The effect of laser pressure welding parameters on GTD-111 superalloy microstructure

The present study introduces a new joining technique called laser pressure welding (LPW) for welding the GTD-111 superalloy used in gas turbine blades. The results showed that LPW causes complex microstructural changes in the weld metal, base metal, and heat-affected zone (HAZ) by absorbing more laser energy in the weld seam. These changes included elongated grains of rolled base metal, recrystallized grains of the HAZ strain-free equiaxed, columnar grains, and equiaxed of the weld metal elliptical pool. The elongated grains of the base metal and parts of the weld metal columnar grains (around the weld seam) that were solid-pressed in the rolling state had lower angle boundaries and stronger textures. It was also found that if the rolling pressure and heat input are applied simultaneously at the maximum state, it has a significant effect on reducing the porosity of the weld metal. This was more important in terms of higher pressure than more heat input.