• Title/Summary/Keyword: Similar Metal Weld

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Fatigue crack growth behaviors of SA508 Gr.3 Cl.2 base and weld material in 290℃ water environment (SA508 Gr.3 Cl.2 저합금강과 용접부의 290℃ 수화학 환경에서 피로균열거동 분석)

  • Cho, Pyungyeon;Kim, Jeong Hyeon;Jang, Changheui;Cho, Hyunchul
    • Corrosion Science and Technology
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    • v.11 no.4
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    • pp.120-128
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    • 2012
  • The fatigue crack growth behaviors of SA508 Gr.3 Cl.2 low alloy steel in high temperature water environment were investigated. Overall, weld metal showed similar crack growth rate as that of base metal. At 0.01 Hz, fatigue crack growth rate (FCGR) was higher than that in air while the difference was smaller at 0.1 Hz. Also, FCGR showed ${\Delta}K$ dependency at 0.1 Hz only, indicating that the environmental effect was much greater at slower loading frequency of 0.01 Hz. FCGR of SA508 Gr.3 Cl.2 low alloy steel was compatible to or smaller than the ASME Sec. XI fatigue reference curves in high temperature water environment.

Welding Characteristics of Aluminized Steel Sheet by Nd:YAG Laser(II) - Behavior of Al element in the weld - (Nd:YAG 레이저를 이용한 알루미늄도금강판의 용접성(II) - 용접부내 알루미늄의 거동 -)

  • Kim, Jong-Do;Lee, Jung-Han;Kim, Ki-Chol
    • Journal of Welding and Joining
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    • v.25 no.4
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    • pp.72-78
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    • 2007
  • Aluminized steel sheet is a material with excellent heat resistance, thermal reflection and corrosion resistance. It has wide applications, owing to its low cost and excellent performance, in the petrochemical industry, electric power and other energy conversion systems, etc and has attracted the attention of many investigators. But the welding of aluminized steel sheet has a problem of decreasing tensile-shear strength, caused by mixed Al in the weld. This study investigated behavior of Al and its structural properties to resolve this problem. Several analysis equipment(SEM, EDX, EPMA) were used to investigate Al element in the weld. Also microhardness tester and TEM equipment were used to find the intermetallic compound. As a result of this study, Al-rich zones existed in the weld and Fe-Al intermetallic compounds were found in these zones. At the same time, the weldability of aluminized stainless steel sheet was investigated and compared with that of aluminized steel sheet. Although there is a difference between the base metal of the low carbon steel and stainless steel, it is interpreted that a behavior of Al element in the weld is similar.

Evaluation of Characteristic for SS400 and STS304 steel by Weld Thermal Cycle Simulation - 2nd Report: Corrosion Characteristics (용접열사이클 재현에 의한 SS400강 및 STS304강의 특성 평가 -제2보: 부식특성)

  • Ahn, Seok-Hwan;Choi, Moon-Oh;Kim, Sung-Kwang;Son, Chang-Seok;Nam, Ki-Wook
    • Journal of Ocean Engineering and Technology
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    • v.21 no.5
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    • pp.33-38
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    • 2007
  • The welding methods have been applied in the most structural products from multi-field of automobile, ship construction and construction, and so on. The structure steel must have enough strength of structure. In this study, SS400 steel and STS304 steel were used to estimate the corrosion characteristics of the weld thermal cycle simulated HAZ. To evaluate the corrosion characteristics, also, the materials with two conditions were used in 3.5% NaCl. The one is to the drawing with diameter of ${\Phi}10$ and the other is to the residual stress removal treatment. The electrochemical polarization test and immersion test were carried out. From test results, corrosion potential, corrosion current density, weight loss ratio and corrosion rate were measured. In the kinds of SS400 steels, corrosion potential of weld thermal cycle simulated specimens after the heat treatment showed somewhat the direction of noble potential. And in the base metal to be drawing weight loss ratio and corrosion rate occurred higher than the other kinds. In the kinds of STS304 steels, the result of base metal to be drawing was similar to results of SS400 steels, too. Two kinds of $750^{\circ}C$ and $1300^{\circ}C$ of weld thermal cycle simulation after the heat treatment were rather higher than the other kinds in weight loss ratio and corrosion rate.

