Hardness and Transverse Rupture Strength of TiC-Reinforced SKD11 Steel Matrix Composite

We investigate the effect of heat treatment on the hardness and transverse rupture strength (TRS) in the particulate TiC-reinforced SKD11 steel matrix composites, fabricated by a pressure infiltration casting process. A tempering process softens the composite as-quenched from the austenitization; however the hardness rebounds once the unstable austenite transforms into martensite upon cooling from higher tempering temperature. The fracture strength of steel matrix as well as the fraction and size of reinforcement is likely to affect the TRS of composite. For a given fraction of the TiC reinforcement, higher fracture strength of steel matrix is advantageous to achieve better TRS. Moreover, a refinement of TiC size makes the TRS of the composite more responsive to the change of fracture strength of steel matrix; increasing the fracture strength of steel matrix brings about more improvement of TRS. Thus, smaller TiC reinforcement size provides a better chance to control of TRS of the composite by altering the properties of steel matrix using a heat treatment.