Laser welding of Al-Li-Mg-Zr alloy

An Al-Li-Cu-Mg-Zr alloy was welded in helium atmosphere with CO2 laser. Full-penetration, single pass butt welds were produced which were generally characterized by low porosity, refined as-cast structure and narrow fusion and heal affected zones. Tensile properties for welded material were lowered in comparison to that measured for unwelded matrix. Initial YS of 487 MPa for unwelded material decreased to 268 MPa after laser welding as well as the measured elongation decreased from 17.48 % to 3.7% respectively. Studies by optical and electron scanning and transmission microcopies were provided in as-welded and as-deformed slates to examine the joint's quality and microstructure, Laser produced joints failed in a brittle intergranular manner. The failure mode was connected with the presence of grain boundary precipitates and delta'-precipitate free zones. The improvement of properties of laser welds was possible by use of appropriate postweld heal treatment.