• Title/Summary/Keyword: 용접구조용강재

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Proposal of Estimation Equation for Nominal Strength of Longitudinal Fillet Welds with Different Types of Steel (강종에 따른 종방향 필릿용접부 공칭강도 계산식의 제안)

  • Jo, Jae-Byung;Lee, Hye-Youn
    • Journal of Korean Society of Steel Construction
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    • v.24 no.5
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    • pp.503-510
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    • 2012
  • High performance, high strength steels were developed and used in steel structures recently. Since the newly developed high strength steels posses different toughness, weldability, yield strength ratio, etc. in compare with conventional structural steels, it is requred to investigate the applicability of the design strength of fillet weld specified in the existing design codes. The comparison of the design strengths of various codes from domestic and overseas shows quite a difference. Test results for fillet weld strengths were collected and statistically analysed. Each of yield strength, tensile strength of parent material and tensile strength of weld metal was selected as a main parameter for each estimation equation respectively. All the estimation equations yield almost same values for each type of steel regardless the type of main parameter selected. Considering the behaviour of fillet welded joints and for practical purposes, it is proposed that the equation with tensile strength of parent material is to be used in design codes. The comparison with the proposed nominal strengths of fillet welds shows that the existing design codes could lead to an uneconomical result for low strength steels and lie on an unsafe side for high strength steels.

Evaluation of Forming Performance of TMC Steel Pipes & Tubes for Building Structure (건축구조용 TMC 강관의 가공성능 평가)

  • Im, Sung Woo;Kim, Jong Seong;Chang, In Hwa
    • Journal of Korean Society of Steel Construction
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    • v.16 no.1 s.68
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    • pp.43-49
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    • 2004
  • With building structures becoming higher and having longer spans, new structural steel with better strength, thicker plate, and performance may be required rather than conventional structural steel. TMC steel is widely used in building structures largely due to its excellent seismic performance, superior weldability, and design strength that is not affected by plate thickness. To make use of TMC steel in pipe structures with large diameter and heavy wall, however, the this study, the degradation of material properties in submerged are welded SM520TMC steel pipes and tubes was evaluated using variable fabrication process and material change. Degradation test results showed that the yield and ultimate strength increased and elongation decreased regardless of the mode of fabrication, i.e., through roll bending or press forming, or steel used, i.e., domestic SM520TMC steel or SM520TMC steel from Japan.

Modeling for isothermal bianite transformation in low alloy steels (저합금강의 베이나이트 등온 변태 거동 예측 모델링)

  • 엄상호;문준오;이창희;윤지현;이봉상
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.194-196
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    • 2004
  • 최근 구조용 강재의 제조 및 적용에 있어 기계적 성질 제어의 필요성이 증가하고 있으며, 이는 공정 중의 미세조직 변화의 예측을 필요로 한다. 이에 상변태 현상에 대한 다양한 모델이 제안되고 있으며, 특히 등온 변태 모델과 비 등온 과정을 미소의 등온구간의 합으로 가정한 가산법칙의 적용을 기본으로 하고 있다. (중략)

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A Study on Elasto-Plastic Behavior of Column-to-Beam Welded Connection with 600MPa Class High Performance Steel (600MPa급(SM 570 TMC) 고성능강 기둥-보 용접접합부의 탄소성 거동에 관한 연구)

  • Kim, Jong Rak;Oh, Young Suk;Baek, Ki Youl;Chang, Sung Yun
    • Journal of Korean Society of Steel Construction
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    • v.20 no.6
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    • pp.783-792
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    • 2008
  • While the recent high demand for mega-tall buildings has led to the development of high-performance and high-strength steels, the requirements for architectural-structure-performance steel have been raised as engineers recognize the potential damage that an earthquake can wreak on a tall building. A 600MPa-class steel has emerged to meet such need, and many studies are currently exploring its practical applications on civil engineering works and mega-tall buildings. The available data on the horizontal-force behaviors of structures built with such new steel, however, are still insufficient. There is an urgent need to look into its design data, especially its toughness, and to compare the plastic strain ratios of column-to-beam connections using high-strength steel and regular steel. One of the first studies on the behavior of a column-to-beam connection using 600MPa-class steel (SM570 TMC), this thesis analyzes such steel's structural performance by conducting a structural test on seismic resistance on a full-scale column-to-beam welded connection with non-scallop and recommended-scallop details. Compared with the previous studies on SM490, this thesis evaluates the weldability of SM570 TMC and presents the latter's seismic design data for use in testing its practical application.

Characteristic study of mechanical properties of Structural rolled steel and Stainless steel for MIG welding (구조용 압연강재와 스테인리스 강재의 MIG 용접에 대한 기계적 특성연구)

  • Lim, J.Y.;Yoon, M.J.;Kim, S.Y.;Kim, T.G.
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.13 no.1
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    • pp.100-106
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    • 2014
  • It is well known that fatigue failures occur on welded structures in industrial application due to repetitive load force. In order to decrease the incidence of fatigue failure, we analyzed the mechanical properties based on structural aspects in rolled steel(SS 400) welded onto stainless steel (STS 304) by the MIG welding method as well as the structure of rolled steel welded onto itself. We compared the hardness, tensile and fatigue properties with two types of samples which had no defects on the welding parts as observed by X-ray topographic analysis. It was found that the tensile and fatigue strength levels of SS 400 welded onto STS 304 by the MIG welding method were higher than those of STS 304 welded onto itself.

