Investigation development on inclusion control and modification in non-oriented silicon steel
WANG Hai-jun1, NIU Yu-hao1, LING Hai-tao1, QIAO Jia-long1,2,3, FU Bing3, QIU Sheng-tao1,2
1. School of Metallurgical Engineering, Anhui University of Technology, Maanshan 243032, Anhui, China; 2. Central Iron and Steel Research Institute Co., Ltd., Beijing 100083, China; 3. Silicon Steel Division, Xinyu Iron and Steel Co., Ltd., Xinyu 338001, Jiangxi, China
Abstract:The micro-inclusions in non-oriented silicon steel can pin the grain boundaries and domain walls, restrict the development of grains and the movement of domain walls, and deteriorate the stability of magnetic properties and magnetic properties of products. Large size inclusions have great influence on the surface quality and performance of products in the manufacturing process of silicon steel. This phenomenon is contrary to the national energy efficiency upgrade and the high-efficiency requirements of traction motor in new energy vehicles. Therefore, how to control the inclusions in non-oriented silicon steel has become research hotspot for many enterprises and scientific research institutes. The process measures for inclusion control in typical domestic non-oriented silicon steel production enterprises are summarized, improving the control level of molten iron pretreatment, converter smelting, RH refining, and continuous casting process can effectively control the formation of inclusions and improve the removal efficiency of inclusions, which effectively promotes the improvement of product quality for non-oriented silicon steel. However, some metallurgical equipment capacity is overused, such as large RH desulfurization load, high unit consumption of desulfurization agent, and low service life of submerged tubes. The latest research results on inclusion modification by domestic and foreign researchers are reviewed. Combined with the research results of author′s team, the shortcomings and future development trends of inclusions control in non-oriented silicon steel are pointed out. The type, size and distribution of inclusions in steel have changed greatly by calcium treatment or rare earth treatment, the number of angular inclusions is reduced, the number of micro-inclusions is significantly reduced, and the magnetic properties of products are improved. However, the appropriate addition amount and addition method of calcium treatment or rare earth treatment for different grades of silicon steel are still controversial. When rare earth treatment is carried out, it brings new challenges to the physical properties of existing covering agent and protective slag. Whether the existing covering agent and protective slag are matched remains to be further studied.
王海军, 牛宇豪, 凌海涛, 乔家龙, 付兵, 仇圣桃. 无取向硅钢夹杂物控制与变质技术研究进展[J]. 中国冶金, 2023, 33(3): 17-28.
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