Effect of Heat Treatment on Microstructure and Mechanical Properties of TA15 Titanium Alloy Repaired by Laser Deposition

To address the challenges associated with difficult-to-process and service-failing titanium alloy parts, laser deposition repair technology is employed to restore their dimensions and mechanical properties. Given the heterogeneous microstructure of laser deposition repair parts, significant changes in mechanical properties can occur. To delve deeper into the mechanical properties of laser deposition repair, TA15 titanium alloy spherical powder is used as the raw material to manufacture TA15 titanium alloy plates through forging. Experimental samples are then prepared using laser deposition repair technology, and the impact of different heat treatment systems on the microstructure and mechanical properties of the laser deposition repaired TA15 titanium alloy is investigated. Furthermore, the fracture mechanism under various heat treatment systems is analyzed. The results reveal that the laser deposition repair of TA15 titanium alloy comprises three distinct regions: the wrought substrate zone (WSZ), the heat-affected zone (HAZ), and the laser deposition repair zone (LDRZ). During the structural transformation process, the equiaxed α phase undergoes disruption. DIC results indicate that the LDRZ plays a predominant role in plastic deformation. Thanks to the formation of short rod-shaped α phases in the LDRZ and the precipitation of additional secondary α phases in both the LDRZ and HAZ, the sample subjected to heat treatment at 910 °C/1 h achieves an optimal balance of strength and plasticity.