This study examines the effect of microstructural factors on the strength and deformability of ferrite-pearlite steels. Six kinds of ferrite-pearlite steel specimens are fabricated with the addition of different amounst of Mn and V and with varying the isothermal transformation temperature. The Mn steel specimen with a highest Mn content has the highest pearlite volume fraction because Mn addition inhibits the formation of ferrite. The V steel specimen with a highest V content has the finest ferrite grain size and lowest pearlite volume fraction because a large amount of ferrite forms in fine austenite grain boundaries that are generated by the pinning effect of many VC precipitates. On the other hand, the room-temperature tensile test results show that the V steel specimen has a longer yield point elongation than other specimens due to the highest ferrite volume fraction. The V specimen has the highest yield strength because of a larger amount of VC precipitates and grain refinement strengthening, while the Mn specimen has the highest tensile strength because the highest pearlite volume fraction largely enhances work hardening. Furthermore, the tensile strength increases with a higher transformation temperature because increasing the precipitate fraction with a higher transformation temperature improves work hardening. The results reveal that an increasing transformation temperature decreases the yield ratio. Meanwhile, the yield ratio decreases with an increasing ferrite grain size because ferrite grain size refinement largely increases the yield strength. However, the uniform elongation shows no significant changes of the microstructural factors.

Abstract
 1. 서 론
 2. 실험 방법
 3. 실험 결과
 4. 결과 및 고찰
 5. 결 론
 Reference

• 홍태운(서울과학기술대학교 신소재공학과) | Tae-Woon Hong (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)
• 심재혁(한국과학기술연구원 고온에너지재료연구센터) | Jae-Hyeok Shim (High Temperature Energy Materials Research Center, Korea Institute of Science and Technology)
• 이준호(고려대학교 신소재공학부) | Junho Lee (Department of Materials and Engineering, Korea University)
• 이명규(서울대학교 재료공학부) | Myoung-Gyu Lee (Department of Materials Science and Engineering, Seoul National University)
• 황병철(서울과학기술대학교 신소재공학과) | Byoungchul Hwang (Department of Materials Science and Engineering, Seoul National University of Science and Technology) Corresponding author