Surface Modification of Diesel Fuel Equipment Parts Made of KhVG Steel by Saturation with Nitrogen and Carbon to Increase Hardness and Wear Resistance

Abstract

Purpose. Show that nitrocarburizing of KhVG steel in a highly active environment significantly increases its hardness and wear resistance due to surface modification with a large amount of carbonitrides. Methods. For research in an induction furnace, samples with a diameter of 50 m, 8 pieces of steel KHVG, were sub-jected to nitrocarburizing in a highly active nitrogen-carbon medium, which would provide saturation of the surface layers of steel with carbonitrides of iron alloys with manganese and chromium. Results. Investigation of the microstructure of modified samples from steel KhVG showed that in all modes of nitro-carburizing, a large amount of a new phase was formed in their surface layers. Inclusions of a new phase in the structure of nitrocarburized layers, as shown by the results of X-ray diffraction analysis, are carbonitrides isomorphic with cementol. The sizes of these carbonitrides vary in the range 3… 10 µm, and the microhardness - in the range Hµ 9150… 10500 MPa. The content of carbonitrides in the modified layers depends on both the temperature and the duration of nitrocarburizing. Conclusion. The presence of carbonitride inclusions in nitrocarburized layers on the surface of parts leads to a sig-nificant increase in their hardness and wear resistance. For practical purposes, it is possible to recommend the con-tent of carbonitrides in modified layers on the surface of parts of 50 ... 60%.