保护气体对管子-管板全位置 TIG 焊接接头质量的影响

摘要

Based on the structure of AP1000 steam generator,the effects of various shield gases on the welding shape and throat dimension of tube to tubesheet joint welded by all-position TIG welding were studied.The morphology and forming mechanism of the cracks appeared during welding under 100%Ar gas and higher heat input were also studied.The results show that under the same welding parameters,the weld pass was the narrowest at the atmosphere of 100%Ar and the widest under 100%He gas.The weld surface was the brightest under 95%Ar+5%H 2 gas.The dimension of welding throat can meet with the technical requirements when welded under the atmosphere of 100%He,95%Ar+5%H 2 and 75%He+25%Ar.The optimum quality of tube to tubesheet joint was obtained when using TIG welding at the atmosphere of 95%Ar+5% H 2 .When improving heat input and lowering weld speed, the dimension of welding throat with 100% Ar could meet the technical requirements, but the probability of thermal cracks also increased.Those cracks were high temperature cracks.%结合核电 AP1000蒸汽发生器产品结构,研究了管子-管板全位置 TIG 焊不同焊接保护气体对焊道成形、焊喉尺寸的影响,研究了100％Ar 保护下在较高热输入下焊接时焊缝根部裂纹的形貌和形成机理。结果表明：相同焊接工艺参数下,100％Ar 保护下的焊道最窄,100％ He 保护下的焊道最宽,95％Ar＋5％H 2保护下的焊缝最光亮；100％ He,95％Ar＋5％ H 2,75％ He＋25％Ar 保护下焊接形成焊缝的焊喉尺寸均满足技术要求,AP1000蒸汽发生器管子-管板 TIG 焊采用95％Ar＋5％H 2保护气体时其焊接质量较好；通过提高热输入并降低焊接速度,100％Ar 保护下的有效焊喉尺寸可满足技术要求,但焊缝根部出现裂纹的几率增加,裂纹为高温裂纹。