The article presents nomographs for the nitriding of carbon steels obt
ained by calculation of a nonlinear model of diffusion with a view to
the dependence of the diffusion coefficients of carbon and nitrogen on
the concentration of these elements in the steel. The nomographs prov
ide more complete information on the conditions and results of nitridi
ng. The suggested method of calculation of the nonlinear model of nitr
iding can also be used (upon change of the corresponding initial data)
for constructing nomographs for the most variegated processes of ther
mochemical treatment involving saturation from the gaseous phase.