Effect of Double-Pulse Characteristics on Weld Bead Formation and Mechanical Properties in Metal Inert Gas Welding

Aluminum alloy has been widely used due to its excellent workability, and double-pulse metal inert gas welding (MIG) has become a popular technique in aluminum alloy welding. In this study, a cross-complementary test was performed to study the effect of double-pulse characteristics on weld bead formation and mechanical properties in MIG welding. The test was carried out on an AA6061 aluminum alloy using flat overlaying welding. After welding, the micro-metallographic structure and macro-mechanical performance of the weld bead were explored. The test results showed that the two methods of increasing the base current amplitude or the low-frequency of the current effectively enhanced the oscillation of the molten pool, refined the grain size of the fusion zone, and improved the mechanical properties of the weld. Additionally, by comparing the macroscopic photograph of the specimen and the corresponding welding parameters in the test, the formation characteristics of the bead’s fish-scale pattern in double-pulse MIG welding were found when appropriate welding parameters were adopted and weld bead formation was good. This test result provides a strong scientific basis for the selection of welding parameters in the actual promotion and application of double-pulse MIG welding.