Alloying steel with nitrogen from gas phase in high‐pressure plasma reactor

Abstract

The paper presents a study of the possibility of saturating austenitic Cr18%–Mn18% steel with nitrogen from the gas phase by use of “low – temperature” thermal plasma. The experimental work was carried out in a DC plasma reactor of the authors' own design working at a total gas pressure of 0.38 MPa on a 20 kg sample. It was evident that it was possible to obtain a very high level of nitrogen saturation close to the level of nitrogen solubility in the metal by the use of plasmogenic gas containing purified nitrogen. The highest content of nitrogen in steel containing 18wt.% chromium and 16.7wt.% manganese was 0.77wt.% at [C] = 0.054. Refining the metal with CaSi additive turned out to have a stabilizing influence, the total amount of oxygen and sulphur being lower than 200 ppm. The material obtained turned out to be also highly homogeneous chemically after solidification.