Effect of Industrial Heat Treatment and Barrel Finishing on the Mechanical Performance of Ti6Al4V Processed by Selective Laser Melting

Abstract

Additive manufacturing is now capable of delivering high-quality, complex-shaped metallic components. The titanium alloy Ti6Al4V is an example of a printable metal being broadly used for advanced structural applications. A sound characterization of static mechanical properties of additively manufactured material is crucial for its proper application, and here specifically for Ti6Al4V. This includes a complete understanding of the influence of postprocess treatment on the material behavior, which has not been reached yet. In the present paper, the postprocess effects of surface finish and heat treatment on the mechanical performance of Ti6Al4V after selective laser melting were investigated. Some samples were subjected to barrel finishing at two different intensities, while different sets of specimens underwent several thermal cycles. As a reference, a control group of specimens was included, which did not undergo any postprocessing. The treatments were selected to be effective and easy to perform, being suitable for real industrial applications. Tensile tests were performed on all the samples, to obtain yield stress, ultimate tensile strength and elongation at fracture. The area reduction of the barrel-finished samples, after being tested, was measured by using a 3D scanner, as a further indication of ductility. Experimental results are reported and discussed, highlighting the effect of postprocessing treatments on the mechanical response. We then propose the optimal postprocessing procedure to enhance ductility without compromising strength, for structures manufactured from Ti6Al4V with selective laser melting.

Areal Analysis Investigation of Selective Laser Melting Parts

“…When the barrel rotates, the charge is moved upward until a critical angle is reached; therefore, a layer called the active layer slides down, resulting in a relative velocity between parts and media, generating a delicate abrasion and microremoval of material [28]. Fixturing of the parts during the process is not required; hence, this process is suitable for components with a variety of sizes, shapes (also complex), and materials, such as AM components [39]. The main BF process parameters are the filling percentage and the rotational speed [40].…”

A Review of Heat Treatments on Improving the Quality and Residual Stresses of the Ti–6Al–4V Parts Produced by Additive Manufacturing

“…Nalli et al [80] investigated the barrel finishing and heat treatment effect on the mechanical properties of Ti-6Al-4V samples manufactured through SLM. For that, some specimens were heat-treated with distinct temperatures (482 • C, 704 • C, 788 • C, and 800 • C) and holding times (3 h, 4 h, 5 h, 6 h, 8 h, and 10 h).…”

A comprehensive investigation of abrasive barrel finishing on hardness and manufacturability of laser-based powder bed fusion hollow components

“…They also found that surface quality was enhanced by ACBF, while shot peening improved mechanical properties because induced compressive residual stresses improve micro and macro defects. Nalli et al [26] worked on the effect of process parameters of ACBF on dimensions and tensile behaviours of Ti-6Al-4 V parts. The results showed that the surface quality improved by increasing rotational speed while time was found as another important factor in this process by Boschato et al [27].…”