Weld shape variation and electrode protection under Ar–(Ar–O2) double shielded GTA welding
Weld shape variation and electrode protection under Ar–(Ar–O2) double shielded GTA welding
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DOI：
10.1179/136217109x412391
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发表时间：
2009-11
影响因子：
3.3
通讯作者：
Shanping Lu;H. Fujii;K. Nogi
中科院分区：
文献类型：
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作者：
Shanping Lu;H. Fujii;K. Nogi
采用纯惰性氩作内层保护、Ar-O2活性气体作外层保护的双保护钨极氩弧焊（GTA焊或TIG焊）对SUS 304不锈钢进行焊接，研究其对钨极保护和焊缝成形的影响。试验结果表明，在焊接过程中，内层惰性氩气可以有效地防止外层活性气体与钨电极的接触和氧化。外层保护中的活性气体氧在电弧中分解并溶解在熔池中，有效地调节了焊缝金属中的活性元素氧含量。当焊缝金属氧含量大于70 ppm时，表面张力引起的Marangoni对流由外向内转变，焊缝形状由宽浅型转变为窄深型。系统地研究了内层气体流量对焊缝形貌和焊缝成形的影响。结果表明，内保护气体流量过低时，焊缝易被氧化，焊缝成形宽而浅。液池上一层厚重的连续氧化层是液池运动的障碍。
Double shielded gas tungsten arc welding (GTA welding or TIG welding) of an SUS304 stainless steel with pure inert argon as the inner layer shielding and the Ar–O2 active gas as the outer layer shielding is proposed in this study in order to investigate its effect on the tungsten electrode protection and the weld shape variation. The experimental results show that the inner inert argon gas can successfully prevent the outer layer active gas from contacting and oxidising the tungsten electrode during the welding process. The active gas, oxygen, in the outer layer shielding is decomposed in the arc and dissolves in the liquid pool, which effectively adjusts the active element, oxygen, content in the weld metal. When the weld metal oxygen content is over 70 ppm, the surface tension induced Marangoni convection changes from outward into inward, and the weld shape varies from a wide shallow one to a narrow deep one. The effect of the inner layer gas flowrate on the weld bead morphology and the weld shape is investigated systematically. The results showed that when the flowrate of the inner argon shielding gas is too low, the weld bead is easily oxidised and the weld shape is wide and shallow. A heavy continuous oxide layer on the liquid pool is a barrier to the liquid pool movement.