低碳硼钢表面缺陷的形成原因与改进措施

Analysis and Improving Measures for Surface Defects on Low Carbon Boron Steel

研究了低碳硼钢连铸坯表面和角部凹坑和裂纹的形成原因。对样品进行了金相组织观察、扫描电子显微镜(能谱分析)、Gleeble-3800热模拟试验、THERMO-CALC软件计算和X射线衍射分析,结果表明,连铸坯表面凹坑缺陷与结晶器保护渣性能有关,表面和角部裂纹是由于二冷矫直区铸坯温度位于该钢种的脆性温度区间以及钢水中BN的析出所致。通过降低钢水含氮量、适当提高热矫温度和调整结晶器保护渣性能等工艺措施,明显减少了低碳硼钢表面缺陷。

The forming reason of pit and crack on the billet surface and corner of low carbon boron steel was investi- gated through using the metallographic microscope, SEM （EDS）, GleebIe-3800 thermal simulator, THERMO- CALC software and X-ray diffraction （XRD）. The results show that the surface pit is related to the properties of mould powder, and the surface crack is related to the hot straightening temperature in the range of low hot ductili- ty and the precipitation of BN. The surface defects of low carbon boron steel can evidently be decreased through optimizing production process, such as decreasing the nitrogen content in liquid steel, adjusting the properties of mould powder and increasing the hot straightening temperature.