Heat treatment of cermets based on titanium carbide preforms infiltrated with steel

Homogeneous and graded cermets based on the titanium carbide over a range of carbon content (TiC_x, 0.70 < x < 0.98) were produced by free infiltration of the porous ceramic performs with plain molten carbon steel (0.8%C) and with alloyed tool steel. The transfer of Ti, C and alloying elements from the ceramic to the metal and vice versa in the course of the infiltrating step and during a post-infiltrating quenching and tempering strongly depends on the composition of both the metal and the carbide. For composites, based on titanium carbide with low carbon content (x<0.8), a transfer of carbon from the metallic to the ceramic phase and a transfer of Ti in the opposite direction were observed. For graded composites, in which unidirectional variations of the carbon content in the titanium carbide were initially present, a redistribution of carbon away from the carbon-rich region was detected. The specific features of austenitizing, carbide dissolution-precipitation, martensite transformation and tempering in the steel component of composites were established. The heat treatment regimes that allow to control macro- and microinhomogeneity in the composition and in the structure of the austenite and martensite in the steel component and to provide a desired hardness profile in the graded composites were describe and discussed.