Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Microstructure and Mechanical Properties of the High-Hardness Armor Steels

고경도 철계 장갑재의 미세조직과 기계적 특성 분석

  • Lee, Ji-Min (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Han, Jong-Ju (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Song, Young-Beum (The 4th R&D Institute, Agency for Defense Development) ;
  • Ham, Jin-Hee (The 4th R&D Institute, Agency for Defense Development) ;
  • Kim, Hong-Kyu (The 4th R&D Institute, Agency for Defense Development) ;
  • Hwang, Byoungchul (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
  • 이지민 (서울과학기술대학교 신소재공학과) ;
  • 한종주 (서울과학기술대학교 신소재공학과) ;
  • 송영범 (국방과학연구소 제4기술연구본부) ;
  • 함진희 (국방과학연구소 제4기술연구본부) ;
  • 김홍규 (국방과학연구소 제4기술연구본부) ;
  • 황병철 (서울과학기술대학교 신소재공학과)
  • Received : 2018.05.24
  • Accepted : 2018.06.28
  • Published : 2018.08.27
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Abstract

This paper presents a study of the microstructure and mechanical properties of commercial high-hardness armor (HHA) steels tempered at different temperatures. Although the as-received specimens of all the steels exhibit a tempered martensite structure with lath type morphology, the A steel, which has the smallest carbon content, had the lowest hardness due to reduced solid solution hardening and larger lath thickness, irrespective of tempering conditions. As the tempering temperature increases, the hardness of the steels steadily decreases because dislocation density decreases and the lath thickness of martensite increases due to recovery and over-aging effects. When the variations in hardness plotted as a function of tempering temperature are compared with the hardness of the as-received specimens, it seems that the B steel, which has the highest yield and tensile strengths, is fabricated by quenching, while the other steels are fabricated by quenching and tempering. On the other hand, the impact properties of the steels are affected by specimen orientation and test temperature as well as microstructure. Based on these results, the effect of tempering on the microstructure and mechanical properties of commercial high-hardness armor steels is discussed.

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