冷轧带钢表面缺陷诊断

针对某冷轧厂生产的带钢表面经常出现锈斑、黑斑等缺陷，对原料、酸洗、轧制、退火和平整等工序进行了现场调研，并对乳化液相关指标、防锈性、耐腐败性及带钢表面缺陷的形貌和成分进行了检测。（1）板面残酸是造成锈斑的主要原因。应重点改进盐酸酸洗工艺和设备：调整挤干辊的压力，保持挤干辊的表面状态，加强水冲洗的压力和温度以及喷嘴的均匀性；同时，严格执行酸洗工艺制度。（2）轧机前后乳化液吹扫不净，卷入板内是造成成品黑斑的主要原因。要改进吹扫装置，保证把残留乳化液吹净，必要时增加一排吹扫喷嘴。（3）应设计合理的退火工艺制度，防止因退火不良或局部烧嘴堵塞加热不均造成油的局部挥发不全形成积碳；应重视退火前的松卷，加强对氨分解的监测。采用上述措施后，带钢表面缺陷大幅度减少：表面锈斑、黑色云纹和黑斑等问题得到彻底解决。

Diagnosis of surface defects of cold-rolled steel strip

According to the defects of rust spots and black spots on the strip surface produced by one cold-reduced plant, a research is carried out for the process of raw material, pickling, rolling, annealing and levding, and the detections of related index of emulsion, antirustability, decay resistance, morphology and components of strip surface defects are carried out. The analysis conclusions are ： （ 1 ） The residual acid of surface is the main reason of causing rust spots. The hydrochloric acid pickling process and equipment should be improved;Adjust the prssure of wringing roller, keep its surface status, and enhance the pressure and temperature of water washing and the uniformity of nozzle. （2） The black spots is caused by emulsion, the purging device should be im proved to ensure the purging residual emulsion. （3） Ensure the reasonable process system of annealing to avoid carbon deposition caused by bad annealing on the block of local burners. The open coiling should be emphasized, and the monitoring of ammonia decomposition should be enhanced. By adopting above methods, the defects of strip surface are greatly reduced ： the surface defects of rust spots, black spots and black moire are all solved completely.