Influence of heat treatment on MnS inclusion in as-cast steel
LIN Teng-chang1, MEN Bing2, CHENG Xiong2, GUO Rui-gang3, DONG Kai4
1. Institute for Metallurgical Proeess, Central Iron and Steel Research lnstitute, Beijing 100081, China; 2. Equipment Department, Jiangyou Changcheng Special Steel Co., Ltd., Pansteel Group, Jiangyou 621000, Sichuan, China; 3. Production Technology Department, Shandong Shiheng Special Steel Group Co., Ltd., Taian 271612, Shandong, China; 4. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
Abstract：Based on the composition of 1215 free-cutting steel, the thermodynamic calculation of Mn-S-O-Fe system was carried out by Factpage software. 1215 free-cutting steel was heated at different temperatures, and changes of MnS inclusions before and after the heat treatment were observed by metallographic microscope and SEM. The results show that MnS inclusions began to precipitate along the grain boundary at 800 ℃ heat treatment, and balling phenomena with aggregation and growth of the precipitated MnS occurred after heat treatment, and the higher the temperature was, the more obvious balling phenomena was. After heat treatment at 1 200 ℃, the ratio of inclusions larger than 10 μm in the steel increased. Based on the result of experiment, the reheating furnace of rolling adopting 800-900, 1 050-1 150 and 1 200-1 220 ℃ heating operation is beneficial to improve form of MnS in free-cutting steel, so as to improve the performance of free cutting steel.
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2021, Vol. 31 
