Tellurium-Induced Reduction in Heat Susceptibility of Gear Steel During High-Temperature Carburizing

High-temperature carburizing of gear steels is a critical process, and increasing the carburizing temperature remains challenging. This work provides a new compositional design strategy to reduce the heat susceptibility of gear steels during high-temperature carburizing. The effect of tellurium addition in the range of 0 to 0.141 wt pct on the inclusion characterization was investigated. Furthermore, the austenite grain size in 20MnCrS5 gear steel for high-temperature pseudo-carburizing was investigated. Tellurium addition was shown to be a feasible way for gear steels to undergo an efficient green carburizing process. The results indicate that adding 0.034 wt pct tellurium is an effective approach to achieving a more efficient and environmentally friendly carburizing process for gear steels. This is attributed to the enhancement of the uniformity of grain boundary distribution of pinning particles in the steel by the surfactant Tellurium. In situ observation experiments demonstrated that the Tellurium-modified sulfide inclusions exhibited a more pronounced pinning effect. Finally, the high-temperature carburizing temperature of 20MnCrS5 was increased from 930 °C to 980 °C.