Study of the Electron Beam Melting Process Parameters’ Influence on the Tensile Behavior of 3D Printed Ti6Al4V ELI Alloy in Static and Dynamic Conditions

Abstract

The Ti6Al4V alloy is widely adopted in many high-end applications in different fields, including the aerospace, biomechanics, and automotive sectors. Additive manufacturing extends its range of possible applications but also introduces variations in its mechanical performance, depending on the whole manufacturing process and the related control parameters. This work focuses on the detailed tensile stress–strain characterization at low and high strain rates of a Grade 23 Ti alloy manufactured by electron beam melting (EBM). In particular, the main aim is to study the effect of the variation of the EBM process parameters on the performance of the material and their consequent optimization in order to obtain the best printed material in terms of ductility and strength. The adopted optical experimental setups allow the semi-local scale analysis of the neck section which makes possible the accurate estimation of stress, strain, and strain rate, all over the post-necking range and up to the very incipient specimen failure. Among the EBM printing process parameters, the speed function was previously identified as the one mainly affecting the material performance at static rates. Therefore, two different parameter sets, corresponding to the standard value and to an optimized value of the speed function parameter, respectively, are tested here at dynamic rates of 1, 15, and 700 s−1, for assessing the effect of the speed function on the dynamic material response. The results show that the optimized parameter set has a better performance compared to the standard one in terms of strength and ductility. In particular, in both static and dynamic conditions, it presents an increase of the true stress–strain curve (about 5% on average) and an increase of the failure strain (about 11% on average). Moreover, in respect to the standard parameter set, the optimized one is also characterized by a huge increase of the amplification due to the strain rate (about 49% on average for the considered strain rates).

Biomechanical evaluation of a custom-made mandibular plate

“…The materials involved in the simulation are the cortical and trabecular bone tissues of the mandible, the titanium alloy Ti6Al4V ELI of the plate [12], and the titanium alloy of the Stryker self-tapping screws. In the analysis, the behaviour of all four materials was assumed to be linear elastic and isotropic, with the values of the respective elasticity constants, Young's Modulus (E) and Poisson's coefficient (ν), shown in Table 1 defined as a meshed deformable contact body, so that the contacts between the bodies could subsequently be imposed.…”

Speed function effects on properties of Ti-5Al-5Mo-5 V-1Cr-1Fe alloy manufactured by electron beam melting

“…It is a unitless value in the range from 1 to 150; a higher value corresponds with higher beam speed. Each value of SF is a unique set of beam speeds and beam current [35][36][37]. The control algorithm for a given value of SF and beam current reads the value of beam speed from a table; this allows to maintain an equal-sized and stable melt pool [34].…”

Fadiga de altíssimo ciclo para o Ti-6Al-4V grau 5 (reciclado) fabricado por manufatura aditiva.

“…Como os materiais são fundidos em temperaturas elevadas, é comum ocorrer algum grau de contração durante o resfriamento, o que pode afetar as dimensões finais da peça. Portanto, a aplicação cuidadosa de fatores de escala ajuda a compensar esse encolhimento e a obter geometrias mais precisas e dimensionais corretas (Barbagallo et al, 2022).…”