A-TIG焊接熔深增加机理

Mechanism of increasing welding penetration with A-TIG welding

关键词:  活性化氩弧焊  镍基合金263  熔深增加  流场  温度场

Key words:  A-TIG welding  nimonic 263  welding penetration increase  welding flow field  temperature field

摘要:

活性化氩弧焊(A-TIG)焊接方法与传统TIG焊相比,具有明显的熔深增加作用.模拟了Nimonic263 A-TIG焊接流场温度场,并对试验与模拟焊缝形状进行了对比.结果表明,同一焊接电流下,与TIG焊缝相比,A-TIG焊缝的熔深较深而熔宽较小.随着焊接电流的增加或者焊接速度的降低,A-TIG焊缝熔深呈线性增加,且比TIG焊的熔深增加效果明显.通过分析流体流动方式,进一步推测了A-TIG熔深增加机理:熔池内液体流动方式是熔深增加的主要原因,熔池中心处液体的流速明显高于熔池边缘,中心由外向内的环流为熔池内液体流动的主导方向.这个方向的环流将高温液体带到熔池底部,使熔池底部的熔化速度较熔池边缘有了明显的增加,且随着焊接电流的增加,熔深增加效果也不断提高。

Abstract:

A-TIG welding has obvious function of increasing welding penetration compared with conventional TIG welding.In this paper, welding flow field and temperature field of nimonic 263 with TIG and A-TIG were simulated and the simulated weld shape and penastration were compared with the experimental results.It is found that the depth of welded molten pool of A-TIG is deeper than that of TIG welding and its width is smaller when the welding current is the same.Moreover, with increasing welding current or decreasing travel speed the depth of welded molten pool of A-TIG increases linealy and the increase is more remarkable for the A-TIG than the TIG welding.The mechanism of increasing welding penetration by A-TIG welding is further deduced by simulating the fluid flow mode in the welded molten pool.It is indicated that flow mode in welding pool is the major factor which causees the increase of welding penetration.The flow rate in the center is obviously larger than that at the edge of the welded molten pool and the circular flow from the outside to the inside is the leading flow direction and brings the fluid with high temperature in the edge to the center which leads to the increase of metal melting rate in the center than that in the edge.Besides, the effect of increasing welding penetration is enhanced constantly by increasing welding current.