通过化学成分分析、金相检验和断口分析等方法检测分析了在某一批次加工304不锈钢冷却管束过程中产生缺陷的原因。结果表明: 缺陷主要有清理焊缝后出现的凹坑和焊后出现的裂纹两种; 由于材料中存在微量氧和锡等有害元素以及分布不均的铜和铈元素，导致在管子焊接过程中，钨极氩弧焊接过程中熔池中产生氧化物熔渣，有的残留在焊缝金属表面被去除后产生凹坑; 焊管在弯曲过程中，由于Cu-Sn合金产生铜脆而在钢管的受拉应力的一侧产生局部裂纹。因此，这些缺陷是由此批次不锈钢的纯净度较差引起的。

The reason which caused the defects in 304 stainless steel pipe in cooling coil making process was analyzed by means of chemical component analysis, metallographic examination and fracture analysis. The results showed that the main defects were pit and crack after welding; there were such harmful elements as O and Sn etc, and unequally-distributed element Cu and Se etc in the steel that led to those defects. When the steel was welded with TIG, oxides in welding pool formed slag particles and some of which remained on the surface of weld metal, and the pit came into being after cleaning the weld joint; when the welded pipe was bended, copper brittleness caused by Cu-Sn eutectic alloy resulted to the local crack in the tension stress side of steel pipe. Therefore, these defects resulted from impurity of steel.