Weld hot crack analysis of 6005A aluminum alloy profile for high-speed train

The hot cracking sensibility of 6005A aluminum alloy was investigated with hot plasticity test, and the weld hot crack of 6005A aluminum alloy profile in laser-MIG hybrid welding was analyzed.Hot plasticity test results indicated that the brittle temperature range(BTR) of 6005A aluminum alloy was 550-640℃, which demonstrated that the hot cracking sensibility of the aluminum alloy was high.High-efficient welding of 6005A aluminum alloy profile can be achieved by utilizing laser-MIG hybrid welding process with I groove and welding speed up to 4.5 m/min.However, hot crack perpendicular to weld bead was found on the back of weld.The increase of dilution rate, caused by changing the groove, was the main reason for the generation of hot crack on the back of weld made by laser-MIG hybrid welding.However, the hot crack can be avoided by using V groove instead of the I groove in the hybrid welding of 6005A aluminum alloy profile.