钛合金非熔透性脉冲激光深熔焊气孔行为初探

Research on Porosity Behavior of Pulse Laser Partial Penetration Welding on Titanium Alloy

钛合金非熔透性脉冲激光深熔焊过程中,随着离焦量的增加焊缝中气孔数量明显降低,当离焦量达到±5mm以上时,焊缝中气孔缺陷几乎可以消除。增加离焦量降低了激光束作用域的能量密度,熔池底部材料气化的剧烈程度与形成金属蒸汽的压力均随之降低,加快小孔底部液态金属的回填;同时会使小孔的开口变大,减缓小孔顶部的闭合,有助于金属蒸汽的溢出,焊缝中气孔缺陷可大幅降低。

During pulse laser partial penetration welding process of Titanium alloy,with the increment of defocusing amount,number of pores in weld lines decreases significantly,and when defocusing amount is more than ±5 mm,the pore defects could be almost eliminated.As the defocusing amount increases,the energy density of laser beam scope declines,the gasification intensity of materials in weld pool bottom and the metal vapor pressure also decrease,speeding up the liquid metal backfill into the holes at the bottom.Moreover,increasing defocusing amount could make the opening of holes bigger,slow down the closure of the holes,and facilitate the metal vapor overflow.So the pore defects in weld lines might be greatly reduced.