Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
권호 표지

Influence of Gas Composition and Treatment Time on the Surface Properties of AISI 316L Austenitic Stainless Steels During Low-Temperature Plasma Nitrocarburizing Treatment

AISI 316L강의 저온 플라즈마침질탄화처리 시 가스조성과 처리시간이 표면특성에 미치는 영향

  • Lee, In-Sup (Department of Advanced Materials Engineering, Dongeui University)
  • Received : 2009.03.25
  • Published : 2009.11.25
⟨ Previous Next ⟩

Abstract

The major drive for the application of low-temperature plasma treatment in nitrocarburizing of austenitic stainless steels lies in improved surface hardness without degraded corrosion resistance. The low-temperature plasma nitrocarburizing was performed in a gas mixture of $N_{2}$, $H_{2}$, and carbon-containing gas such as $CH_{4}$ at $450^{\circ}C$. The influence of the processing time (5~30 h) and $N_{2}$ gas composition (15~35%) on the surface properties of the nitrocarburized layer was investigated. The resultant nitrocarburized layer was a dual-layer structure, which was comprised of a N-enriched layer (${\gamma}_N$) with a high nitrogen content on top of a C-enriched layer (${\gamma}_C$) with a high carbon content, leading to a significant increase in surface hardness. The surface hardness reached up to about $1050HV_{0.01}$, which is about 4 times higher than that of the untreated sample ($250HV_{0.01}$). The thickness of the hardened layer increased with increasing treatment time and $N_{2}$ gas level in the atmosphere and reached up to about $25{\mu}m$. In addition, the corrosion resistance of the treated samples without containing $Cr_{2}N$ precipitates was enhanced than that of the untreated samples due to a high concentration of N on the surface. However, longer treatment time (25% $N_{2}$, 30 h) and higher $N_{2}$ gas composition (35% $N_{2}$, 20 h) resulted in the formation of $Cr_{2}N$ precipitates in the N-enriched layer, which caused the degradation of corrosion resistance.

Keywords

Acknowledgement

Supported by : 한국학술진흥재단

References

  1. John Sedriks, Corrosion of stainless steels, p.16, John Wiley & Sons, 2nd ed., New York (1996)
  2. M. Tsujikawa, S. Noguchi, N. Yamauchi, N. Ueda, and T. Sone, Surf. & Coat. Tech. 201, 5102 (2007) https://doi.org/10.1016/j.surfcoat.2006.07.127
  3. T. Bell, Y. Sun, and A. Suhadi, Vacuum. 59, 14 (2000) https://doi.org/10.1016/S0042-207X(00)00250-5
  4. Y. Sun, Mater. Lett. 59, 3410 (2005) https://doi.org/10.1016/j.matlet.2005.06.005
  5. Y. Sun and E. Haruman, Vacuum. 81, 114 (2006) https://doi.org/10.1016/j.vacuum.2006.03.003
  6. C. Blawert, H. Kalvelage, B. L. Mordike, G. A. Collins, and K. T. Short, Surf. & Coat. Tech. 136, 181 (2001) https://doi.org/10.1016/S0257-8972(00)01050-1
  7. Insup Lee, J. Kor. Inst. Met. & Mater. 46, 357 (2008)
  8. T.-H. Lee and S.-J. Kim, J. Kor. Inst. Met. & Mater. 35, 1146 (1997)
  9. Z. Cheng, C. X. Li, H. Dong, and T. Bell, Surf. & Coat. Tech. 191, 195 (2005) https://doi.org/10.1016/j.surfcoat.2004.03.004
  10. Y. Sun, Mater. Proc. Tech. 168, 189 (2005) https://doi.org/10.1016/j.jmatprotec.2004.10.005
  11. H. Baba, T. Kodama, and Y. Katada, Corros. Sci. 44, 2393 (2002) https://doi.org/10.1016/S0010-938X(02)00040-9
  12. B. Larisch, U. Brusky, and H.-J. Spies, Surf. and Coat. Tech. 116-119, 205 (1999) https://doi.org/10.1016/S0257-8972(99)00084-5