针对36Mn2V热轧圆钢轧制后出现表面纵裂纹缺陷,采用光学显微镜、扫描电镜和能谱仪等设备对该裂纹的宏观特征、形成原因进行了系统地分析。结果表明:36Mn2V热轧圆钢表面纵裂纹是在轧制过程中形成的,其裂纹源是在连铸过程中,由于结晶器液面波动造成保护渣卷入形成的皮下夹渣,而塞棒机构动作失灵是造成结晶器液面波动的主要原因。通过采取一系列有效的工艺技术措施,铸坯皮下夹渣可基本消除,避免了热轧圆钢表面纵裂纹缺陷的产生。 Aiming at the surface longitudinal crack defects of rolled 36Mn2V hot rolled steel, the macroscopic characteristics and formation causes of the crack were systematically analyzed by optical microscope, scanning electron microscope and energy dispersive spectrometer. The results show that the longitudinal cracks on the surface of 36Mn2V hot-rolled steel are formed during the rolling process. The source of the cracks is the subcutaneous slag entrapment caused by the fluctuation of the liquid level during the continuous casting process. Institutional malfunction is the main reason for the mold liquid level fluctuations. By adopting a series of effective technological measures, slag sub-slag can be basically eliminated, to avoid the longitudinal cracks on the surface of hot-rolled bar defects.