不锈钢原料内在缺陷致冷轧断带的分析与改进

Analysis and improvement of cold-rolling strip breaking caused by internal defects of stainless-steel raw materials

针对不锈钢原料内在缺陷导致的冷轧断带,采用扫描电子显微镜对断口形貌和成分进行分类,并对异物轧入、夹杂物和脆断的影响因素进行了探讨。结果表明,需根据断口不同的微观形貌和成分特征去制定改进措施。通过精炼工序适当延长软吹镇静时间可以减少辅料及炉衬耐材夹渣;通过连铸工序稳定拉速、改善冷却、优化结晶器流场及加强结晶器液面监控可以减少保护渣卷渣并提高板坯质量;通过调整板坯喷码字号和位置可以消除残留涂料轧入;通过微调钢种化学成分并减薄原料厚度可以降低冷轧脆断风险。以上改进措施实施后,不锈钢原料内在缺陷导致冷轧断带的次数较改进前减少了70%以上。

In view of the strip breaking during cold rolling caused by internal defects of stainless-steel raw materials,the morphology and composition of the fracture surface were analyzed by scanning electron microscopy(SEM).Moreover,the influencing factors of rolled-in extraneous material,inclusions and brittle fracture were discussed.The results showed that the improvement measures should be made according to the different micro morphology and composition characteristics of the fracture.The slag inclusion of auxiliary materials and lining refractory could be reduced by prolonging the soft blowing and sedation time properly in refining process.The slag entrapment could be reduced and the slab quality could be improved by stabilizing casting speed,improving the cooling condition,optimizing the mold flow field,and strengthening the monitoring of mold liquid level in continuous casting process.The rolled-in coatings residual could be eliminated by adjusting the marking-code size and position of slabs.The risk of cold-rolled brittle fracture could be decreased by finely tuning the steel chemical composition and reducing the thickness of raw materials.After the implementation of improvement measures above,the frequency of strip breaking during coldrolling caused by internal defects of stainless-steel raw materials reduced by more than 70%compared with before.