冷轧薄板钙镁铝尖晶石类夹杂物成因分析

Analysis of formation mechanism about Ca-Mg-Al spinel-type inclusions in cold thin rolling sheet

针对超低碳铝脱氧镇静钢在冷轧冲压过程中出现开裂情况进行了电镜和能谱成分分析,确定了主要夹杂物含有Al_(2)O_(3)、CaO及MgO,为钙镁铝尖晶石类夹杂物。研究了该问题炉次的钢包顶渣组分、中间包覆盖剂及涂层侵蚀情况,讨论了夹杂物的来源。结果显示,Al_(2)O_(3)为脱氧产物及二次氧化的产物;CaO的来源为渣中较高活度的CaO与钢水中酸溶铝Al_(s)反应导致Ca元素进入钢水,进而与钢水中的O生成CaO。MgO主要为中间包覆盖剂氧化镁及涂层融蚀的氧化镁进入中间包渣系,与钢水中的Al_(s)反应导致Mg元素进入钢水,再与钢水中的O生成MgO。

The cracking of ultra-low carbon Al deoxidized killed steel during cold rolling and stamping was analyzed by SEM and EDS.It was determined that the main inclusions consisted of Al_(2)O_(3),CaO and MgO,which are Ca-Mg-Al spinel inclusions.The composition of the ladle top slag and corrosion of the tundish covering agent and coating were investigated,and the source of inclusions was discussed.It was found that Al_(2)O_(3) is the product of deoxidation and secondary oxidation.The source of CaO is the reaction between CaO of higher activity in slag with acid soluble aluminum Al_(s) in molten steel,which leads to the entry of element Ca into molten steel and the formation of CaO with oxygen in molten steel.The reaction of MgO,which comes from MgO in tundish covering slag and MgO corroded from tundish coating,with Al_(s) in molten steel leads to element Mg entering molten steel,and then MgO is formed with oxygen in molten steel.