Phase Composition of the Surface Zone of Nitrided Cast Steels and Their Mechanical Properties

Conversion electron Mössbauer spectroscopy and structural X-ray diffractometry have been used to study nitrides formation in the surface layer of cast steels subjected previously to low-temperature nitriding. It has been found that creation of iron-nitrogen phases strongly depends on sample composition. Nitrides: $γ^\prime-Fe_{4}N$ and $\epsilon-Fe_{2-3}N$ arise in the course of the nitriding procedure in most investigated cast steels. Moreover, considerable changes in their microstructure and tribological properties occur. The depth profile of nitrides has been derived for selected cast steel.