Study of anisotropy through microscopy, internal friction and electrical resistivity measurements of Ti-6Al-4V samples fabricated by selective laser melting

Abstract

Purpose This paper aims to investigate the microstructural anisotropy of Ti-6Al-4V samples fabricated by selective laser melting. Design/methodology/approach Specimens are fabricated through a Renishaw AM400 selective laser melting machine. Three microstructures (as-built, 850°C annealed and 1,050°C annealed) and two building orientations, parallel (PA) and perpendicular (PE) to the building platform, are considered. Starting from in-depth microscopic observations and comprehensive electron backscattered diffraction imaging, the study addresses non-conventional techniques such as internal friction and electrical resistivity measurements to assess the anisotropy of the fabricated parts. Findings Microscope observations highlight a fine texture with columnar grains parallel to the building direction in the as-built and 850°C annealed samples. Besides, coarse grains characterized the 1,050°C annealed specimens. Internal friction measurements pointed out the presence of internal stress while storage modulus analyses appear sensitive to texture. Electrical resistivity is resulted to be dependent on grain orientation. Originality/value The work uses some novel characterization techniques to study the anisotropy and internal stresses of Ti-6Al-4V samples processed by selective laser melting. Mechanical spectroscopy results suitable in this kind of study, as it mimics the operating conditions of the material.

Effect of Post-Processing Heat Treatments on Short-Term Creep Response at 650 °C for a Ti-6Al-4V Alloy Produced by Additive Manufacturing

“…The second post-processing treatment consisted of annealing at 1050 °C, i.e., well above β-transus, for 1 h, followed by cooling in Ar (condition "T2", Cr = 0.4 °C/s). Similar treatments are known to cause full recrystallization; in addition, the relatively slow cooling should lead to the formation of a Widmanstätten structure with reduced internal stresses [17]. The last treatment, the "reference" one, consisted of a 1 h annealing at 704 °C, followed by cooling in argon (Cr = 0.35 °C/s), as prescribed by AMS2801 standards (condition "R").…”

Automation of Property Acquisition of Single Track Depositions Manufactured through Direct Energy Deposition

“…The successful production of components through this technology thus revolves around the optimisation of the aforementioned variables for each material-substrate combination and its subsequent analysis, a process common for both DED and SLM technologies that is often expensive and time-consuming as it is based on trial-and-error depositions [2]. DED has already been used in depositing nickel-based super alloys, such as Inconel 625 [12,13] and Inconel 718 [14], 316L stainless steel [15], tool steels, such as AISI H13 [16], as well as in developing functionally graded materials (FGMs), which are components whose chemical and/or conditions show a spacial variation across the component [17]; SLM, on the other hand, has also been used to successfully deposit precipitation-hardened steel, such as 17-4PH [18], Ti6Al4V [19], 316L stainless steel [20], nickel super alloys [21] and aluminium alloys [22], among others.…”

Combination of Scanning Strategies and Optimization Experiments for Laser Beam Powder Bed Fusion of Ti-6Al-4V Titanium Alloys

“…Since the properties of L-PBF-formed Ti-6Al-4V (TC4) titanium alloys vary with their microstructures and have directional anisotropy [17], different scanning strategies have essential effects on the microstructure of the L-PBF samples [18,19]. At the same time, the scanning strategy has a particular influence on the anisotropy of the formation, and the anisotropy of the forming sample is closely related to the resistivity and other properties of the material [20]. Amir Mahyar Khorasani et al [21] investigated the single-contour-and-fill method (SC+F) to form lattice structures and find the potential of the unfilled single-contour (SC) scanning strategy to improve the reproducibility of porous lattices.…”