某直缝埋弧焊管焊接缺陷原因分析

Welding Defects Analysis of A Longitudinal Submerged Arc Welded Pipe

为了分析某直缝埋弧焊管焊接缺陷产生的原因,采用X射线检测、磁粉检测、弯曲性能检测等方法对含缺陷直缝埋弧焊管进行了分析,并对磁粉检测发现的纵向磁痕处进行了扫描电镜及能谱分析。研究结果表明,距离管端约70 mm处直焊缝热影响区外表面存在深度为0.122 mm的冷裂纹,该裂纹是由于焊接接头承受较大的拘束应力所致。建议有效减小焊接应力,同时调整焊缝冷却速度以改善焊缝组织,从而防止冷裂纹的形成。

In order to analyze the causes of welding defects in a longitudinal submerged arc welded pipe,X-ray detection,magnetic particle testing,and bending performance detection were carried out on the pipe,and the longitudinal magnetic traces found in the magnetic particle testing were further analyzed by SEM and energy spectrum analysis.The results show that the cold crack with a depth of 0.122 mm exists on the outer surface of the heat affected zone of the longitudinal weld about 70 mm from the pipe end,which is caused by the large constraint stress of the welded joint.It is suggested to reduce the welding stress effectively,adjust the cooling rate of the weld and improve the weld microstructure,so as to prevent the formation of cold crack.