Q235B钢级螺旋埋弧焊管连续气孔缺陷分析

针对Q235B钢级Φ1 220 mm×16 mm螺旋埋弧焊管生产中焊缝存在连续性气孔缺陷的问题，采用SEM-EDS对气孔缺陷微观形貌及夹杂物成分进行了分析，并从原料卷板合金成分、匹配焊剂、环境因素、焊接参数等方面对缺陷形成原因进行了讨论。结果显示，焊缝气孔缺陷主要为CO气孔，生产用焊剂SJ301氧化性强、熔点高、焊渣黏度大，易使熔池中C被氧化生成CO气体，是造成焊缝产生气孔缺陷的主要原因。另外，焊剂因受潮发生粉化，吸收空气中水分，也会增大焊缝产生气孔的几率。通过优化焊剂匹配、控制焊剂添加与清空时间，此类缺陷明显减少。

Analysis of Continuous Porosity Defects in Q235B SSAW Pipe

In view of the problem of continuous porosity defects in the weld of Q235B grade Φ1 220 mm×16 mm spiral submerged arc welded pipe, the microscopic morphology and inclusion composition of the porosity defects was studied by SEM-EDS. At the same time, the causes of defects were discussed from the aspects of raw material alloy composition, matching flux, environmental factors and welding parameters. The results show that the weld porosity defects are mainly CO pores. Because SJ301 flux has strong oxidizing property, high melting point and high viscosity of welding slag, C is easily oxidized to form CO gas in the molten pool, which is the main reason for the occurrence of porosity defects in the weld. In addition, the flux is pulverized by moisture, and the moisture in the air is absorbed, which also increases the probability that the weld will generate pores. These defects are significantly reduced by optimizing flux matching, controlling flux addition and cleaning time.