Microtexture of Ti6Al4V Obtained by Direct Energy Deposition (DED) Process

Abstract

The microstructure of bulk samples prepared by CLAD® additive manufacturing of Ti-6Al-4V (Ti64) powder have been investigated by means of SEM and phase reconstruction. The CLAD® technique (laser blown powder processing) developed at IREPA LASER provides very high cooling rate promoting the formation of the martensitic ' phase in the form of thin needles. Using Merengue 2 software developed at LEM3, the analysis of the martensitic phase orientation by EBSD enables the reconstruction of the primary -phase that formed at high temperature. Microstructural observations performed at various locations within the samples revealed marked heterogeneities in the microstructure. After the first deposited layer characterized by fine and equiaxed grains, the grains located in the central region of the samples tend to grow in a direction perpendicular to the deposited layer plan with a coarse columnar structure. By opposition, the grains on the sample side were found to grow at angle of about 60° from the deposited layer plan. The main difference with others additive manufacturing techniques is that, only a weak crystallographic texture was detected in these samples prepared by CLAD®.

Functionally graded Ti6Al4V-Mo alloy manufactured with DED-CLAD® process

“…This value is lower than pure Ti (3.32 Å) [18] due to the presence of vanadium. An increase in the amount of Mo in the deposition leads to a decrease in the lattice parameter, which is consistent with the observations of Qiang [19]. The value of the lattice parameter of the gradient with both Ti6Al4V and Mo is lower than expected due to the presence of unmelted molybdenum particles.…”

An application of differential injection to fabricate functionally graded Ti-Nb alloys using DED-CLAD® process

“…The Ti6Al4V substrate displayed a typical α-phase corresponding to the hexagonal structure. The Ti6Al4V deposition consisted of a hexagonal α'-phase formed by the rapid cooling of columnar beta grains, as explained by Weiss et al (Weiss et al, 2016). When Nb content is ramped up to 25%, the high temperature bcc βphase was entirely retained.…”

Influence of Process Parameters and Deposition Strategy on Laser Metal Deposition of 316L Powder

“…Some approaches are based on modelling and measuring the melt pool dimensions, and on the understanding of their overlapping, others select the process parameters based on bulk components' porosity, geometrical accuracy, or microstructure and mechanical properties [5,[11][12][13][14]. Recently LMD 2 of 11 has been successfully used to process different alloys such as AlSi10Mg, Ti6Al4V, IN625 and 316L SS, showing several promising results [15][16][17][18]. In particular, some studies focused on the mechanical and microstructural characterisation of steel samples built by LMD and on the influence of process parameters on its mechanical behaviour.…”