometry, and the tilt angle play a significant role in the joint soundness. A wide experimental characterization has been carried out on FSW T-joints of AA 6056 T4 extrudes to AA 2198 T3 rolled plates. The results attained allow to put in evidence some critical issues on the investigated configuration and can be considered as a further acquired knowledge in the understanding and the design of friction stir processes.

Astarita, A.; Squillace, A.; Scala, A.; Prisco, A.

2012-08-01

208

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

NASA Astrophysics Data System (ADS)

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

Almaguer, P.; Estrada, R.

2014-07-01

209

Development of Laser Welding of Ni based Superalloys for Aeronautic Engine Applications (Experimental Process and Obtained Properties).  

NASA Astrophysics Data System (ADS)

Superalloys are designed for service at temperatures above 540 °C. Due to their properties at high temperatures, this family of materials is used in different aircraft engine components. Aeronautic components demand reliable joining technologies. The laser welding of three different superalloys have been performed and analysed. Due to reduced extension of the heat affected zone (HAZ), and high quality and ratio “depth/width” of welded seams, laser welding has been a first joining technology candidate to new designs of components for new engines. The laser welding trials results, properties obtained, and development of the homologation of laser welding process are described.

Zapirain, Fidel; Zubiri, Fidel; Garciandía, Fermín; Tolosa, Itziar; Chueca, Samuel; Goiria, Aimar

210

Robotic gas metal arc welding of small diameter saddle type joints using multi-stripe structured light  

NASA Astrophysics Data System (ADS)

Single-stripe structured light sensors are widely used in conjunction with arc welding robots for seam-tracking purposes. The interaction of the projected light with the weld joint and component surfaces produces characteristic line shapes with feature points that can be recognized at high speed by an underlying vision system. Unfortunately they are suitable only for the major classes of weld joint typically encountered within industry--long, straight, or gently curving fillet or butt joints. We present a multistripe structured light sensor that detects and measures the position of the saddle type weld joint formed by two small (< 50-mm)-diameter intersecting tubes. The underlying image processing algorithms detect the weld feature points from each stripe along with four calibration points to generate the entire weld path in the robot workcell base coordinate system before welding commences. The system is validated within an existing welding application; detecting 93% of the weld feature points within +/- 0.4 mm when used on 30-mm-diam tubes.

Bonser, Gary R.; Parker, Graham A.

1999-11-01

211

Effects of neutron irradiation on strength of fusion reactor materials and their electron beam welded joints  

NASA Astrophysics Data System (ADS)

Several aluminum alloys (A7N01, A5083 and A6061) and a ferritic martensitic steel (JFMS) were used in the present study of the effects of neutron irradiation on the strength of base materials and their electron beam welded joints. Neutron irradiation tests were performed using the core irradiation facility at Kyoto University Reactor (KUR). Neutron fluences were 2.0 × 10 22 9.1 × 10 22 and 1.7 × 10 23n/ m2 ( E > 0.1 MeV). Tensile tests were performed at 4.2, 77 and 293 K on miniature specimens prepared from both the base and welded materials. Aluminum alloys exhibit serrations in the nominal stress-nominal strain curve at 4.2 K. Little effect of neutron irradiation on the serration is observed. The ductility decrease of base metal and welded joints of aluminum alloys by neutron irradiation is smaller than that of JFMS. JFMS, especially welded joints, showed strong radiation embrittlement at cryogenic temperatures.

Kaga, S.; Tamura, T.; Yoshida, H.; Miyata, K.

1991-03-01

212

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

SciTech Connect

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

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

2012-07-01

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

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

216

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

217

Fatigue analysis of thin AlMgSi welded joints under constant and variable amplitude block loadings  

Microsoft Academic Search

This paper reports the fatigue behaviour of thin AlMgSi1 aluminium alloy weldments and the improvement in fatigue strength due to post-weld treatments. Several fatigue tests were performed using two distinct types of thin welded joints, T and single lap, manufactured using a 6xxx series aluminium alloy, and the efficiency of fatigue life improvement techniques, such as post-weld heat treatment and

J. A. M Pinho-da-Cruz; J. A. M Ferreira; J. D. M Costa; L. F. P Borrego

2003-01-01

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

Effect of welding processes and consumables on high cycle fatigue life of high strength, quenched and tempered steel joints  

Microsoft Academic Search

Austenitic stainless steel (ASS) welding consumables are traditionally used for welding quenched and tempered steels as they have higher solubility for hydrogen in austenitic phase. An attempt was made in this investigation to explore an alternate consumable to replace expensive ASS consumables. Austenitic stainless steel and low hydrogen ferritic steel were used to fabricate the joints by shielded metal arc

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

2008-01-01

220

Artificial neural networks for pitting potential prediction of resistance spot welding joints of AISI 304 austenitic stainless steel  

Microsoft Academic Search

The aim of this work is to predict the influence of welding process on pitting corrosion behaviour (PCB) of resistance spot welding (RSW) joints of AISI 304 austenitic stainless steel (ASS). PCB is estimated from the pitting potential (Epitt), which is predicted from three RSW parameters. The prediction is carried out by artificial neural networks (ANNs) because the phenomena that

Óscar Martín; Pilar De Tiedra; Manuel López

2010-01-01

221

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

222

Influence of preheating on API 5LX80 pipeline joint welding with self-shielded flux-cored wire  

Microsoft Academic Search

The present work refers to the characterization of the mechanical properties of API 5L-X80 pipeline joints welded with self-shielded flux-cored wire. This process was evaluated under preheating conditions, with a uniform and steady heat input. All joints were welded in a flat position (IG), with the pipe turning and the torch still. Tube dimensions were 762 mm in external diameter

R. Cooper; J. H. F. Silva; R. E. Trevisan

2005-01-01

223

Effect of abnormal grain growth on tensile strength of Al–Cu–Mg alloy friction stir welded joints  

Microsoft Academic Search

An Al-4.5%Cu-1.5%Mg aluminum alloy with a T4 temper was friction stir welded, and the effect of the abnormal grain growth\\u000a on the tensile strength of joints was investigated. Abnormal grain growth usually happens during post weld heat treatment.\\u000a It is found that the tensile strength and elongation of the heat-treated joint will increase significantly if this phenomenon\\u000a completely happens in

M. A. Safarkhanian; M. Goodarzi; S. M. A. Boutorabi

2009-01-01

224

Numerical study of electron beam welded butt joints with the GTN model  

NASA Astrophysics Data System (ADS)

The fracture behavior of S355NL electron beam welded steel joints is investigated experimentally and numerically. The simulation of crack propagation in an electron beam welded steel joint was performed with the Gurson-Tvergaard-Needleman (GTN) damage model. A parameter study of the GTN model was adopted which reveals the influence of parameters on the material behavior of notched round and compact tension specimens. Based on the combined method of metallographic investigations and numerical calibration, the GTN parameters were fixed. The same parameters were used to predict the ductile fracture of compact tension specimens with the initial crack located at different locations. Good match can be found between the numerical and experimental results in the form of force versus Crack Opening Displacement as well as fracture resistance curves.

Tu, Haoyun; Schmauder, Siegfried; Weber, Ulrich

2012-08-01

225

Numerical Simulation on Weld Joint Offset for Tailor-Welded Blank in MultiPoint Forming  

Microsoft Academic Search

Multi-point forming (MPF) is a novel manufacturing technique for three-dimensional sheet metal. It employs two reconfigurable element groups to approximate the continuous upper and lower solid dies. With the technique, rapid fabrication of 3D sheet metal part is realized. In this paper, to investigate the feasibility of the multi-point forming for the tailor-welded blank (TWB), the explicit finite element model

Wei Liu; Mingzhe Li

2009-01-01

226

Friction stir welding of aluminium lap joint by tool without probe  

Microsoft Academic Search

A friction stir welding process, with a rotating tool without a probe, was employed and applied to a lap joint of aluminium plate. The thickness of the aluminium plates was 0.5 mm. New tool shapes were developed. The tops of the tool were dome shaped. In this process, the rotating tool was plunged into the aluminium plate. The tool-rotating axis was

Kinya Aota; Kenji Ikeuchi

2010-01-01

227

Bucket wheel excavator: Integrity assessment of the bucket wheel boom tie-rod welded joint  

Microsoft Academic Search

The bucket wheel boom tie-rods are vital structural parts of the bucket wheel excavators (BWE). Their failures inevitably cause BWE collapse and are followed, among other things, by a substantial financial loss (millions of €). Non-destructive testing revealed a flaw in the butt welded joint of the body and eye-plate of the bucket wheel tie-rod. Its size exceeds the level

Sr?an M. Bošnjak; Miodrag A. Arsi?; Nenad ?. Zrni?; Marko P. Rakin; Milorad P. Panteli?

2011-01-01

228

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

229

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

230

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

NASA Astrophysics Data System (ADS)

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

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-03-01

231

Tensile properties of austenitic stainless steels and their weld joints after irradiation by the ORR-spectrally-tailoring experiment  

NASA Astrophysics Data System (ADS)

Tensile specimens of the Japanese heat of PCA (JPCA) and type 316 stainless steels were irradiated in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) to a peak dose of 7.4 dpa and a peak helium level of 105 appm in the temperature range between 328 and 673 K. Specimens of type 316 steel with weld joints produced by tungsten inert gas (TIG) and electron beam (EB) welding techniques were also included. Irradiation caused both increases in flow stress and decreases in elongation. Weld joint specimens exhibited both lower strength and elongation after irradiation. The reduction of area (RA) for the TIG weld joint specimens decreased by a factor of 5 compared to unirradiated base metal specimens, however, they still fractured in a ductile mode. The EB weld joints maintained RA levels similar to that of the unirradiated base metal specimens. Post-radiation ductilities of weld joints and base metal specimens of these steels should be adequate for their application to next generation fusion experimental devices, such as the International Tokamak Experimental Reactor (ITER).

Jitsukawa, S.; Maziasz, P. J.; Ishiyama, T.; Gibson, L. T.; Hishinuma, A.

1992-09-01

232

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

SciTech Connect

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

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

2012-10-15

233

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

234

Effect of interfacial reaction layer continuity on the tensile strength of resistance spot welded joints between aluminum alloy and steels  

Microsoft Academic Search

We have joined aluminum alloy A5052 to cold-rolled steel SPCC and austenitic stainless steel SUS304 using resistance spot welding. The interfacial microstructures have been observed using scanning electron microscopy and the tensile strength of the joints have been examined by cross tension testing. We have investigated the effect of interfacial reaction layer on the tensile strength of the joints based

Ranfeng Qiu; Shinobu Satonaka; Chihiro Iwamoto

2009-01-01

235

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

236

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

NASA Astrophysics Data System (ADS)

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

Harooni, Masoud

237

Microstructure and Softening of Laser-Welded 960 MPa Grade High Strength Steel Joints  

NASA Astrophysics Data System (ADS)

The microstructural evolution of laser-welded 960 MPa grade high strength steel joints and its effect on softening behavior of heat affected zone (HAZ) were investigated in this paper. The results show that microstructure of HAZ and fusion zone (FZ) is composed of lath martensite and bainitic ferrite. The microstructure of mixed grained zone presents strip-like characteristics and small block martensite distributes along the grain boundary. The grain size near the fusion line is about 25 ?m, and the grain size in the fine grain zone is less than 5 ?m. Microhardness of HAZ and FZ is lower than base metal. The soft zone locates in transitional region between tempering zone and mixed grained zone due to the interaction of the martensite tempering and the recovery and recrystallization of the rolled microstructure. Microhardness of soft zone is 310 HV and drops 18% compared to base material. Welding heat input has a remarkable effect on the width of soft zone and microhardness. The tensile properties of weld joints are closely related to the softening behavior of HAZ.