The effect of Heat input and PWHT on the microstructure and mechanical properties of HSB600 steel weldments (HSB600강 GMA 용접부에서 입열량과 용접후 열처리가 미세조직과 기계적 특성에 미치는 영향)

  • Koh, Jin-Hyun;Kim, Nam-Hoon;Jang, Bok-Su;Ju, Dong-Hwi;Lim, Young-Min
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.12
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    • pp.5405-5411
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    • 2011
  • The effects of heat input (1.5~3.6 kJ/mm) and post weld heat treatment (PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strengths and hardness of as-welded specimens were decreased as heat input increased, but CVN (Charpy V-Notch) impact energy did not show any differences. The fine-grained acicular ferrite was mainly formed in the low heat input while polygonal and side plate ferrites were dominated in the high heat inputs. Meanwhile, tensile strength and hardness of PWHT weldments were decreased due to the coarsening and globular of microstructure as well as reduction of residual stresses.

Numerical Analysis of Chromium Distributions in Laser-Arc Hybrid Welding of Structural Steel Using Stainless Steel Solid Wire (스테인리스강 솔리드와이어를 이용한 구조용 강재의 레이저-GMA 하이브리드 용접에서 크롬 분포의 해석적 분석)

  • Cho, Won-Ik;Na, Suck-Joo;Cho, Min-Hyun;Lee, Jong-Sub
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.110-110
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    • 2009
  • 본 연구에서는 전산유체역학적 방법을 이용하여 레이저-GMA 하이브리드 용접에서 용융풀 거동에 대한 3차원 과도해석을 수행하였다. 철강재의 주요 합금원소 중 하나인 크롬의 용융풀에서의 거동을 구현하기 위해 크롬에 대해 추가적인 보전 방정식을 도입하였다. 이를 이용하여 합금원소 분포에 대한 용접 변수별 영향을 해석적으로 분석하였으며 이를 EPMA(Electron Probe Micro Analyzer)를 통해 분석한 시험결과와도 비교하였다. 결과적으로 용접변수 중 선행 조건이 합금원소 분포에 구별할만한 영향을 미침을 알 수 있었고 이는 용융풀의 거동을 지배하는 주요 유동 패턴의 상이함에 기인한 것으로 보여진다.

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Evaluation of Mechanical Test Characteristics according to Welding Position in FCAW Heterojunction (FCAW 이종접합에서 용접자세에 따른 기계적 시험 특성 평가)

  • Cho, Byung-Jun;Lee, Soung-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.8
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    • pp.649-656
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    • 2019
  • Flux cored arc welding (FCAW), which is used widely in many fields, such as shipyards, bridge structures, construction machinery, and plant industry, is an alternative to shielded metal arc welding (SMAW). FCAW is used largely in the welding of carbon and alloy steel because it can be welded in all poses and obtain excellent quality in the field under a range of working conditions. In this study, the mechanical properties of welded parts were analyzed after different welding of SS400 and SM490A using FCAW. The following conclusions were drawn. The tensile test results satisfied the KS standard tensile strength in the range of 400~510 N/mm2 in all welding positions. The bending test confirmed that most of the specimens did not show surface breakage or other defects during bending and exhibited sufficient toughness, even after plastic deformation. The hardness test results were lower than the standard value of 350 Hv of KS B 0893. Similar to the hardness test, were greater than the KS reference value. The macro test revealed no internal flaws, non-metallic inclusions, bubbles or impurities on the entire cross section of the weld, and there were no concerns regarding lamination.

Experimental Study on Making Databases for Fire Resistant Steel at High Temperature (내화강재의 고온특성 데이터베이스 구축 연구)

  • Kwon, In-Kyu
    • Fire Science and Engineering
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    • v.27 no.5
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    • pp.1-7
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    • 2013
  • Fire at building can occur enormous damages to life, properties, and environment and the risk of fire breakout is going up higher because of application of combustible materials than before. Therefore, the steel industries are trying to develop fire resistant steel in order to sustain the load bearing capacity of steel structures during fire situation. In this paper, to give the basis data-bases for evaluation of structural stability of steel structures applied fire resistant steel, FR 490, the tests of mechanical and thermal properties at high temperature were conducted and the comparisons are done with the SM 490 that has the same mechanical one.

A Study on the Impact Toughness and Microstructure change for Low carbon TMCP Structural Steel Alloy with Welding Heat Impact (용접 입열량에 따른 저탄소형 TMCP 구조용 강재의 용접부 충격인성 및 미세조직 변화에 관한 연구)

  • Gwon Sun Du;Lee Gwang Hak;Park Dong Hwan
    • Proceedings of the KWS Conference
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    • v.43
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    • pp.101-102
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    • 2004
  • This study was investigated on the impact toughness and microstructure of welded metal and heat affected zone for B grade steel. With welding procedures, welding heat inputs applied were 30, 79 and 264 kJ/cm, Prior austenite grain size in coarse zone has increased with increasing welding heat input for B grade steel. The toughness of fusion line zone of Bgrade steel has decreased with increasing welding heat input while the toughness fusion line +3 and +5 mm zone increased contrarily.

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