Autoradiographic studies of the influence of atmosphere composition on carbon migration in steels during nitriding and oxynitriding processes

Using the method of autoradiography combined with the skew sections technique the carbon migration processes were investigated for steel samples subjected to modern thermochemical treatment. Diffusion profiles in two processes of controlled nitriding (Nitreg method) varying in the composition of the nitriding atmosphere and in three oxynitriding processes (ONS-K and fluidized bed method) were determined. The carbon diffusion profiles were very similar in the two Nitreg processes and in ONS-K2 and fluidized bed oxynitriding processes. The character of the diffusion profile for the ONS-K1 process was distinctly different. The quantitative interpretation of the autoradiograms obtained indicated minor differences (of the order 0.01%) in the carbon concentration in surface layers in the investigated processes. (author). 5 refs, 6 figs, 3 tabs