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

2013-12-01

238

The influence of radiation on the properties of welds and joints  

NASA Astrophysics Data System (ADS)

The effect of radiation on mechanical properties of candidate structural materials for the first wall and breeder blanket of fusion reactors is reviewed. The emphasis is placed on austenitic stainless steel type 316L and its weld metals; design parameters considered are similar to those currently specified for the Next European Torus, namely, irradiation doses ?15 dpa, temperatures ? 400°C, number of pulse cycles ?10 5 and hold times ?15 mn. The effect of irradiation on other materials, including austenitic stainless steel Type 304L, weld metal Type 308L and ferritic/martensitic steels (9-12% Cr-Mo), as well as other service conditions such as temperatures as high as 550°C are also briefly discussed. The data collected and presented in this review are those usually measured before and after irradiation, through tensile, impact toughness, fracture toughness, fatigue, creep-fatigue and fatigue crack propagation testing. In each case the influence of irradiation parameters on the observed changes are discussed and relative conclusions are drawn. The most important observation made is the lack of medium dose irradiation data on the weld metal and in particular on the electron beam welded joints.

Tavassoli, A. A.

1988-07-01

239

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

240

Effects of Electrode Force on the Characteristic of Magnesium Alloy Joint Welded by Resistance Spot Welding with Cover Plates  

Microsoft Academic Search

Magnesium alloy AZ31B sheets were welded using the technique of resistance spot welding with cover plates. The effects of electrode force on the joining performance and pore formation during welding were investigated. The results reveal that the enhanced electrode force is an effective way to inhibit pore formation and improve magnesium alloy resistance spot welding performance.

Ranfeng Qiu; Hongxin Shi; Hua Yu; Keke Zhang; Yimin Tu; S. Satonaka

2010-01-01

241

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

242

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

243

A robust method for vision-based seam tracking in robotic arc welding  

Microsoft Academic Search

This paper presents a robotic seam tracking system which is aimed at achieving robustness against some welding noises such as arc glares, welding spatters, fumes etc. In particularly, a syntactic analysis is used to improve the extraction reliability of the joint features. The joint features thus obtained are used to extract the 3-dimensional information of the weld joint and then

Jae Seon Kim; Young Tak Son; Hyung Suck Cho; Kwang Il Koh

1995-01-01

244

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

245

Dynamic Separation of Resistance Spot Welded Joints: Part II—Analysis of Test Results and a Model  

Microsoft Academic Search

The ultimate strength of resistance spot welded joints fabricated from a wide range of steel grades, weld button size, and\\u000a sheet thickness are reported for lap-shear and cross-tension specimens subjected to quasi-static and impact loading conditions.\\u000a Test data are analyzed with respect to energy, impact speed, and loading rate. Loading rate is identified as a critical, test\\u000a system independent parameter

K. Wang; Y. J. Chao; X. Zhu; K. W. Miller

2010-01-01

246

Annealing temperature effects on superduplex stainless steel UNS S32750 welded joints. II: pitting corrosion resistance evaluation  

Microsoft Academic Search

This study deals with the effect of the annealing temperature on the pitting corrosion resistance of UNS S32750 submerged-arc\\u000a welded joints. In a companion article (Part I), the influence of post-weld annealing temperature on microstructure evolution\\u000a and chemical composition of austenite and ferrite was analyzed; this study can thus be considered directly connected with\\u000a the previous one. The pitting corrosion

R. Cervo; P. Ferro; A. Tiziani; F. Zucchi

2010-01-01

247

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

248

Influence of Heat Input on the Content of Delta Ferrite in the Structure of 304L Stainless Steel GTA Welded Joints  

NASA Astrophysics Data System (ADS)

Welding of austenitic stainless steel has its specific issues, even when the weldability is considered good. The main problems of austenitic stainless steel welding are connected with its metallurgical weldability. The amount of the components presented in the structure of stainless steel welded joint affect its properties, therefore the understanding of the behavior of stainless steel during its welding is important for successful processing and allows the fabricators the possibility to manage the resulting issues. This paper is focused on the influence of heat input on the structural changes in GTA welded joints of austenitic stainless steel designated: ASTM SA TP 304L.

Sej?, Pavol; Kubí?ek, Rastislav

2011-12-01

249

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

E-print Network

of the thermit reaction into a usable welding process is attributed to Dr. Hans Goldschmidt of Germany. In 1895, Goldschmidt discovered that a mixture of iron oxide and aluminum could be ignited in one spot using magnesium powder as a starter. In 1898... on AISI 1020 steel tubing. (ASTM 513-66 TYPE 1, Electric resistance welded steel tubing, 7-gauge and 16-gauge wall thickness. ) The scope of this study included only samples welded under laboratory conditions of cleanli- ness, with joints prepared...

Glynn, Thomas Michael

2012-06-07

250

Study of the martensite structure at the weld interface and the fracture toughness of dissimilar metal joints  

SciTech Connect

In austenitic-ferritic dissimilar metal welded joints, the content of alloying elements in the transition zone varies continuously from the heat-affected zone (HAZ) to the weld metal. Due to the low level of Ni content, a martensite layer is formed in this zone during the welding process. The Charpy impact test performed previously by other researchers indicated that the martensite layer was the weakest zone in toughness in the joints. In this study, color metallography and transmission electron microscope (TEM) analysis were used to show the martensite structures at the weld interface. The results show that the structures of the martensite layer at the weld interface are lath martensite. The martensite starting points vary with the distance from the fusion line and are controlled by composition gradient. The boundary of the transition zone could be divided into two types: the blurred type, and the sharp type, which are controlled by diffusion of elements. A simulation test, in which specimens were prepared by casting steels in accordance with the compositions of the martensite layer, was conducted to evaluate the fracture toughness of the martensite layer. The experiments were also made to investigate the distribution of toughness in the different regions of the joints. The results show that the weakest region in toughness in the dissimilar metal joints is not the martensite layer but the overheated zone in HAZ.

Zhiui Wang; Biyu Xu; Ciqi Ye (Beijing Polytechnic Univ., Beijing (China). Dept. of Materials Science and Engineering)

1993-08-01

251

A new perspective on the influence of thickness and post-weld heat treatment for large scale welded joints  

Microsoft Academic Search

CTOD, Charpy, and wide plate results from welded constructional steels are collected from nine companies. The resulting large data bank is analyzed statistically to identify general trends in properties of welded constructional steels. The present paper uses the data bank to review the effect of post-weld heat treatment (PWHT) on the fracture behavior of the weldments. Analysis shows the beneficial

P. Hancock; J. P. Chubb; J. Spurrier

1995-01-01

252

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

253

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

USGS Publications Warehouse

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

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

2011-01-01

254

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

255

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

SciTech Connect

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

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

2011-01-15

256

Numerical study of local PWHT condition for EB welded joint between first and side walls in ITER-TBM  

NASA Astrophysics Data System (ADS)

The stress relaxation behavior of post-weld heat treatment (PWHT) F82H was examined to determine the appropriate PWHT condition for electron beam welded joints between the first and side walls of the International Thermonuclear Experimental Reactor (ITER) test blanket module. Thermal elastic-plastic creep finite element analyses were conducted assuming Norton creep law. Uniform heat treatment and four types of local heating near the weld line were studied. Numerical analyses concluded that the welding residual stress could be reduced by a local heat treatment near the penetration from both the first and side walls, where the cooling area and rate could be controlled. In addition, the stress on the channel surface in the first wall was found to decrease to less than 50 MPa with the appropriate local PWHT.

Serizawa, Hisashi; Nakamura, Shinichiro; Tanigawa, Hiroyasu; Ogiwara, Hiroyuki; Murakawa, Hidekazu

2013-11-01

257

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

258

Influence of aluminum, silicon, and copper on the properties of composite welded joints in an iron base  

Microsoft Academic Search

The properties of welded steel-aluminum joints is governed to a considerable extent by the type of plating preliminarily applied to the steel and the dimensions and character of the diffusion layer produced at the boundary between the iron and molten aluminum [1]. The present investigation completed our study of the influence of alloying Of the iron base on the properties

V. R. Ryabov; V. I. Yumatova

1975-01-01

259

Development of Mathematic Model of Cold Welding at Drawing-up the Flange Joint of Pneumohydraulic Systems  

NASA Astrophysics Data System (ADS)

Provision of high airtightness of joints of pipe- lines of pneumohydraulic systems (PHS) operating under high pressure, is an important task for designing and operation of launch vehicles. In the process of assembly and tests of PHS of launch vehicles, it was found that detachable flange joints do not lose their airtightness after removal of fastening elements, even in conditions of standard loads. The task of this work is in studying a phenomenon connected with initiation of the observed effect of adhesion and also stresses in the zone of contact at drawing- up the flange detachable joints with a plastic gasket. Investigations have shown that density of the joint is kept due to cold welding, as the created conditions are helpful for that process. As a result of the investigations performed, we have developed a mathematic model which is based on application of the theory of metal bonds; that theory explains the essence of the effect observed. Basic factors which provide optimum mode of cold welding, are effort which can cause microplastic deformation and form maximum contact, and also quality of processing the material of the surfaces joined. Strength of all- metal joint depends on factual area of contact. So, surface processing quality defines a configuration of microbulges which come into contact not simultaneously, and their stressed state is different, and it influences the character of dependence of the contact area on loading. Results of calculations by the mathematic model are expressed by dependencies of factual area of contact and a single diameter of the contact spot on the load applied which compresses the materials with various physical properties, and on the surface processing quality. The mathematic model allows to explain the common character of the cold welding process in detachable flange joints with the plastic gasket, to determine the nature and the character of acting forces, to define kinetics and the mechanism of formation of cold welding of detachable joints. It also helps to analyze the state of airtightness and to metal welding technology in the plastic state at drawing- up of detachable flange joints with a plastic gasket and to review cold welding as a positive phenomenon.

Boyko, Y. S.

