2219厚板铝合金VPTIG焊接接头组织及性能

Microstructure and properties of VPTIG welded joints of 2219 aluminum alloy thick plate

针对15 mm厚板2219铝合金板材对接,提出了一种适合于大厚度铝合金的VPTIG焊接工艺方法,该方法通过设计新型坡口形式,优选“打底+盖面1+盖面2”的焊接工艺,实现单面焊双面成形。试验结果表明,焊缝成形良好,焊缝质量达到一级焊缝水平;焊缝中心组织为均匀等轴树枝晶,盖面焊缝比打底焊缝晶粒更加细小密集,熔合区中组织晶粒大小不一,其中在熔化边界存在一个狭小的非枝晶等轴区,热影响区晶粒则发生了明显的长大;接头常温抗拉强度能达到母材的60%,断后伸长率大于4%,断裂路径均沿打底焊缝和盖面焊缝熔合区,与熔合区组织不均匀、溶质偏析造成熔合区性能薄弱有关。

A variable polarity tungsten inert gas(VPTIG)welding method was applied for welding 15 mm thick 2219 aluminum plates with a new designed groove form,and the welding process of backing weld+cosmetic weld 1+cosmetic weld 2 was selected to achieve one-side welding with back.The experimental results showed that the weld was well formed and the internal quality was level 1.The microstructure of central weld area was uniform equiaxed dendrite,the grain size of the cosmetic weld was finer and denser than that of the backing weld.The grain size in the fusion zone was different,in which there was a narrow equiaxed grain zone and the grain in the heat affected zone grew obviously.The ultimate tensile strength of joints at room temperature reached 60%of the base metal and the elongation rate was more than 4%.The fracture path was along the weld fusion line in backing weld and cosmetic weld,which was related to the uneven microstructure and weak properties caused by solute segregation.