厚板铝合金变极性等离子弧焊电弧物理特性

Physical characteristics of VPPAW arc for thick plate aluminum alloys

为克服厚板铝合金穿孔焊接熔池极易失稳的难题,该研究从厚板焊接时电弧温度场出发,旨在探究厚板穿孔焊接熔池稳定性的机理。通过建立三维数值模型,研究了焊接母材厚度分别为5 mm和16 mm下变极性等离子电弧的温度场、流场和电流密度分布。结果表明,随着板厚的增加,变极性等离子电弧温度场分布发生改变,5 mm板厚电弧温度的衰减情况为线性,而16 mm厚板焊接的电弧温度衰减情况为二次型,使得温度变化更加复杂。变极性等离子弧焊接5 mm厚度铝合金时,整个小孔熔池的电流密度呈1.0×10^(6) A/m^(2)以上,但是在焊接16 mm厚板铝合金时,相同电流密度仅达到小孔深度的12 mm处。该研究有望对实现大厚度铝合金稳定焊接,拓宽变极性等离子弧焊接应用范围提供理论指导。

In order to overcome the problem of easily unstable molten pool in thick plate aluminum alloys perforation welding,this study started from arc temperature field during thick plate welding,aiming to explore mechanism of molten pool stability of thick plate piercing welding.By establishing a three-dimensional numerical model,temperature field,flow field and current density distribution of variable polarity plasma arc(VPPA)with 5 mm and 16 mm thickness of welding base metal were studied.The results showed that with the increase of plate thickness,temperature field distribution of VPPA changed.Arc temperature decay of 5 mm plate thickness was linear,while that of 16 mm plate welding was quadratic,which made temperature change more complicated.When welding 5 mm thick aluminum alloy plates by VPPAW,current density of the entire keyhole molten pool was above 1.0×10^(6) A/m^(2),but when welding 16 mm thick aluminum alloy plates,the same current density only reached 12 mm depth of the small hole.This study was expected to provide theoretical guidance for realizing stable welding of large thickness aluminum alloy and broadening application range of VPPAW.