Chuanchuan Jia, Wenlong Li, Guorui Sun, Mengying Zhang, Yao Meng, Jiuqing Liu, Chao Chen
In addressing the limitations of MIG welding for Ti-alloys, current approaches primarily seek to enhance stability by introducing additional energy fields and heat sources. However, the specific mechanism of action for the shielding gas-flow field—a critical factor influencing the welding process—remains to be thoroughly investigated. This paper introduces a controllable coaxial dual-path shielding gas-flow field during MIG welding of Ti6Al4V alloys to regulate the welding arc and droplet transition. The experimental results demonstrated that when the internal and external gas-flow performed synergistically, the arc achieved a comprehensive compression effect in the longitudinal and transverse directions, thereby enhancing the arc energy density and attaining a greater welding penetration. In the short-circuit transfer mode, the upper limit of the welding voltage interval increased from 22 V to 24.4 V. Concurrently, the short-circuit contact time decreased, the short-circuit peak current decreased, and the dependence of the short-circuit transfer on the voltage was reduced. In globular transfer mode, the upper limit of welding current was reduced from 200A to 164A, and the frequency of droplet transfer was increased and stabilized above 30Hz, which improves over conventional MIG welding was attributed to the reduction in large heat input.