关键词: 100tBOF-CAS-RH-230mm板坯连铸, 无取向电工钢50W350, 夹杂物

Abstract: The production process of tested non-oriented electrical steel 50W350 (/%: 0.002C, 2.66Si, 0.25Mn, 0.012P, 0.002S, 0.760Als, 0.762Alt) is hot-metal pretreatment, adding 300kg lime in tapping of an 100t BOF, controlling end [C]≤0.05% and tapping liquid temperature 1640〜1650℃ , CAS treating for 5min, RH blowing oxygen to decarburize, adding 99.0% Al-Fe alloy 6.69kg/t and 70% Si-Fe alloy 15.7kg/t in RH refining process, in whole process shielding-atmosphere casting 230mm slab, and using special carbon-free basic shielding agent. Analysis results show that at end CAS treatment the number of inclusions in steel is 306.26 piece/mm², in cast slab that decreases to 145.12 piece/mm² and the ≤3μm inclusions make up more than 90 percent of the total amount of inclusions; in steelmaking process the main inclusions are high-aluminum inclusions, some single Al₂O₃ inclusions exist in liquid at end argon blowing and in ladle ,in tundish and cast slab the Al₂O₃ combines with other inclusions to form complex inclusions in steel；besides the AIN inclusions are found in liquid in ladle and in cast slab； the total amount of large scale inclusions in cast slab is 6.20mg/10kg, the 140〜300μm inclusions make up about 60 percent of total large scale inclusions, and a small amount of large scale inclusions containing Na and K exists in slab.