热轧钢带板形缺陷的成因与控制

Causes and Control of Flatness Defects of Hot Rolled Steel Strip

通过对热轧钢带开平后出现的板形缺陷进行跟踪调查,对板形缺陷的机理进行了详细分析。结合现场实际,讨论了精轧出口钢带板形和温度均匀性对最终板形的影响。具体分析了层流冷却系统中水比、侧喷、冷却模式对板形的影响和优化措施。结果表明:钢带的板形缺陷与温度分布不均匀产生的内应力有关;经过层流冷却后,边部温降过快造成压应力过大并且在开平后得到释放,是造成开平后边浪和纵切后侧弯的共同原因;通过优化水比、侧喷、冷却模式可以有效控制板形缺陷。

The mechanism of flatness defects was analyzed in detail by investigating the shape of hot rolled steel strip after uncoiling.Combined with practice,the influence of strip shape and temperature distribution after finish rolling was discussed. The influence of the ratio of water flow for laminar cooling, side spray and cooling methods and optimization measures were analyzed in detail.The results show that flatness defects of steel strip are related to the internal stress after uncoiling caused by the uneven temperature distribution.The common cause of edge waves after uncoiling and lateral bending after length cutting is that the compressive stress, caused by the temperature drop of strip edge, released. The flatness defects could be effectively controlled by optimizing the ratio of upper and lower water flow, side spray and type of cooling.