Characterization of functional gradient structures in duplex stainless steel castings

Titanium carbide particle reinforced metal-matrix composite coatings, formed on duplex (austenitic/ferritic) stainless steel castings, were studied. These coatings, developed for wear applications, develop a functional gradient structure through a self-propagating high-temperature synthesis (SHS) of titanium carbide (TiC). This SHS-reaction was ignited in reactive inserts by the heat of liquid steel. The reactive inserts were compressed from mixtures of titanium, carbon and molybdenum powders together with iron or duplex stainless steel powders. The coating micro-structure depends on the reactive insert composition. Molybdenum reduced the TiC particle diameter, and reducing the binder content reduced the areal fraction of TiC.