2002-01-01

260

Finite element analysis for the initiation of lamellar tearing in welded joints  

SciTech Connect

A numerical procedure using the finite element method is presented for predicting the initiation of lamellar tearing in fillet welded T-joints commonly employed in large structures. Starting with a prescribed geometry, the welding process is approximated by a known time-dependent volumetric heat source which simulates the arc heating and deposition of liquid metal. The transient nonlinear thermal and stress problems are then solved using finite element computer codes. Results of the elastic-plastic stress analysis are presented showing a predicted region of incipient lamellar tearing based on a ductile fracture theory which qualitatively agrees with the size and location of tears typically observed in photomicrographs. Additional insight into post failure crack length and stability is presented based on a simplified linear elastic fracture mechanics approach. Although the analysis procedure shows signs of promise, several weak points in the model are pointed out which must be improved before lamellar tearing can be quantified in an approach of this general type.

Krieg, R.D.; Thomas, R.K.

1980-01-01

261

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

262

RESISTANCE SPOT REPAIR WELDING OF SPOT WELDED STEEL SHEET  

Microsoft Academic Search

Repeated resistance spot repair welding over the poor spot weld and interface fractured spot weld of low carbon steel sheet has been studied. The repair welding has been carried out at different parameters to optimize the welding current, weld time, and electrode force as the primary welding parameters for maximum joint strength. The optimum strengths of the repaired weld under

P. K. Ghosh; Vinay Kumar Patel

2005-01-01

263

Numerical simulation of mechanical stress relieving in a multi-pass GTA girth welded pipe flange joint to reduce IGSCC  

NASA Astrophysics Data System (ADS)

Welding of piping components produces highly non-uniform residual stresses in the weldment which consequently affect material structural response under loading and also expedite origination/propagation of defects such as stress corrosion cracking and brittle fracture. For welding-induced residual stresses, mechanical stress relieving (MSR) is one of the mitigation techniques to improve the service life of pressure vessel components. However, its application to piping systems is rarely reported in the literature. This paper presents a two-dimensional axisymmetric finite element model of a pipe-flange joint subjected to a multi-pass girth welding followed by an MSR process. Sequentially coupled non-linear transient thermo-mechanical analysis for multi-pass gas tungsten arc welding is first performed to calculate welding residual stresses. Subsequently separate parametric studies for three different types of MSR load including internal pressure, external pressure and axial pull are performed on the pre-stressed model, and stress relieving behaviour is studied. It is concluded that both the internal pressure and axial pull have a significant effect on residual stresses on the inner surface of the joint.

Siddique, Muhammad; Abid, Muhammad

2005-12-01

264

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

265

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

266

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

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.

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

1998-01-01

268

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

269

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

270

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

Microsoft Academic Search

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

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

2009-01-01

271

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

Microsoft Academic Search

The nanostructured ferritic alloy (NFA) MA957 was joined by friction stir welding (FSW) and electro-sparked deposition (ESD) welding. Transmission electron microscopy (TEM) and small angle neutron scattering (SANS) characterization studies showed a uniform fine-scale equiaxed ferrite structure with a high dislocation density and slightly coarsened nm-scale particles in the joint region of the FSW weld compared to the base metal.

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

2007-01-01

272

On the occurrence of Portevin-Le Chatelier effect in fusion welded 2091 Al-Li based alloy joints  

SciTech Connect

Al-Li based alloys are characterized by their lower density and higher stiffness, in comparison with conventional aluminum alloys. This makes the former very attractive for replacing the latter in structural and cryogenic applications, particularly in aeronautic and aerospace industries. The potential use of lithium-bearing also has stimulated studies on the weldability of these alloys as well as on the mechanical properties of the resulting welded joints. Al-Li-Cu-Mg alloy systems studied by Gomiero were found to exhibit serrations in their stress-strain curves, indicating the occurrence of Portevin-Le Chatelier (PLC) effects during plastic flow in these systems. The present study was therefore undertaken to determine the effect of fusion welding on the uniaxial tensile behavior of a 2091 (Al-Li-Cu-Mg-Zr) alloy. Microstructural aspects pertinent to the PLC effect are to be emphasized and the influence of post-weld heat treatment is to be presented and discussed.

Vidal, A.C.; Darwish, F.A.; Solorzano, I.G. [Catholic Univ., Rio de Janeiro (Brazil)] [Catholic Univ., Rio de Janeiro (Brazil)

1995-09-01

273

The effect of yield strength mis-match on the fracture analysis of welded joints: slip-line field solutions for pure bending  

Microsoft Academic Search

Plane strain and plane stress slip-line solutions for single notched bending specimens with a central mismatched welded joint have been derived. The crack has been located on the fusion line (interface) and at the middle of the weld metal. 2D and 3D finite element analysis has been performed to verify the theoretical results and to investigate the effect of specimen

S. Hao; K.-H. Schwalbe; A. Cornec

2000-01-01

274

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

275

Method of welding joint in closed vessel improves quality of seam  

NASA Technical Reports Server (NTRS)

To facilitate welding of closed vessels, a metal backup strip is used at the junction inside the vessel. After welding from the outside, this strip is dissolved by a chemically reactive solvent poured through a filler hole into the vessel.

Freeman, R.; Levoe, C.

1964-01-01

276

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

277

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

278

Development of Residual Stress Improvement for Nuclear Pressure Vessel Instrumentation Nozzle Weld Joint (P-43+P-8) by Means of Induction Heating  

SciTech Connect

As a counter measurement of intergranular stress corrosion cracking (IGSCC) in boiling water reactors, the induction heating stress improvement (IHSI) has been developed as a method to improve the stress factor, especially residual stresses in affected areas of pipe joint welds. In this method, a pipe is heated from the outside by an induction coil and cooled from the inside with water simultaneously. By thermal stresses to produce a temperature differential between the inner and outer pipe surfaces, the residual stress inside the pipe is improved compression. IHSI had been applied to weld joints of austenitic stainless steel pipes (P-8+P-8). However IHSI had not been applied to weld joints of nickel-chromium-iron alloy (P-43) and austenitic stainless steel (P-8). This weld joint (P-43+P-8) is used for instrumentation nozzles in nuclear power plants' reactor pressure vessels. Therefore for the purpose of applying IHSI to this one, we studied the following: Investigation of IHSI conditions (Essential Variables); Residual stresses after IHSI; Mechanical properties after IHSI. This paper explains that IHSI is sufficiently effective in improvement of the residual stresses for this weld joint (P-43+P-8), and that IHSI does not cause negative effects by results of mechanical properties, and IHSI is verified concerning applying it to this kind of weld joint. (authors)

Takuro Terajima; Takashi Hirano [Ishikawajima-Harima Heavy Industies Co., Ltd (Japan)

2006-07-01

279

Microstructure and pitting corrosion of friction stir welded joints in 2219-O aluminum alloy thick plate  

Microsoft Academic Search

Effect of welding parameters on the microstructure and pitting corrosion of different positions along the thickness of weld nugget zone in friction stir welded 2219-O aluminum alloy plate was investigated using scanning electron microscopy (SEM), polarization experiment and electrochemical impedance tests (EIS). It was found that the material presents significant passivation and the top has best corrosion resistance compared to

Weifeng Xu; Jinhe Liu

2009-01-01

280

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

281

Weld penetration and defect control  

NASA Astrophysics Data System (ADS)

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 necessity. 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.

1992-05-01

282

Periscope For Viewing Weld Penetration  

NASA Technical Reports Server (NTRS)

Periscope enables viewing of weld joint from inside cylindrical duct to determine when weld penetration occurs. Supplies steady stream of inert gas to shield joint. Device used to calibrate and evaluate techniques for sensing weld penetration.

Gordon, Stephen S.; Marman, Jonathan M.

1988-01-01

283

Welding Many Thin Metal Layers  

NASA Technical Reports Server (NTRS)

Electron-beam welding yields reliable, leakproof joints. Welding bands (also called "doublers") sandwiched between layers welded to increase final weld-section thickness. New technique ensures repeatable leakproof assemblies.

Hartwell, B. O.; Caras, P.; Hobbes, P. H.

1985-01-01

284

Development of simple model for creep analysis of thick welded joints (1st report): Creep characteristics of thick welded joints and their improvement  

Microsoft Academic Search

To ensure the safety of high?temperature facilities, such as fast breeder reactors, throughout their service life, it is necessary to be able to predict their creep deformation with sufficient accuracy. The welds produced in the thick plates of these facilities have an extremely complex thermal history and therefore extremely in?homogeneous characteristics, including creep behaviour. This makes it difficult and laborious

K. Nakacho; Y. Ueda; J. Kinugawa; M. Yamazaki

1994-01-01

285

Effects of strain-rate and pre-fatigue on tensile properties of laser welded joint of high strength steel plates  

Microsoft Academic Search

The impact tensile properties of laser welded butt joints of two kinds of high strength steel plates with the tensile strength level of 590 MPa and 780 MPa (denoted by HR590 and HR780, respectively), were investigated using split Hopkinson bar tensile testing apparatus. Impact tension tests for the joint specimens pre-fatigued were also carried out to examine the effect of

H. Kobayashi; M. Daimaruya; H. Tsuda; K. Horikawa

2006-01-01

286

Mechanical properties of laser-welded cast titanium joints under different conditions  

Microsoft Academic Search

Statement of the problem. Data on optimal conditions for laser welding commercial pure cast titanium used in dental restorations are sparse and not well established.Purpose. The mechanical properties of laser-welded cast commercially pure titanium under different laser welding conditions were evaluated to find the optimal parameters in terms of duration and voltage (energy level).Material and methods. Fifty-seven cast pure titanium

Tsongi Chai; Chia Kai Chou

1998-01-01

287

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

Microsoft Academic Search

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

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

2008-01-01

288

Robotic welding  

SciTech Connect

The purpose of this book is to provide the reader with the latest up-to-date information on robotic welding, associated components, and systems. This information has been compiled on automatic robotic arc welding systems which are presently employed and being worked on for future applications along with various adaptive control techniques and welt joint seam,-tracking systems being investigated for continuous robotic arc welding. In addition to arc welding, robotic resistance welding and laser welding systems and applications are presented with the idea of illustrating detailed knowledge on the most established and the newest robotic integrated systems, respectively.

Lane, J.D.

1986-01-01

289

Interfacial microstructure and strength of steel\\/aluminum alloy joints welded by resistance spot welding with cover plate  

Microsoft Academic Search

We joined aluminum alloy A5052 to cold-rolled steel SPCC (Steel Plate Cold Commercial) and austenitic stainless steel SUS304 using resistance spot welding with a cover plate. The interfacial microstructure was observed using transmission electron microscopy. A thick two-layered reaction layer contains Fe2Al5 and FeAl3 and a thin serration reaction layer contains Fe2Al5 and FeAl3 were observed at the A5052\\/SPCC and

Ranfeng Qiu; Chihiro Iwamoto; Shinobu Satonaka

2009-01-01

290

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

291

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

292

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

293

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

NASA Astrophysics Data System (ADS)

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

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

294

Optimization of pulsed GTA welding process parameters for the welding of AISI 304L stainless steel sheets  

Microsoft Academic Search

Optimization of pulsed gas tungsten arc welding (pulsed GTAW) process parameters was carried out to obtain optimum weld bead\\u000a geometry with full penetration in welding of stainless steel (304L) sheets of 3 mm thickness. Autogenuous welding with square\\u000a butt joint was employed. Design of experiments based on central composite rotatable design was employed for the development\\u000a of a mathematical model correlating

P. K. Giridharan; N. Murugan

2009-01-01

295

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

296

Thermal modeling and adaptive control of scan welding  

SciTech Connect

This article introduces scan welding as a redesign of classical joining methods, employing automation technology to ensure the overall geometric, material and mechanical integrity of the joint. This is obtained by real-time control of the welding temperature field by a proper dynamic heat input distribution on the weld surface. This distribution is implemented in scan welding by a single torch, sweeping the joint surface by a controlled reciprocating motion, and power adjusted by feedback of infrared temperature measurements in-process. An off-line numerical simulation of the thermal field in scan welding is established, as well as a linearized multivariable model with real-time parameter identification. An adaptive thermal control scheme is thus implemented and validated--both computationally and experimentally on a robotic plasma arc welding (PAW) station. The resulting thermal features related to the generated material structure and properties of the joint are finally analyzed in scan welding tests and simulations.

