Influence of Treatment Temperature on Surface Characteristics during Low Temperature Plasma Carburizing and DLC duplex treatment of AISI316L Stainless Steel

doi:2011.25.6.60

J. Ocean Eng. Technol. > Volume 25(6); 2011 > Article

J. Ocean Eng. Technol. 2011;25(6):60-65.
DOI: https://doi.org/10.5574/KSOE.2011.25.6.060

Lee In-Sup

Department of Advanced Materials Engineering Dongeui University

AISI316L 강에 저온 플라즈마침탄 및 DLC 복합 코팅처리 시 처리온도에 따른 표면특성평가

이인섭

동의대학교 신소재공학과

Keywords: Austenitic stainless steel, Low temperature plasma carburizing, Expanded austenite, Corrosion resistance, DLC Film

핵심용어: 오스테나이트계 스테인레스 강, 저온 플라즈마침탄, 확장된 오스테나이트, 내식성, DLC 박막

Abstract

A low temperature plasma carburizing process was performed on AISI 316L austenitic stainless steel to achieve an enhancement of the surface hardness without degradation of its corrosion resistance. Attempts were made to investigate the influence of the processing temperatures on the surface hardened layer during low temperature plasma carburizing in order to obtain the optimum processing conditions. The expanded austenite (${gamma}_c$) phase, which contains a high saturation of carbon (S phase), was formed on all of the treated surfaces. Precipitates of chromium carbides were detected in the hardened layer (C-enriched layer) only for the specimen treated at $550^{circ}C$. The hardened layer thickness of ${gamma}_c$ increased up to about $65{mu}m$ with increasing treatment temperature. The surface hardness reached about 900 $HK_{0.05}$, which is about 4 times higher than that of the untreated sample (250 $HK_{0.05}$). A minor loss in corrosion resistance was observed for the specimens treated at temperatures of $300^{circ}C{sim}450^{circ}C$ compared with untreated austenitic stainless steel. In particular, the precipitation of chromium carbides at $550^{circ}C$ led to a significant decrease in the corrosion resistance. A diamond-like carbon (DLC) film coating was applied to improve the wear and friction properties of the S phase layer. The DLC film showed a low and stable friction coefficient value of about 0.1 compared with that of the carburized surface (about 0.45). The hardness and corrosion resistance of the S phase layer were further improved by the application of such a DLC film.