冷轧304不锈带钢边鳞缺陷的成因分析及其改进措施

针对冷轧304不锈带钢表面的边鳞缺陷，采用扫描电镜对带钢表面及横截面缺陷形貌和成分进行了分析，并对实际生产数据进行了统计，分析了冶炼化学成分、连铸二冷比水量、板坯加热工艺参数与边鳞缺陷降级率的关系。结果表明，冷轧304不锈带钢边鳞缺陷的产生是板坯高温塑性不佳及其加热工艺不合理造成的。为此提出了针对性的改进措施：严格控制钢液化学成分，N质量分数小于0.045%，Cu质量分数小于0.15%，并加入适量的B（0.001 5%~0.003 5%）；同时保证连铸二冷比水量控制在0.60~0.75 L/kg；优化加热工艺，控制板坯在炉加热时间小于220 min，均热段温度不高于1 220 ℃。采用上述改进措施，冷轧304不锈带钢边鳞缺陷降级率显著降低，从8.5%降至1.2%以下。

Cause analysis of edge scale defect of cold rolled 304 stainless steel strip and its countermeasures

In view of the edge scale defects on the surface of cold rolled 304 stainless steel strip,the morphology and composition of the defects on the strip surface and cross-section were analyzed by scanning electron microscopy.The relationship of the steelmaking composition,the secondary cooling water ration of the casting,the slab heating process parameters and the degrading rate of edge scale defects were analyzed by production data statistics.The results show that the defects are caused by the poor high temperature plasticity of the slab and the unreasonable heating process.Therefore,targeted improvement measures are proposed,including strictly controlling the chemical composition of the molten steel,optimizing the N mass fraction in the molten steel less than 0.045%,Cu mass fraction less than 0.15%,and add an appropriate amount of B (0.001 5%~0.003 5%),controlling the water ratio of the secondary cooling of the continuous casting at 0.60~0.75 L/kg,optimizing the heating process of controlling the heating time of the slab in the furnace to be less than 220 min and the temperature in the soaking section to be less than 1 220 ℃.By using these improvement measures,the degradation rate of edge scale defects of cold rolled 304 stainless steel strip is significantly reduced from 8.5% to below 1.2%.