Doumanidis, C.C. [Tufts Univ., Medford, MA (United States). Dept. of Mechanical Engineering

1998-11-01

297

Deconvoluting the Friction Stir Weld Process for Optimizing Welds  

NASA Technical Reports Server (NTRS)

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

Schneider, Judy; Nunes, Arthur C.

2008-01-01

298

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

299

A sub-structural analysis of friction stir welded joints in an AA6056 Al-alloy in T4 and T6 temper conditions  

Microsoft Academic Search

Friction stir welds in an Al-alloy AA6056 in T4 and T6 temper were investigated in terms of grain structure, dislocation density and second phase particles at the different zones of the welded joint. These results were subsequently compared with the unaffected base material. The aim of this investigation was to understand the metallurgical phenomena controlling the microstructural evolution associated with

C. A. W. Olea; L. Roldo; J. F. dos Santos; T. R. Strohaecker

2007-01-01

300

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

Microsoft Academic Search

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

Algirdas Vaclovas VALIULIS

2007-01-01

301

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

302

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

NASA Astrophysics Data System (ADS)

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

Adamiec, J.

2011-05-01

303

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

304

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

305

Fatigue strength evaluation of cross-tension spot weld joints of cold rolled mild steel sheet  

Microsoft Academic Search

In this study, cross-tension type specimens of cold rolled mild steel sheet were prepared varying the welding conditions in order to investigate the effect of welding time and current on the tensile strength and fatigue life. A decrease of 2kA from the normal current condition of 10kA caused a large amount of reduction in both the static joining strength and

Doo-Hwan Kim; Ho-Kyung Kim

2009-01-01

306

Fatigue Strength Prediction of Spot-Welded Joints Using Small Specimen Testing  

Microsoft Academic Search

It is well known that fatigue strength of spot weld of high strength steel sheet is not improved, compared with that of mild\\u000a steel sheet. In this study, the governing factors and the effects of steel grade on fatigue strength of spot weld is investigated.\\u000a Firstly, small specimens with total length of less than 3mm are taken from the spot

Eisuke Nakayama; Manabu Fukumoto; Mitsuo Miyahara; Kazuo Okamura; Hiroki Fujimoto; Kiyoyuki Fukui

307

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

308

Optimizing friction stir welding parameters to maximize tensile strength of AA2219 aluminum alloy joints  

Microsoft Academic Search

AA2219 aluminium alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring\\u000a a high strength-to-weight ratio and good corrosion resistance. In contrast to the fusion welding processes that are routinely\\u000a used for joining structural aluminium alloys, the friction stir welding (FSW) process is an emerging solid state joining process\\u000a in which the material that is being

S. Babu; K. Elangovan; V. Balasubramanian; M. Balasubramanian

2009-01-01

309

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

Microsoft Academic Search

The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile\\u000a properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite\\u000a and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in

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

2011-01-01

310

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

311

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

312

Experimental and calculated evaluation of the supporting capacity of steel 13KhGMF welded joints in the low endurance region  

SciTech Connect

In recent years thermally-hardened low-alloy steel 13KhGMF, which exhibits high mechanical properties and good weldability, has found use in hydrotechnical structures. In this work, besides studying static and cyclic properties of individual zones of butt joints in steel 13KhGMF, consideration is given to regularities of deformation and failure for welded joints made by the methods indicated with measurement of the geometric parameters of the joints, and a calculated evaluation is also given for their supporting capacity in the region of loading cycles not exceeding 10/sup 5/. The results show that the mechanical properties of the different zones of joints made by manual and electroslag welding differ markedly. The metal resistance of different joints to low-cycle failure is presented. A comparison is shown of experimental and calculated curves for the development of a fatigue crack in welded joints of steel 13KhGMF. The effect of nonuniformity in mechanical properties on the supporting capacity of joints in steel 13KhGMF is shown to be most marked in the quasistatic failure region.

Yakubovskii, V.V.

1987-03-01

313

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

314

Effect of 0.5 wt.% hydrogen addition on microstructural evolution of Ti–6Al–4V alloy in the friction stir welding and post-weld dehydrogenation process  

Microsoft Academic Search

The ?+? titanium alloy, Ti–6Al–4V, was thermohydrogen processed with 0.5wt.% hydrogen and friction stir welded using a W–Re pin tool. Defect-free joints were obtained with proper parameters. Hydrogen was removed from the joint through a post-weld dehydrogenation process. The microstructures of the as-welded and dehydrogenated joints were examined. The effect of 0.5wt.% hydrogen addition on microstructural evolution of Ti–6Al–4V alloy

L. Zhou; H. J. Liu

2011-01-01

315

Effect of Pre-Fatigue on Dynamic and Static Tensile Properties of Laser Welded Butt Joints Between Different High Strength Steel Plates  

Microsoft Academic Search

In this research, the effects of pre-fatigue on the dynamic and quasi-static tensile properties of laser welded butt joints between three kinds of steel plates, i.e. HR270, HR590 and HR780 steels, were investigated using tensile split Hopkinson bar apparatus. There were no significant effects of pre-fatigue on the dynamic and static tensile properties of HR780-HR270 and HR780-HR590 joints. Their fracture

H. Kobayashi; M. Daimaruya; H. Tsuda; K. Horikawa; Y. Yamada

2008-01-01

316

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

317

Annealing temperature effects on super duplex stainless steel UNS s32750 welded joints. I: microstructure and partitioning of elements  

Microsoft Academic Search

Welding of austenitic-ferritic stainless steels is a crucial operation and all the materials and parameters used in this process\\u000a must be optimized in order to obtain the suitable corrosion and mechanical properties. Since a great part of super duplex\\u000a stainless steels is used in very aggressive environment, their corrosion resistance, referred in particular to pitting and\\u000a crevice corrosion, is an

R. Cervo; P. Ferro; A. Tiziani

2010-01-01

318

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

319

Microstructure and hardness of friction stir welded 7075 aluminium alloy joints  

Microsoft Academic Search

Friction stir welding (FSW) is a process which induces a reduction in flow stress owing to friction heat generated by pressing a protruded object into a solid material and rotating it at high speed. It induces part of the material to have plastic flow owing to friction force in order to join materials together. The FSW method was developed for

T. Shibayanagi; M. Maeda

2005-01-01

320

Identification of diffusion parameters in welded joints of titanium and its alloys  

Microsoft Academic Search

Titanium and its alloys may experience a progressive embrittlement leading to catastrophic failure. Such embrittlement is a consequence of hydrogen migration and the accumulation of brittle titanium hydrides in the presence of a sharp alloy composition gradient near a weld fusion line. The governing equations for such migration are presented. The identification problem for parameters responsible for this phenomenon is

Andrzej Sluzalec

2009-01-01

321

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

322

Fatigue reliability-based assessment of welded joints applying consistent fracture mechanics formulations  

Microsoft Academic Search

Design of welded structures for fatigue limit state is normally carried out by means of either single- or two-sloped SN curves. To properly assess the effect of an inspection and repair strategy of structures degrading due to crack growth, fracture mechanics (FM) models need to be applied to describe crack propagation. To provide a proper tool for making decisions regarding

Efren Ayala-Uraga; Torgeir Moan

2007-01-01

323

Performance of cold formed welded tubular steel joints under moment loading.  

E-print Network

??Includes abstract. Although exhibiting many superior properties to open sections structural hollow sections (SHS) have seen limited application in structures where joints resist moments. Their… (more)

Mudenda, Kenny.

2008-01-01

324

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

325

Fatigue Analysis of Welding Seams and Spot Joints in Automotive Structures  

Microsoft Academic Search

For lightweight automotive structures, the stiffness and the fatigue behaviour is greatly influenced by the properties of its joints. The used joining technology, the number and locations of the spot joints are of high importance for both engineers and cost accountants. An overview of common computational procedures including European and national standards is given for the assessment of the stiffness

Helmut Dannbauer; Christian Gaier; Klaus Hofwimmer

326

Fatigue crack initiation life prediction in high strength structural steel welded joints  

NASA Astrophysics Data System (ADS)

The local approach method is used to calculate the fatigue crack initiation/early crack growth lives (N(i)) in high strength structural steel weldments. Weld-toe geometries, welding residual stresses and HAZ (heat affected zone) cyclic mechanical properties are taken into account in the N(i) estimation procedure. Fatigue crack initiation lives are calculated from either a Basquin type or a Manson-Coffin type equation. The local (HAZ) stress and strain amplitudes and the local mean stress are determined from an analysis based on the Neuber rule and the Molski-Glinka energy approach. The accuracy of the different methods is evaluated and discussed. Finally the previous methods are used with HAZ cyclic mechanical properties estimated from hardness measurements.

Tricoteaux, A.; Fardoun, F.; Degallaix, S.; Sauvage, F.

1995-02-01

327

Multiple-beam irradiation effects in electron-beam-welded F82H joint  

NASA Astrophysics Data System (ADS)

Electron-beam-welded reduced-activation ferritic/martensitic steel F82H, which is one of prime candidate materials for experimental fusion reactors, have been irradiated by electron and helium ion beams using a High Voltage Electron Microscope (HVEM) as the experimental evaluation of the modeling and simulations. Growth rate and saturated number density of dislocation loops have been measured to calculate the migration energies of point defects. Electron irradiation experiment indicated that net migration energy of vacancy in the welded metal of F82H tended to be lower compared to that in base metal, which could be relating to difference of carbon concentration in matrix. In the case of dual beam (electron and helium) irradiation, net migration energies of vacancy were slightly higher than that in electron beam irradiation. This result indicates that vacancy would be trapped by implanted helium due to their strong interaction and appeared to have higher migration energy.

Hashimoto, N.; Tanigawa, H.; Kinoshita, H.; Ohnuki, S.

2011-10-01

328

SELECTED ALGORITHMS OF BACKGROUND GENERATION USED FOR FLAW DETECTION IN WELDED JOINTS  

SciTech Connect

Effectiveness of flaws detection process using various algorithms of background generation and various algorithms of image thresholding was evaluated. The results of background generation using a median filter method, a polynomial approximation method and an iterative Gaussian approximation method were presented. The received background images were subtracted from the base image. After background subtraction process the global and local thresholding algorithms were applied. All analysis were carried out using digital radiographs of real welds.

