Alloy design for suppressing eutectoid reaction in high nitrogen austenitic steels

In austenitic steels, nitrogen is an important alloying element in terms of phase balance, austenite stabilizing effect and solid solution hardening. In case a large amount of nitrogen is added to high chromium steels, austenitic stainless steels can be produced in Fe-Cr-N ternary alloys without nickel. For instance, Fe-23%Cr-0.9%N is just the composition which provides stable austenitic structure at room temperature. This alloy shows excellent mechanical properties; high yield stress, large work-hardening rate and good ductility. However, such excellent properties are guaranteed only on the condition that the alloy was quenched from an elevated temperature to avoid an eutectoid reaction; decomposition of austenite to Cr2N and ferrite, because eutectoid structure gives a harmful effect to the ductility of austenitic steels. In this paper, an alloy design for suppressing the eutectoid reaction was suggested and the effect of manganese addition to Fe-Cr-N ternary alloy was presented as an example.