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针对生产中出现的厚规格Q345B板材厚度中心分层缺陷进行了调查分析,结果表明:板材中心分层是由于连铸坯中较为严重的中心疏松在后期轧制过程中未能轧合所致。进一步对Q345B连铸坯轻压下工艺调查发现,实际凝固终点位置比模型计算值靠后,且凝固末端扇形段压下率低,不足以补偿其凝固收缩,从而形成较为严重的中心疏松缺陷。在调查分析基础上,通过将该规格连铸坯轻压下区间后延并加大轻压下量,增加了凝固末端压下率,降低了连铸坯中心疏松和中心偏析程度,从而彻底解决了板材中心分层问题。
Aiming at the thickness delamination center of the thick gauge Q345B sheet produced in the production, the investigation shows that the delamination center of the sheet is due to the serious looseness in the continuous casting slab. A further investigation on the process of soft reduction of Q345B slab found that the actual solidification end point is located behind the calculated value of the model and the reduction rate of the segment at the end of solidification is low, which is not enough to compensate its solidification and shrinkage, thus forming a serious center loose defect. On the basis of investigation and analysis, the slab of the specification was gently postponed, and the amount of soft reduction was increased to increase the reduction rate of the solidification end, thereby reducing the degree of slackness and center segregation in the center of the slab, thus completely solving the problem Layered center of the sheet problem.