The Formation and Growth of Sulfides in Free‐Cutting Stainless Steel

Abstract

The effect of oxygen content on the manganese sulfide in the process of cooling and heat treatment is studied. The experimental results show that the changes of oxygen content have a great effect on the formation and growth of sulfide in free‐cutting steel. And the morphology of sulfides transforms from Type II to type I in cooling process with the increase of oxygen content contribute to the formation of some oxides during initial solidification stage, which results in the formation of MnS from eutectic reaction to monotectic reaction. Oxygen content has a great effect on nucleation through decreasing nucleation work, increasing the oxygen content helps heterogeneous nucleation process. In slow cooling and heat treatment process, with the increase of oxygen content, sulfide inclusion coarsening rate is increasing and size of inclusion is remarkably magnifying, using Ostwald ripening theory.