Intervention mechanism of carbide precipitation during tempering and its impact on residual stress and mechanical properties of wear-resistant steels

The production of low-stress, high-performance wear-resistant steels poses a formidable challenge in the steel industry. This article delves into the carbide precipitation behaviour of wear-resistant steel NM300TP during tempering and its subsequent impact on residual stress and mechanical properties. Our findings reveal a crucial aspect: prolonging the holding time can interfere with the precipitation behaviour of carbides, thereby altering the relaxation mechanism of residual stress and its influence on material properties. Remarkably, we discovered that substituting the formation of θ-cementites with the precipitation of ε-transition carbides can yield a steel with significantly lower residual stress while maintaining exceptional mechanical properties. Specifically, when θ-cementites precipitate, the residual stress in the wear-resistant steel diminishes by 54.23%, accompanied by a hardness measurement of 299.58 HV_0.5. However, when a substantial quantity of ε-transition carbides is dispersed and precipitated, the residual stress is further diminished by 69.51%, and the hardness reaches 317.2 HV_0.5. Furthermore, this precipitation of ε-transition carbides exhibits superior wear resistance compared to θ-cementites. These groundbreaking discoveries offer critical theoretical insights for the development of low-stress, high-performance wear-resistant steels, paving the way for innovative advancements in the steel industry.