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Ferritic nitrocarburising of tool steels

journal contribution
posted on 2005-04-01, 00:00 authored by P King, R Reynoldson, Allan Brownrigg, John LongJohn Long
Four different tool steel materials, P20, H13, M2 and D2, were nitrocarburised at 570°C in a fluidised bed furnace. The reactive diffusion of nitrogen and carbon into the various substrate microstructures is compared and related to the different alloy carbide distributions. The effect of carbon bearing gas (carbon dioxide, natural gas) on carbon absorption is reported, as well as its influence on compound layer growth and porosity. Partial reduction of Fe3O4 at the surface resulted in the formation of a complex, epsi-nitride containing oxide layer. In H13, carbon was deeply absorbed throughout the entire diffusion zone, affecting the growth of grain boundary cementite, nitrogen diffusivity and the sharpness of the compound layer: diffusion zone interface. When natural gas was used, carbon became highly concentrated in the compound layer, while surface decarburisation occurred with carbon dioxide. These microstructural effects are discussed in relation to hardness profiles, and compound layer hardness and ductility. The surfaces were characterised using glow discharge optical emission spectroscopy, optical and scanning electron microscopy and X-ray diffraction.

History

Journal

Surface engineering

Volume

21

Issue

2

Pagination

86 - 98

Publisher

Maney Publishing

Location

London, England

ISSN

0267-0844

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2005, Institute of Materials, Minerals and Mining