Tailoring Martensite and Ferrite via Tempering to Improve Impact–Abrasive Wear Resistance in Lower Alloy Medium-Carbon Steel
摘要
Although tempering martensite is a proper matrix to withstand various wear conditions, it could not answer all wear requirements. To address impact wear conditions, tailoring martensite and ferrite for achieving outstanding impact toughness as a trade-off for reduction in strength therefore a lower alloy medium-carbon steel would be developed to satisfy wear resistance requirements. This study aimed to optimize the steel’s microstructure by adjusting tempering temperatures (350-500 °C), transitioning from pure martensite to a martensite–ferrite coexistence while reducing the use of alloying elements (Ni and Mo), and exploring the impact of tempering temperature on the mechanical properties and impact–abrasive wear resistance of low-alloy medium-carbon wear-resistant steels. As the tempering temperature increased, the hard martensite content decreased significantly, while the soft ferrite content increased. Compared to Hardox steel, the impact toughness improved significantly from 48 to 136 J/cm2. Despite the improvement in impact toughness, the tensile strength dropped from 1214 to 875 MPa, and the hardness decreased from 458 to 230 HB. This was attributed to the softening effect of ferrite, which enhanced toughness but reduced surface hardness. For impact–abrasive wear conditions, the wear rate did not decrease but instead increased. The optimal microstructure for balancing strength and plasticity was achieved at a tempering temperature of 450 °C, where the martensite–ferrite coexistence was ideal for impact–abrasive wear conditions. These findings indicate that achieving controlled martensite–ferrite equilibrium is crucial for improving wear resistance under impact-abrasive conditions.