• Title/Summary/Keyword: T-joint Welding

Search Result 126, Processing Time 0.022 seconds

Effects of Tool Plunge Position on Mechanical Properties of Friction-stir-weleded Region in A6061-T6/AZ31 Dissimilar Metals (A6061-T6/AZ31 이종금속 마찰교반접합부의 기계적 특성에 미치는 툴 삽입 위치의 영향)

  • Lee, Kwang-Jin;Kim, Sang-Hyuk
    • Journal of Welding and Joining
    • /
    • v.30 no.5
    • /
    • pp.22-26
    • /
    • 2012
  • Butt-joints of A6061-T6 and AZ31 plates were successfully manufactured by using a friction stir welding method. Off-set free joints and off-set joints were fabricated to investigate the effect of the tool plunge position on the mechanical properties of the joints. Hardness test, tensile test and charpy impact test was performed to evaluate the mechanical properties of the joints. Off-set condition resulted in increase of mechanical properties of the joints. The variation of the hardness distribution in the SZ was also stabilized in the off-set condition. Tensile strength of the off-set joint was about 85% against to that of the AZ31 base metal. Impact absorption energy by Charpy-Impact-Test of the off-set joint also increased by almost 2 times against to that of the AZ31 base metal.

Microstructural Characteristics of T-bar Welding Zone for Shipbuilding and Offshore Plants (조선해양플랜트용 T-bar 용접부의 미세조직학적 특성에 관한 연구)

  • Hwang, Y.J.;Choi, Y.S.;Jang, J.H.;Lee, S.I.;Gong, K.Y.;Lee, DG.
    • Transactions of Materials Processing
    • /
    • v.27 no.5
    • /
    • pp.296-300
    • /
    • 2018
  • T-type and H-type section steels were generally used in shipbuilding and offshore plants and were produced by welding technology. These section steels were produced by handwork, and the supplying amounts can't satisfy the demand amounts of the fabrication companies. In case of fillet welding, there are some gaps in weld-joint region due to no groove preparation processing and it can occur crack initiation in the welded region. It is important to evaluate the microstructural and mechanical properties of welded zone to solve these problems. To satisfy the demand amounts of T-bar parts, automatic welding technology was introduced and several conditions as a function of welding speeds were carried out to improve the manufacturing speed. Heat-affected zone may be affected by variation of heat input and cooling rate through automatic welding speed and welding speed is necessary to be optimized. In this study, fusion zone and heat-affected zone were investigated by microstructural and mechanical analysis and were evaluated whether the welded parts were sound or not.

Effect of Process Parameters on Friction Stir Welds on AA2219-AA2195 Dissimilar Aluminum Alloys (마찰교반접합의 공정변수가 AA2219-AA2195 이종 알루미늄 접합에 미치는 영향)

  • No, Kookil;Yoo, Joon-Tae;Yoon, Jong-Hoon;Lee, Ho-Sung
    • Korean Journal of Materials Research
    • /
    • v.27 no.6
    • /
    • pp.331-338
    • /
    • 2017
  • This study was carried out to investigate the optimum condition of a friction stir welding process for a joint of AA2219-T87 and AA2195-T8 dissimilar aluminum alloys. These alloys are known to have good cryogenic properties, and as such to be suitable for use in fuel tanks of space vehicles. The welding parameters include the travelling speed, rotation speed and rotation direction of the tool. The experiment was conducted under conditions in which the travelling speed of the tool was 120-300 mm/min and the rotation speed of the tool was 400-800 rpm. To investigate the effect of the rotation direction of the tool, the joining was performed by switching the positions of the two dissimilar alloys. After welding, the microstructure was observed and the micro-hardness were measured; non-destructive evaluation was carried out to perform tensile tests on defect-free specimens. The result was that the microstructure of the weld joint underwent dynamic recrystallization due to sufficient deformation and frictional heat. The travelling speed of the tool had little effect on the properties of the joint, but the properties of the joint varied with the rotation speed of the tool. The conditions for the best joining properties were 600 rpm and 180-240 mm/min when the AA2219-T8 alloy was on the retreating side(RS).

