• Title/Summary/Keyword: Butt weld

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Evaluation of Mechanical Properties of Welded Joints by an Instrumented Indentation Test and Fatigue Life Evaluation (계장화 압입시험에 의한 용접부의 물성 측정 및 피로수명 예측)

  • Goo, Byeong-Choon;Lee, Dong-Hyung;Kwon, Dong-Il;Choi, Yeol
    • Journal of the Korean Society for Railway
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    • v.7 no.2
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    • pp.142-148
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    • 2004
  • When material properties depend much on positions in a material or it is difficult to make test specimens from a material or component, an instrumented indentation test described in ISO 14577-1, 14577-2 or KS B 0950 can be used to measure material properties and damage. In this study, first of all, the principals of the instrumented indentation test, KS B 0950 are introduced and yield strengths, tensile strengths and work hardening exponents of base materials, heat affected zones and weld materials are measured. In addition, the influence of post-weld heat treatment on the material properties is investigated. Finally the fatigue lift of butt welded specimens are evaluated by the local strain approach. To calculate local strains and stresses, elasto-plastic finite element analysis is conducted using the measured properties.

FSW Process Optimization for Al 2519 Alloys and Its Joint Characteristics(II) (후육 고강도 Al 2519합금의 FSW 접합기술 및 접합부 특성(II))

  • Kim, Heung-Ju;Jang, Ung-Seong;Yang, Gwang-Ha;Bang, Han-Seo
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.174-176
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    • 2005
  • On the basis of successful experiences and data from author's past experimental results of friction stir welding on thin aluminum plates, thick aluminum plate of high strength 2000 series has been carried out in this study. For various combination of rotating speed, welding speed and tool (RIWRC38-C) shape, the butt welded specimens has been prepared to check the metallurgical characteristics, hardness distributions and defects. From the results, feasible welding conditions have been obtained as 450 rpm rotating speed and 5 mm/min welding speed. Using these optimum welding parameters, 38.1mm-thickness A2519-T87 plates have been FSWelded in single pass. A good weld surface appearance and defects free weld zone has been observed in X-ray inspection. Softened region has been generated by dissolution of precipitates and coarsened microstructure in the stir zone after FSWeld.

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A Study on the Temperature Distribution of Welding Zone in Carbon Steel (탄소강재 용접부의 온도분포에 관한 연구)

  • 남궁재관;홍재학
    • Journal of the Korean Society of Safety
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    • v.5 no.3
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    • pp.33-38
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    • 1990
  • In this study, the transient temperature distribution of welded zone was analyzed by Finite Element Method for the optimal design of weldment. This study was carried out for the steel plate 8mm thick, 100mm wide, 100mm long that butt weld. The weld was made with a heat input of 2,250 joule/cm(arc current : 180 amperes ; arc voltage :25 volts ; and arc travel steed : 0.28 cm/sec). In the analysis of temperature, cooling in the welded zone by the conduction between materal was almost completed at 600 sec when a unique temperature field was formed. after this, the material was gradually cooled by the heat transfer to the circumference. In the early phase the temperature in base metal zone is little changed. but after the rise in temperature the whole area is cooled gradually.

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A Study on the CO $_2$Laser Beam Welding of Thin Steel Sheets and Tailor Welded Blank (박판 $CO_2$레이져 빔 용접과 소재접합일체성형에 관한 연구)

  • 이희석
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1996.03a
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    • pp.159-164
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    • 1996
  • For the purpose of establishing laser welding condition(laser power, welding speed and beam focus) and of evaluating tailor welded blank for three kinds of thin steel sheets of SPCC, SK5M and SUS304 using in the thin plate structure such as automobile, train and so on. Their $CO_2$ laser weldability were primarily tested under various welding condition. SPCC and SUS304 thin sheets showed good weldability under some welding condition. But, high carbon steel sheet SK5M needs heat treatment after welding to obtain higher tensile strength and ductility of the welded joint. And next, laser welding condition. Butt-welded specimens were not nearly broken at weld bead. However, base material were ruptured in the direction of circumference. The forming depths by tailor weld bead. However, base material were ruptured in the direction of circumference. The forming depths by tailor welded blank were SPCC+SPCC=22~25mm, SUS304+SUS304=25~43mm and SK5M+SK5M=13~17mm.

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Studies on the Influence of Various factors in Ultrasonic Flaw Detection in Ferrite Steel Butt Weld Joints

  • Baby, Sony;Balasubramanian, T.;Pardikar, R.J.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.3
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    • pp.270-279
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    • 2003
  • Parametric studies have been conducted into the variability of the factors affecting the ultrasonic testing applied to weldments. The influence of ultrasonic equipment, transducer parameters, test technique, job parameters, defect type and characteristics on reliability far defect detection and sizing was investigated by experimentation. The investigation was able to build up substantial bank of information on the reliability of manual ultrasonic method for testing weldments. The major findings of the study separate into two parts, one dealing with correlation between ultrasonic techniques, equipment and defect parameters and inspection performance effectiveness and other with human factors. Defect detection abilities are dependent on the training, experience and proficiency of the UT operators, the equipment used, the effectiveness of procedures and techniques.

