Semi-analytical modeling of thermo-metallurgical-induced wave propagation for titanium alloy parts in laser powder bed fusion

Thermal-induced wave propagation frequently occurs during the laser powder bed fusion (LPBF) process due to the laser-material interaction. However, the effect of thermal variation and the resulting metallurgical phase transition on the wave propagation characteristics remains unclear. This paper presents a semi-analytical modeling of thermo-metallurgical-induced wave propagation in the LPBF of titanium alloys. In this modeling, the transient temperature field related to laser motion is first predicted based on the differential quadrature method. Subsequently, the temperature and corresponding metallurgical phase transition are employed to analytically obtain the wave propagation characteristics based on the higher-order shear deformation theory. The accuracy of the proposed model is verified by the comparison with the results in the literature. In addition, the impact of process parameters, part geometries, and heat source parameters on the temperature field and wave propagation of LPBF-built titanium alloys is analyzed. The predicted results show that the temperature field increases with higher energy densities and laser penetration, while decreasing with the increased preheating temperature, length-to-width ratio, laser semi-axis, and layer thickness. The elevated temperature leads to the decreasing wave frequency and phase velocity. These results can serve as a guideline for health monitoring and defect determination during the LPBF process of titanium alloys.