2219铝合金横焊接头的补焊性能研究

Study on Repair Welding Performance of 2219 Aluminum Alloy Cross-welded Joint

针对未来运载火箭立式装配横向焊接的工程化应用需求,以厚度8 mm的2219铝合金变极性TIG横焊接头为研究对象,开展了在水平状态下对原始横焊接头进行一道补焊及二道横向补焊试验,在获得成形良好的补焊接头的基础上,研究了原始焊缝、一道补焊焊缝、二道补焊焊缝的组织形貌、力学性能及显微硬度。试验结果表明,对原始横焊焊缝上端开槽进行一道、二道补焊之后,可消除焊缝内部连续超标的气孔缺陷;一道补焊及二道补焊后的接头上层均为柱状晶,下层均为等轴晶,一道补焊及二道补焊后接头力学性能比原始焊缝要低,主要与补焊后在接头熔合线附近产生大量的共晶组织有关;二道补焊接头比一道补焊接头弯曲性能好,显微硬度高,说明厚度8 mm的2219横焊接头缺陷补焊更适合于采用较小的焊接规范及两道焊(填充+盖面)工艺。

With respect to the engineering application requirement of horizontal welding of vertical launch vehicle in the future, a variable polarity TIG horizontal welding joint of 8 mm thick 2219 aluminum alloy was used as the research object to carry out repair welding test of the first pass and horizontal repair weld- ing test of second pass on the original horizontal welded joint in the horizontal state. On the basis of obtai- ning well formed repair welded joint, the microstructure, mechanical properties and microhardness of the original weld ,first pass repair welded joint and the second pass repair welded joint were researched. The test results show that ： after a groove was made at the upper end of the original horizontal weld and the first and second pass repair welding were carried out, the continuous off-spec blowhole defects in the weld can be eliminated;both the upper layers of the joint after first pass repair welding and second pass repair welding were column crystal ,and both the lower layers of the joint were equiaxed crystal, the mechanical properties of the joint after the first and second pass repair welding were lower than the original weld, which was mainly.related to the production of a large number of eutectic structure nearby the fusion line of the joint after repair welding; the bending performance of the second pass repair welded joint was betterthan the first pass repair welded joint with a higher micro-hardness, indicating the defect repair welding of the 8 mm thick 2219 horizontal welded joint was more suitable for the use of smaller welding specifications and two-pass （filling ＋ cover） welding processes.