Deformation mechanisms of L-PBF-processed Ti-6Al-4V investigated using a combined experimental and simulation approach

TL;DR

This study combines experimental HEXRD and crystal plasticity modeling to elucidate the deformation mechanisms of Ti-6Al-4V produced by laser powder bed fusion, revealing phase-dependent elastic and plastic behaviors.

Contribution

It provides new insights into the phase-specific elastic anisotropy and slip activation sequences in L-PBF Ti-6Al-4V using combined experimental and simulation methods.

Findings

Similar elastic anisotropy in both phases with highest modulus along {00.2}.

Distinct slip activation sequences for as-built and heat-treated phases.

Higher CRSS in {eta} phase for most slip systems.

Abstract

Despite the significant application potential of laser powder bed fusion (L-PBF) processed Ti-6Al-4V components, a detailed understanding of their deformation mechanisms remains limited. This study investigates the deformation behavior of the {\alpha^\prime} and {\alpha} phases in the as-built and heat-treated specimens, respectively, using in-situ high-energy X-ray diffraction (HEXRD) combined with crystal plasticity modeling. Both phases exhibited similar elastic anisotropy, with the highest modulus along \{00.2\} and the lowest along \{10.0\}, although the {\alpha} phase consistently showed higher directional moduli than the {\alpha^\prime} phase. Their plastic deformation responses differed markedly: in the as-built {\alpha^\prime} phase, slip activation followed the sequence prismatic \rightarrow basal \rightarrow pyramidal I \langle c+a \rangle, whereas in the heat-treated {\alpha} phase, the sequence was basal \rightarrow prismatic \rightarrow pyramidal I \langle c+a \rangle. Analyses of full width at half maximum (FWHM) and diffraction peak intensities further supported these observations. Finally, inverse modeling within a crystal plasticity framework was employed to determine slip family--specific critical resolved shear stresses (CRSS), revealing higher CRSS values in the {\alpha^\prime} phase for all slip systems except the prismatic family.