Study of the Effect of Thermal Diffusion Borosiliconizing on the Structure and Properties of the 30KhGSA Steel

The study of the microstructure and microhardness of borosiliconized diffusion layers on the 30KhGSA steel is presented. Diffusion coatings on cylindrical specimens of the 30KhGSA steel are obtained using simultaneous diffusion saturation with boron, chromium, titanium, and silicon. Metallographic analysis is carried out with the aid of a Carl Zeiss Axio Observer Z1m metallographic microscope and a ThixoMet PRO software. When silicon carbide SiC is introduced into the saturating mixture for borating at a concentration of 10 wt %, a diffusion layer (a solid solution of silicon in α-iron) is formed on the surface of the 30KhGSA steel, which is confirmed by the value of microhardness at a level of 180–186 HV 0.1 . During hardening of the diffusion-hardened 30KhGSA steel, the hardness of diffusion coatings also increases: the hardness of the borated layer increases by 25% due to hardening compared to the non-hardened layer, while the hardness of the borosiliconized layer increases by a factor of 2.7. At the same time, the borosiliconized layer, having a lower hardness, is more capable of running in under conditions for sliding friction and in the presence of aggressive salt solutions, in which the thrust bearings of drilling rigs operate.