Crystallographic texture dependent bulk anisotropic elastic response of additively manufactured Ti6Al4V

Abstract

Rapid thermokinetics associated with laser-based additive manufacturing produces strong bulk crystallographic texture in the printed component. The present study identifies such a bulk texture effect on elastic anisotropy in laser powder bed fused Ti6Al4V by employing an effective bulk modulus elastography technique coupled with ultrasound shear wave velocity measurement at a frequency of 20 MHz inside the material. The combined technique identified significant attenuation of shear velocity from 3322 ± 20.12 to 3240 ± 21.01 m/s at 45$$^\circ$$ ∘ and 90$$^\circ$$ ∘ orientations of shear wave plane with respect to the build plane of printed block of Ti6Al4V. Correspondingly, the reduction in shear modulus from 48.46 ± 0.82 to 46.40 ± 0.88 GPa was obtained at these orientations. Such attenuation is rationalized based on the orientations of $$\alpha ^\prime$$ α ′ crystallographic variants within prior columnar $$\beta$$ β grains in additively manufactured Ti6Al4V.

Measurement of the Anisotropic Dynamic Elastic Constants of Additive Manufactured and Wrought Ti6Al4V Alloys

“…Sol et al [34] revealed the anisotropic nature of the elastic moduli of AM AlSi10Mg by focusing on the angle dependence of V t . A similar observation was recently reported [25] for Ti6Al4V prepared by laser PBF.…”

“…The SWV can be calculated from the measured time between two back-wall echoes (i.e., from the TOF) and the traveled distance between the two back-wall echoes, which is twice the sample thickness [34]. Material responses to the propagation of the waves include change in the attenuation coefficient, amplitude, and velocity of the ultrasonic wave, primarily due to scattering [25]. These responses are affected by both crystallographic orientation and defects, such as coherent and incoherent phase/grain boundaries, dislocations, vacancies, and process-induced defects, such as cracks and porosity [25].…”

“…Material responses to the propagation of the waves include change in the attenuation coefficient, amplitude, and velocity of the ultrasonic wave, primarily due to scattering [25]. These responses are affected by both crystallographic orientation and defects, such as coherent and incoherent phase/grain boundaries, dislocations, vacancies, and process-induced defects, such as cracks and porosity [25].…”

“…Many studies have reported anisotropic properties of AM Ti6Al4V [1,[12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Wang et al [14] reported that the heterogeneous nucleation sites in the melt pool and the associated grain morphology of DED titanium alloy are highly dominated by the PMFR.…”

A Review of Diagnostics Methodologies for Metal Additive Manufacturing Processes and Products

“…Besides the conventional ultrasonic testing methods such as the contact sound velocity measurement, the new technique presented other information related to the quality and even microstructure. A recent work [ 109 ] demonstrated the use of angle-dependent ultrasonic elastic modulus distribution to show the anisotropic response of crystal texture in an SLM-printed Ti6Al4V sample ( Figure 21 ). The spatial map of the mechanical properties showed the homogeneity of the elastic modulus along the building plane and the building directions.…”