Residual stresses measurement in the butt joint welded metals using FSW and TIG methods

  • Taheri-Behrooz, Fathollah;Aliha, Mohammad R.M.;Maroofi, Mahmood;Hadizadeh, Vahid
    • Steel and Composite Structures
    • /
    • v.28 no.6
    • /
    • pp.759-766
    • /
    • 2018
  • Friction Stir Welding (FSW) is a solid-state process, where the objects are joined together without reaching their melting point. It has been shown that this method is a suitable way to join dissimilar aluminium alloys. The current article employed hole drilling technique to measure the residual stress distribution experimentally in different zones of dissimilar aluminium alloys AA6061-T6 and AA7075-T6 Butt welded using FSW. Results are compared with those of similar AA6061-T6 plates joined using a conventional fusion welding method called tungsten inert gas (TIG). Also, the evolution of the residual stresses in the thickness direction was investigated, and it was found that the maximum residual stresses are below the yield strength of the material in the shoulder region. It was also revealed that the longitudinal residual stresses in the joint were much larger than the transverse residual stresses. Meanwhile, Vickers micro hardness measurements were performed in the cross-section of the samples. The largest hardness values were observed in the stir zone (SZ) adjacent to the advancing side whereas low hardness values were measured at the HAZ of both alloys and the SZ adjacent to the retreating side.

A Study on Insert Metal in Friction Welding of A2024 to SM45C (마찰용접에서 A2024와 SM45C의 삽입재에 관한 연구)

  • 윤병수
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.7 no.6
    • /
    • pp.19-27
    • /
    • 1998
  • This study was investigated on the friction welding of A2024 aluminum alloy to SM45C carbon steel with insert metals. The tensile strength of welded joints, the hardness distribution of welds, the microstructure of welds and the tensile fracture surfaces were mainly investigated through this experiment. When aluminum alloy A6351 was used as insert metal, the maximum tensile strength of welded joint was obtained. In this case, the maximum joint efficiency was 76.2 percent of base metal. Optimal welding conditions were N=2,000rpm. $P_1$=40MPa, $P_2$, $t_1$=1.5 sec, $t_2$=5 sec.

  • PDF

A Study on Friction Welding of SM45C to SCM4 Steel Bars and the Fatigue Properties (SM45C와 SCM4의 마찰용접 및 피로특성에 관한 연구)

  • O, Se-Gyu;Kim, Bu-An;Kim, Seon-Jin;Nam, Sang-Hun
    • Journal of Ocean Engineering and Technology
    • /
    • v.2 no.2
    • /
    • pp.112-121
    • /
    • 1988
  • A study on friction welding of carbon steel bar (SM45C) to chrome molybedenum steel bar(SCM4) is examined experimentally through tensile test, hardness test, microstructure test and fatigue test. so, this paper deals with optimizing the welding concitions and analyzing various mechanical properties about friction welds of SM45C to SCM4 steel bars. The results obtained are summarized as follows; 1) For friction welded joints of SM45C to SCM4 steel bars, the total upset(U)increases linearly with an increase of heating time ($t_{1}$) till 6s. 2) The determined optimum welding conditions are heating time ($t_{1}$)2s, upsetting time($t_{2}$), 3s, heating pressure($p_{1}$), 4kgf/$mm^{2}$(39.2MPa), upsetting pressure($p_{2}$, 8kgf/mm$^{2}$(78.4MPa) and rotating speed(N), 2, 000rpm when the total upset(U) is 3.4mm, resulting in a computed relationship between the joint tensile strength .sigma.$_{t}$ (kgf/mm$^{2}$and the total upset U(mm); .sigma.$_{t}$ =$0.21U^{3}$ - $3.38U^{2}$ +17.03U + 66.00 3) As the elongation is increased more and more, the fracture position becomes away from weld interface and the fractures are similar to those of SM45C. Fracture is taken place on SM45C side. 4) The weld interface of two dissimilar materials is mixed strongly, and the heat affected zone is about 2.0mm at SM45C while about 2.7 mm at SCM4 side. Therefore, the welded zone and heat affected zone are very narrow, comparing with those of the joints welded by the other welding methods. 5) The fatigue strengths at N=10$^{6}$ cycles of SM45C, SCM4 and friction welded joints are 23kgf/$mm^{2}$, 33kgf/$mm^{2}$(220.5 MPa), and 22.5kgf/$mm^{2}$(220.5MPa) respectively, and fracture at friction welded joint takes place at the side of SM45C. 6) The hardness of the friction weld interface is 3 times higher than that of base metal. 7) Fatigue strength of friction welded joint is higher than that of base metal. 8) Notch sensitivity factor of friction welded joint is lower than that of base metal.

