热轧中碳钢卷边部裂纹的形成机理与控制

为了研究中碳钢热轧卷边部裂纹缺陷的形成机理,制定相应工艺控制措施,降低中碳钢热轧卷边部裂纹废次率。通过在热轧中碳钢卷缺陷位置取样进行金相观察、扫描电镜分析以及对比轧制试验。结果表明,中碳钢热轧卷边部山峰裂纹的形成原因是连铸坯存在角部横裂纹,轧制后延伸造成;边部发纹的形成是轧制过程连铸坯窄面折叠至宽面造成。根据这一研究结果,通过调整中碳钢成分、提高连铸机精度、优化二冷配水模型、应用倒角结晶器和动态调整结晶器锥度等措施,中碳钢热轧卷裂纹废次率降低到0.10%以下,降幅达到了90.59%,改善效果非常明显。

Control measures and formation mechanism about edge-crack of hot-rolling coil of midium carbon steel

In order to study the formation mechanism of crack defects in the hot rolling of medium carbon steel, the corresponding process control measures were formulated to reduce the down grade rate of cracks in the hot rolling of medium carbon steel. Metallographic observation, SEM analysis were carried out by sampling the defect of hot rolled coil of medium carbon steel, and comparative rolling test was also carried out. The results show that the peak crack at the edge of hot rolling medium carbon steel is caused by the transverse crack at the corner of continuous casting slab, which extends after rolling. The formation of edge lines is caused by the folding of narrow surface to wide surface during rolling process. According to the research results, by adjusting the composition of medium carbon steel, improving the accuracy of caster, optimizing the secondary cooling water distribution, applying chamfering mould and dynamically adjusting the taper of mould, the down grade rate of cracks in medium carbon steel hot rolling coil is reduced to less than 0.10%, with a decrease of 90.59%. The improvement effect is very obvious.