高强铝合金VPPA-MIG复合焊接焊缝成形机理

Mechanism of weld formation in variable polarity plasma arc-MIG hybrid welding of high strength aluminium alloy

VPPA-MIG复合焊集VPPA穿透力强和MIG焊熔敷效率高的优点,弥补了单VPPA焊工艺区间窄且需立焊和MIG焊熔深浅的不足.使用Red Lake Y4高速摄像获取6 mm厚2A12铝合金VPPA-MIG复合焊接熔池图像,建立了熔池受力模型.对比分析了复合热源不同能量配比对焊缝成形和熔池形貌的影响及VPPA-MIG与单MIG焊缝成形特点.结果表明,VPPA-MIG复合热源相比单VPPA热源易保持焊缝成形稳定性.VPPA电流接近穿孔阈值时,配合较低功率MIG热源可以获得6 mm厚2A12铝合金良好焊缝成形;VPPA能量比例过低时,小孔较浅,熔化效率较低,不能起到增加熔深的作用;VPPA能量比例过大,易使熔池失稳,焊缝成形不良.热源输入功率相同时,VPPA-MIG复合焊比MIG焊显著增加焊缝熔深和深宽比,提高生产效率.

VPPA-MIG hybrid welding integrates the advantages of strong arc penetrability of VPPA and high deposition efficiency in MIG welding. It can overcome the disadvantages of narrow range of stable technological parameters in vertical position in VPPA welding and shallow penetration in MIG welding.The weld pool images on 2 A12 aluminum alloy with thickness of 6 mm in VPPA-MIG hybrid welding were obtained by Red Lake Y4 high-speed camera acquisition system. The force model of weld pool was established. The influence of different energy ratio of the hybrid heat source on the weld formation and the weld pool was analyzed. The weld formation in VPPA-MIG hybrid welding and MIG welding were investigated. The results show that VPPAMIG hybrid heat source is easier to maintain weld formation stability than single VPPA heat source. When the VPPA current is close to the perforation threshold,a low-power MIG heat source can be used to achieve the weld formation on 2 A12 aluminum alloy with thickness of 6 mm; When the VPPA energy ratio is too low,the keyhole is shallower,the melting efficiency is lower,and the effect of increasing the penetration depth can not be achieved; When the VPPA energy ratio is too large,it can damage the stability of weld pool and the weld formation. Under the same heat input power,the weld formation in VPPA-MIG hybrid welding was narrower and deeper when comparing with conventional MIG welding. The welding productivity was improved dramatically