The resistance of metallic materials to ballistic penetration generally depends on a number of parameters related to projectile, impact, and armor plate. Recently, armor materials have been required to have various properties such as hardness, strength, and impact toughness in order to maintain an excellent ballistic resistance even after impact. In the present study, the influence of tempering on the microstructure and mechanical properties of an ARMOX 500T armor steel plate was investigated and then compared with those of S45C and SCM440 steels. As the tempering temperature increased, the hardness and strength gradually decreased, whereas the ductility and impact toughness clearly increased because the hardness, tensile, and impact properties were affected by the microstructural evolution and precipitation occurring during tempering. On the other hand, temper embrittlement appeared at tempering temperatures of 300 to 400 °C for the impact specimens tested at low temperature.

• 임현석(서울과학기술대학교 신소재공학과) | Hyeon-Seok Lim (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 이지민(서울과학기술대학교 신소재공학과) | Jimin Lee (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea)
• 송영범(국방과학연구소) | Young-Beum Song (Agency for Defense Development, P. O. Box 35-5 Daejeon 34060, Republic of Korea)
• 김홍규(국방과학연구소) | Hong-Kyu Kim (Agency for Defense Development, P. O. Box 35-5 Daejeon 34060, Republic of Korea)
• 황병철(서울과학기술대학교 신소재공학과) | Byoungchul Hwang (Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea) Corresponding author