Nitriding of Cr and Cr-Ni Steels

  1. Prof. Dr. P. Neumann2,
  2. Dr. D. Allen3 and
  3. Prof. Dr. E. Teuckhoff4
  1. J. Baranowska,
  2. K. Szczeciński and
  3. M. Wysiecki

Published Online: 5 JAN 2006

DOI: 10.1002/3527606181.ch30

Steels and Materials for Power Plants, Volume 7

Steels and Materials for Power Plants, Volume 7

How to Cite

Baranowska, J., Szczeciński, K. and Wysiecki, M. (2000) Nitriding of Cr and Cr-Ni Steels, in Steels and Materials for Power Plants, Volume 7 (eds P. Neumann, D. Allen and E. Teuckhoff), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, FRG. doi: 10.1002/3527606181.ch30

Editor Information

  1. 2

    Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany

  2. 3

    ABB Asltom Power UK Ltd., Cambridge Road, Whetstone, Leicester LE9 GLH, United Kingdom

  3. 4

    Siemens AG, Postfach 3240, 91050 Erlangen, Germany

Author Information

  1. Institute of Materials Engineering, Technical University of Szczecin, Szczecin, Poland

Publication History

  1. Published Online: 5 JAN 2006
  2. Published Print: 27 JUN 2000

Book Series:

  1. EUROMAT 99

ISBN Information

Print ISBN: 9783527301959

Online ISBN: 9783527606184

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Keywords:

  • steels for power plants;
  • materials for power plant;
  • nitriding of Cr steels;
  • nitriding of Cr-Ni steels

Summary

Nitriding of high chromium steels and austenitic chromium-nickel steels is a well known process used to enhance tensile strength and fracture toughness and improve wear resistance. To eliminate the oxide layer that prevents the formation of diffusion layer in these steels, etching and phosphatizing prior to gas nitriding or adding ammonium or hydrogen chloride during nitriding are recommended.

In this paper the cathode sputtering as a pre-treatment process is proposed. Specimens of Cr and Cr-Ni steels were sputtered before the nitriding. The process of cathode sputtering was performed in separated chamber in nitrogen atmosphere with voltage 1350 V, pressure 13 Pa and time 20 min. The sample was connected as a cathode and immediately after exposition was introduced into the reaction zone of the furnace. The nitriding was performed in an ammonia-nitride mixture at the temperature 843 K.

The layers were compared with those obtained after nitriding with etching and phosphatizing and with the ammonium chloride addition.

Thickness and microhardness of the compound cases and the internal diffusion zones were measured. Moreover the layers were investigated by metallographic testing (scanning and light microscopy) and the phase composition - evaluated by X-ray diffraction. The result show that process of cathode sputtering increases the kinetics of nitriding layer formation therefore it could replace such inconvenient methods as e.g. phosphatizing.