High Temperature Gas Nitriding of Austenitic Stainless Steels

오스테나이트계 스테인리스강의 고온질화

  • Kong, J.H. (Department of Materials Science and Engineering, Dong-A University) ;
  • Yoo, D.K. (Steel Making Department Hyundai Steel Company) ;
  • Park, J.H. (CANSMAC Dong-A University) ;
  • Lee, H.W. (Department of Materials Science and Engineering, Dong-A University) ;
  • Sung, J.H. (Department of Materials Science and Engineering, Dong-A University)
  • 공정현 (동아대학교 신소재공학과) ;
  • 유대경 (현대제철 소형제강부) ;
  • 박준홍 (동아대학교 신소형재 가공청정 공정개발 연구센터) ;
  • 이해우 (동아대학교 신소재공학과) ;
  • 성장현 (동아대학교 신소재공학과)
  • Published : 2007.11.30

Abstract

This study examined the phase changes, nitride precipitation and variation in mechanical properties of STS 304, STS 321 and STS 316L austenitic stainless steels after high temperature gas nitriding (HTGN) at temperature ranges from $1050^{\circ}C\;to\;1150^{\circ}C$. Fine round type of $Cr_2N$ nitrides were observed in the surface layers of 304 and 316L steels, even more in STS 321. Additionally, square type of TiN was found in STS 321 austenitic matrix too. As a result of many precipitates in the surface layer of the STS 321, it was seen $370{\sim}470Hv$ hardness variation depending on the HTGN treatment conditions, and interior region of austenite represented 150Hv. The surface hardness value of STS 304 and STS 316L showed $255{\sim}320Hv$, respectively. The nitrogen content was shown 0.27, 1.7 and 0.4% respectively at the surface layers of the STS 304, STS 321 and STS 316L. After the HTGN it was shown the improvement of corrosion resistance of the STS 321 and STS 316L compared with solution annealed steels in the solution of 1N $H_2SO_4$ whereas the STS 304 was not.

References

  1. J. C. Bavay : Stainless Steels, Proceedings of the 1989 Spring School Organization, France (1993) 551
  2. M. O. Speidel : HNS 88, Lille, France, May 1988, The Institute of Metals, London (1989) 92
  3. K. J Irvine, T. Gladman and F. B. Pickering : JISI, 199 (1969) 1017
  4. M. L. G. Byrnes, M. Grujicic and W. S. Owen: Acta Metall., 7 (1987) 1853
  5. L. A. Norstrom: Metal Science, June (1997) 208
  6. E. Werner: Mater. Sci. Eng., A101 (1988) 93
  7. H. Berns and Sibine Siebert: lSIJ International, 36 (1996) 9271
  8. D. K. Yoo, D. W. Joo, I. S. Kim, C. Y. Kang and J. H. Sung: J. of the Korean Society for Heat Treatment, 15(2) (2002) 57
  9. D. K. Yoo, H. J. Lee, C, Y. Kang, K. H. Kim, Y. H, Kim and J. H. Sung: Solid State Phenomena, 118 (2006) 149 https://doi.org/10.4028/www.scientific.net/SSP.118.149
  10. N. Akdut and J. Foct : lSIJ International, 36 (1996) 883
  11. CLI Brochure, FGD Equipments Metallic Solutions, (1994) 35