Relaxation processes in nitrogen alloyed austenitic steels

The process of stress relaxation in nitrogen alloyed (0.2-0.9 wt.%) Fe-Cr-Mn and Fe-Cr-Mn-Ni steels by the internal friction method in the temperature range of 20-640 deg C on hot-rolled specimens quenched from 1130 deg C was investigated. For Fe-Cr-Mn-N steels with a total content of manganese and chromium of over 30% and nitrogen over 0.5%, a relaxation maximum at a temperature of 360 deg C and a frequency of approximately 1 Hz was obtained on the curve for the temperature dependence of the internal friction, whereas for Fe-Cr-Mn-Ni-N steels two maxima are observed at 260 deg and 360 deg C and at a frequency of approximately 1 Hz. Nickel-containing austenite alloyed with nitrogen has a less pronounced concentration dependence of the heights of the relaxation maxima and higher values of the distribution parameters, which is due to the existence of a larger number of relaxation processes than in manganese austenite