Chady, T.; Caryk, M. [Szczecin University of Technology, Department of Electrical Engineering, 70-313 Szczecin (Poland)

2008-02-28

329

Heat Insulators for Heat Treatment of Welded Joints in Power Equipment  

Microsoft Academic Search

Preweld heat treatment is a routine technological operation in the installation and repair of steam lines; much of its success is centered on the proper choice and application of heat-insulating materials. The material for steam lines are heat-resistant steels of grades 12KhMF (12Cr-Mo-V), 15Kh1M1F (12Cr-1Mo-1V) and others, which, after welding operations, are subjected to high-temperature annealing. The heat treatment cycle

S. G. Parshin

2004-01-01

330

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

331

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

332

Sensor fusion using neural network in the robotic welding  

SciTech Connect

It is important to realize intelligent welding robots to obtain a good quality of the welding results. For this purpose, it is required to detect the torch height, the torch attitude, the deviation from the center of the gap. In order to simultaneously detect those, the authors propose the sensor fusion by using the neural network, i.e., the information concerning the welding torch is detected by using both the welding current and the welding voltage. First, the authors deal with the welding phenomena as the melting phenomena in the electrode wire of the MIG welding and the CO{sub 2} short circuiting welding. Next, the training data of the neutral networks are made from the numerical simulations. The neuro arc sensor is trained so as to get the desired performance of the sensor. By using it, the seam tracking is carried out in the T-joint.

Ohshima, Kenji; Yabe, Masaaki; Akita, Kazuya; Kugai, Katsuya; Yamane, Satoshi [Saitama Univ., Urawa, Saitama (Japan); Kubota, Takefumi [Himeji Inst. of Tech., Himeji, Hyougo (Japan)

1995-12-31

333

Influence of welding consumables on high cycle fatigue life of flux cored Arc welded high strength, quenched and tempered steel joints  

Microsoft Academic Search

Quenched and tempered (Q&T) steels are prone to hydrogen induced cracking after welding. Austenitic stainless steel (ASS)\\u000a welding consumables are traditionally used for welding of high hardness, Q&T steels as they have higher solubility for hydrogen\\u000a in the austenitic phase. The use of stainless steel consumables for a non stainless steel base metal is not economical. Hence,\\u000a in the present

Govindaraj Magudeeswaran; Visvalingam Balasubramanian; Gankidi Madhusudhan Reddy

2008-01-01

334

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

335

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

336

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

E-print Network

Modulus Tests and Tensile Tests .............................28 Section 3.4 Rockwell Hardness Testing fabrication, material characteristics, statistical analysis of fatigue testing results, a comparison of material selection in the fatigue life of HSS Y-joints. All fabrication of components, besides the test

Foley, Christopher M.

337

Dual wire welding torch and method  

SciTech Connect

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

338

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

339

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

340

Analysis of the Creep Behavior of P92 Steel Welded Joint  

NASA Astrophysics Data System (ADS)

Different regions of heat-affected zone (HAZ) were simulated by heat treatment to investigate the mechanisms of the Type IV fracture of P92 (9Cr-2W) steel weldments. Creep deformation of simulated HAZ specimens with uniform microstructures was investigated and compared with those of the base metal (BM) and the weld metal (WM) specimens. The results show that the creep strain rate of the fine-grained HAZ (FGHAZ) is much higher than that of the BM, WM, the coarse-grained HAZ (CGHAZ), and the inter-critical HAZ (ICHAZ). According to the metallurgical investigation of stress-rupture, the FGHAZ and the ICHAZ have the most severely cavitated zones. During creep process, carbides become coarser, and form on grain boundaries again, leading to the deterioration of creep property and the decline of creep strength. In addition, the crack grows along the FGHAZ adjacent to the BM in the creep crack growth test (CCG) of HAZ.

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

2011-11-01

341

Sheet metal welding using a pulsed Nd: YAG laser-robot  

NASA Astrophysics Data System (ADS)

This paper presents a pulsed Nd: YAG laser-robot system for spot and seam welding of mild steel sheets. The study evaluates the laser beams behaviour for welding, and then investigates pulsed Nd: YAG laser spot and seam welding processes. High pulse power intensity is needed to initiate the key-hole welding process and a threshold pulse energy to reach full penetration. In seam welding, a weld consists of successive overlapping spots. Both high pulse energy and high average power are needed to keep the key-hole welding going. A 70% overlap is used to define overlapping spot welding as seam welding and to optimize process parameters because a high tensile strength joint compatible with the strength of the base material can be obtained when the overlap is ? 70%; at the same time a smooth seam with full penetration is obtained. In these cases, the joints in pulsed Nd: YAG laser welding are comparable in strength to those obtained with CO 2 laser welding. Robot positioning and motion accuracies can meet the demands of Nd: YAG laser sheet metal welding, but its cornering accuracy affects the welding processes. The purpose of the study is to evaluate the YAG laser-robot system for production in the automotive industry.

Huang, Qi; Kullberg, Gunnar; Skoog, Hans

342

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

343

Diffusion welding of SUS304L stainless steel to titanium  

Microsoft Academic Search

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

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

1996-01-01

344

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

345

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

346

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

347

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

348

Microstructure of the interface in magnesium alloy to aluminium alloy dissimilar joints produced by friction stir welding  

Microsoft Academic Search

Friction stir welding (FSW) is a process that was developed by the UK Welding Institute (TWI) in 1991. Because of its status as a solid-phase joining process operating at a temperature below the melting point of the materials being joined, FSW usually generates less residual stress than fusion welding, being also advantageously free from fume, porosity, and solidification cracking. The

S. Hirano; K. Okamoto; M. Doi; O. Kamura; M. Inagaki; Y. Aono

2004-01-01

349

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

E-print Network

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

Paris-Sud XI, Université de

350

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

351

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

352

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

E-print Network

(spot weld + adhesive bonding) are widely used in a number of industries. Spot welding that combines the stiffness and productivity benefits of adhesive bonding with the proven-technology attributes aluminum is amenable to both spot welding and adhesive bonding, composites will, most likely, be entirely

Giurgiutiu, Victor

353

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

354

Robotic welding  

Microsoft Academic Search

The purpose of this book is to provide the reader with the latest up-to-date information on robotic welding, associated components, and systems. This information has been compiled on automatic robotic arc welding systems which are presently employed and being worked on for future applications along with various adaptive control techniques and welt joint seam,-tracking systems being investigated for continuous robotic

1986-01-01

355

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

NASA Astrophysics Data System (ADS)

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

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

356

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

357

The variable polarity plasma arc welding process: Characteristics and performance  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

358

Automated Variable-Polarity Plasma-Arc Welding  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

359

Efficient weld seam detection for robotic welding based on local image processing  

Microsoft Academic Search

Purpose – The weld seam detection is required for a welding robot to preplan the weld seam track before the actual welding. The purpose of this paper is to investigate this subject in natural lighting conditions. Design\\/methodology\\/approach – This paper presents an efficient algorithm of weld seam detection for butt joint welding from a single image. The basic idea of

Fanhuai Shi; Tao Lin; Shanben Chen

2009-01-01

360

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

361

The choice of welding parameters and prediction of weld seam dimensions for welding rapid prototyping  

Microsoft Academic Search

The data of welding seam width and height were obtained by TIG welding experiments. Two models were established using BP neural networks: One can predict the weld seam dimensions by inputting the welding parameters, and the other model can perform oppositely. Originally by inputting given welding seam dimensions to the model one, the welding parameters can be predicted. Then change

Jian-ning Xu; Hua Zhang; Guang-yun Zhang; Yu-long Li; Rong-hua Hu

2008-01-01

362

The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys  

NASA Astrophysics Data System (ADS)

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

Güler, Hande

2014-09-01

363

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

364

Adaptive welding of fillet welds using a fast seam-tracking sensor in combination with a standard industrial robot  

NASA Astrophysics Data System (ADS)

In laser welding, problems often arise from the accuracy required by the laser process, particularly where joints have narrow tolerance limits, e.g. with a fillet weld at an overlap joint. In a number of applications seam-tracking sensors can improve this situation. They are able to detect and follow the joint geometry autonomously. In addition to the tolerances, a varying gap between the parts to weld can cause welding flaws. To solve the problems caused by the height of the gap a functionality for adaptive welding can be integrated into the tracking sensor, rendering possible a determined influence on process parameters. Functional dependencies between the height of the gap and the welding parameters are presented in this paper. To further enhance the accuracy of path tracking the dynamic behavior of the system is investigated. With the integration of these dependencies into the tracking sensor, an algorithm for adaptive welding has been obtained, which takes another step towards the raise of profitability of laser installations by a simplified weld seam preparation and an enhanced stability of the welding process.

Pischetsrieder, Alexandra

1996-08-01

365

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

366

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

367

Automated and aluminum welding technology  

NASA Astrophysics Data System (ADS)

Automated welding technology and techniques for welding advanced aluminum alloys with potential for industrial and commercial applications have been developed by the National Aeronautics and Space Administration at the Marshall Space Flight Center. These technologies are being offered to private companies for commercial development, and include: Variable polarity plasma arc welding, a welding process that produces high-quality aluminum welds for fabrication of the space shuttle external tank and space station common module structures. This process uses reverse polarity pulses to produce welds virtually free of internal defects. Advanced weld sensor technology, comprised of machine vision-based weld seam tracking that uses both structured and global laser illumination for finding weld joints, even those difficult to discern by the human eye. Weld pool feedback is accomplished with a vision system to measure arc symmetry and molten weld pool geometry. A weld bead profiler trails the welding torch. It provides feedback to the process control system, which records quality control data.

Jones, Clyde S.

1994-10-01

368

Welding Tubes In Place  

NASA Technical Reports Server (NTRS)

Special welding equipment joins metal tubes that carry pressurized cyrogenic fluids. Equipment small enough to be used in confined spaces in which such tubes often mounted. Welded joints lighter in weight and more leak-proof than joints made with mechanical fittings.

Meredith, R.

