RF nitriding of severely deformed Armco iron and St2K50

The nitriding behaviour of specimens of severely deformed Armco iron and St2K50 steel was compared with that of as-received specimens of the same materials. Radio frequency (RF) nitriding with −1 kV bias was performed for 3 h at 350 and 400 °C in pure nitrogen atmosphere at a pressure of 10−5 bar. Results of scanning electron microscopy, glancing angle XRD, as well as hardness and corrosion measurements are presented and discussed with regard to the influence of severe deformation on the nitriding behaviour, particularly nitride formation and nitride layer growth, and on the mechanical and corrosion properties. The results show a remarkable increase of the nitrogen inward diffusion and enhanced corrosion resistance of severely deformed material.