Analysis on the tendency of welding hot cracks of aluminum alloy increased by longitudinal pre-tension

Numerical simulation calculation of TIG welding of thin wall aluminum cylinder by the thermo-elastic FEM has been conducted. Based on the generating of analysis model, the values and distribution at the centre of weld seam for transverse tensile stress and strain produced by pre-tension upon the solidification metal at the back of molten pool. Experiments were performed to verify the simulation results. It can be drawn that, for weld metal just solidified at the joint pre-tension load can produce transverse tensile stress, which increases the tendency of welding hot cracks. And with the increasing of pre-tension load, the transverse tensile stress increases. When the pre-tension stress is 60, 120, 150 and 210 MPa, the crack length in specimens is 5.2 mm, 8.1 mm, 8.9 mm and 10.6 mm, respectively. The tests results indicates the reliability of simulation results.