铝合金激光填丝和电弧复合焊接技术研究.pdf

摘耍摘要铝合金密度低,耐腐蚀性能好,抗疲劳性能高,以及具有较高的比强度和比刚度,是飞机结构的理想材料。激光焊接具有能量密度高、焊接变形小、生产效率高等优点,利用激光填丝焊和复合焊接技术可以降低对接装配精度、改善焊缝冶金特性、提高接头机械性能等。 铝锂合金激光填丝焊以及3mm厚5A90铝锂合金激光电弧复合焊接技术展开研究,为航空用铝合金的推广应用提供数据参考。激光填丝焊接时,通过焊接工艺参数(送丝速度、激光功率、焊接速度和送丝几何位置)的优化控制焊缝背宽比(焊缝的背面宽度与表面宽度之LL),从而控制焊缝的成形质量。当其它优化工艺参数固定时,光丝间距必须严格控制在+~ +,而激光复合焊由于引入电弧,两热源产生“协同效应”,对光丝间距的要求可以放宽在0"---'6mm范围内。优化的复合焊接工艺可以增加焊缝熔宽和熔深,但是在其它参数一定时,只有当焊接电流超过一定阈值,复合焊的优势才能充分体现。在激光填丝焊和复合焊接主要工艺参数中,优化送丝速度的选择也与输入功率有关,且母材板厚较小有利于填丝焊优化送丝速度的提高及其范围的扩大。激光填丝焊和复合焊均能有效改善激光焊接的间隙适应性,,是激光焊的4"--'6倍。铝合金的主要焊接缺陷是成形不良和气孔,母材板厚较大时,焊缝中气孔数量增多且尺寸增大趋势加剧,但通过严格的焊前表面处理,并实现全熔透焊接均能获得成形较好且基本无气孔的焊缝。另外,利用高速摄像监测激光填丝焊接过程中的熔滴过渡方式,发现光丝间 gE+lmm时的表面张力过渡比光丝间距+;而复合焊时呈现一脉一滴的射滴过渡方式,焊接过程也相对平稳。在激光填丝焊和复合焊接过程中热源和物质的相互作用呈现周期性变化。激光填丝焊可以提高材料对激光的吸收率,增加焊缝熔宽,提高接头的拉伸性能,如与激光焊接头相比,5A06铝合金激光填丝焊接头抗拉强度提高10%左右。激光填丝焊和复合焊均有利于铝锂合金焊缝硬度的均匀化。关键词铝合金;铝锂合金;激光填丝焊;复合焊;焊缝成形 ABSTRACT II| ABSTRACT Aluminum alloy is an ideal material for aerocrafl structure,because of itslight weight, superior strength·to-weight ratio,and excellent welding withhi曲er energy density Can offerremarkable advantage over conventional fusion welding processes,such as ponent distortion andhigh welding with filling wire and laser-archybridwelding are new technologies,which call reduce assembled precision ofbutt-joint, improve metallurgic characteristic ofweld enhance joints’mechanical this paper,the experiments of 5A06 aluminum alloy with thickness and 5A90 aluminum-lithium alloy with 3mm thickness by laserwelding withfillingwire,and the5A90 alloy by laser-archybrid welding have been investigated,which could offer data reference forjoint technology of aluminum alloy inaerospace. While laserwelding with fillingwire,the back width to surface width ratioand the weld shaping quality are controlled by optimizing welding parameters,such as thewire feedspeed, laserpower,welding speed andgeometry position offillingwi