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The effect of deformation temperature and strain rate on the hot deformation behavior and dual-phase microstructure evolution of the titanium alloy Ti62A was examined using electron backscatter diffraction. In general, the activation energy of Ti62A during steady-state deformation in the (α + β) phase is 295 kJ/mol. The primary recovery mechanisms of the β phase during hot deformation are dynamic recovery and dynamic recrystallization (DRX). Moreover, discontinuous DRX occurs at low temperatures and high strain rates, whereas continuous DRX occurs at high temperatures and low strain rates. Furthermore, high strain rates in the (α + β) phase and high deformation temperatures are advantageous to dynamic phase changes during dynamic transformation (DT). The β phase penetrates the lamellar αs phase, causing fragmentation and spheroidization of the α<sub>s phase. Finally, DT begins more easily in the fine α<sub>s phase than in the coarse αp phase.

In order to study the influence of process parameters on the residual stress of TB18 titanium alloy produced by laser directed energy deposition, a method combining numerical simulation with experimental verification was adopted. The distribution of residual stress in the deposited layer was obtained through experiments, and the influence of process parameters on the residual stress in the deposited layer was analyzed by finite element simulation. Finite element simulation is carried out for different cooling time and scanning strategy between layers. The results show that the residual stress of the deposited layer increases with the increase of the interlayer cooling time. By changing the scanning strategy, the peak residual stress can be reduced by 84.3% at most. This study provides guidance for selecting appropriate process parameters and reducing the residual stress of TB18 titanium alloy produced by laser directional energy deposition.&#xD;

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