• 제목/요약/키워드: Similar Metal Weld

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

  • 조평연;김정현;장창희;조현철
    • Corrosion Science and Technology
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    • 제11권4호
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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.

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

  • 김종도;이정한;김기철
    • Journal of Welding and Joining
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    • 제25권4호
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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.

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

  • 안석환;최문오;김성광;손창석;남기우
    • 한국해양공학회지
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    • 제21권5호
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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.

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

  • 박치용;이휘승;허남수
    • 대한기계학회논문집A
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    • 제38권2호
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    • pp.177-184
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    • 2014
  • 본 논문에서는 보수용접부 폭 변화에 따른 이종금속 맞대기 용접부(Dissimilar metal butt weld) 용접잔류응력의 분포 및 동종금속용접/기계적 하중에 의한 재분배 거동을 평가하였다. 이를 위해 5가지 다른 보수용접부 폭을 고려한 상세 2차원 유한요소 열해석 및 응력해석을 수행하였다. 유한요소해석 결과를 바탕으로 보수용접에 의한 용접잔류응력 분포를 평가하였으며, 동종금속용접 및 기계적 하중에 의한 응력 재분배 특성을 평가하였다. 보수용접에 의해 배관 내면에서는 큰 인장 용접잔류응력이 축방향과 원주방향에 대해 발생하는 것으로 나타났으며 보수용접부 폭이 특정값 이상이 되면 용접잔류응력 분포가 변하는 것으로 나타났다. 그러나 동종금속용접과 기계적 하중을 고려하면 인장잔류응력값이 크게 감소하였으며 그 경향은 보수용접부 폭에 무관한 것으로 나타났다.

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

  • 이진범;김동철;남대근;강남현;김순국;유지훈;임영목;박영도
    • 대한금속재료학회지
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    • 제49권1호
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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.

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

  • 김대용;김지훈;유동훈;정관수;김용;이문용
    • 소성∙가공
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    • 제20권5호
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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 $800^{\circ}C$.

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

  • 오창영;송태광;심광보;김지수;김윤재;이경수
    • 한국전산구조공학회논문집
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    • 제22권6호
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    • pp.557-564
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    • 2009
  • 용접과정 중 발생되는 인장잔류응력은 원전 배관 이종용접부의 PWSCC가 발생되는 원인 중 하나라고 알려져 있다. 일반적으로 보수용접은 용접과정 중 흔히 일어나는 현상이다. 보수용접은 강한 인장잔류응력을 유도하기 때문에 이종용접부의 PWSCC를 유도하기 쉽다. 본 논문에서는 강한 인장잔류응력이 발생되는 보수용접부에 대해 보수용접 깊이에 따라 동종용접과 예방용접 overlay로 인하여 인장잔류응력의 크기가 변화하는 것을 정량적으로 확인하였다.

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

  • 이희준;강성수;유금빈;배원학;문현수
    • Journal of Welding and Joining
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    • 제27권2호
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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

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

  • 한종만;한기형;이은배;허만주;한용섭
    • Journal of Welding and Joining
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    • 제14권3호
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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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    • 제4권3호
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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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