Nitriding of chromium and its alloys at 1000?1200�C

Abstract

1. After nitriding, at the surface of chromium and its alloys there is formation of a nitride layer consisting of Cr2N nitride. Alloying elements in the test concentration range have almost no effect on kinetics of the growth of the outer nitride layer. 2. In alloys of the Cr-Ti system beneath the chromium nitride layer a zone of internal nitriding is observed, strengthened by dispersed particles of titanium nitride TiN. The growth kinetics for the diffusion layer obeys a parabolic rule and is controlled by nitrogen diffusion in the alloy. 3. Distribution and morphology of the titanium nitride precipitate are determined by titanium concentration in the alloy, temperature, and nitriding duration. With an increase in nitriding temperature there is coalescence of particles and a reduction in hardness in the internal nitriding zone. 4. Values of coefficients for penetration of nitrogen into chromium alloys calculated by experimental data correlate with the results of other works.