摘  要：针对某钢厂生产的20#钢管在穿孔过程中出现表面外折缺陷的质量问题，利用金相显微镜、扫描电镜及能谱仪对穿孔样品表面缺陷与连铸坯表面缺陷进行系统分析。通过对大量实验数据进行比较研究，得到表面缺陷的形态、分布及化学成分，并结合生产工艺分析外折缺陷产生的原因：连铸坯表面存在纵裂纹缺陷是导致穿孔管表面出现外折缺陷的主要原因。最后，结合该钢种的连铸生产工艺提出具体的改进建议。
关键词：20#钢；外折缺陷；连铸坯；纵裂纹；改进对策
中图分类号：TG335.71；TG806；TM930.12；TG356.2+1    文献标志码：A    文章编号：1674-5124（2013）05-0028-03
Causes and solutions of outer fold on surface of 20# steel pipes
ZHANG Ke， WU Yuan-yuan， DONG Deng-chao
（Research Institute of Iron and Steel （Sha-Steel） of Jiangsu Province，Zhangjiagang 215625，China）
Abstract: Defects of outer fold were found in cone-roll piercing of 20 steel pipes， which greatly affect the product quality. The surface defects of pierced samples and continuous casting billets were investigated by optical microscope， SEM and EDS. Morphology， distribution and composition were obtained after comparing and analyzing large number of experimental data. Furthermore， the cause was deduced according to the actual production. The results showed that the outer fold on the surface was mainly caused by the longitudinal crack defect on the surface of continuous casting billet. Correspondingly， solutions and suggestions for improvement were proposed in terms of the continuous casting process of this steel.
Key words: 20# steel； outer fold； continuous casting billet； longitudinal crack； solution