Tribological characteristics of hardened-and-tempered structural steels turned by inserts covered with multicomponent PVD coatings

The effect of coatings deposited on cutting tools using the PVD method on the tribological characteristics of the surface layer after the finish turning of 41Cr4 and 30CrMnSi steels is considered. The tribological characteristics of the turned surfaces change substantially. The best results are achieved when using the (AlTi)N coating, which ensures substantial decreases in the coefficient of friction (by 35–40%) and the temperature in the friction zone (by up to 30%). The dependences of the wear on the friction path are linear; the wear rate of the surfaces turned by the coated tools is significantly lower than that for the surfaces turned by the uncoated tools. Compared to the uncoated R25 hard alloy, the difference in the wear rates reaches 60% in favor of (AlTi)N and (TiAl)N coatings. A decrease in the thickness of the coating from 4 to 2 μm leads to a growth in the coefficient of friction and the temperature. An X-ray structural analysis of the surface layers of the turned specimens has revealed the presence of Fe-Al solid phases, which improve the wear resistance of the surface and the efficiency of coatings like (AlTi)N.