• Title/Summary/Keyword: Weld Strength

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Effects of the Stand-off Distance on the Weld Strength in Magnetic Pulse Welding (전자기펄스용접에서 용접강도에 미치는 접합간격의 영향)

  • Kim, Sung-Wook;Chun, Chang-Keun;Kim, Sook-Hwan
    • Journal of Welding and Joining
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    • v.26 no.6
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    • pp.48-53
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    • 2008
  • Although Magnetic Pulse Welding(MPW) is not a recently developed technique, it has gained the attention of the automotive industry. MPW has become an accepted welding process because it enables the joining of similar, and dissimilar materials, with a very short cycle time, without the need for filler metal and gases. In this study, the effect of the stand-off distance on the weld strength has been investigated. The compressive strength of the MPW joints was evaluated using UTM. The interface of weld, IMC composition and morpology were studied by SEM and EDS. It was concluded that the stand-off distance and the voltage are the main parameters influencing the strength of weld. In case of too high stand-off distance, it influenced harmful effect because of the resistance of deformation.

Laser Weldability of Sheet Steels for Tailored Blank Manufacturing (II) -Effect of Joint Configuration- (테일러드 블랭크용 박판 강재의 레이저 용접성 (II) -이음 형상이 용접성에 미치는 영향-)

  • 김기철;이기호;이목영
    • Journal of Welding and Joining
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    • v.16 no.2
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    • pp.100-110
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    • 1998
  • In this paper, the laser weldability of thin gage steels for automobile application is discussed. Welding was carried out with a high power carbon dioxide laser system, and the laser energy was concentrated through a plano-convex lens. Test results showed that the joint gap in the butt welding proved to be one of the critical conditions for an acceptable weld. In the case where the ratio of the gap clearance to the material thickness was slightly bigger than optimal value, the weld strength was reduced showing weld metal fracture. It was possible to obtained a weld penetration ratio of 0.91 when the vertical offset ratio was controlled to be 0.4 or smaller. Results also demonstrated that the weld strength of the lap joint was influenced by travel speed. At the travel speeds lower than 37 mm/s, the weld strength indicated higher value than that of class A recommendation strength of a resistance spot weld based on the KS code. It was clear that the complicated effect of specimen alignment should be considered so as to make a sound weld with high integrity when the laser process was applied to the long weld line.

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An Experimental Study on Allowable Size of Incomplete Penetration in Butt Joint Bridge Weld Considering Fatigue Strength (교량의 피로강도를 고려한 맞대기용접부 불안전용입 한계결함 결정에 관한 연구)

  • 백영남;장영권
    • Journal of Welding and Joining
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    • v.18 no.3
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    • pp.68-75
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    • 2000
  • The incomplete penetration(IP) discontinuity in butt joint weld, which is detected during safety analysis of the steel bridge by nondestructive evaluation(NDE) method, is classified as unacceptable defect according to the NDE codes and standards. In fact, there are a little allowance in butt joint weld in the view point of design criterion, and also detected IP discontinuity should be classified and evaluated for the fatigue strength and residual life estimation. In this study, we performed fatigue test to evaluate the fatigue strength of high strength steel(SWS490A) containing IP discontinuities in various size, the results compared and classified according to the bridge construction standard specification which published by korea administration of construction and traffic. Experimental results could be used to evaluate and estimate the IP discontinuities considering different stress range in butt joint bridge weld during periodic safety inspection.

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Cold Cracking Susceptibility in Weld Metal of High Strength-Toughness Steel (고강도 고인성강 용접금속의 저온균열 감수성에 관한 연구)

  • 이종봉;안상곤;안영호;김영우
    • Journal of Welding and Joining
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    • v.13 no.4
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    • pp.46-54
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    • 1995
  • The cold cracking susceptibility of a variety of weld metals deposited by GMAW with several kinds of commercial solid wires for high strength-toughness steel was investigated. G-BOP test and LB-TRC test were carried out to study the effects of preheat, chemical composition and hydrogen level on the weld metal cold cracking. The results obtained are as follows. 1) 10% CPT obtained by G-BOP test was the most valuable criteria for evaluating the cold cracking susceptibility of weld metals compared with percentage of cracking at room temperature and crack free temperature, and it had good correlation with the results of LB-TRC test. 2) Cold cracking susceptibility of weld metals was high in the row of MG100A, MG100C, MG100D and MG100B. Welds deposited with MG130 and MG80 showed similar icidents of cracking with MG100C and MG100B respectively, even though their strength levels were different. 3) Diffusible hydrogen level in weld metals which has good relation with hydrogen content in wire itself was the most critical factor for controlling the cold cracking susceptibility of weld metal.

