To combine high surface strengthening with low deformation, the effect of induction quenching temperature on the microstructure and mechanical properties of 16Cr3NiWMoVNbE gear steel after carburizing was investigated. The analysis includes metallographic observation, tensile testing, and hardness measurement. The results show that compared with conventional 850°C integral quenching, 850°C induction quenching produces finer martensite structure and better surface hardness. As the induction temperature increases from 850°C to 1000°C, the microstructure gradually coarsens, the residual austenite content increases, and grain boundary cracks appear at 1000°C. The cryogenic and tempering treatment further transforms the retained austenite into martensite, which significantly improves the hardness of the carburized layer. Among them, the comprehensive mechanical properties of the 900°C induction quenching group are the best: Compared with the conventional process, the maximum hardness of the carburized layer is increased by 11.0%, the tensile strength is increased by 9.9%, and the surface residual austenite content is reduced by 3.8%. This combined heat treatment process successfully achieves the optimal performance matching of an ultra‐hard surface and a strong‐tough core, which is difficult to realize via a single heat treatment.
Du et al. (Fri,) studied this question.