On the Role of TiC in the Carbon Steel-Titanium Joining

TiC interfacial layer is formed during titanium alloy to carbon steel diffusion bonding and prevents the formation of FeTi and Fe2Ti intermetallic compounds, which have detrimental effect on the properties of joints. The TiC layer is extremely thermodynamically stable in contact with austenite and is formed at the steel/titanium interface even in the case when carbon content is about 0.1wt.%. The evolution of an initially formed interfacial titanium carbide layer includes its growth and simultaneously changing the composition of austenite (towards lower carbon content) and titanium (towards higher carbon content). The kinetics parameters of the interfacial layer growth (carbon diffusion coefficient and the activation energy) reflect the grain boundary mechanism of carbon diffusion through the interfacial layer with submicron grains microstructure.