Journal of Welding and Joining

The Korean Welding and Joining Society (대한용접접합학회)
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An Investigation on the Microstructure Evolution and Tensile Property in the Weld Heat-Affected Zone of Austenitic FeMnAlC Lightweight Steels

오스테나이트계 FeMnAlC 경량철강의 용접열영향부 미세조직 변화 및 인장특성에 관한 연구

  • Moon, Joonoh (Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science) ;
  • Park, Seong-Jun (Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science)
  • 문준오 (한국기계연구원 부설 재료연구소 철강재료연구실) ;
  • 박성준 (한국기계연구원 부설 재료연구소 철강재료연구실)
  • Received : 2017.01.31
  • Accepted : 2017.02.17
  • Published : 2017.02.28
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Abstract

IMicrostructure evolution and tensile property in the weld heat-affected zone (HAZ) of austenitic Fe-30Mn-9Al-0.9C lightweight steels were investigated. Five alloys with different V and Nb content were prepared by vacuum induction melting and hot rolling process. The HAZ samples were simulated by a Gleeble simulator with welding condition of 300kJ/cm heat input and HAZ peak temperatures of $1150^{\circ}C$ and $1250^{\circ}C$. Microstructures of base steels and HAZ samples were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and their mechanical properties were evaluated by tensile tests. The addition of V and Nb formed fine V and/or Nb-rich carbides, and these carbides increased tensile and yield strength of base steels by grain refinement and precipitation hardening. During thermal cycle for HAZ simulation, the grain growth occurred and the ordered carbide (${\kappa}-carbide$) formed in the HAZs. The yield strength of HAZ samples (HAZ 1) simulated in $1150^{\circ}C$ peak temperature was higher as compared to the base steel due to the formation of ${\kappa}-carbide$, while the yield strength of the HAZ samples (HAZ 2) simulated in $1250^{\circ}C$ decreased as compared to HAZ 1 due to the excessive grain growth.

Keywords

References

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