Effects of nitriding parameters on the microstructure and properties of laser-cladding and plasma-nitriding composite modified layers

Abstract

In order to further improve the wear and corrosion resistance of traditional nitriding steel parts, the Cr₂Ni₁Ti_0.05La_0.05 laser-cladding and plasma-nitriding composite modified layers were prepared on N80 steel surface. The effects of plasma-nitriding temperature and time on the microstructure, wear and corrosion resistance of the modified layers were studied. The composite-treated nitriding layers are mainly composed of CrN phase and the content of γ′-Fe₄N increases with the increase of the nitriding temperature and holding time. The hardness of the cladding layer is three times that of the N80 substrate, which effectively reduces the hardness gradient and enhances the strength support for the nitriding layer. The structure of the nitriding layer at 460°C for 10 h is the most compact one and it has the best wear and corrosion resistance. Compared with the uncladded nitrided sample, its nitrided thickness is increased by 5.4 times, its wear weight loss is reduced by 90%, its self-corrosion potential is increased by 0.288V and its self-corrosion current density is decreased by 96%, the wear resistance and corrosion resistance have been significantly enhanced.