摘要
咬边是钛合金激光焊常见的焊缝成形缺陷,文中将A-TIG焊用活性剂应用于TA15钛合金CO2激光焊的研究结果表明,活性剂不仅可有效地改善焊缝咬边缺陷,而且可降低激光深熔焊的激光功率密度和热输入阈值。同样的焊接工艺参数,活性剂使钛合金CO2激光焊全熔透焊缝的背宽比增大,焊缝表面熔宽减小而中部熔宽增大,但过高的激光功率密度和热输入,活性剂反而影响激光对钛合金的作用,焊缝背宽比减小,表面熔宽增大,可能与金属汽化过于强烈有关。活性剂改善钛合金激光焊焊缝成形的作用主要有三方面,即增加钛合金对激光能量的吸收;降低熔池表面张力,改变表面张力流方向;降低光致等离子体的电离度,缩小等离子体云。
The CO2laser welding was conducted to investigate the effect of activating flux on laser welding of TA15 titanium alloy with 2.5 mmthickness.Results show that the activating flux can eliminate weld undercut defect,and increase the weld depth with the same laser welding pa-rameters.It is also found that the activating flux can improve the back width to surface width ratio (Rw) of TA15 titanium alloy weld,and re-duce the weld surface width for full penetration laser welding,but too high laser power and too lowwelding speed will result in theRwdecreasingand surface width increasing.As a result,it could be assumed that the activating flux decrease obviously both laser energy density and heat-inputthresholds that laser deep penetration welding occurs for titanium alloy,because it can improve the absorption of laser energy by titanium alloy.By means of a high speed camera,the effect of activating flux on the plasma/ metal vapor plume behavior in CO2laser welding of titanium alloy can be observed.The too high laser energy density and heat-input will produce intensive evaporation of metal and activating flux.It leads to thatthe activation flux could not play its role in full penetration laser welding.According to the activating flux action mechanism,it would also be re-sponsible for improving the weld quality of titanium alloy that it can modify surface tension and change Marangoni fluid flow in pool.
出处
《焊接》
北大核心
2008年第11期32-37,共6页
Welding & Joining
关键词
激光焊
活性剂
钛合金
焊缝成形
laser welding, activating flux, titanium alloy, plasma plume
