厚壁螺旋埋弧焊管焊缝反弯试验断裂原因分析

为了探寻厚壁螺旋埋弧焊管焊缝反弯试验断裂的原因，对壁厚21.4 mm的螺旋埋弧焊管焊缝反弯试样断口进行了分析。结果表明，此次反弯试样的断裂主要原因是内焊部位纵向断续分布多处凝固裂纹，尺寸较大夹杂物也在一定程度上破坏了焊缝的韧性，加速了试样的断裂。可通过控制钢管成型角稳定性、保证钢带有效变形量以及调整焊缝形貌变宽变平的方式降低管坯成型残余应力和焊接应力，从而避免内焊凝固裂纹的产生；还可选用杂质含量低的优质碱性焊剂，保证对焊剂进行烘干以及杂质筛除等措施来避免焊缝产生尺寸较大的夹杂物，提升焊缝质量。

Fracture Cause Analysis in Weld Reverse Bending Test of Thick Wall SSAW Pipe

In order to find out the cause of the fracture in the reverse bending test of the thick wall spiral submerged arc welded pipe，the fracture of the 21.4 mm spiral submerged arc welded pipe was analyzed. The results show that the main reason for the fracture of the specimen is that several solidification cracks in the longitudinal intermittent distribution of the internal welding position are existed and the large-scale inclusions also destroys the toughness of the weld to a certain extent，accelerating the fracture of the specimen. The forming residual stress and welding stress can be reduced by controlling the forming angle stability of the steel pipe，ensuring the effective deformation of the steel strip and adjusting the width and flattening of the weld morphology，so as to avoid the internal welding solidification crack. In addition，the high-quality basic flux with the low impurity content can be selected to ensure the drying of the flux and impurity screening to avoid large inclusions in the weld and improve the weld quality.