Q355B延伸率不合格原因分析与改进

Reason Analysis and Improvement of Unqualified Q355B Elongation

某2050热轧产线生产Q355B钢种时出现部分钢卷延伸率不合格的情况。经实验室调查分析,确定夹杂物含量高以及成分偏析是导致本批次延伸率不合格的直接原因。通过排查各生产工序,发现性能不合格炉次转炉脱氧剂采用硅铁进行脱氧,相比于铝脱氧模式来说,硅铁脱氧容易造成S含量偏高。同时本浇次连铸机辊缝精度超出标准要求,二者共同作用造成MnS夹杂物升高以及偏析加剧是本次伸率不合格的根本原因。通过改变脱氧模式、调整设备精度等手段使延伸率得到显著改善。

During the production of Q355B steel on a 2050 hot rolling production line,there was a situation where some of the steel coils had inadequate elongation.After laboratory investigation and analysis,it was determined that the high content of inclusions and component segregation were the direct reasons for the unsatisfactory elongation of this batch.Through investigation of various production processes,it was found that the performance of the converter deoxidizer was not satisfactory.Silicon iron was used for deoxidation,and compared to aluminum deoxidation mode,silicon iron deoxidation easily caused a higher S content.At the same time,the precision of the roll gap of the continuous casting machine exceeded the standard requirements,and the combined effect of the two caused an increase in MnS inclusions and intensified segregation,which was the fundamental reason for the non conformance of the elongation in this casting.By changing the deoxygenation mode and adjusting equipment accuracy,the elongation rate has been significantly improved.