Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Effect of Heat Treatment on Microstructure and Mechanical Properties of an Fe-6.5Mn-0.08C Medium-Manganese Steel

열처리에 따른 Fe-6.5Mn-0.08C 중망간강의 미세조직과 기계적 특성

  • Yoon, Young-Chul (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Lee, Sang-In (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Hwang, Byoungchul (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
  • 윤영철 (서울과학기술대학교 신소재공학과) ;
  • 이상인 (서울과학기술대학교 신소재공학과) ;
  • 황병철 (서울과학기술대학교 신소재공학과)
  • Received : 2019.09.30
  • Accepted : 2019.12.01
  • Published : 2020.01.27
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Abstract

Effect of heat treatment on microstructure and mechanical properties of an Fe-6.5Mn-0.08C medium-manganese steel is investigated in this study. Three kinds of medium-manganese steel specimens are fabricated by varying heat treatments of intermediate quenching (IQ), step quenching (SQ), and intercritical annealing (IA). Hardness and tensile tests are performed to examine the correlation of microstructure and mechanical properties for the Fe-6.5Mn-0.08C medium-manganese steel specimens. The IQ and SQ specimens have microstructures of martensite matrix with ferrite, whereas IA specimen exhibits microstructure of acicular ferrite matrix with martensite. The tensile test results show that the SQ specimen with martensite matrix has the highest yield strength and the lowest elongation. On the other hand, the SQ specimen has the highest hardness due to the relatively lower reduction of carbon content in martensite during intercritical annealing. According to the fractography of tensile tested specimens, the SQ specimen exhibits a dimple and quasi-cleavage fracture appearance while the IQ and IA specimens have fully ductile fracture appearance with fine-sized dimples caused by microvoid coalescence at ferrite and martensite interface.

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References

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