The aim of this work is to investigate the influence of the volumetric energy density (EV) on the microstructure, texture and Vickers hardness of Ti-6Al-4V (wt%) processed by laser powder bed fusion (LPBF), both in the as-built and heat-treated conditions. With this goal, Ti-6Al-4V powder was processed using energy densities ranging between 24.2 and 71.4 J/mm3. Analysis by electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) revealed that LPBF processing gives rise to high density of fine α/α′laths, whose size and orientation is highly dependent on EV, as this parameter influences the size and orientation of prior β grains. In particular, at low energy density (EV < 37 J/mm3) the microstructure of the LPBF sample is formed by near-equiaxed prior β grains that are densely populated with randomly oriented α/α′ laths. It is proposed that, under these conditions, the presence of significant thermal gradients and internal stresses during solidification induces a high density of nucleation sites for β grains during subsequent layer deposition. On the contrary, the use of high energy density (37 J/mm3 < EV < 71.4 J/mm3) results in the growth of columnar prior-β grains oriented with a 〈111〉 direction parallel to the building direction (BD), from which α/α′laths with a strong 〈11-20〉||BD fiber texture form, which is associated to the scanning strategy selected in this study. This research demonstrates that energy density is a key parameter to process Ti-6Al-4V specimens with random texture and high density.

Effect of energy density on the microstructure and texture evolution of Ti-6Al-4V manufactured by laser powder bed fusion / Cepeda-Jimenez, C. M.; Potenza, F.; Magalini, E.; Luchin, V.; Molinari, A.; Perez-Prado, M. T.. - In: MATERIALS CHARACTERIZATION. - ISSN 1044-5803. - 163:(2020), p. 110238. [10.1016/j.matchar.2020.110238]

Effect of energy density on the microstructure and texture evolution of Ti-6Al-4V manufactured by laser powder bed fusion

Molinari A.;
2020

Abstract

The aim of this work is to investigate the influence of the volumetric energy density (EV) on the microstructure, texture and Vickers hardness of Ti-6Al-4V (wt%) processed by laser powder bed fusion (LPBF), both in the as-built and heat-treated conditions. With this goal, Ti-6Al-4V powder was processed using energy densities ranging between 24.2 and 71.4 J/mm3. Analysis by electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) revealed that LPBF processing gives rise to high density of fine α/α′laths, whose size and orientation is highly dependent on EV, as this parameter influences the size and orientation of prior β grains. In particular, at low energy density (EV < 37 J/mm3) the microstructure of the LPBF sample is formed by near-equiaxed prior β grains that are densely populated with randomly oriented α/α′ laths. It is proposed that, under these conditions, the presence of significant thermal gradients and internal stresses during solidification induces a high density of nucleation sites for β grains during subsequent layer deposition. On the contrary, the use of high energy density (37 J/mm3 < EV < 71.4 J/mm3) results in the growth of columnar prior-β grains oriented with a 〈111〉 direction parallel to the building direction (BD), from which α/α′laths with a strong 〈11-20〉||BD fiber texture form, which is associated to the scanning strategy selected in this study. This research demonstrates that energy density is a key parameter to process Ti-6Al-4V specimens with random texture and high density.
Cepeda-Jimenez, C. M.; Potenza, F.; Magalini, E.; Luchin, V.; Molinari, A.; Perez-Prado, M. T.
Effect of energy density on the microstructure and texture evolution of Ti-6Al-4V manufactured by laser powder bed fusion / Cepeda-Jimenez, C. M.; Potenza, F.; Magalini, E.; Luchin, V.; Molinari, A.; Perez-Prado, M. T.. - In: MATERIALS CHARACTERIZATION. - ISSN 1044-5803. - 163:(2020), p. 110238. [10.1016/j.matchar.2020.110238]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/343745
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