Effect of Quenching and Aging on the Microstructure and Mechanical Properties of Welded Joints Obtained by Laser Welding of Titanium and Aluminum Alloys

The effect of quenching and aging on the microstructure and mechanical properties of welded joints obtained by laser welding of titanium alloy Grade 2 and aluminum alloy 2024 is studied. Microstructural analysis of the welded joints is carried out using light and scanning electron microscopes. The samples are tested on a slice. It is shown that during heat treatment, the columnar heat-affected zone of aluminum undergoes a significant change, in which the grain width increases from 5 - 7 to 20 - 40 mu m, and the length from 30 - 100 to 100 - 200 mu m. The shear strength of the welded joint after a heat treatment increases from 120 to 195 MPa, and the microhardness of the columnar heat-affected zone changes from 100 - 111 HV to 145 - 161 HV. The effect of the heat treatment on the distribution of chemical elements in the weld metal is not revealed, whereas the columnar heat-affected zone contains presumably a hardening Al2Cu phase.