Solid State Nitriding of Fe-Cr-Mn Stainless Steel in 0.1 MPa Nitrogen Atmosphere at 1473K

Solid state nitriding of Fe-Cr-Mn stainless steel in 0.1 MPa nitrogen atmosphere at 1473 K has been investigated. The results show that the average nitrogen contents in those solid state steel samples are proportional to the square root of nitriding time during solid state nitriding. The nitriding time needed is influenced by the chemical composition of steel. The saturated nitrogen content can be described as w_\eq=0.066w_\+0.029 w_\-0.608. The nitrogen absorption rate can be markedly improved by adding 0.5% H_2 gas into nitrogen. It is also found that the average nitrogen content has exceeded 0.5% after solid state nitriding for 12.5 h in 0.1MPa nitrogen atmosphere at 1473 K,with the mass percent of w_\+w_\≥20%and austenite single phase obtained.