Formation, microstructure and mechanical properties ofdouble-sided laser beam welded Ti-6Al-4V T-joint
(1. College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China;
2. Science and Technology on Power Beam Processes Laboratory,
Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China)
2. Science and Technology on Power Beam Processes Laboratory,
Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China)
Abstract: The T-joints of Ti-6Al-4V alloy were manufactured by double-sided synchronized laser beam welding with the homologous filler wire. The formation, microstructure and mechanical properties of welded joints as well as the correlations of each other were investigated. The results indicate that the quality of weld seams is good without defects such as discontinuity, beading, visible cracks or porosity, which is linked to the steady molten pool behavior and droplet transition. The morphologies of the heat affected zone (HAZ) located on the skin and stringer are disparate. The microstructure of the HAZ and fusion zone (FZ) is mainly comprised of acicular martensitic α′ phases. The microhardness of the HAZ and FZ is higher than that of the base metal (BM) and reaches a maximum value at the HAZ near FZ on the stringer. The tensile specimens along the skin and stringer fractured at the BM with ductile fracture surfaces.
Key words: Ti-6Al-4V alloy; double-sided laser beam welding; T-joint; high-speed photography; microstructure; mechanical property