On the coefficient of compositional stability of nitrogen for high-nitrogen alloys of the Fe-Cr-Mn-Mo-N system, obtained by the SHS method under nitrogen pressure

Abstract

The value of the nitrogen compositional stability coefficient has been determined for the alloys of the Fe-Cr-Mn-Mo-N system obtained by self-propagating synthesis, namely, aluminothermy under nitrogen pressure. It is shown that the heat treatment of the alloy containing 14.3 wt.% of chromium, 12.2 wt.% of manganese, 4.0 wt.% of molybdenum and 0.92 wt.% of nitrogen at 1250°C for 2 h leads to the dissolution of a pseudo-perlitic structure (ferrite-nitride mixture) and complete austenization of samples. In this case, the alloy hardness decreases from 255 to 208 HB. The obtained results permit to predict the maximum possible content of nitrogen in continuous ingots (without bubbles and gas porosity in the volume) and, consequently, the structural-phase composition of alloy and optimal regimes of alloying. A method based on iterative calculation is proposed.