高牌号无取向硅钢热轧边部裂口原因分析及控制

Analysis on Causes Leading to Edge Cracks of High Grade Non-oriented Silicon Steel during Hot Rolled and Control of Cracks

利用金相显微镜、扫描电镜、能谱仪、热模拟等试验设备,对高牌号无取向硅钢边裂的成因进行了分析。结果表明,高牌号无取向硅钢在加热过程中由于加热时间过长,造成晶粒较粗大及晶界氧化和脱碳;在粗轧过程中晶界脆化、开裂,且边部的微裂纹不能通过轧制愈合。通过采取减少轧制过程中冷却水的投入,减少粗轧轧制道次和提高轧制速度,投入边部加热器对边部进行温度补偿等工艺措施,可以改善边部裂口缺陷问题,边裂发生率由8%下降到2%,效果显著。

The causes leading to edge cracks of high grade non-oriented silicon steels were analyzed by such devices as metallographic microscope,scanning electron microscope,energy spectrometer and thermal simulator.The analytical results showed that high grade non-oriented silicon steels had coarse grain sizes and grain boundary oxidation and decarburization occurred due to the long heating time during heating.Then grain boundary embrttlement and cracking occurred during rough rolling,and the microcracks at the edge could not be healed by rolling.By taking these measures such as reducing the input of cooling water in the rolling process,reducing the rolling pass in rough rolling and increasing the rolling speed and carrying out the temperature compensation by installing the edge heater,the problem concerning the defect of the edge cracks could be improved.Therefore the incidence rate of the edge cracks decreased from 8% to 2% with remarkable effect.