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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 (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Kim, Nam-Hoon (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Jang, Bok-Su (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Ju, Dong-Hwi (School of Energy.Materials.Chemical, Korea University of Technology and Education) ;
  • Lim, Young-Min (School of Energy.Materials.Chemical, Korea University of Technology and Education)
  • 고진현 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 김남훈 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 장복수 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 주동휘 (한국기술교육대학교 에너지.신소재.화학공학부) ;
  • 임영민 (한국기술교육대학교 에너지.신소재.화학공학부)
  • Received : 2011.09.20
  • Accepted : 2011.12.13
  • Published : 2011.12.31

Abstract

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.

본 연구에서는 교량용 구조용 강재인 HSB600 강의 용접부에서 입열량 (1.5~3.6 kJ/mm)과 용접후 열처리(PWHT, $600^{\circ}C$, 40hr.)가 미세조직과 기계적 특성에 미치는 영향에 관해 연구하였다. HSB600 강재를 GMA용접을 실시하였다. 용접된 상태에서는 인장강도와 경도는 입열량이 증가할수록 저하되었으며 충격 흡수 에너지는 큰 차이를 보이지 않았다. 낮은 입열량인 1.5 kJ/mm에서 침상형 페라이트가 가장 많이 생성되었다. 용접후 열처리를 통해 경도와 인장강도가 저하되었고, 용착금속의 충격흡수에너지가 증가되었다.

Keywords

References

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