Intercritical quenching treatment was applied to high-performance 18CrNiMo7-6 gear steel to investigate the influence of QQ′T (quenching–quenching–tempering) process parameters on the microstructure and friction and wear performance. The results revealed as the secondary quenching temperature increased from 720 to 870 °C, the grains were initially refined and subsequently coarsened. When the secondary quenching temperature is 810 °C, the prior austenite grain size reached a minimum of 8.62 \({\mu m}\) , and the hardness of the tested steel reaches 385.0 HV, representing a 21.18% improvement over the conventional quenching and tempering process. Under these conditions, the material’s friction and wear performance were significantly enhanced: the average friction coefficient decreased to 0.636 (a 36.3% reduction compared to the untreated sample) and a lower wear rate of 72.67 \({\mu m}^{3} /\left( {{\text{N}}\cdot{\text{m}}} \right)\) . Moreover, the tested steel exhibits an excellent combination of strength and ductility, with a tensile strength of 1209 MPa and an elongation of 8.58%. The study confirms that 810 °C is the optimal secondary quenching temperature. These findings confirm the important role of intercritical quenching treatment in optimizing the comprehensive properties of 18CrNiMo7-6 steel.
