采用酸洗、形貌分析、金相分析和扫描电镜分析等方法对圆管表面折叠裂纹成因进行了研究。结果表明:铸坯的表面划伤、表面和皮下气孔均可导致圆钢表面裂纹,圆钢裂纹内没有发现夹杂物,裂纹没有向内继续延伸的趋势。圆管和圆钢的脱碳层分析表明:圆钢表面裂纹是导致钢管表面折叠的直接原因。 The cause of the folding cracks on the surface of the pipe was studied by pickling, morphology analysis, metallographic analysis and scanning electron microscopy. The results show that the surface of the slab is scratched, the surface and the subcutaneous pores can lead to the surface crack of the round bar, and no inclusions are found in the crack of the round bar, and the crack does not continue to extend inward. Analysis of the decarburization of the round pipe and the round bar shows that the surface crack of the round bar is the direct cause of the folding of the pipe surface.