  • PDF

Development of Non-Scallop Block Joint Welding Method (논-스캘럽 블록 조인트 용접법 개발)

  • Kim, Ho-Kyeong;Ko, Dae-Eun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.15 no.9
    • /
    • pp.5419-5424
    • /
    • 2014
  • A weld scallop is a small quadrant or half circle type hole installed in the weld line cross area for easy welding operation. Many types of T-bars with a scallop can be welded in a block assembly stage in shipbuilding. The difficulties arise from the fact that scallops are to be filled by build-up welding after welding of the cross line is complete. In this study, a non-scallop block joint welding method was developed using special type CBM (ceramic backing material). The wedge shaped CBM was devised to insert a CBM into just the V groove of weld line cross area without weld scallop. A saw-toothed shape was adopted for easy cutting of the unnecessary part in the CBM fitting process. The applicability of the developed method was verified through welding experiments based on the yard welding conditions.

DEVELOPMENT OF A PRACTICAL METHOD FOR THE ESTIMATION OF WELD INDUCED CRACK IN THICK PLATE WELDMENTS

  • Lee, Jae-Myung;Yoon, Dong-Ryul;Heo, Hee-Young;Jang, Tae-Won;Lee, Jae-Won
    • Proceedings of the KWS Conference
    • /
    • 2002.10a
    • /
    • pp.396-401
    • /
    • 2002
  • A practical method for evaluating the possibility of the occurrence of cracking in actual thick-plate T-joint weldments is presented in this study. Systematic experiments based on the method of the design of experiment are conducted in order to investigate the crack tendency in relation to typical welding parameters such as diffusible hydrogen, restraint intensity, preheating temperature and so on. The elastic analysis using the [mite element techniques is employed to quantify the restraint intensities of the specimens. The defined restraint intensities are treated in numerical way for the sake of considering the most uncertain factor among some major factors that govern the cracking phenomena due to welding. The critical plane for judgment of the crack occurrence or crack density is presented as a function of typical welding parameters including determined restraint intensities. The results of numerical estimation by the proposed method for the experimental specimens show the usefulness as a practical tool in welding induced crack problem having extensive uncertainties.

  • PDF

Temperature Behavior in Dissimilar Butt Joint During TIG Assisted Friction Stir Welding (TIG-FSW 하이브리드 용접을 이용한 이종재 맞대기 용접부의 온도 분포 특성)

  • Bang, Hee-Seon;Bijoy, M.S.
    • Journal of Welding and Joining
    • /
    • v.29 no.5
    • /
    • pp.63-71
    • /
    • 2011
  • Three-dimensional finite element analysis is performed to study the temperature distribution phenomenon of TIG assisted friction stir welding (TAFSW) between dissimilar plates (Al 6061-T6 and stainless steel 304). TAFSW is a solid-state welding process that integrates TIG (Tungsten Inert Gas) into a friction stir welding (FSW), to preheat the harder material ahead of FSW tool during welding. In order to facilitate the industrial application of welding, 3D numerical modeling of heat transfer has been carried out applying Finite Element Method (FEM). The temperature distribution due to heat generation during TAFSW on dissimilar materials joint is analysed using in-house solver. Moving heat source along with frictional heat between the work specimens and tool surface is considered to calculate the heat input. The analytical model used predicts successfully the maximum welding temperatures that occur on the dissimilar materials during TAFSW. Comparison with the infra red camera and thermocouple measurement results shows that the results from the current numerical simulation have good agreement with the measured data.