This study deals with the yielding behavior and strain aging properties of three bake hardening steels with dualphase microstructure, fabricated by varying the annealing temperature. Bake hardening and aging tests are performed to examine the correlation of martensite volume fraction with yielding behavior and strain aging properties of the bake hardening steels with dual-phase microstructure. The volume fraction of martensite increases with increasing annealing temperature. Roomtemperature tensile test results show that the yielding behavior changes from discontinuous-type to continuous-type with increasing volume fraction of martensite due to higher mobile dislocation density. According to the bake hardening and aging tests, the specimen with the highest fraction of martensite exhibited high bake hardening with low aging index because solute carbon atoms in ferrite and martensite effectively diffuse to dislocations during the bake hardening test, while in the aging test they diffuse at only ferrite due to lower aging temperature.

Abstract
1. 서 론
2. 실험 방법
3. 결과 및 고찰
    3.1 어닐링 온도에 따른 미세조직 변화
    3.2 마르텐사이트 분율에 따른 항복 거동 및 시효 특성
4. 결 론
References

• 이승완(서울과학기술대학교 신소재공학과) | Seung-Wan Lee (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
• 이상인(서울과학기술대학교 신소재공학과) | Sang-In Lee (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