马氏体钢40Crl0Si2Mo线材表面裂纹原因分析和工艺改进

40Cr10Si2Mo钢Φ6.5mm线材产品经过调质处理和矫直研磨后,发现磨光棒表面存在表面裂纹。通过进行40Cr10Si2Mo钢淬火回火模拟试验,得出造成40Cr10Si2Mo钢线材表面出现裂纹的原因为线材热轧后冷却时间短,冷却速度快,热轧线材表面存在较大的残余应力,从而形成表面裂纹。通过对40Cr10Si2Mo钢的生产工艺进行了优化改进,包括延长斯太尔摩辊道缓冷时间,终轧温度和吐丝温度由原来的900～950℃和850～900℃均调整为800～850℃,线材轧制后24 h内退火,从而避免了40Cr10Si2Mo钢线材表面裂纹的产生。

Analysis on Surface Cracks of Martensitic Steel 40Crl0Si2Mo Wire and Process Improvement

After quenching and tempering, straightening and grinding, the surface cracks are found on the polished rod surface of steel 40Crl0Si2Mo 6. 5 mm wire rod. Through the simulation test of quenching and tempering of steel 40Crl0Si2Mo, it is obtained that the reason for the surface crack of steel 40Crl0Si2Mo wire rod is the short cooling time after hot rolling, the cooling speed is fast, and there is a large residual stress on the surface of the hot rolled wire rod leading to form the surface crack. The production process of steel 40Crl0Si2Mo is optimized and improved, including prolonging Stelmo roller slow cooling time, adjusting the finishing rolling temperature and lay-off temperature from 900 ~ 950 °C and 850 ?900 °C to 800 ?850 °C ,and within 24 hours after rolling to anneal the wire, the surface crack of steel 40Crl0Si2Mo product has been avoided.