低功率激光-双电弧焊接钛合金中厚板工艺及机理

Process and mechanism of low power laser-double arc welding of titanium alloy plate

采用单钨极惰性气体保护焊(Single tungsten inert gas welding,STIG焊)、双钨极惰性气体保护焊(Double tungsten inert gas welding,DTIG焊)、激光-SDTIG电弧(L-SDTIG)复合焊和激光-DTIG电弧(L-DTIG)复合焊4种方式对6 mm厚TA2钛合金进行对接焊试验,实现单面焊双面成形。结果表明,L-DTIG复合焊的电弧能量更为集中,焊接速度可达680 mm/min。L-DTIG复合焊的热输入为605.5 J/mm,仅是DTIG焊的35.5%和L-SDTIG复合焊的59.0%。L-DTIG复合焊接头的焊缝区晶粒细小,显微硬度可达229.5 HV。拉伸试样在母材处断裂,接头抗拉强度优于母材。加入激光后,L-DTIG复合焊的电弧等离子体中心导电区在xOz和yOz平面电弧分别收缩51.0%,45.5%,电弧根部收缩75.0%。测得L-DTIG复合焊热源在工件上的电弧压力为3465 Pa,分别是DTIG焊和L-SDTIG复合焊的4.17和2.25倍。较高的电弧收缩比和电弧压力可显著提高焊接效率,降低焊接热输入。

Single tungsten inert gas welding(STIG),double tungsten inert gas welding(DTIG),laser-single TIG arc hybrid welding(L-SDTIG)and laser-double TIG arc hybrid welding(L-DTIG)were used to weld TA2 titanium alloy butt joints with 6 mm thickness,and one-side welding with back formation were achieved.The results show that the arc energy of L-DTIG hybrid welding is more concentrated,and the welding speed can reach 680 mm/min.The heat input of L-DTIG hybrid welding is 605.5 J/mm,which is only 35.5%of DTIG and 59.0%of L-SDTIG.The grain size of L-DTIG weld zone is fine,and the microhardness can reach 229.5 HV.Tensile specimens fracture at the base material and the joint strength is better than that of the base material.After the addition of laser,the arc plasma central conductive zone of L-DTIG shrinks by 51.0%and 45.5%in the xOy and yOz planes,respectively,and the arc root shrinks by 75.0%.The measured arc pressure of the L-DTIG composite welding heat source on the workpiece was 3465 Pa,which was 4.17 and 2.25 times higher than that of DTIG and L-SDTIG composite welding,respectively.The higher arc shrinkage ratio and arc pressure can significantly improve the welding efficiency and reduce the welding heat input.