%0 journal article
%@ 1073-5623
%A Liu, J., Ventzke, V., Staron, P., Schell, N., Kashaev, N., Huber, N.

%D 2014
%J Metallurgical and Materials Transactions  A
%N 1
%P 16-28 
%R doi:10.1007/s11661-013-1886-5
%T Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of Laser Beam Welded TiAl-based Alloy
%U https://doi.org/10.1007/s11661-013-1886-5
1 
%X Post-weld heat treatment is carried out on the laser beam welded γ-TiAl-based alloy Ti-48Al-1Cr-1.5Nb-1Mn-0.2Si-0.5B (at. pct). The macro/microstructure and mechanical properties of both as-welded and heat-treated specimens are investigated by radiography, SEM, and tensile tests. Moreover, high energy synchrotron X-ray diffraction is performed to measure the residual stresses and evaluate the microstructure evolution. It is found that the residual stresses are distributed in a three-peak shape in the region of the weld zone and heat-affected zone of the as-welded specimen due to the microstructural transformation and heat softening. The residual stresses are largely relieved after the heat treatment. The heat-treated specimens have a near fully lamellar microstructure and show balanced mechanical properties of strength and ductility. The diffraction shows that the phase transformation from α2 to γ takes place under tensile load at 1023 K (750 °C), and the grain size and lamellar spacing are refined in the weld zone. Finally, the fracture mechanisms are found to be controlled by the local stress concentration-induced strain misfit between α2 and γ phases in the near γ grains and delamination and debonding in the lamellae. Boride ribbons of 5 μm in the near fully lamellar microstructure are found not to be detrimental to the tensile properties.