Influence of thermal processing on the structural and phase content of high-strength laser welded joints of the aluminum alloy system Al-Mg-Li

The paper deals with the analysis of the structural and phase content of the laser welded joints and basic alloy 1424 of the system Al-Mg-Li by electronic microscopy and X-ray analysis. The total comparative investigation has been carried out to evaluate the influence of the thermal processing such as quenching and artificial ageing on the mechanical properties and structure of welded joints and basic alloy. The investigation shows that the welded joint structure is dendritic. In the welded joint, the two-phase state of the solid solution is observed after the re-melting (α-Al+S1(Al2MgLi)), the strengthening phase δ'(Al3Li) is diluted. The thermal processing (quenching and artificial ageing) of the welded joint (alloy 1424) results in the increased tensile strength of up to 0.95 of the basic alloy strength. (paper)