STUDY OF THE INFLUENCE OF THERMAL DIFFUSION BOROSILICONIZATION ON THE STRUCTURE AND PROPERTIES OF STEEL 30KhGSA

10.25712/ASTU.1811-1416.2022.01.015

Abstract

The paper presents studies of the microstructure and microhardness of borosiliconized diffusion layers on steel 30KhGSA. Diffusion coatings on cylindrical specimens of 30KhGSA steel were obtained by simultaneous diffusion saturation with boron, chromium, titanium, and silicon. Metallographic analysis was carried out using «Carl Zeiss Axio Observer Z1m» metallographic microscope and the «ThixoMet PRO» software package. The conducted studies have shown that in the case of introducing silicon carbide SiC into the saturating mixture for borating in an amount of 10 wt. %, a diffusion layer is formed on the surface of steel 30KhGSA, which is a solid solution of silicon in α-iron, which is confirmed by the value of microhardness at the level of 180–186 HV_0.1. During hardening of diffusion-hardened steel 30KhGSA, the hardness of diffusion coatings also increases: the hardness of the borated layer during hardening increases by 25 % compared to the non-hardened layer, while the hardness of the borosiliconized layer increases by 2.7 times. At the same time, the borosiliconized layer, having a lower hardness, is more capable of running in under conditions of sliding friction and in the presence of aggressive salt solutions, in which the thrust bearings of drilling rigs operate.