Effect of Aging Temperature on the Impact Wear Properties and Wear Mechanism of Lightweight Wear-Resistant Steel

In this study, the microstructure, mechanical properties, wear resistance, and wear-hardening mechanism of Fe-28Mn-8.5Al-1.0C lightweight wear-resistant steel after heat treatment at different aging temperatures were examined. The results show that the nano-scale κ-carbides precipitated in the grains after aging treatment increased the strength and hardness of the material through the strengthening effect of the second phase. The yield strength of the material is 697 MPa, the tensile strength is 905 MPa, and the hardness is up to 294 HB after aging at 500 °C for 5 h. However, the large-sized κ-carbides precipitating continuously at the grain boundary are unfavorable to the plasticity and toughness of the material. Compared with the aging treatment at 300 °C for 5 h, the elongation and low-temperature impact energy decreased by 12.0% and 47.1%, respectively. Except for the dominant wear mechanism being plastic deformation after heat treatment at 500 °C for 5 h with a 4J impact energy, the predominant wear mechanisms for different impact energies under all other heat treatment conditions are micro-cutting. The increase in aging temperature increases the number and volume of κ-carbide precipitation, which leads to enhanced second-phase strengthening and dislocation strengthening, and the wear resistance of the material is improved. The hardening mechanism of the material after wear at different impact energy levels under aging treatment conditions is a cross-distributed dislocation wall and high-density dislocation entanglement. The increase in aging temperature reduces the spacing of the dislocation wall, increases the area and density of dislocation entanglement, and enhances the work-hardening effect.