大径中厚壁管道坡口对MAG焊操作的影响

Influence of large diameter medium-thick-walled pipe groove on MAG welding operation

多层多道焊是核电大直径厚壁管道常用的焊接工艺,坡口形式作为影响焊道层数和道数的直接因素,不仅决定了生产成本和效率,还进一步影响着焊接过程中焊缝排道及焊枪的可操作性。采用TIG打底、MAG进行填充、盖面,分别对20°、15°和9°的U形坡口进行了试验,分析了不同坡口形式下的电弧稳定性、焊缝排道和焊枪可操作性。结果表明:坡口尺寸对电弧稳定性影响较小;15°的U形坡口既可以使电弧对坡口两侧壁进行相对充分的加热和填充,又可以保证较小的填充量,打底焊可操作性好、焊接效率高。

Multi-layer and multi-pass welding is a common welding process for large-diameter thick-walled applications.As a direct factor affecting the number of weld layers and passes,the groove form not only determines production costs and efficiency but also further influences the arrangement of weld seams and the operability of the welding torch during the welding process.In this paper,experiments on 20°,15°,and 9°U-groove were conducted based on TIG root welding and MAG filling and capping welding processes.The arc stability,weld seam arrangement,and welding torch operability under different groove forms were analyzed.The results indicate that the groove size has virtually no impact on arc stability.The arc can adequately heat and fill both sides of the groove while ensuring a relatively smaller fill volume under the 15°U-groove.Therefore,15°U-groove offers good operability and high welding efficiency for root welding.