Investigation into Variations of Welding Residual Stresses and Redistribution Behaviors for Different Repair Welding Widths (보수용접부 폭에 따른 용접잔류응력의 변화 및 재분배 거동 평가)

  • Park, Chi-Yong;Lee, Hwee-Sueng;Huh, Nam-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.2
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    • pp.177-184
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    • 2014
  • In this study, we investigated the variations in welding residual stresses in dissimilar metal butt weld due to width of repair welding and re-distribution behaviors resulting from similar metal welding (SMW) and mechanical loading. To this end, detailed two-dimensional axi-symmetric finite element (FE) analyses were performed considering five different repair welding widths. Based on the FE results, we first evaluated the welding residual stress distributions in repair welding. We then investigated the re-distribution behaviors of the residual stresses due to SMW and mechanical loads. It is revealed that large tensile welding residual stresses take place in the inner surface and that its distribution is affected, provided repair welding width is larger than certain value. The welding residual stresses resulting from repair welding are remarkably reduced due to SMW and mechanical loading, regardless of the width of the repair welding.

Assessment of Resistance Spot Weldability of Dissimilar Joints of Austenitic Stainless Steels/IF Steels and Ferritic Stainless Steels/IF Steels (페라이트계 및 오스테나이트계 스테인리스강과 IF강의 이종 접합부의 저항 점 용접성 평가)

  • Lee, Jin-Beom;Kim, Dong-Cheol;Nam, Dae-Geun;Kang, Nam Hyun;Kim, Soon-Kook;Yu, Ji-Hun;Rhym, YoungMok;Park, Yeong-Do
    • Korean Journal of Metals and Materials
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    • v.49 no.1
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    • pp.64-72
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    • 2011
  • The spot weldability of dissimilar metal joints between austenitic stainless steels (STS316)/IF steels and ferritic stainless steels (STS430)/IF steels was investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensile-shear strength, hardness, and microstructure. The comparison of these results was described in terms of fracture behavior. Compared with the weld lobe of similar metal joints, dissimilar metal joints (STS430/IF) had reduced weld current range. However, the weld lobe of STS316/IF steel joint showed increased weld current range. This is because the dilution of chemical composition in the molten weld pool suppressed the heat input being caused by Joule heat with current flow through the samples. The microstructure of the fusion zone was fully martensite and mixture of ferrite and martensite for austenitic stainless steel/IF steel and ferritic stainless steel/IF steel combination, respectively. The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the austenitic and ferritic stainless steel sheet was larger due to the higher bulk-resistance. The predicted microstructure by using the Schaeffler diagram was well matched with experimental results. After peel test, the fracture was initiated from heat affected zone of ferritic stainless steel sheet side, however the final fracture was propagated into the IF steel sheet side due to its lower strength.

Flow Behavior of Laser Welded Boron Steel Sheet in Uniaxial Tension at Elevated Temperature (레이저 용접된 보론강판의 고온 인장 특성 평가)

  • Kim, D.;Kim, J.H.;Yoo, D.H.;Chung, K.;Kim, Y.;Lee, M.Y.
    • Transactions of Materials Processing
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    • v.20 no.5
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    • pp.362-368
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    • 2011
  • For the purpose of improving crashworthiness qualities and maximizing weight saving efficiency, TWB's(tailor welded blanks) of quench-hardenable boron steel sheet formed by hot stamping processes has been used for automotive BIW (body in white) applications. In this work, the flow behaviors of TWB of quench-hardenable boron steel sheet were investigated in uniaxial tension tests at elevated temperature. TWB's having a uniform thickness of 1.4mm were fabricated by laser welding. Specimens with two weld line directions were used to test the mechanical property and reliability of the weld zone. After heating at $950^{\circ}C$ for 5min, the specimens were subjected to tension test at 650, 700 and $800^{\circ}C$ with a strain rate of 0.01 /s and at $700^{\circ}C$ with strain rates of 0.01, 0.1 and 1/s. The ultimate strength of the weld zones was higher than that of the base materials at 650 and $700^{\circ}C$, but was similar to the base metal at $800^{\circ}C$. Fracture occurred at the base material at 650 and $700^{\circ}C$, but at the weld zone at $800^{\circ}C$.

