A novel Ni–Mo–W–V martensitic steel for hot working dies: Improved elevated–temperature mechanical properties and wear resistance via thermally stable MC nanoprecipitates

With the continuous advancement of industrial technologies, there is an increasing demand for hot working dies that can withstand higher operational temperatures and more severe loading conditions. Consequently, hot working die steels must exhibit exceptional elevated temperature strength to improve wear resistance. In this study, a martensitic low–alloy 23CrNi3Mo2WV (PG) steel is developed by incorporating Mo, W, and V to promote the precipitation of MC nanoscale carbides. Experimental results demonstrate that the ultimate tensile strength of PG reaches 543 ± 15 MPa at 700 °C, which is 322 ± 20 MPa higher than that of 5CrNiMo steel. Furthermore, the wear rate of PG is 4.39 ± 0.24 × 10^–7 mm³/N/m after a wear test at 500 °C, significantly lower than that of 5CrNiMo. Microstructural analysis further reveals the precipitation of needle–like MC nanocarbides in the PG steel after tempering, which exhibits higher thermal stability relative to M₃C carbides in the 5CrNiMo steel. The MC carbides follow a Baker–Nutting (B–N) orientation relationship (OR) of ${\left(100\right)}_{\text{MC}}{//\left(100\right)}_{\text{α}\prime }$ with the martensitic matrix, and this B–N OR is remained following the wear test at 500 °C. This stable orientation relationship in PG steel contributes to the higher strength and lower wear rate compared to 5CrNiMo steel. Therefore, PG steel is a promising material for hot working die applications, offering an extended service life at elevated temperatures.