前箱底焊缝的断裂失效分析

Fracture failure analysis of fore tank bottom weld seam

油箱前箱底γ环和前底通过自动氩弧焊焊接而成,在水压试验过程中出现漏水现象。通过荧光无损探伤、断口分析、金相检验、残余应力测试确定了前箱底的失效原因。结果表明,焊缝组织中的富氧α层导致前箱底脆性裂纹的萌生,是其开裂的主要原因,焊缝存在较大的残余拉应力、焊缝组织粗大促进了前箱底脆性开裂。建议加强焊接过程中的气氛保护,以避免在零件表面形成富氧α层,并检查和完善焊接工艺、热处理工艺。

Gamma ring and bottom of a fore tank bottom were welded by automatic argon arc welding , and the leak appeared in hydrostatic test.The failure cause of the fore tank bottom was analyzed by means of fluorescence nondestructive testing , fracture observation, metallographic examination and residual stress test .The results indicate that the oxygen rich alpha case in the weld seam causes brittle cracks initiating, which is the main reason of fracture .Residual tensile stress and coarse grains in the weld seam promote the fore tank bottom brittle fracture.It is suggested that gas protection should be strengthened during the welding process to avoid the formation of alpha case , and the welding process , heat treatment process should also be examined and improved .