Effect of laser remelting on microstructure and mechanical properties of Ti-6Al-4V alloy prepared by inside-beam powder feeding

Ti-6Al-4V alloys fabricated by inside-beam powder feeding (IBPF) generally exhibit coarse columnar alpha-lath resulting in slightly poorer mechanical properties than forged parts. In this study, a laser remelting strategy with an annular beam was used to improve the microstructure and refine grain size, thus improving the mechanical properties of IBPF components. This is realized by the formation of ultrafine secondary precipitation alpha s and more recrystallized nuclei. The formation mechanism of compression twins {10 1 1} and dislocation pinning effect in remelted layer were investigated in detail through TEM analysis. Furthermore, texture evolution and slip systems of the remelted layers were analyzed to determine the deformation patterns. Fine grain strengthening and dislocation strengthening was significant, and the tensile strength of Ti-6Al-4V components after laser remelting is higher than those fabricated by inside-beam powder feeding by about 12.7% and 9.3% in transverse and longitudinal directions, respectively.