Review on regulation of MnS in non-quenched and tempered steel

An overview of the current research status and control methods of MnS in non-quenched and tempered steel was provided. As a low-melting plastic inclusion, the morphology and distribution of MnS were influenced by various production processes. Therefore, control of MnS is a systematic problem that must be integrated into the entire production process. Based on the production process, the factors affecting the morphology and distribution of MnS in steel were introduced. The effects of oxygen activity, manganese, sulfur, and some alloys on MnS inclusion precipitation were summarized, mainly including MnS modification treatment and oxygen–sulfide composite precipitation control. It is believed that MnS precipitates during the solidification process of steel, and controlling the solidification cooling rate could effectively regulate the size and morphology of MnS, avoiding the precipitation of II-MnS. Additionally, by changing the deformation rate, deformation amount, deformation temperature during the hot deformation process, and heating time and temperature during heat treatment, the distribution and morphology of MnS could be improved. Through the fine control of the above process parameters, the number of II-MnS in steel could be effectively reduced, and their morphology could be improved, thereby enhancing the performance of non-quenched and tempered steel and promoting its wider application. Furthermore, applying laboratory research results to industrial production is an important direction for future research efforts in this field.