Laser Beam Welding of Aeronautical Al-Cu-Li Sheets: Quasi-static Tensile Mechanical Performance and Quality Assessment of Welded Joints

The present article investigates the effect of different filler materials, different nominal sheet thickness as well as different post welding heat treatments, on the tensile mechanical performance of laser beam welded (LBWed) joints from aluminium alloy (AA) Al-Cu-Li 2198. LBWed joints were produced either using Al-Si (AA4047) or Al-Cu (AA2319) filler wires. The test results indicated that the exploitation of Al-Si filler material is beneficial for the tensile mechanical behavior of the welded joint, while it also corresponds to artificial ageing conditions with a significant increase in yield stress over artificial ageing. On the contrary, the exploitation of Al-Cu filler material demonstrated lower yield stress values and for all investigated aged conditions. Sheet thickness-dependent behavior showed that the investigated higher 5.0 mm sheet thickness exhibited higher mechanical properties compared to lower 3.2 mm sheet thickness specimens. A quality index was exploited to evaluate the global tensile mechanical performance of the investigated LBWed joints. It was observed that the LBWed joints with Al-Si filler material showed higher ‘quality’ values that the respective joints with Al-Cu filler material, with the highest quality to be achieved for the peak-aged condition.