Special features of vacuum carburizing of heat-resistant steel in acetylene

The mechanism of formation of the diffusion layer due to vacuum carburizing of complexly alloyed steel 16Kh3NVFMB-Sh (VKS5) in a medium of acetylene is considered. It is shown that the process of carburizing occurs in a self-regulation mode without the danger of carbon black due to the high rate of arrival of carbon from the gas medium as a result of catalytic dissociation of acetylene molecules, intense process of carbide formation on the saturated surface, and absence of catalytic activity of carbides. The diffusion layer forms under a thin layer of the carbide phase in a kinetic regime, the intensity of which is determined by the rate of dissolution of carbides.