1984-01-01

369

Comparative and Joint Analysis of Two Metagenomic Datasets from a Biogas Fermenter Obtained by 454-Pyrosequencing  

PubMed Central

Biogas production from renewable resources is attracting increased attention as an alternative energy source due to the limited availability of traditional fossil fuels. Many countries are promoting the use of alternative energy sources for sustainable energy production. In this study, a metagenome from a production-scale biogas fermenter was analysed employing Roche's GS FLX Titanium technology and compared to a previous dataset obtained from the same community DNA sample that was sequenced on the GS FLX platform. Taxonomic profiling based on 16S rRNA-specific sequences and an Environmental Gene Tag (EGT) analysis employing CARMA demonstrated that both approaches benefit from the longer read lengths obtained on the Titanium platform. Results confirmed Clostridia as the most prevalent taxonomic class, whereas species of the order Methanomicrobiales are dominant among methanogenic Archaea. However, the analyses also identified additional taxa that were missed by the previous study, including members of the genera Streptococcus, Acetivibrio, Garciella, Tissierella, and Gelria, which might also play a role in the fermentation process leading to the formation of methane. Taking advantage of the CARMA feature to correlate taxonomic information of sequences with their assigned functions, it appeared that Firmicutes, followed by Bacteroidetes and Proteobacteria, dominate within the functional context of polysaccharide degradation whereas Methanomicrobiales represent the most abundant taxonomic group responsible for methane production. Clostridia is the most important class involved in the reductive CoA pathway (Wood-Ljungdahl pathway) that is characteristic for acetogenesis. Based on binning of 16S rRNA-specific sequences allocated to the dominant genus Methanoculleus, it could be shown that this genus is represented by several different species. Phylogenetic analysis of these sequences placed them in close proximity to the hydrogenotrophic methanogen Methanoculleus bourgensis. While rarefaction analyses still indicate incomplete coverage, examination of the GS FLX Titanium dataset resulted in the identification of additional genera and functional elements, providing a far more complete coverage of the community involved in anaerobic fermentative pathways leading to methane formation. PMID:21297863

Jaenicke, Sebastian; Ander, Christina; Bekel, Thomas; Bisdorf, Regina; Droge, Marcus; Gartemann, Karl-Heinz; Junemann, Sebastian; Kaiser, Olaf; Krause, Lutz; Tille, Felix; Zakrzewski, Martha; Puhler, Alfred

2011-01-01

370

Microstructure and XRD analysis of FSW joints for copper T2\\/aluminium 5A06 dissimilar materials  

Microsoft Academic Search

Copper (T2) and aluminium alloy (5A06) were welded by friction stir welding (FSW). The microstructure, mechanical properties and phase constituents of FSW joints were studied by metallography, tensile testing machine and X-ray diffraction. The results indicated that the high quality weld joint could be obtained when tool rotational speed is 950 rpm, and travel speed is 150 mm\\/min. The maximum value of

Peng Liu; Qingyu Shi; Wei Wang; Xin Wang; Zenglei Zhang

2008-01-01

371

Shipyard Welding - Applicability of Firecracker Welding to Ship Production.  

National Technical Information Service (NTIS)

Firecracker welding is a technique in which standard electrodes are used to automatically produce welds by placing them in the groove, starting the arc, and allowing it to travel along the joint. The report establishes procedures, specifies the operating ...

W. C. Brayton, R. M. Evans, R. P. Neister

1975-01-01

372

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)  

Microsoft Academic Search

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.

Musubu Koishi; Koichi Nishizawa; Shigeru Kawai

2011-01-01

373

Preliminary study on the microstructure and mechanical properties of dissimilar friction stir welds in aircraft aluminium alloys 2024-T351 and 6056-T4  

Microsoft Academic Search

Aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactory producing aluminium joints, in a faster and reliable manner. In the present work dissimilar Al alloys (AA2024-T351 and AA6056-T4) were friction stir welded. Butt joints were obtained by varying process parameters, namely the

S. T. Amancio-Filho; S. Sheikhi; J. F. dos Santos; C. Bolfarini

2008-01-01

374

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

375

Friction stir welding of aluminium plate  

Microsoft Academic Search

Friction stir welding is a novel welding process which is a solid state butt welding process for sheet or plate using the friction phenomenon.This paper describes the effect of the rotation speed of the stir rod and the plate traverse speed during the friction stir welding process on the quality of welded joints. It was found that aluminium plates could

T. Shinoda; Y. Kondo

1997-01-01

376

Welding Processes and Applications. Future Trends (Resistance, Electron Beam and Laser Welding).  

National Technical Information Service (NTIS)

United Nations Industrial Development Organization publication on advanced technology in welding. Electron beam welding is discussed including its principles, control methods, process variables, component design, joint design, and applications. Laser weld...

S. Muthukrishnan

1984-01-01

377

Microstructure, local and global mechanical properties of friction stir welds in aluminium alloy 6005AT6  

Microsoft Academic Search

The effect of the welding speed on the microstructure, local and overall mechanical properties of friction stir welded joints has been investigated in the aluminium alloy 6005A-T6. The fine hardening precipitation within the heat-affected zone has been characterized by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Post-welding heat treatments have been applied to obtain indications on the level

A. Simar; Y. Bréchet; B. de Meester; A. Denquin; T. Pardoen

2008-01-01

378

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

379

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

380

A robust visual seam tracking system for robotic arc welding  

Microsoft Academic Search

A robotic seam tracking system is developed to achieve robustness against optical noises such as arc glares, welding spatters, fume, and other unexpected brightness sources. The profile data of a weld joint to be welded are reliably extracted using two separate vision processing algorithms: the first is for joint modeling before welding starts, while the second is for joint feature

Jae Seon Kim; Young Tak Son; Hyung Suck Cho; Kwang Il Koh

1996-01-01

381

Development of the weld-braze joining process  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

382

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

383

Weld pool oscillation during pulsed GTA welding  

SciTech Connect

This paper deals with weld pool oscillation during pulsed GTA welding and with the possibility to use this oscillation for in-process control of weld penetration. Welding experiments were carried out under different welding conditions. During welding the weld pool was triggered into oscillation by the normal welding pulses or by extra current pulses. The oscillation frequency was measured both during the pulse time and during the base time by analyzing the arc voltage variation using a Fast Fourier Transformation program. Optimal results are obtained when full penetration occurs during the pulse time and partial penetration during the base time. Under these conditions elliptical overlapping spot welds are formed. In the case of full penetration the weld pool oscillates in a low frequency mode (membrane oscillation), whereas in the case of partial penetration the weld pool oscillates in a high frequency mode (surface oscillation). Deviation from the optimal welding conditions occurs when high frequency oscillation is observed during both pulse time and base time (underpenetration) or when low frequency oscillation is observed during both pulse time and base time (overpenetration). In line with these results a penetration sensing system with feedback control was designed, based on the criterion that optimal weld penetration is achieved when two peaks are observed in the frequency distribution. The feasibility of this sensing system for orbital tube welding was confirmed by the results of experiments carried out under various welding conditions.

Aendenroomer, A.J.R.; Ouden, G. den [Delft Univ. of Technology (Netherlands)

1996-12-31

384

Thick sandwich panel fabrication for bridge deck structure and its joint strength  

NASA Astrophysics Data System (ADS)

The purpose of this study is to evaluate the static strength of thick plate laser welded lap joint and the performance of thick sandwich panel for bridge deck structure. The strength of thin sheet laser welded lap joint whose thickness is less than 1.6 mm have been already reported, but the strength of thick plate laser welded lap joint whose thickness is more than 10 mm is not known. The authors believe this thick laser welded lap jont enable heavy industries to make a revolution on applying it for sandwich panel fabrication. Then, they have conducted mechanical tests of 10 mm + 6 mm thick laser welded lap joints to grasp their static strength. According to the obtained data, they fabricate a thick sandwich panel model of newly designed bridge deck structure for evaluation. The static lading test, cyclic loading test and collapsing test show that the thick sandwich panel has enough performance for the practical application.

Kitagawa, Akikazu; Fukuda, Naoaki; Takeda, Shinnosuke; Matsunawa, Akira

2003-03-01

385

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

386

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

SciTech Connect

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

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

2009-01-01

387

A comparison of impedance and Lamb wave SHM techniques for monitoring structural integrity of and through welded joints  

NASA Astrophysics Data System (ADS)

In this study, the feasibility of monitoring the structural integrity of welded thick aluminum plates was experimentally tested using two widely used SHM methods: impedance and Lamb wave analyses. The test structure was fabricated from two 1/4 inch thick aluminum plates welded together, and various structural defects, such as holes and cuts, were applied. At each of these damage steps, data were collected for both the impedance and Lamb wave techniques. Results consistently revealed the impedance method to be sensitive to damage in and through the weld. The envelopes of the Lamb wave signals were calculated using the S-transformation of the time histories. There was significant change to the curves when different defects were added to the plate. Both of the SHM methods studied detected each of the cuts and holes acting to reduce the overall strength of the structure. Each technique also detected the hole damage on the opposite side of the weld as the sensor(s) used for damage detection. The study further verified that surface waves move across welds allowing SHM methods to detect the defects even if the sensors are located on neighboring plates or geometries.

Grisso, Benjamin L.; Salvino, Liming W.; Singh, Gurjiwan; Singh, Gurjashan; Tansel, Ibrahim N.

2011-04-01

388

Fracture toughness of partially welded joints of SUS316 stainless steel at 4 K by large bend tests  

SciTech Connect

Austenitic stainless steels in relatively thick sections are specified in support structure designs for huge superconducting magnets in fusion energy machines such as the Large Helical Device (LHD). In the LHD under construction at the National Institute for Fusion Science (NIFS) in Japan, partial welding of SUS 316 stainless steel is employed to fabricate the 100-mm thick coil can and coil support structures. Partial welding lowers the heat input and reduces residual deformation after welding. The main disadvantage is that a sizable crack-like defect remains embedded in the unwelded portion of the primary structural component. Here, SUS 316 stainless steel bars were partially welded and tested in 3-point bending to evaluate the effect of natural cracks on fusion zone toughness at 4 K. The specimens had a cross-section 87.5 mm {times} 175 mm and were fractured in liquid helium using a 10 MN cryogenic mechanical testing machine. In two tests, unstable fracture occurred at maximum load and at critical stress intensity factors K{sub max} = 227 and 228 MPa{radical}m. Results indicate a high resistance to fracture initiation but no stable tearing. Therefore, no resistance to crack propagation may exist in a fusion zone at a weld root under cryogenic temperature.

Nishimura, A.; Tobler, R.L.; Tamura, H.; Imagawa, S.; Mito, T.; Yamamoto, J.; Motojima, O. [National Inst. for Fusion Science, Toki, Gifu (Japan)] [National Inst. for Fusion Science, Toki, Gifu (Japan); Takahashi, H.; Suzuki, S. [Hitachi, Ltd., Ibaraki (Japan)] [Hitachi, Ltd., Ibaraki (Japan)

1996-07-01

389

Numerical Study for Gta Weld Shape Variation by Coupling Welding Arc and Weld Pool  

Microsoft Academic Search

A numerical modeling of the welding arc and weld pool is studied for moving GTA welding to investigate the effect of the surface active element oxygen and the plasma drag force on the weld shape. Based on the 2D axisymmetric numerical modeling of the argon arc, the heat flux, current density and plasma drag force are obtained under different welding

Wenchao Dong; Shanping Lu; Dianzhong Li; Yiyi Li

2009-01-01

390

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

391

Residual stress reduction and fatigue strength improvement by controlling welding pass sequences  

Microsoft Academic Search

The effects of residual stress on fatigue strength at a weld toe in a multi-pass fillet weld joint were evaluated. The residual stresses in the weld joints were varied by controlling the sequence of welding passes. The residual stress at the weld toe was 80 MPa in the specimen whose last welding pass was on the main plate side, but

Masahito Mochizuki; Toshio Hattori; Kimiaki Nakakado

2000-01-01

392

The use of exploratory experimental designs combined with thermal numerical modelling to obtain a predictive tool for hybrid laser/MIG welding and coating processes  

NASA Astrophysics Data System (ADS)

While hybrid laser welding and coating processes involve a large number of physical phenomena, it is currently impossible to predict, for a given set of influencing factors, the shape of the molten zone and the history of temperature fields inside the parts. This remains true for complex processes, such as the hybrid laser/MIG welding process, which consists in combining a laser beam with a MIG torch. The gains obtained result essentially from the synergy of the associated processes: the stability of the process, the quality of the seam realized, and the productivity are increased. This article shows how, by means of a reduced number of experiments (8), it is possible to predict the shape of the molten zone and the temperature field inside parts, for a given window of influencing factors. This method consists in combining the method of exploratory experimental designs with a numerical modelling of the thermal phenomena that occurs during the process, by using the 'heat equivalent source" approach [1-4]. Two validations of this method have been carried out: the first for a set of parameters inside the experimental design, and the other for a set of parameters that lies outside the experimental design, but inside the domain investigated.

