Abstract: Analysis on surface upwarp defects of hot rolled plate of high strength alloying steel Q345E produced by 120 t converter-RH-CC melting process has been carried out by using scanning electron microscope and optical microscope, and it is found that there are ferroferric oxides, residuum of mold shielding slag and secondary oxides in micro-regions of upwarp, and in the upwarp regions the arrangement of ferrite and pearlite is out of order, and the proportion of ferrite is higher than normal with serious decarburization. Further found the main reason for formation of surface upwarp defects of hot rolled plate is the higher argon flow rate in tundish which leads to bubble wrapping slag into liquid and forming subskin blowhole of casting slab, re-oxidizing in heating to form oxide scale then being pressed in plate during rolling. The occurrence rate of upwarp defects decreases from 3. 86% to 0. 8% by adopting the process measures including decreasing argon flow rate in tundish from 65 L/min to 50 L/min and adjusting casting speed from 1.0 m/min to 1.2 m/min.

Key words: Surface Upwarp, Argon Gas Flow, Slag Entrapping, Subcutaneous Blowhole, Stability

摘要： 采用扫描电镜和光学显微镜对120 t转炉-RH-CC冶炼工艺生产的Q345E高强度合金钢热轧板表面翘皮缺陷进行了分析,发现在翘皮微区域出现了铁氧化物和保护渣残留物及二次氧化物,铁素体和珠光体排列没有规律,铁素体比例很高,脱碳严重。并发现,中间包氩气流量过大导致气泡包裹保护渣进入钢液形成铸坯表层皮下气孔,加热时二次氧化以及轧制时氧化铁皮压入钢板是热轧板中形成翘皮缺陷的主要原因。通过将中间包吹氩流量从65 L/min降至50 L/min、拉速由1.0 m/min调整到1.2 m/min等工艺措施,使翘皮缺陷发生率由3.68%降至0.8%。

关键词: 表面翘皮, 氩气流量, 卷渣, 皮下气孔, 稳定性