Analysis and control of macro-inclusion of bearing steel in tundish first heat
LI Yong-chao1, LU Cai-ling1, ZUO Jian-cheng1, BAI Rui-juan1,2, WANG Wei1,2, HAN Huai-bin1,2
1. Technical Centre, Henan Jiyuan Iron and Steel Group Co., Ltd., Jiyuan 454650, Henan, China; 2. Technical Centre, Henan Special Steel Advance Material Research Institute Co., Ltd., Jiyuan 454650, Henan, China
Abstract:In order to realize the rapid analysis of the cleanliness of bearing steel, the macro-inclusion in different heats of tundish was detected by high-frequency immersion ultrasonic testing. The results show that the macro-inclusion in tundish first heat severely exceed the limit. The major components of the macro-inclusion was calcium aluminate type inclusions by scanning election microscopy after locate sawing. According to the production practice of bearing steel in a certain factory, the main source of macro-inclusion is reoxidation of molten steel and its product adhesion to the nozzle inner wall, which promotes the deposition of the original calcium aluminate type inclusions in the molten steel, finally the clogging drop into the molten steel. By optimizing baking temperature of tundish, decreasing reoxidation of molten steel, applying four-port swirling nozzle, the cleanliness value of tundish first heat was significantly decrease. The water immersion ultrasonic inspection results showed that the cleanliness value (total defect length/test volume) of tundish first heat was reduced from 170.4 to 12.0 mm/dm3.
李永超, 卢彩玲, 左健成, 白瑞娟, 王维, 韩怀宾. 轴承钢中间包首炉大型夹杂物分析及控制[J]. 连铸, 2021, 40(3): 35-39.
LI Yong-chao, LU Cai-ling, ZUO Jian-cheng, BAI Rui-juan, WANG Wei, HAN Huai-bin. Analysis and control of macro-inclusion of bearing steel in tundish first heat. CONTINUOUS CASTING, 2021, 40(3): 35-39.