Non-Metallic Inclusions in Carburizing Steels as a Contributory Factor for the Formation of Carbide Net

The article deals with the issue of identifying structural defects that contribute to the formation of a carbide net during thermochemical treatment of steel parts, which negatively affects the mechanical properties complex of finished products. Based on the available data, a theory has been put forward regarding the influence of the present non-metallic inclusions in the carburizing steels structure on carbide formation process in the hardened layer. As an experimentally the samples have been produced from the varying chemical composition alloy structure carburized steel (0.17-0.23 % C, 0.17-0.37 % Si, 0.80-1.10 % Mn, 1.00-1.30 % Cr, 0.03-0.09 % Ti). During microstructure analysis of the samples it has been establish that non-metallic inclusions, in particular sulfides, contribute to the formation of carbides and carbide net in steel due to their high chemical activity with carbon. Thus, contamination of the metal of carburizing steels with non-metallic inclusions is not only a defect in itself, but also causes the occurrence of other structural defects during subsequent thermochemical and thermal treatment.