Effect of Similar Metal Weld & Preemptive Weld Overlay On Residual Stress of Repair Weldment In Surge Nozzle (고리 원전 밀림관 노즐의 동종용접과 예방용접 Overlay가 보수용접 잔류응력에 미치는 영향)

  • Oh, Chang-Young;Song, Tae-Kwang;Shim, Kwang-Bo;Kim, Ji-Soo;Kim, Yun-Jae;Lee, Kyung-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.6
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    • pp.557-564
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    • 2009
  • Welding residual stress is occurred after welding process. Tensile residual stress is one factor of PWSCC. Repair welding usually happened during the manufacturing welding process. Repair welds cause strong tensile residual stress. In PWR, Repair weldments made by Alloy 82/182 is susceptible to PWSCC caused by tensile stress, material and environment. Therefore, mitigation of welding residual stress in weldments is important for reliable operating. PWOL is one of the methods for mitigation and verified for over twenty years. In this paper, residual stress distribution of repaired weldments and the effect of PWOL on mitigation is examined for surge nozzle.

Comparison of Mechanical Properties and Microstructural Charateristies of Tandem GMAW Weld Metal in 490MPa Grade Steel (490MPa급 고장력강 탄뎀 가스메탈아크 용접부에 대한 기계적 성질과 미세조직 비교)

  • Yi, Hui-Jun;Kang, Sung-Soo;Yu, Gum-Bin;Bae, Won-Hak;Moon, Hyun-Soo
    • Journal of Welding and Joining
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    • v.27 no.2
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    • pp.76-81
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    • 2009
  • Tandem GMAW is one of the high performance welding process and used in many industries to increase the productivity. An evaluation is presented of the mechanical properties and microstructural characteristics of the Tandem GMAW and conventional Single GMAW welds in 30mm thickness 490MPa grade steel by comparison method. Welding sequence and bead with and hight was kept, avoiding the effect of the bead shape and welding sequence. Tension, bending, hardness and Charpy impact test results of Tandem GMAW met the requirement of specification and showed similar distribution with conventional Single GMAW. Volume fraction of ferrite phase in weld metal showed little difference between Tandem GMAW and Single GMAW

The influence of post weld heat treatment on mechanical properties of stainless steel weldment (스테인리스강 용접부의 기계적 성질에 미치는 후열처리의 영향)

  • 한종만;한기형;이은배;허만주;한용섭
    • Journal of Welding and Joining
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    • v.14 no.3
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    • pp.75-85
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    • 1996
  • In this paper the influence of postweld heat treatment on mechanical properties of SMAW and FCAW stainless steel weldments was examined and the obtained results are as follows ; (1) The amount of $\delta$-ferrite formed by SMAW and FCAW process decreased with increasing holding temperature and time in post weld heat treatment(PWHT), and it was found that the reduced ferrite was transformed into sigma phase after $800^{circ}C{\times}50hr$ PWHT. This sigma phase, even though it was very small, resulted in brittleness of dissimilar weldment between carbon steel and stainless steel in bending test, however in similar weldment between stainless steel and stainless steel was not occured. (2) The chemical composition of sigma phase was measured to 28-30%Cr, 7-9%Mo, 4-6Ni in 316L weldment, and also 35-37%Cr, 0.9-1.0Mo, 6-8%Ni in 309L weldment by EDS analysis.

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강의 마찰용접에 미치는 탄소당량의 영향

  • 나석주;양영수
    • Journal of Welding and Joining
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    • v.4 no.3
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    • pp.32-42
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    • 1986
  • In this study, the influence of carbon equivalents on friction welds of dissimilar steels was investigated. Four types of carbon steels with 10mm diameter were welded to a high-speed tool steel SKH 9. Main experimental results could be summarized as follows (1) Under constant friction pressure, the friction time increased almost linearly with the increasing burn-off length, while the forge length decreased almost linearly. (2) The maximum hardness in carbon steels increased almost linearly with the increasing carbon equivalent, but was much lower than that in the high speed steel. (3) After quenching and tempering of dissimilar steel friction welds, the hardness in carbon steel weldments became similar as that in the base metal, while the hardness in SKH 9 weld was still higher that of the base metal. (4) Relative movement in the friction phae occurred not at the interface of the weldments, but in the high speed steed steel near the interface. (5) For considered material combinations and welding parameters, most of fractures in tension and twisting tests occurred in the base metal. And welds with so high strength could produced in a wide range of welding parameters.

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