The Cooling Gradient and Microstructure Control In Laser Beam Welded TiAl Alloy Assisted by Temperature Field Simulation

Abstract

Assisted by temperature field finite element simulation, TiAl-based alloys were welded and heat treated with laser systems combined with precise control of the temperature gradient in the welding zone and the heat-affected zone. The welded samples were investigated by scanning electron microscope and high-energy X-ray diffraction. It is found out that by careful control of the cooling rate, the residual stresses are largely removed in the weld seam and the microstructure is improved. Tensile tests are carried out for the comparison of the nonheated and the heat treated joints. It is proved that the mechanical properties of the joints are balanced by the careful temperature control.