• Title/Summary/Keyword: 용접봉

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Characteristics of dissimilar laser welding of high Mn steel (고Mn강의 이종 레이저용접 특성)

  • Jeong, Bo-Yeong;Han, Tae-Gyo;Lee, Jong-Bong
    • Proceedings of the KWS Conference
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    • 2007.11a
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    • pp.190-192
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    • 2007
  • High Mn steel has been developed for automotive applications since the steel has an excellent combination of strength and ductility. However, from the viewpoint of welding, high Mn steel has a few problems related to its chemical composition. In this study, development of dissimilar laser welding technology has been investigated for expanding application of high Mn steel. The results have shown that dissimilar weld joint between high Mn steel and carbon steel has poor erichsen property using STS309L filler wire or not.

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High Temperature Crack Growth Behavior at Heat Affected Zone (용접열영향부 균열의 고온에서의 성장거동)

  • 백운봉;윤기봉
    • Proceedings of the KWS Conference
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    • 2001.05a
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    • pp.104-107
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    • 2001
  • Creep-fatigue crack growth behavior at the heat affected zone of 1Cr-0.5Mo steel weldment has been experimentally studied. Load hold times of the tests for trapezoidal fatigue wave-shapes were varied among 0, 30, 300 and 3,600 seconds. Time-dependent crack growth rates were characterized by the $C_{t}$ estimated with the equation proposed by the previous finite element analysis work. It was concluded that the $C_{t}$ values calculated from the properties of parent metal were quite comparable to the accurate $C_{t}$ values calculated from both of weld and parent metals.etals.

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Effect of Nitrogen Content on SAW Weld Metal Properties (SAW 용접금속 성질에 미치는 질소함량의 영향)

  • Byeon, Ji-Cheol;Bang, Guk-Su;Lee, Jong-Bong;An, Yeong-Ho
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.147-149
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    • 2005
  • Effect of nitrogen content on SAW weld metal properties were investigated. Weld metal nitrogen content increased with an increase of base metal nitrogen content due to dilution. High nitrogen content in weld metal resulted in high free nitrogen content, and consequently reduced impact toughness due to, mainly, strain aging effect.

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HAZ Microstructure and Toughness in High Heat Input Welding (대입열용접 열영향부의 조직과 인성)

  • 방국수;이종봉;장래웅
    • Journal of Welding and Joining
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    • v.10 no.1
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    • pp.12-19
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    • 1992
  • 용접능률의 향상을 위한 대입열용접법의 적용은 과도한 입열량으로 인하여 용접부의 인성이 저 하한다는 점에서 그 적용에 주의를 요한다. 본 보에서는 대입열용접시 열영향부의 인성 저하의 원인과 그 대책을 강재의 측면에서 검토하였다. 고장력강을 용접하면 입열량이 증가함에 따라 오스테나이트 결정립이 조대화되고 상부 베이나이트와 도상 마르텐사이트가 생성되어 인성이 저하한다. 그 대책으로서는 용접 열싸이클과정중 안정한 질화물, 산화물등을 모재에 미세분산시켜 오스테나이트 결정립 성장을 억제하고, 페라이트, 펄라이트 변태를 촉진시킨다. 이러한 석출물의 형성을 위해서는 주로 Ti, Ca, REM, B등의 합금원소가 이용된다. 소입성이 높은 주질고장력 강에서는 석출물의 분산에 의한 페라이트의 변태 촉진 보다는 Mn, Ni, Cr, Mo, V등의 합금원 소를 첨가하여 소입성을 높여 인성이 우수한 하부 베이나이트 조직을 형성하든가, 탄소량을 저 감시켜 도상 마르텐사이트의 생성을 억제하므로서 인성을 확보한다. 현재 국내에서 제조되고 있는 대입열용접용강중 인장강도 50kgf/mm$^{2}$급강은 기본적으로 용접부 인성이 우수한 TMCP법으로 제조되며, Ti등을 첨가하여 석출물의 효과를 이용하고 N을 억제하여 기지의 인 성을 향상시키는 등의 방법을 병용하고 있다. 인장강도 60kgf/mm$^{2}$ 급강은 조질처리에 의하여 제조되며, 50kgf/mm$^{2}$급강과 같이 Ti, B등의 첨가에 의한 석출물의 효과를 이용 하고 있다.

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A Study for Mitigating Residual Stress in CRDM Penetration Nozzle Weld (제어봉구동장치 관통노즐 용접부의 잔류응력 완화를 위한 연구)

  • Lee, Seung-Gun;Kim, Jong-Sung;Jin, Tae-Eun
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.90-95
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    • 2004
  • In this study, we proposed new method to mitigate tensile welding residual stress for preventing PWSCC in CRDM nozzle. Residual stress analysis using finite element method is performed to confirm benefit of the new method. In case of applying existing method, tensile axial residual stress decrease by about 28% and tensile hoop residual stress decrease by about 33%. In case of applying the new method, tensile axial residual stress decrease by about 32% and tensile hoop residual stress decrease by about 43%. Therefore, we conclude the new proposed method is more effective to prevent PWSCC than existing method.

