한국표면공학회지 (56권1호 94-103)
Effect of process pressure and nitrogen addition ratio on the uniformity of hardening depth and surface properties of Cr-Mo low alloy steel in vacuum carburizing
Cr-Mo 저합금강의 진공침탄 공정 압력 및 질소 첨가 비율에 따른 경화깊이 균일도 및 표면 특성 효과
권기훈a,b, 박현준a, 안기원a, 이영국b, 문경일a,*
Gi-hoon Kwona,b, Hyunjun Parka, Young-Kook Leeb, Kyoungil Moona*
a한국생산기술연구원 친환경열표면처리연구부문, b연세대학교 신소재공학과
aHeat & Surface Technology R&D Group, Korea Institute of Industrial Technology, Siheung, 15014,Korea bDepartment of Materials Science and Engineering, Yonsei University, Korea
The effects of carburizing pressure and gas ratio on vacuum carburizing properties (uniformity and surface characteristics) have been studied through the analyses of carbon concentration, hardness, surface color, surface roughness and type of carbon bonding. AISI 4115 steel specimens were carburized with various pressures (1, 5, and 10 Torr) at different locations (P1, P2, P3, P4, P5, and P6) inside a furnace held at 950 ℃. Since the carburizing pressure represents the density of the carburizing gas, it plays an important role in improving the carburizing uniformity according to locations in the furnace. As the carburizing pressure increased, the carburizing uniformity according to the sample location was improved, but the surface of the carburized specimen was discolored due to the residual acetylene gas, which does not contribute to the carburizing reaction. Therefore, the carburizing uniformity and surface discoloration have been improved by injecting acetylene gas (carburizing gas) and nitrogen gas (non-reactive gas) in a specific ratio.
Vacuum carburizing; Pressure; Uniformity; Acetylene; Nitrogen.
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