热轧带钢Q235B边裂缺陷成因及控制

Causes and control research on the edge crack defect of hot-rolled strip Q235B

通过对热轧带钢Q235B边裂缺陷进行检验和分析,认为造成带钢边裂的主要原因是快换中包期间连铸拉速陡然变化时,各工艺参数不匹配,铸坯角部过冷,在振痕波谷处产生角部横裂纹,这些横裂纹在后续工序中进一步恶化,最终演变为边裂缺陷。采取优化后的连铸工艺可有效改善板坯角部横裂纹,消除热轧带钢边裂缺陷;同时板坯角部缺陷经修磨后再轧制可避免边裂缺陷产生。

Inspection and analysis of the edge crack defect of hot-rolled strip Q235B show that the main reason for the edge crack is mismatching of various processing parameters and supercooling of the slab corner at the juncture of the sudden fluctuation of casting speed in the process of fast changing the tundish. The transverse corner cracks taking place at the wave hollows of the oscillation marks further deteriorates and finally evolves into edge cracking defects. By adoption of the optimized continuous casting process the transverse corner cracks of the slab can be effectively reduced and the edge cracks of the hot rolled strip can be eliminated as well. In the meanwhile the edge crack defects can be avoided in rolling the trimmed slab by grinding the corner defect of the slab.