Q235B钢连铸板坯中间裂纹成因分析及改进措施

Cause analysis and improving measures of central crack in continuous casting slab of Q235B steel

针对Q235B钢连铸板坯出现的中间裂纹,运用金相观察、扫描电镜和能谱分析等检测手段,对中间裂纹宏观和微观特征进行研究。结果表明:裂纹处S杂质元素有明显的富集,S元素的晶间偏析是铸坯产生中间裂纹的重要内因;钢基体中的大颗粒且不易变形的Al_2O_3类夹杂物,易成为裂纹源,加速内裂纹的产生。通过分析连铸板坯中间裂纹的成因,结合现场生产工艺,提出应对措施,可使铸坯的中间裂纹得到有效的控制。

Based on the central crack in continuous casting slab, the metaUography observation, scanning electron microscope and power spectrum analysis were adopted to test and analyse central crack. The results show that there are impurity elements segregations such as sulfur in the crack band, the intergranular segregation of sulfur element is the central cause of producing in central crack. The Al2O3 inclusions, which are the large particles in the steel matrix and not easy to deform, can easily become the source of the crack, and accelerate the generation of central cracks. Through analysis of the causes of the central cracks in the continuous casting slab and the actual production process, the corresponding measures are put forward, which can effectively control the central crack in the slab.