Bidi, Lyes; Mattei, Simone; Cicala, Eugen; Andrzejewski, Henri; Le Masson, Philippe; Schroeder, Jeanne

2011-04-01

393

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

394

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

395

Effect of welding parameters on microstructure in the stir zone of FSW joints of aluminum die casting alloy  

Microsoft Academic Search

The effect of the welding speed and the rotation speed on the microstructure in the stir zone has been investigated by measuring the Si particle distribution in the ADC12 alloy. The stir zone has fine recrystallized grains without dendritic structures, and the eutectic Si was uniformly dispersed in the stir zone. The size of the Si particles was statistically determined

Y. G. Kim; H. Fujii; T. Tsumura; T. Komazaki; K. Nakata

2006-01-01

396

Autonomous Mobile Robot System for Monitoring and Control of Penetration during Fixed Pipes Welding  

NASA Astrophysics Data System (ADS)

In order to obtain sound welded joints in the welding of horizontal fixed pipes, it is important to control the back bead width in the first pass. However, it is difficult to obtain optimum back bead width, because the proper welding conditions change with welding position. In this paper, in order to fully automatize the welding of fixed pipes, a new method is developed to control the back bead width with monitoring the shape and dimensions of the molten pool from the reverse side by autonomous mobile robot system. This robot has spherical shape so as to move in a complex route including curved pipe, elbow joint and so on. It has also a camera to observe inner surface of pipe and recognize a route in which the robot moves. The robot moves to welding point in the pipe, and monitors the reverse side shape of molten pool during welding. The host computer processes the images of molten pool acquired by the robot vision system, and calculates the optimum welding conditions to realize adaptive control of welding. As a result of the welding control experiments, the effectiveness of this system for the penetration control of fixed pipes is demonstrated.

Muramatsu, Masahiro; Suga, Yasuo; Mori, Kazuhiro

397

Optimization of laser butt welding parameters with multiple performance characteristics  

NASA Astrophysics Data System (ADS)

This paper presents a study carried out on 3.5 kW cooled slab laser welding of 904 L super austenitic stainless steel. The joints have butts welded with different shielding gases, namely argon, helium and nitrogen, at a constant flow rate. Super austenitic stainless steel (SASS) normally contains high amount of Mo, Cr, Ni, N and Mn. The mechanical properties are controlled to obtain good welded joints. The quality of the joint is evaluated by studying the features of weld bead geometry, such as bead width (BW) and depth of penetration (DOP). In this paper, the tensile strength and bead profiles (BW and DOP) of laser welded butt joints made of AISI 904 L SASS are investigated. The Taguchi approach is used as a statistical design of experiment (DOE) technique for optimizing the selected welding parameters. Grey relational analysis and the desirability approach are applied to optimize the input parameters by considering multiple output variables simultaneously. Confirmation experiments have also been conducted for both of the analyses to validate the optimized parameters.

Sathiya, P.; Abdul Jaleel, M. Y.; Katherasan, D.; Shanmugarajan, B.

2011-04-01

398

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

399

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

400

Development of Mathematic Model of Cold Welding at Drawing-up the Flange Joint of Pneumohydraulic Systems  

Microsoft Academic Search

Provision of high airtightness of joints of pipe- lines of pneumohydraulic systems (PHS) operating under high pressure, is an important task for designing and operation of launch vehicles. In the process of assembly and tests of PHS of launch vehicles, it was found that detachable flange joints do not lose their airtightness after removal of fastening elements, even in conditions

Y. S. Boyko

2002-01-01

401

Welding blades to rotors  

NASA Technical Reports Server (NTRS)

A process is described to form T-joints between dissimilar thickness parts by magnetic force upset welding. This type of resistance welding is used to join compressor and turbine parts which thereby reduces the weight and cost of jet engines.

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

1973-01-01

402

A Feasiblity Study on Spot Friction Welding of Magnesium Alloy AZ31  

SciTech Connect

Spot friction welding (SFW) is a novel variant of the linear friction stir welding process with the potential to create strong joints between similar, as well as dissimilar sheet metals. It is particularly suitable for soft, low melting point metals such as aluminum, magnesium, and their alloys where resistance spot welding can cause defects such as voids, trapped gas and micro-cracks due to the intense heat requirement for joint formation. Up to now, spot friction welding has focused primarily on aluminum alloys. This paper presents a feasibility study on spot friction welding of AZ31, a wrought magnesium alloy available in sheet form. Lap joints of 1.58-mm-thick magnesium alloy AZ31B-O sheet were produced by spot friction welding. The spot welds were made in 2 sec with 15-mm-diameter pin tool rotating at 500-2,000 rpm. The tool was inserted into 2-sheet stack-ups to depths of either 2.4 or 2.8 mm relative to the top sheet surface. Tensile-shear testing showed that joint strengths up to 4.75 kN were obtained. The removal of surface oxides from the sheets prior to welding increased lap shear strengths about 50% at the 2.4-mm insertion depth and it promoted failure by nugget pull-out rather than by interface separation.

Santella, Michael L [ORNL; Pan, Dr. Tsung-Yu [Ford Motor Company; Frederick, David Alan [ORNL; Schwartz, William [ORNL

2007-01-01

403

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

404

Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm  

NASA Astrophysics Data System (ADS)

A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

405

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

406

Formation of thermal localized structures in a weld in pulse-arc welding by a nonmelting electrode  

Microsoft Academic Search

The technological regimes of welding that promote uniform distribution of the properties over the length of a welded joint\\u000a are studied by numerically modeling the formation of a weld seam by a nonmelting electrode.

O. N. Bezhin; V. A. Kosyakov; R. A. Krektuleva

1998-01-01

407

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

408

Microstructure and mechanical properties of an inertia friction welded INCOLOY alloy 909–INCONEL alloy 718 joint for rotating applications  

Microsoft Academic Search

Inertia welding is a common practice to join axially symmetrical parts for aero-engine applications. The shaft for a new advanced high-pressure compressor will be produced ed by joining the high strength superalloys INCOLOY® alloy 909 (Incoloy909) and INCONEL® alloy 718 (IN718). IN718 is the work-horse nickel-iron-chromium alloy for a variety of parts for aero-engine applications due to a good combination

O. Roder; J. Albrecht; G. Lütjering

2006-01-01

409

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

410

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

SciTech Connect

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

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

1992-01-01

411

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

412

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

413

Experimental investigation on mechanical behavior of friction welded AL7075  

Microsoft Academic Search

Friction welding is widely used as a mass production method in various industries. In friction welding, the joints are formed in the solid state by utilizing the heat generated by friction. Friction welding can be used to join different types of ferrous metals and non-ferrous metals that cannot be welded by traditional welding processes. The process parameters such s friction

M Rajendran

2012-01-01

414

FUNDAMENTAL ASPECTS OF ELECTROSLAG WELDING OF TITANIUM ALLOYS  

E-print Network

( > 25 mm [1"] thick) have been limited to gas tungsten arc welding, plasma arc welding and electron beam) . l J FUNDAMENTAL ASPECTS OF ELECTROSLAG WELDING OF TITANIUM ALLOYS J. H. Devletian, S. J. Chen-4V alloy plates. The welding procedures, weld-joint mechanical properties and microstructure of Ti

Eagar, Thomas W.

415

Internal Filler-Wire Feed For Arc Welding  

NASA Technical Reports Server (NTRS)

Tungsten electrode for gas/tungsten arc welding contains lengthwise channel for feeding filler wire to weld joint. Channel makes it unnecessary to feed wire through guides outside electrode, conserving valuable space near weld and protects wire from deformation by contact with other parts in vicinity of weld. Helpful in robotic or automatic welding.

Morgan, Gene E.; Dyer, Gerald E.

1990-01-01

416

Sensitivity of the stability of a waste emplacement drift to variation in assumed rock joint parameters in welded tuff  

SciTech Connect

This report presents the results of a numerical analysis to determine the effects of variation of rock joint parameters on stability of waste disposal rooms for vertical emplacement. Conditions and parameters used were taken from the Nevada Nuclear Waste Storage Investigation (NNWSI) Project Site Characterization Plan Conceptual Design report (MacDougall et al., 1987). Mechanical results are presented which illustrate the predicted distribution of stress, joint slip, and room deformations for times of initial excavation and after 50 years heating. 82 refs., 93 figs.

Christianson, M.

1989-04-01

417

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

E-print Network

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

Medraj, Mamoun

418

Investigation of the mechanical properties and microstructure of friction welded joints between AISI 4140 and AISI 1050 steels  

Microsoft Academic Search

Joining of dissimilar metals is one of the most essential needs of industries. Manufacturing with joint of alloy steel and normal carbon steel is used in production, because it decreases raw material cost. In this study, joining of AISI 4140 steel (medium carbon and low alloy steel) and AISI 1050 steel (medium carbon steel) was successfully achieved. Mechanical properties, macro

Sare Celik; Ismail Ersozlu

2009-01-01

419

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

420

Parametric Studies Of Weld Quality Of Tungsten Inert Gas Arc Welding Of Stainless Steel  

Microsoft Academic Search

Effect of current and gas flow rate on quality of weld in tungsten inter gas arc welding of austenitic stainless steel has been studied in the present work through experiments and analyses. Butt welded joints have been made by using several levels of current and gas flow rate. The quality of the weld has been evaluated in terms of ultimate

Pradip Kumar Pal; Goutam Nandi; Nabendu Ghosh

2011-01-01

421

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

422

Investigation of microstructures and fatigue properties of friction stir welded Al–Mg alloy  

Microsoft Academic Search

FS welds have a sound joint for the lack of voids, cracks and distortions. When compared to the base material, friction stir welding (FSW) joints exhibit a finer crystal grain in the weld nugget, and advancing side has a clearer boundary with the weld nugget than that of the retreating side. The fatigue life of FS welds is 6–14 times

Caizhi Zhou; Xinqi Yang; Guohong Luan

2006-01-01

423

Effect of proof testing on the flaw growth characteristics of 304 stainless steel. [crack propagation in welded joints  

NASA Technical Reports Server (NTRS)

The effects of proof overload frequency and magnitude on the cyclic crack growth rates of 304 stainless steel weldments were investigated. The welding procedure employed was typical of those used on over-the-road cryogenic vessels. Tests were conducted at room temperature with an overload ratio of 1.50 to determine the effect of overload frequency. Effect of overload magnitude was determined from tests where a room temperature overload was applied between blocks of 1000 cycles applied at 78 K (-320 F). The cyclic stress level used in all tests was typical of the nominal membrane stress generally encountered in full scale vessels. Test results indicate that judicious selection of proof overload frequency and magnitude can reduce crack growth rates for cyclic stress levels.

