2.25Cr-1Mo-0.25V钢148 mm厚板尾部分层缺陷分析及控制工艺

Analysis on Causes of Delamination Defect at 148 mm Heavy Thickness Plate Tail of 2.25Cr-1Mo-0.25V Steel and Control Process

采用扫描电镜及电子探针对55 t钢锭成材148 mm厚2.25Cr-1Mo-0.25V钢板尾部分层缺陷进行观察分析,结果表明:分层缺陷是由于模铸保护渣卷入钢液造成的。为减少钢板尾部分层缺陷,对冶炼工艺进行优化,精炼过程中采用碳粉、电石及1.2~2.0 kg/t钢Al线复合脱氧工艺,真空后软吹12~14 min,采用高粘度、低熔点、高熔速及膨胀系数较大的模铸保护渣。优化工艺后,钢板尾部分层缺陷出现概率分别为11.3%、9.6%、6.9%,分层缺陷导致钢板废品率由原8.1%降至1.7%。

The delamination defects at the tail of 148 mm thickness 2.25Cr-1Mo-0.25V steel plate made of 55 t ingot is observed and analyzed by scanning electron microscope and electron probe microanalysis.The results show that the delamination defects are caused by the involvement of mold flux in the molten steel.In order to reduce the delamination defects at the tail of steel plate the smelting process is optimized,i.e.in refining process,the composite deoxidation process of carbon powder,calcium carbide and 1.2-2.0 kg/tsteelAl line is adopted.After vacuum,it is soft blown for 12-14 min.The mold casting protective slag with high viscosity,low melting point,high melting rate and large expansion coefficient is used.After optimizing the smelting process,the ratio of delamination defects at the tail of steel plate is 11.3%,9.6%and 6.9%respectively,and the scrap rate of steel plate caused by delamination defects decreases from original 8.1%to 1.7%.