The effect of intercritical annealing temperature on the microstructure and mechanical properties of Fe-9Mn-0.2C- 3Al-0.5Si medium manganese steels containing Cu and Ni is investigated in this study. Six kinds of medium manganese steels are fabricated by varying the chemical composition and intercritical annealing temperature. Hardness and tensile tests are performed to examine the correlation of microstructure and mechanical properties for the intercritical annealed medium manganese steels containing Cu and Ni. The microstructures of all the steels are composed mostly of lath ferrite, reverted austenite and cementite, regardless of annealing temperature. The room-temperature tensile test results show that the yield and tensile strengths decrease with increasing intercritical annealing temperature due to higher volume fraction and larger thickness of reverted austenite. On the other hand, total and uniform elongations, and strain hardening exponent increase due to higher dislocation density because transformation-induced plasticity is promoted with increasing annealing temperature by reduction in reverted austenite stability.

Abstract
1. 서 론
2. 실험 방법
3. 결과 및 고찰
    3.1 2상역 어닐링 온도에 따른 미세조직 변화
    3.2 경도 및 인장 특성
4. 결 론
References

• 이승완(서울과학기술대학교 신소재공학과) | Seung-Wan Lee (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 신승혁(서울과학기술대학교 신소재공학과) | Seung-Hyuk Sin (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 황병철(서울과학기술대학교 신소재공학과) | Byoungchul Hwang (Department of Materials Science and Engineering, Seoul National University of Science and Technology) Corresponding author