Development and characterization of in-situ reinforced TiC - high manganese steel particle reinforced metal matrix composite

The increasing demand for mineral resources, along with the need to increase the efficiency of mining operations, continues to drive advances in mining operations. A key component of supporting these advances is to increase the wear resistance of materials used in comminution circuit equipment. A very cost-effective method to improve wear life is by replacing monolithic alloys with metal matrix composites, especially particle-reinforced metal matrix composites (PRMMCs). This study aimed to develop in-situ titanium carbide (TiC)-reinforced high-manganese (Mn) steel alloy composites via casting route. The effect of alloy modification via the addition of titanium (Ti) on the microstructural evolution and tribomechanical behaviour of the alloy was investigated. The results of the microstructural evolution revealed that the addition of Ti to the alloy resulted in the in-situ formation of TiC particles during solidification. In the as-cast condition, the TiC particles facilitated grain refinement through heterogeneous nucleation. Additional grain refinement of the composite was observed after heat treatment. In-situ observation of the microstructure evolution up to 1125°C confirmed the stability of the formed TiC particles, and also revealed a potentially new mechanism of grain refinement during a solution heat treatment. Charpy impact toughness testing of the virgin high-Mn steel and in-situ TiC reinforced composite was performed. The results suggest that Ti addition contributed to significant improvement in the impact toughness of the composite. A detailed investigation of the strengthening mechanisms contributing to the observed enhancement in the composite material's impact toughness revealed the simultaneous contributions of Orowan strengthening, load-transfer strengthening, and increased grain-boundary strengthening. TWIP and TRIP effects enhanced the composite material’s impact properties. Dry sliding reciprocating wear testing of the two materials revealed a significant improvement in the composite's wear resistance due to the formation of the in-situ TiC particles. The composite experienced a 15%, 17%, and 23% reduction in volume loss at sliding distances of 300m, 600m, and 900m, respectively. The observed improvement in the wear resistance of the composite material was associated with the TiC-induced grain refinement, dispersion strengthening and shielding of the matrix by the TiC particles and increased work hardening with Ti addition.