Effect of heat treatment on microstructure and mechanical properties of a Ti-bearing hypereutectic high chromium white cast iron

The effect of heat treatment temperature on the microstructure and mechanical properties of a Fe-4.0C-18.0Cr-1.0Mo-1.0Ti (wt.%) hypereutectic high chromium white cast iron was investigated. The response of the alloy to heat treatment and, therefore, the microstructures developed, differed significantly. With the increase of the heat treatment temperature, the precipitated secondary carbides changed from M₃C to M₇C₃ and the retained austenite content increased. With the increase of the heat treatment temperature, the bulk hardness and matrix microhardness both increased and reached peak values of 64.6 HRC and 850 HV, respectively at the temperature of 1000 °C. But they all decreased at the heat treatment temperature of 1050 °C. The impact toughness of the alloy increased significantly compared with the conventional cast hypereutectic high chromium white iron (containing 4.0 wt.% C and 17.0 wt.% Cr) without titanium and inoculation and its value was in the range of 6.1-6.9 J/cm², but it did not change very much with the increase of heat treatment temperature.