Microzone deformation behavior of inhomogeneous microstructure in laser-remanufactured TC4 titanium alloy

Laser remanufacturing technology inevitably generates an inhomogeneous microstructure at the repair interface, which severely affects the service performance of remanufactured components. This paper focused on the mesoscopic deformation behavior of the inhomogeneous microstructure in laser-remanufactured TC4 titanium alloy under loads. A crystal plasticity finite element model was established based on the authentic microstructure. Different microzones of the inhomogeneous microstructure were selected for simulation analysis, and the stress contour maps of different microzones under loads were analyzed. The results indicate that according to the action of the laser heat source, the inhomogeneous microstructure in laser-remanufactured TC4 titanium alloy is divided into five different zones: remanufactured zone, HAZ_β zone, coarse-grained HAZ_{α + β} zone, fine-grained HAZ_{α + β} zone, and base metal zone. The stress distribution in different zones is closely related to the microstructural morphology. The remanufactured zone exhibits two modes: dislocation accumulation caused by intragranular slip and strain mismatch at the phase interface. In the HAZ_β zone, the stress is concentrated in the boundary regions with large grain orientation differences and significant size differences. The HAZ_{α + β} zone effectively disperses stress by coordinating intragranular and intergranular deformation through massive α phases, showing a high resistance to stress concentration.