Electron beam weldability of titanium alloy (타이타늄합금의 전자빔용접성)

  • Lee, Chae-Hun;Yun, Jong-Won;Park, No-Gwang
    • Laser Solutions
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    • v.10 no.4
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    • pp.13-17
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    • 2007
  • Electron beam weldability was investigated for 1mm thick cold rolled sheets of commercially pure grade titanium and Ti-6Al-4V alloy. Accelerating voltage of 40kV, beam current of 6mA, and weld speed of 0.8m/min was used and focal position of focused electron beam was just on the surface of workpiece. Microstructure of weld metal, the heat affected zone and base metal was observed using optical microscope. Vickers hardness was measured across the welds and the transverse tensile test was carried out. Hydroformability test was also carried out for the butt welded coupons of commercially pure grade titanium. For the electron beam welded C P Ti, the average grain size was equiaxed $\alpha(15{\sim}25{\mu}m)$ for base metal, coarse equiaxed $\alpha(80{\sim}200{\mu}m)$ for weld metal and annealed and enlarged grain($40{\sim}120{\mu}m$) for the HAZ. The vickers hardness of C P Ti was $180{\sim}200Hv$ for base metal, and $160{\sim}180Hv$ for the weld metal and the HAZ. For the electron beam welded Ti-6Al-4V alloy, the vickers hardness was 360Hv for the base metal, abd $400{\sim}425Hv$ for the weld metal and the HAZ. All the failure occurred at the base metal, when the transverse weld tensile test was carried out for both electron beam welded C P Ti and Ti-6Al-4V alloy. The formability of electron beam welded C P Ti was decreased compared with that of C P Ti base alloy.

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A Study on the Fatigue Characteristics of Transverse Butt-Welded Joints containing Blowholes (블로우홀을 가진 횡방향 맞대기 용접부의 피로특성에 관한 연구)

  • Chang, Dong Il;Kyung, Kab Soo;Cho, Kwang Hyun;Hong, Sung Wook
    • Journal of Korean Society of Steel Construction
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    • v.11 no.4 s.41
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    • pp.339-350
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    • 1999
  • In this study, blowholes, a kind of solid defects, were intentionally introduced in transverse butt-welded joints which are widely used for the connection of main members in steel structures to evaluate the fatigue characteristics of these joints with blowholes according to the difference of the size and shape of blowholes, and a series of tests were performed. Static test results proved that the static strength of these joints with blowholes was not affected by their size and shape. From the fatigue test results on these joints with blowholes, the size and shape of blowholes inside the weld metals were strongly affected in fatigue strength, and we suggested the relationship between fatigue strength and their size and shape quantitatively. Also, Using the relationship of fatigue crack growth rate and stress intensity factor range, the fatigue life of transverse butt-welded joints with blowholes can be estimated properly.

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Evaluation of Fatigue Behavior for Laser Welded High Strength Steel Sheets (SPFC590) (고장력 강판(SPFC590)의 레이저 용접부 피로거동 평가)

  • Heo, Cheol;Kwon, Jong-Wan;Cho, Hyun-Deog;Choi, Sung-Jong;Chung, Woo-Young
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.5
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    • pp.53-64
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    • 2012
  • Deep and narrow welds can be produced by laser welding at high welding speeds with a narrow heat-affected zone (HAZ) and little distortion of the workpiece. This study aims to evaluate the usefulness of laser welding at automobile component manufacture. Microstructure observation, hardness test, tensile test and fatigue life test are performed by using the fiber laser welded SPFC590 steel sheets which is used widely in the manufacture of automotive seat frame. Three kinds of specimens are only a SPFC590 steel plate, quasi-butt joint plate and lap joint plate by laser welding. The following results that will be helpful to understand the static strength, fatigue crack initiation and growth mechanism were obtained. (1) The tensile strength of quasi butt joint specimens nearly equal to base metal specimens, but lap joint specimens fractured in shear area of weld metal. (2) The fatigue strength of quasi-butt joint specimen was approximately 8 percent lower than that of the base metal specimens. Furthermore, the lap joint specimens were less than 86 percent of the base metal specimens. (3) The lap joint fatigue specimens fractured at shear area in high level stress amplitude, while fractured at normal area in low level stress amplitude. From these results, the applicability of the laser welding to the automobile component is discussed.

Process Development of Rotor Shaft using a Large Friction Welding (대형마찰용접을 이용한 로타샤프트 제조공정개발)

  • Jeong, H.S.;Cho, J.R.;Lee, N.K.;Park, H.C.;Choi, S.K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.401-404
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    • 2007
  • Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint face, and energy required for welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy, amount of upset, working time, and residual stresses in the joint. Inertia welding was conducted to make the large rotor shaft for low speed marine diesel engine, alloy steel for shaft of 140mm. Due to different material characteristics, such as, thermal conductivity and flow stress, on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters.

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Characteristics of Fatigue Behavior and Fracture Surfaces by Rotary Bending Test in SM45C Welding Zone (SM45C용접부에서 회전굽힘시험에 의한 피로 및 파단면의 특성)

  • Lee, Yong-Bok
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.1
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    • pp.26-32
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    • 2010
  • SM45C steel rods using generally for machine components were selected and welded by butt-GMA welding method for this study. And then they were studied about characteristics of fatigue behavior and fracture surfaces by rotary bending test. Fatigue strength in weld zone present highly in order of the boundary between deposited metal zone and heat affected zone, deposited metal zone, heat affected zone. The region of infinite life by Haigh diagram present highly in order of the boundary between deposited metal zone and heat affected zone, deposited metal zone, heat affected zone. Fatigue cracks in unnotched specimens of base metal and weld zone introduce simultaneously from extensive out-side of circumferential cross-section and propagate to the other side indicating beach markings and dimples according to consolidation of fatigue cracks. Fatigue cracks in all of notched specimens introduce simultaneously in out-side of circumferential cross-section by high stresses and propagate to center of it indicating beach markings.