Insights into the microstructure evolution and wear resistance of Nano-TiC particles reinforced High-Cr hot work die steel

Abstract

The current study innovatively proposed to prepare TiC nanoparticles reinforced high-Cr hot work die steels through an aluminum master alloy. The influences of TiC nanoparticles on the microstructure and wear resistance of high-Cr hot work die steels were thoroughly investigated. It was found that the addition of nanoparticles refined the pro-eutectoid ferrite in the as-cast condition, and the granular pearlite in the isothermal spheroidized condition, respectively. After receiving the quenching and tempering heat treatment, the size of lath martensite, retained austenite and nanosized precipitates were reduced. The TiC nanoparticles were used as heterogeneous cores to improve the nucleation rates of austenite and ferrite during phase transformation. The finer grains with more grain boundaries and nanoparticles refined the size of tempered microstructure of high-Cr hot work die steels. In ball-on-plate reciprocating sliding wear tests, it was found that the presence of TiC nanoparticles enhanced the wear resistance of high-Cr hot work die steels under various test conditions. The nanoparticles increased the strength of the substrate and inhibited the formation of cracks. More grain boundaries and nanoparticles hindered the migration of dislocations, which resulted in less plastic deformation. Also, the nanoparticles could partially withstand the external load during the relative motion. The results obtained in this research provide applicable values for optimizing the strength-ductility and tribological performance of hot work die steels.