AISI304L 스테인리스강의 저온 플라즈마 침탄처리 후 질화처리 시 Ar 가스가 표면경화층에 미치는 영향 (The Influence of Ar Gas in the Nitriding of Low Temperature Plasma Carburized AlSi304L Stainless Steel)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 46권 / 3호 / 125 ~ 130페이지
· 저자명 : 정광호, 이인섭

초록

Conventional plasma carburizing or nitriding for austenitic stainless steels results in a degradation of corrosion resistance. However, a low temperature plasma surface treatment can improve surface hardness without deteriorating the corrosion resistance. The 2-step low temperature plasma processes (the combined carburizing and post nitriding) offers the increase of both surface hardness and thickness of hardened layer and corrosion resistance than the individually processed low temperature nitriding and low temperature carburizing techniques. In the present paper, attempts have been made to investigate the influence of the introduction of Ar gas (0~20%) in nitriding atmosphere during low temperature plasma nitriding at 370°C after low temperature plasma carburizing at 470o C. All treated specimens exhibited the increase of the surface hardness with increasing Ar level in the atmosphere and the surface hardness value reached up to 1050 HV0.1, greater than 750 HV0.1 in the carburized state. The expanded austenite phase (γN) was observed on the most of the treated surfaces. The thickness of the γN layer reached about 7 µm for the specimen treated in the nitriding atmosphere containing 20% Ar. In case of 10% Ar containing atmosphere, the corrosion resistance was significantly enhanced than untreated austenitic stainless steels, whilst 20% Ar level in the atmosphere caused to form CrN in the N-enriched layer (γN), which led to the degradation of corrosion resistance compared with untreated austenitic stainless steels.

영어초록

Conventional plasma carburizing or nitriding for austenitic stainless steels results in a degradation of corrosion resistance. However, a low temperature plasma surface treatment can improve surface hardness without deteriorating the corrosion resistance. The 2-step low temperature plasma processes (the combined carburizing and post nitriding) offers the increase of both surface hardness and thickness of hardened layer and corrosion resistance than the individually processed low temperature nitriding and low temperature carburizing techniques. In the present paper, attempts have been made to investigate the influence of the introduction of Ar gas (0~20%) in nitriding atmosphere during low temperature plasma nitriding at 370°C after low temperature plasma carburizing at 470o C. All treated specimens exhibited the increase of the surface hardness with increasing Ar level in the atmosphere and the surface hardness value reached up to 1050 HV0.1, greater than 750 HV0.1 in the carburized state. The expanded austenite phase (γN) was observed on the most of the treated surfaces. The thickness of the γN layer reached about 7 µm for the specimen treated in the nitriding atmosphere containing 20% Ar. In case of 10% Ar containing atmosphere, the corrosion resistance was significantly enhanced than untreated austenitic stainless steels, whilst 20% Ar level in the atmosphere caused to form CrN in the N-enriched layer (γN), which led to the degradation of corrosion resistance compared with untreated austenitic stainless steels.

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