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A Study on the Optimum Welding Conditions for Reducing the Depth of Indentation of Surface in Spot Welding (점용접 시 압흔 깊이 감소를 위한 최적 용접조건 선정에 관한 연구)

  • 서승일;이재근;장상길;차병우
    • Journal of Welding and Joining
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    • v.14 no.2
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    • pp.57-64
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    • 1996
  • In this paper, authors are trying to find optimum spot weldig conditions to minimize indentation of the plate surface which is crucial to quality of stainless rolling stocks. At first, to derive a simple equation to estimate the depth of indentation, a simplified one-dimensional bar model is proposed and validity of the model is confirmed by experiments. And also, to find proper welding conditions giving satisfied tensile strength of the welded joint, a simple formula is derived referring to the standard spot welding conditions by AWS. Optimization problem is formulated to find welding conditions such as welding current, time and applied force which give minimum indentation and proper tensile strength of joint, and solutions are found out. According to the results, the depth of indentation can be expressed by applied electrode froces and it can be shown that an optimum applied force exists.

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Wear characteristics of build-up weld metal using CH-90 Electrode (CH-90 용접봉을 이용한 육성 용접부의 마모 특성에 관한 연구)

  • Lee, Bo-Yeong;An, Dae-Hwan;Kim, Jae-Seong;Jin, Hyeong-Guk
    • Proceedings of the KWS Conference
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    • 2006.10a
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    • pp.225-227
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    • 2006
  • As rail steel at a crossing area must undergo much higher loading than those at regular railway, Mn-alloyed steel is normally used for its high load-carrying capability and reduced wear rate. However, as these Mn-alloyed steel is tend to have casting defects, manufacturing cost to produce defect-free Mn-alloyed steel becomes quite expensive. Therefore, in order to replace Mn-alloyed steel, we performed build-up welding using CH-90 and investigated regarding to wear characteristics of build-up weld metal.

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Welding Characteristics of Recently Developed 9% Ni Steel (최근 9%Ni강의 용접특성)

  • 이종봉;한재광
    • Journal of Welding and Joining
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    • v.13 no.3
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    • pp.34-45
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    • 1995
  • 9%Ni강은 1944년 미국의 INCO(International Nickel Co., Ltd.)에 의해 최초 로 개발된 강도가 높고 용접성이 우수한 강제로서, 특히 극저온에서의 충격 인성이 우수하고 경제적으로도 유리하여 LNG 탱크 소재로서 사용한 실적이 많으며, 그동안 일본이 주축이 되어 강재의 품질개선 및 고능률.고품질의 용접기술 개발 등을 비롯 하여 탱크의 대형화 추세에 따른 안전성 확보를 위한 연구도 계속되고 있다. 이러한 추세에 동참하여 우리나라도 1993년 국산의 9%Ni강을 성공적으로 개발하게 되었고, 그 품질특성에 대해서도 국내외에 발표되었으나 여건이 미비하여 현재 국내에서 건설 중인 탱크의 소재로서는 공급되지 못하였다. 그러나 최근에 개발된 국산 강제는 자체 시험결과 뿐 아니라 외국 유수 연구기관의 시험결과에서도 각종 품질특성이 선진 제품 과 동등 이상으로 우수함이 입증되어, 가까운 장래 건설예정인 국내공사에는 물론 해외에서도 사용될 것으로 기대되고 있다. 따라서 본 해설은 향후 국내외의 LNG 수요 를 고려할 때 대형 저장탱크의 건설이 활발해 질 것으로 전망됨에 따라 9%Ni강의 현황 과 함께 최근 개발된 국산 강재의 용접특성에 대하여 소개하고자 한다.

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Characteristics of Rail head Upbringing Welding using CH-90 Electrode (CH-90 용접봉을 이용한 레일 두부 육성용접의 특성)

  • Lee, Bo-Yeong;An, Dae-Hwan;Kim, Jae-Seong;Ryu, Deok-Hui;Jin, Hyeong-Guk;Gwon, Ho-Jin
    • Proceedings of the KWS Conference
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    • 2005.11a
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    • pp.177-179
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    • 2005
  • As rail steel at a crossing area must undergo much higher loading than those at regular railway, Mn-containing casting steel is normally used for its high load-carrying capability and reduced wear rate. However, as these Mn-containing casting steel is tend to have casting defects, manufacturing cost to produce defect-free Mn-containing casting steel becomes quite expensive. Therefore, in order to investigate the possibilities of replacing expensive Mn-containing casting steel with a mild steel with a surface build-up using a Mn-alloyed steel electrode.

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A Study on the Properties of Underwater Wet Arc Welding for the Mild Steels (연강의 습식 수중 아크 용접 특성에 관한 연구)

  • Kwak, H.H.;Kim, C.G.
    • Journal of Power System Engineering
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    • v.11 no.1
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    • pp.107-114
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    • 2007
  • Underwater wet arc welds were experimentally performed on 11mm thick SS400 mild steel plate as base metal by using six different types of flux coated electrodes of 4.0mm diameter; KSKR, KSKT, USBL, JPUW, UWEA, and UWEB. As results, the developed flux coated underwater electrode had a good weldability compared with other domestic terrestrial electrodes. By rapid cooling rate, the hardness value of HAZ were increased by quenching effects. Mechanical properties for the multi-pass butt-welding specimen are also tested experimentally. The feasibility of the developed underwater electrode was experimentally studied and the results achieved in this wet arc welds have shown that the developed wet welding electrode UWEB can have a degree of integrity.

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