Development of Heat Treatments for Selective Laser Melting Ti6Al4V Alloy: Effect on Microstructure, Mechanical Properties, and Corrosion Resistance

Abstract

To evaluate the introduction of selective laser melting (SLM) for serial application, some features directly related to the components safety and performances are to be deeply analyzed. To this purpose, the present article applies three different types of heat treatment on Ti6Al4V as‐received samples produced by SLM: 1) annealing stress relieving, 2) solubilization super‐β transus, and 3) sub‐β transus followed by a tempering. Then, the related microstructures, mechanical resistance, residual stresses, and corrosion resistance are studied. The results identify a set of heat treatment parameters (super‐β transus followed by tempering), which guarantee the required properties. These samples show equiaxial grains composed of α + β phase, good mechanical properties, a high resistance to corrosion, and residual stresses almost null. Finally, this study confirms that Ti6Al4V made by SLM is applied in the transport field.

Numerical, Mechanical, and Metallurgical Investigation of an Innovative Near Net Shape Titanium Selective Laser Melting Engine Component and Comparison with the Conventional Forged One

“…Indeed, the equiassic and isotropic macrostructure of SLM, composed of a mixture of thin α lamellae and β phase, guarantees the proper match of mechanical strength and ductility. This confirms that the heat treatment, selected after preliminary investigations, [25] guaranteed the achievement of the proper microstructure on the SLM conrod to respect the mechanical requirements during its operation. The positive comparison with the tensile properties of the forged samples confirmed these conclusions, proving that the SLM microstructure induced by the heat treatment was proper for the application.…”

“…The two processes present different microstructure, as expected in relation with process dissimilarities, but the aforementioned features were achieved for both CM and SLM samples. It is important to remember that these features were achieved due to the detailed preliminary researches on heat treatments [ 25 ] that guaranteed the achievement of the proper microstructure on the SLM conrod. In addition, both the microstructures are expected to give good mechanical properties.…”

“…For major details, see the related previous research about this topic. [25] Microstructure at higher magnification was analyzed looking at SEM images, as shown in Figure 10 and 11 for forged and SLM section, respectively. For SEM analysis, α phase is dark while β phase is light.…”

“…From the analysis of the aforementioned literature and after a previous research work on samples produced in the same batch of the conrod, [ 25 ] the following heat treatment was considered the best option to achieve the desired mechanical properties on the SLM conrods: super‐β transus solubilization followed by a tempering. Indeed, considering the specific application, this heat treatment shows the best match of mechanical properties, residual stresses, and corrosion resistance.…”

Nanomechanical Characterization of the Deformation Response of Orthotropic Ti–6Al–4V

“…[11][12][13][14][15][16] Several manufacturing processes among the aforementioned applications contemplate the implementation of material characterization procedures, either on pristine samples of the material or on previously manufactured parts. The most commonly applied experimental procedures to identify the macroscopic orthotropic elastoplastic properties of a material include monotonic tensile, [17,18] compression, [19,20] and shear [21,22] tests of material samples obtained from its orthogonal directions. The main limitations of these tests are the size of the specimens and their subsequent destruction,…”