Abstract
This paper describes a way to improve the microstructure and mechanical properties of welding seams by in situ and conventional post-weld heat treatments for laser beam welding of the Ti–45Al–5Nb–0.2C–0.2B alloy. The seams are crack-free with reduced longitudinal residual stress and higher elongation to fraction after post-weld heat treatment. The welding zone consists of α2 after welding, transforms to a massive γ during in situ post-weld heat treatment, and finally forms a convoluted microstructure after conventional heating. The phase composition across the welding zone is discussed.