Probing the Thermo-Mechanical Behaviour of Multi-Track, & Multi-Layer Deposition of Lightweight α+β Ti-Alloy Using Finite Element Modelling Tool

One of the main barriers to the broader application of Laser powder bed fusion (LPBF) technique among additive manufacturing processes is residual stress evolution. Out of the several factors, the sharp temperature gradients caused by a moving localized heat source predominantly plays a role in developing residual stresses. Predicting the residual stresses with precision is essential due to their detrimental impact on the structural and functional features of additively manufactured parts. However, numerical simulations provide a way to save time and material instead of relying on trial-and-error techniques and experimental trials. In order to forecast thermal fields and residual stresses for multi-pass, multi-layer deposition of dual-phase Ti-alloy, a 3D-FE thermo-mechanical model is created. Other parameters are kept constant, and the laser power (500, 2000 W) and laser scan velocity (5, 20 mm/s) are varied. Four build structures with five layers, each having two tracks, are simulated using ABAQUS®2020 commercial software. As the scan speed increases, the residual stress in the build-substrate system increases for a given laser power. This is because a faster scan speed reduces the size of the melt pool, leading to a higher temperature gradient. Consequently, a higher temperature gradient results in greater residual stress. On the other hand, increasing the laser power at a fixed scan speed lowers the residual stress, as a large heat-affected zone (HAZ) is created, which decreases the temperature gradient.