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Nature of Surface Changes in Stamping Tools of Gray and Ductile Cast Iron During Gas and Plasma Nitrocarburizing

  • E. RolińskiEmail author
  • A. Konieczny
  • G. Sharp
Article

Abstract

Two cast irons, pearlitic-ferritic gray and ferritic ductile, were plasma and gas nitrocarburized at the same temperature and for the same processing time to produce a compound zone of about 10-14 μm thick. It was demonstrated that both processes caused changes in the surface roughness of the irons, and the most dramatic increase of roughness was observed after gas nitrocarburizing of the gray cast iron. It was shown that the primary reason that the results were not the same is the difference in the nitriding mechanism. Significant penetration of the surface voids and imperfections between the graphite particles and the metallic matrix by ammonia molecules led to the formation of a locally thicker compound zone and a bulging of the metallic matrix above the surface. This phenomenon did not occur in the plasma process and as a result the surface changes were much smaller than in the gas process.

Keywords

cast irons gas nitrocarburizing heat treating plasma nitrocarburizing surface engineering surface roughness 

Notes

Acknowledgments

The authors thank Dr. Witold Liliental at Nitrex Metal Technologies Inc., Burlington, Ontario, for his help with the metallography and Henry Zmijewski at the U.S. Steel Automotive Center, Troy, Michigan, for his help with SEM. The help of Dr. George Tymowski of Ottawa and Andrew Paczuski of Ann Arbor for their comments and suggestions is also greatly appreciated.

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Copyright information

© ASM International 2009

Authors and Affiliations

  1. 1.Advanced Heat Treat Corp.MonroeUSA
  2. 2.U S Steel Automotive CenterTroyUSA
  3. 3.Advanced Heat Treat Corp.WaterlooUSA

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