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A Study on the Fatigue Strength Improvement of the Fillet Welded Connections with respect to Post-Weld Treatment (용접 후처리에 의한 필렛용접부의 피로강도 향상에 관한 연구)

  • Lee, Seung Yong;Kyung, Kab Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.5A
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    • pp.665-672
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    • 2008
  • In the study herein, the fatigue test was conducted on the fillet welds of the load carrying cruciform joint, which is frequently used in the steel structures such as bridges, ships, etc. In addition, the fatigue strength was analyzed with respect to the different post-weld treatment. The treatment methods used include Toe Grinding, TIG Dressing, and Weld Profiling. The fatigue test was under constant amplitude with repeated load for these test specimens. In the load carrying full penetration fillet welded joints, regardless the conduction of the post-weld treatment or not, they all secured the fatigue strength of category "F", which exceeds the fatigue design specifications of BS Code. In the comparison of the fatigue strength upon the post-weld treatment, the fatigue strength tends to increase according to the order: Toe Grinding, TIG Dressing, and Weld Profiling.

Realation of Injection Temperature and Weld-quality in Injection Molding (사출 성형 시 수지온도와 웰드품질과의 관계)

  • Noh, Keon-Cheol;Lee, Gyu-Ho;Jang, Min-Kyu;Jeong, Yeong-Deug
    • Design & Manufacturing
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    • v.9 no.1
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    • pp.27-30
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    • 2015
  • The injection molding is used in more than 70% of total production of plastic products. Weld line in injection molded part is one of the defects in injection molding process. Weld line deteriorates not only appearance quality but also mechanical property. In this study, tensile strength about material such as ABS, PP, PA and PS was tested. as the results, the first result appears that weld's strength retention ratio's are 0.90, 0.84, 0.85, 0.76 and the second result apeears that weld depth decrease as processing temperature increased.

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Influence of Lap Weld Shapes on Shear Strength by Plasma Arc Welding of SUS 304L (플라즈마 아크 용접에 의한 SUS 304L Lap 용접부형상이 강도에 미치는 영향)

  • 문종현;윤동렬;김동철;이동우;장태원
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.129-130
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    • 2004
  • The stainless steel sheet which is one of primary barrier components for membrane on LNG ship is ordinarily welded by either TIG or PAW. The weld shapes of acceptant tolerance for membrane construction are scripted by G.T.T.(Gaztransport & Technigaz)‘s rules such as penetration depth, weld throat and weld length etc. This paper presents relationship between weld metal shear strength and weld penetration formed with plasma arc welding. The results show penetration depth is not decisive factor on shear strength, but weld throat and length.

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Al-7020의 Pulse-GMA용접에 관한 연구 2

  • 김재웅;허장욱;나석주;백운형
    • Journal of Welding and Joining
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    • v.6 no.4
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    • pp.54-62
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    • 1988
  • Major problems in welding Al-7020 include shrinkage, rpopositgy in welds and loss of strength in the heat affected zone. Thus it is important to examine the mechanical properties and reliability of welds. In this study, a series of experiments was carried out to determine the mechanical properties such as micro-hardness distribution, tensile strength, porosity and residual stress distribution of the Al-7020 weldment made by pulse-GMA welding. The resuts of the experiemnts are as folows. 1) The micro-hardness of weld metal and heat affected zone was lower than that of the base metal. 2) The tensile strength of the deposited metal was much lower than that of the base metal. 3) The porrosity in weld metal zone was negligible under the adopted conditsion of experiemnts. 4) The residual stress in the weld metal was lower than that of the heat affected zone, because the weld metal was softened. And the mciro-hardness distribution, the tensile strength and the residual stess distribution of the weldment in the as-welded condition were compared with those of the weldment after heat treatment.

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A Feasibility Study on Dissimilar Metals Friction Weld Strength Analysis by Ultrasonic Techniques (초장파에 의한 이종재 마찰용접 강도해석 가능성에 관한 연구)

  • 오세규;김동조
    • Journal of Welding and Joining
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    • v.4 no.2
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    • pp.47-52
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    • 1986
  • Friction Welds are formed by the mechanisms of diffusion as well as mechanical inter-locking. The severe plastic flow at the interface by the forge action of the process brings the subsurface so close together that detection of any unbounded area becomes very difficult. No reliable method is available so fat to determine the weld quality nondestructively. The paper presents an attempt to determine weld strength quantitatively using the ultrasonic pulseecho method. The new approach calculates the coefficient of reflection based on measured amplitudes of the echoes. This coefficient provides a single quantitative measurement which involves both acoustic energy reflected at the welded interface as well as transmitted across the interface. As a result, it was known that the quantitative relationship between the coefficient and the weld strength (torsional strength) could be drawn.

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Study on Friction Welding of Torsion Bar Material(II) - Effect of PWHT on Friction Weld Quality- (토션바재의 마찰용접에 관한 연구(II) -용접 후열처리가 마찰용접 품질에 미치는 영향-)

  • Oh, Sae-Kyoo;Lee, Jong-Du
    • Journal of Ocean Engineering and Technology
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    • v.4 no.2
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    • pp.94-99
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    • 1990
  • This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT. 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal. 3) The micro-structure of the base meta., HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.

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