Influence of Laser Power on Grain Refinement of Ti5321G Alloy Fabricated by Laser Powder Direct Energy Deposition Assisted with Ultrasonic Energy Field

Herein, laser power, as one influenced factor, is used to investigate the evolution of microstructure refinement in Ti5321G alloys fabricated by laser powder direct energy deposition (LP‐DED) assisted with ultrasonic energy field (UEF). The microstructures and mechanical properties of Ti5321G deposition layers at high temperature assisted with UEF under 1800, 2100, 2400, and 2700 W are characterized and measured. The results show that the microstructure refinement is promoted and the equiaxed grains region is expanded with increasing laser power. The probability of equiaxed grains rises ≈3 times from 1800 to 2700 W. In addition, the refinement of grain structure with increasing laser power substantially weakens and diminishes the texture density. Thoroughly, the recovery of dislocations dominates from 1800 to 2100 W, while recrystallization becomes the dominant process under 2700 W. In addition, the recrystallization fraction increases from 8.2% under 1800 W to 32.3% under 2700 W. It is beneficial to study the effects of laser power on Ti5321G alloys, fabricated by UEF‐assisted LP‐DED, for regulating the microstructures and providing the basis for subsequent studies of recrystallization mechanisms.