Evolution of inclusions in G102Cr18Mo stainless bearing steel during VIM-VAR refining process
XU Tao1, MA Hong-jun1, WU Zhen-zhong1, SHU Mei-liang1, CHANG Li-zhong2
1. Anhui Fukai Special Material Co., Ltd., Jixi 245300, Anhui, China; 2. School of Metallurgy Engineering, Anhui University of Technology, Maanshan 243000, Anhui, China
Abstract：The ingot of G102Cr18Mo stainless bearing steel was prepared by vacuum induction smelting and vacuum consumable remelting. The variations of inclusion number, size and area were analyzed by Aspex scanning electron microscope, and the element distribution of inclusions was further observed by SEM-EDS. The experimental results showed that the composition of inclusions had little change in both vacuum induction ingot and consumable remelting ingot. The inclusions were mainly composed of MnS, xAl2O3·yCaO and Al-Ca-Mn-(Ti)-O-S composite inclusions, among which Al-Ca-Mn-(Ti)-O-S inclusions had the largest number and the largest diameter (area). However, compared with the vacuum induction ingot, after vacuum consumable remelting, the total amount of inclusions decreased by more than 55%, and there were no inclusions larger than 15 μm. Compared with the lower part of the vacuum consumable ingot, the number of inclusions in the upper part of the consumable ingot was further reduced, and the diameter of the largest inclusion was no more than 10 μm. The main reason for the emergence of large particle inclusions was that the sulfide in the solidification process took the residual calcium aluminate inclusions in molten steel as the nucleation core, and further enriched and grew on its surface. Therefore, in order to reduce the large particle inclusions in steel, calcium aluminate inclusions in molten steel should be reduced as much as possible to reduce the number of inclusion nucleation cores. At the same time, the sulfur content in raw materials should be reduced as much as possible to avoid the combination of calcium aluminate and manganese sulfide.
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2021, Vol. 31 
