药芯焊丝焊接储罐纵焊缝裂纹形成原因分析

Cracks in the Flux-cored Weld of the Vertical Welding of Cylindrical Tank

对采用Φ1.6 mm药芯焊丝EG-60气电立焊方法焊接的储罐纵焊缝进行X射线复检,发现了横向裂纹。对储罐SPV490Q高强钢板材、施焊工艺以及焊丝EG-60熔覆金属的化学成分和力学性能及其扩散氢含量进行了分析。SPV490Q高强钢板材、施焊工艺均符合设计要求。焊缝显微组织为贝氏体加少量铁素体,裂纹中存在夹杂。EG-60熔覆金属化学成分及力学性能在JIS Z3319验收标准范围内,而扩散氢含量为5.3×10-2mL/g,高于标准要求。高的扩散氢含量和药芯焊丝焊接过程产生的夹杂导致了储罐纵焊缝横向裂纹的形成。

The vertical welds welded with 1.6 mm EG-60 in a vertical cylindrical storage tanks has been detected by x-ray radiographic testing,founding transverse cracks in the welds.The SPV490Q materials and the welding process of the tank were analyzed,the chemical composition and mechanical properties and the diffusible hydrogen content in the welds has been investigated.The morphology of a crack and the structure of the weld with the crack have been investigated by using photomicrography.Remnant defects have been found among the crack and bainite with some ferrite have been observed in the weld with the crack.The average component content and mechanical property of the welds welded with EG-60 was accorded with the inspection certificate.The diffusible hydrogen content in the weld with EG-60 was 5.3×10-2 mL/g,which were higher than the design requirement of 5 ×10-2mL/g.It was found that the higher diffusible hydrogen and remnant defects in the welding cause the transverse cracks in the welds.