Finger, R. W.

1974-01-01

424

Welding Characteristics of Ultrasonic Seam Welding System Using a Complex Vibration Circular Disk Welding Tip  

Microsoft Academic Search

The continuous welding characteristics of a 27 kHz ultrasonic seam welding system using a complex vibration circular disk welding tip are studied. The vibration characteristics of a complex vibration converter were improved compared with the prototype model. The circular disk welding tip vibrates in both transverse and torsional vibration modes and an elliptical vibration locus is obtained at the circumference

Jiromaru Tsujino; Tetsugi Ueoka

2000-01-01

425

Research on laser welding of aluminum matrix composite SiCw\\/6061  

Microsoft Academic Search

Effects of laser welding parameters on strength of welded joint were studied. Mechanism of loss of joint strength was analyzed. It was pointed out that an important factor affecting joint strength is the reaction between matrix and reinforced phase. On the basis of this, the concept of critical Si activity was proposed. In appropriate welding parameters and Si activity, welded

Jitai Niu; Longxiu Pan; Muzhen Wang; Chengbin Fu; Xiaodong Meng

2006-01-01

426

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

427

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

SciTech Connect

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

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

2008-01-01

428

Seam Tracking of Intelligent Arc Welding Robot  

Microsoft Academic Search

Intelligent welding robots obtain a good quality of the welding results. Research on automatic and intelligent control of Arc welding is an important means for ensuring weld quality, raising productivity, and improving labor conditions. Despite its widespread use in the various manufacturing industries, the full automation of the robotic welding has not yet been achieved partly because mathematical models for

KHADIJEH DAEINABI; MOHAMMAD TESHNEHLAB

2006-01-01

429

Calibration Fixture For Welding Robot  

NASA Technical Reports Server (NTRS)

Compact, lightweight device used in any position or orientation. Calibration fixture designed for use on robotic gas/tungsten-arc welding torch equipped with vision-based seam-tracking system. Through optics in hollow torch cylinder, video camera obtains image of weld, viewing along line of sight coaxial with welding electrode. Attaches to welding-torch cylinder in place of gas cup normally attached in use. By use of longer or shorter extension tube, fixture accommodates welding electrode of unusual length.

Holly, Krisztina J.

1990-01-01

430

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

431

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

432

Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint  

NASA Astrophysics Data System (ADS)

To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

2014-10-01

433

Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint  

NASA Astrophysics Data System (ADS)

To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

2014-07-01

434

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

435

Correlation between microstructure, hardness and strength in HAZ of dissimilar welds of rotor steels  

Microsoft Academic Search

Correlation between microstructure, hardness and strength was investigated in heat affected zone (HAZ) of dissimilar welding joints of newly developed rotor steels in terms of both the traditional micro-hardness testing and the nanoindentation technique. Relationships between micro-hardness and nano-hardness were obtained for HAZ of welds, where the mechanical properties were microstructure dependent. Lath width of the tempered martensites was selected

Ming-Liang Zhu; Fu-Zhen Xuan

2010-01-01

436

Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy  

PubMed Central

The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr. PMID:19088892

Watanabe, Ikuya; Wallace, Cameron

2008-01-01

437

49 CFR 213.119 - Continuous welded rail (CWR); plan contents.  

Code of Federal Regulations, 2013 CFR

...shall either, within 60 days— (i) Weld the joint; (ii) Install a joint with...the track owner shall either— (i) Weld the joint; (ii) Replace the broken...adjust the anchors and, within 30 days, weld the joint; (iii) Replace the...

2013-10-01

438

49 CFR 213.119 - Continuous welded rail (CWR); plan contents.  

Code of Federal Regulations, 2011 CFR

...shall either, within 60 days— (i) Weld the joint; (ii) Install a joint with...the track owner shall either— (i) Weld the joint; (ii) Replace the broken...adjust the anchors and, within 30 days, weld the joint; (iii) Replace the...

2011-10-01

439

49 CFR 213.119 - Continuous welded rail (CWR); plan contents.  

Code of Federal Regulations, 2012 CFR

...shall either, within 60 days— (i) Weld the joint; (ii) Install a joint with...the track owner shall either— (i) Weld the joint; (ii) Replace the broken...adjust the anchors and, within 30 days, weld the joint; (iii) Replace the...

2012-10-01

440

Weld braze technique  

DOEpatents

High-strength metal joints are formed by a combined weld-braze technique. A hollow cylindrical metal member is forced into an undersized counterbore in another metal member with a suitable braze metal disposed along the bottom of the counterbore. Force and current applied to the members in an evacuated chamber results in the concurrent formation of the weld along the sides of the counterbore and a braze along the bottom of the counterbore in one continuous operation.

Kanne, Jr., William R. (Aiken, SC); Kelker, Jr., John W. (North Augusta, SC); Alexander, Robert J. (Aiken, SC)

1982-01-01

441

The effect of welding parameters on fracture toughness of resistance spot-welded galvanized DP600 automotive steel sheets  

Microsoft Academic Search

The aim of this study was to evaluate the fracture toughness of resistance spot welded (RSW) lap joints of galvanized DP600\\u000a steels. RSW lap joints galvanized DP600 steel sheets were performed on spot welded in a pneumatic, phase-shift-controlled,\\u000a and 0–9 kA effective weld current capable AC spot welding machine. Defect-free RSW lap joints were produced on galvanized\\u000a DP600 steel sheets. Fracture

Fatih Hayat; ?brahim Sevim

442

Efficient Weld Seam Detection for Robotic Welding from a Single Image  

Microsoft Academic Search

The weld seam recognition is a key technology in robotic welding. This paper presents an efficient algorithm of weld seam\\u000a detection for butt joint welding from a single image. The basic idea of our approach is to find a pair of weld seam edges\\u000a in the local area first. Then, starting from the two endpoints of each edge, search for

Fanhuai Shi; Lv Zhou; Tao Lin; Shanben Chen

443

Submerged arc fillet welds between mild steel and stainless steel  

SciTech Connect

Submerged arc fillet welds between mild steel and Type 304 stainless steel, made with ER309L wire, may contain no ferrite and be at risk of hot cracking, or they may be sufficiently diluted that they transform to martensite with both hot cracking risk and low ductility. This situation is most prevalent when direct current electrode positive (DCEP) polarity is used and when the flange is the mild steel part of the T-joint. A flux that adds chromium to the weld can somewhat alleviate this tendency. Direct current electrode negative (DCEN) polarity greatly reduces this tendency by limiting dilution. Fillet weld compositions and dilutions are obtained for a number of welding conditions and fluxes.

Kotecki, D.J.; Rajan, V.B. [Lincoln Electric Co., Cleveland, OH (United States)

1997-02-01

444

CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS  

SciTech Connect

Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions, defect characteristics and weld residual strains were examined by optical metallography, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Industry-supplied mock-up welds were characterized including alloy 52 and 152 weldments, alloy 52M overlay and inlay welds, and an alloy 52 overlay. II. WELDMENTS II.A. Alloy 52 and 152 Weld Mockups The alloy 52 and 152 weld mockups were fabricated by MHI for the Kewaunee reactor and were obtained from the EPRI NDE Center. The mockups were U-groove welds joining two plates of 304SS as shown in Figure 1. Alloy 152 butter (heat 307380) was placed on the U-groove surface for both mockups by shielded metal arc welding (SMAW). For the alloy 152 weld mockup, the alloy 152 fill (heat 307380) was also applied using SMAW while for the alloy 52 weld mockup, the alloy 52 fill (heat NX2686JK) was applied using gas tungsten arc welding (GTAW). Welding parameters for the fill materials were substantially different with the alloy 152 SMAW having a deposition speed of 4-25 cm/min with a current of 95-145 A and the alloy 52 GTAW having a deposition speed of 4-10 cm/min with a current of 150-300 A. One prominent feature in these mockup welds is the presence of a crack starting at the 304SS butt joint at the bottom of the U-groove and extending up into the weld. It appears that the 304SS plate on either side of the butt joint acted as an anchor for the weld resulting in a stress rise across the slit that drove crack formation and extension up into the fill weld. As will be shown in the next section, the extent of the cracking around this stress riser was much greater in the MHI 52 weld mockup.

Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

2009-08-27

445

Establishing empirical relationships to predict grain size and tensile strength of friction stir welded AA 6061-T6 aluminium alloy joints  

Microsoft Academic Search

AA 6061-T6 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high specific strength and good corrosion resistance. Compared with 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 welded does not

S. RAJAKUMAR; C. MURALIDHARAN; V. BALASUBRAMANIAN

2010-01-01

446

Investigation of the fatigue behaviour of butt-welded joints treated by ultrasonic peening process and compared with fatigue life assessment standards  

Microsoft Academic Search

Ultrasonic peening is a technique to be used for improving the fatigue life of welded structures. The technique makes use\\u000a of an ultrasonically vibrated pin which is pressed against the toe regions of the weld. The beneficial effect is mainly due\\u000a to the introduction of favourable compressive stresses on weld toe regions, causing local plastic deformation and reducing\\u000a stress concentration

G. R. Jinu; P. Sathiya; G. Ravichandran; A. Rathinam

2009-01-01

447

Viewing electron-beam welds in progress  

NASA Technical Reports Server (NTRS)

With aid of optical filter, operator of electron-beam welding machine can view TV image of joint that is being welded and can make corrections as necessary. Operator can see when weld bead gets out of alinement, for example, and compensate for deflection of electron beam caused by changes in magnetic field.

Armenoff, C. T.

1980-01-01

448

Mössbauer characterization of joints of steel pieces in transient liquid phase bonding experiences  

NASA Astrophysics Data System (ADS)

Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Mössbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.

di Luozzo, N.; Martínez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B.

2011-11-01

449

Dependence of overload performance on weld attributes for resistance spot welded galvanized low carbon steel  

Microsoft Academic Search

Microstructure and failure behavior of galvanized low carbon steel resistance spot welds were investigated. Failure mode, peak load and energy absorption obtained in tensile-shear test were used to describe spot welds performance. It was found that weld fusion zone size, electrode indentation and expulsion can significantly affect the mechanical performance of spot welds. Failure mechanism of spot weld which fail

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

2009-01-01