Effect of pre-heating and post-weld heat treatment on structure and mechanical properties of laser beam-welded Ti2AlNb-based joints

The effect of pre-heating and post-weld heat treatment on microstructure mechanical properties laser-welded joints in a Ti–23Al–23Nb-1.4V-0.8Zr-0.4Mo-0.4Si (at.%) alloy was studied. Laser beam-welding carried out at room temperature as well after up to 800°С. comprised either air quenching from 920°С followed by aging 800°С or only the fusion zone consisted columnar β-grains welding 400 °C both large equiaxed crystals 600 800 °C. An increase caused β-crystals growth an heat-affected widths. Meanwhile, decrease Al Ti content, porosity gaseous elements content (O N) 600–800 were found. microhardness each joint obtained with temperatures lower than that base material. All welded showed yield strength ultimate tensile levels between 1070 1110 MPa, which correspond approximately 80% metal level. Reasonable total elongation achieved (4.3%). involving 920 subsequent for 6 h demonstrated best results. resulted precipitation O- α2-phases 6.5%.