Effect of Ultrasonic Impact Treatment on the Microstructure and Properties of Laser Solid Formed Ti60 Alloy

The influence of ultrasonic impact treatment (UIT) on the microstructure, mechanical properties and burn resistance of laser solid forming (LSF) Ti60 titanium alloy samples was studied. The UIT has an obvious effect on grain refinement, residual tensile stress elimination and the improvement of burn resistance performance. After UIT, the deposition layer had severe plastic deformation, the equiaxed grains on the surface and bottom were significantly increased, the porosity was reduced, and nanocrystals with uniform distribution and random orientation were formed on the surface of the sample. The main phase of the LSFed Ti60 sample after UIT was α-Ti, the height of the diffraction peak was obviously decreased, and the half peak width was increased. After UIT, the microhardness of the deposition layer surface increased significantly, and the minimum residual stress changed from tensile stress to compressive stress, which prolonged fatigue life. After UIT, the area of the ablative hole was reduced by 21%, and the content of burn resistance elements increased, so the burn resistance performance of the Ti60 alloy was improved. Therefore, UIT can improve the microstructure and properties of LSFed Ti60 samples to a certain extent