Morphology and Wear Resistance of Multicomponent Diffusion Coatings

Boronizing is one of the most effective methods of thermochemical treatment of iron-carbon alloys. Boride layers formed with the diffusion can considerably increase abrasion resistance (up to 5-30 times), heat resistance (up to 1.5-2 times) of steels. The aim of this paper is to study structure and wear resistance of diffusion layers after simultaneous saturation with boron, chromium, titanium on 1045 and D2 steels. Layer after chromium boronizing on 1045 steel has a classic needle structure of boride layer. The microstructure of layer on D2 steel is significantly different. The chromium boronizing layer has sufficiently smooth border. Globular particles of carbides and borides are relatively distributed in the iron matrix. After simultaneous saturation by boron and titanium the layer has multi-zone structure. The layer can be divided into 3 zones: upper zone consisting of titanium borides; medium zone consisting of titanium borides and carbides; bottom zone with titanium carbides. It was found that wear depends on the type of used steel. For steel D2 the diffusion layer splits off into pieces of abrasive particles, it leads to reduce durability of diffusion layer on this steel. For steel 1045 it manages to increase the resistance of parts due to the plasticity of the diffusion layers. And it is recommended that the high-alloy steel D2 can be replaced with the steel 1045 with the diffusion layer based on boron and chromium.