Plasma nitriding, instead of chromium plating, is proposed as an alternative surface-hardening technology for intake and exhaust valve stems made of 40Cr9Si2 and 55Cr20Mn9NNi4 steels after bulk hardening. Wear resistance of valve materials and the Bronze AlFe9-4 bushings that work with them was assessed individually and in combination. Conclusions are drawn regarding the influence of the chemical composition of heat-resistant steel and its surface hardening technology on wear resistance.
Boldyrev et al. (Sat,) studied this question.