Effect of post heat treatment on the phase composition and strength of laser welded joints of an Al-Mg-Li alloy

In the present work, the effects of laser beam welding and post-weld heat treatment on the phase composition and mechanical properties of the 1424 alloy (Al-Mg-Li) joints were investigated. Holding the joints at a certain temperature was followed by quenching and artificial aging. The structural studies were carried out using electron microscopy, conventional X-ray diffractometry, and synchrotron radiation diffractometry. The heat treatment conditions were optimized to favor the formation of strengthening phases in the welds, the presence of which imparted mechanical strength to the joints. For the first time, 1424 Al alloy joints with a weld strength of (sigma(uts) = 500 MPa have been obtained; this value of strength was achieved by applying post-weld annealing followed by quenching and artificial aging.