Competition Between Solute Drag and Pinning in Grain Growth of MnS/MnSe-Bearing Ferritic Steel with Sn/Sb Additions

Abstract Grain growth in ferritic steels containing MnS or MnSe is governed by the interplay of pinning particles and solute atoms, but the dominant controlling factor under simultaneous action has not been clarified. In this study, the controlling factors for grain growth were examined in MnS- and MnSe-bearing ferritic steels with Sn and Sb additions. Heat treatment experiments were conducted to observe grain growth and precipitate evolution, and the results were analyzed by combining quantitative modeling of pinning and solute drag terms. Experimental observations showed that Sn suppressed the grain growth, while Sb additions reduced MnS growth as well as grain growth. In MnSe-bearing steels, the additional effects of Sn and Sb were relatively small, and pinning by MnSe was identified as the dominant factor. Computational analyses further confirmed that the experimental grain growth behavior could be reproduced when both pinning and solute drag contributions were considered, whereas removing individual terms from the calculations failed to capture the observed trends. These findings establish the respective roles of Sn and Sb in governing grain growth and precipitate evolution in ferritic steels containing MnS or MnSe.