2A97铝锂合金激光焊T形接头组织及性能

采用异种模式与同步模式双光束DISK激光焊接1.5 mm厚的2A97-T3铝锂合金T形接头，对比研究两种模式T形接头的微观组织，硬度分布和拉伸性能.结果表明，两种模式接头的焊缝区显微硬度仅为母材的61%~67%，但异种模式接头深熔焊缝的显微硬度偏高，表明沉淀相的溶解使焊缝区出现软化，而热导焊过程对深熔焊缝有强化作用.异种模式T形接头蒙皮和桁条的抗拉强度分别为415和337 MPa，为母材的84.8%和68.9%；而同步模式分别达到母材的90.6%和59.4%.异种模式T形接头蒙皮和桁条拉伸均断在热导焊缝的过渡区，表明热导焊缝过渡区是异种模式T形接头最薄弱区域.

Study on the microstructure and mechanical properties of 2A97 Al-Li alloys laser beam welded T-joints

Successive mode and simultaneous mode were used in two-side and two-beam DISK laser welding for T-joints of 1.5 mm-thickness 2A97-T3 aluminum-lithium alloy, and the microstructure, hardness distribution and tensile properties of T-joints obtained by two modes were investigated in comparison. The results show that, for simultaneous-mode joints and the heat conduction welding side in successive-mode joints, the fusion zone (FZ) micro-hardness are 61%-67% of base metal''s (BM). The softening of FZ is attributed to the dissolution of the precipitate phase. However, the micro-hardness of the deep penetration weld in successive-mode joints is higher, indicating that the heat conduction welding process has a strengthening effect on the deep penetration weld. The tensile strength of the skin and the stringer of successive welding T-joints reach 415 and 337 MPa respectively, approximately 84.8% and 68.9% of the BM''s, while that of simultaneous welding T-joints are 90.6% and 59.4% of the BM''s respectively. For successive-mode T joints, the fracture occurs in transition zone (TZ) on the side of heat conduction weld, indicating that TZ on the side of heat conduction weld is the weakest part in T-joints.