Influence of heat treatments and hot isostatic processes (HIP) on microstructure and mechanical behavior of Ti-6Al-4V alloy produced by Powder Bed Fusion Using Electron Beam (PBF-EB)

This study investigates the effects of heat treatments and hot isostatic pressing (HIP) on the microstructure and mechanical behavior of Ti-6Al-4V parts manufactured by electron-beam powder bed fusion. Solution treatment at 950℃, followed by aging at 500–600℃, did not alter porosity. Aging increased the α-phase ratio and compensated for the strength reduction induced by ST. All HIP cycles significantly reduced pore size and pore count, with the 800℃/200 MPa cycle yielding the highest average relative density of 99.86 %, resulting in a maximum yield strength of 948 MPa and a maximum ultimate tensile strength of 1013 MPa. An 800℃/200 MPa HIP cycle increased ductility while maintaining strength, owing to limited α-lath coarsening. Super-transus HIP at 1050℃/100 MPa transformed columnar β grains into equiaxed structures, causing significant α-lath coarsening, a loss of mechanical strength, and increased anisotropy. These findings emphasize the need to optimize post-processing to balance porosity elimination, microstructural refinement, and mechanical performance in Ti-6Al-4V components.