Solubility of Nitrogen in Austenitic Cr-Ni and Cr-Ni-Mo Steels.

The steels investigated contained 18%Cr, 14%Ni, 2. 5%Mo and less than 0. 02%C. After supersaturation with nitrogen at between 650 and 1000 degree C, the steels were first solution treated and then isothermally annealed until thermodynamic equilibrium was reached. The precipitation process was studied as a function of annealing time and temperature. The phases were identified by x-ray measurements and the limits of nitrogen solubility analytically established after electrochemical isolation. Precipitation of chromium nitride, Cr//2N, which starts at the grain boundaries, noticeably reduces the impact strength. The intermetallic phases formed in addition to chromium nitride greatly increase the volume of precipitation. A significantly more marked embrittlement as a result was not observed.