Wire based additive layer manufacturing: Comparison of microstructure and mechanical properties of Ti–6Al–4V components fabricated by laser-beam deposition and shaped metal deposition (original) (raw)
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Additive manufacturing and postprocessing of Ti-6Al-4V for superior mechanical properties
MRS Bulletin
The capabilities of metal additive manufacturing (AM) are evolving rapidly thanks to both increasing industry demand and improved scientifi c understanding of the process. This article provides an overview of AM of the Ti-6Al-4V alloy, which has essentially been used as a yardstick to gauge the capability of each metal AM process developed to date. It begins by summarizing the metal AM processes existing today. This is followed by a discussion of the macro-and microstructural characteristics, defects, and tensile and fatigue properties of AM Ti-6Al-4V by selective laser melting, laser metal deposition (both powder and wire), and selective electron-beam melting compared to non-AM Ti-6Al-4V. The tensile and fatigue properties of as-built AM Ti-6Al-4V (with machined or polished surfaces) can be made comparable, or even superior, to those of Ti-6Al-4V in the most commonly used millannealed condition. However, these properties can exhibit a large degree of scatter and are often anisotropic, affected by AM build orientations. Post-AM surface treatments or both the post-AM surface and heat treatments are necessary to ensure the minimum required properties and performance consistency. Future directions to further unlock the potential of AM of Ti-6Al-4V for superior and consistent mechanical properties are also discussed.
Journal of Alloys and Compounds, 2019
As one of the most important additive manufacturing (AM) techniques, laser metal deposition (LMD) has been extensively studied specially during the last few years. Similar to other AM techniques, the quality of LMD parts is highly dependent on the processing parameters that need to be optimized so as to obtain geometrically accurate parts as well as favorable microstructures and, thus, mechanical properties. The present review paper therefore aims to present a critical analysis and overview of the relationship between processing parameters, microstructure, and mechanical properties of LMD components made from the Ti-6Al-4V alloy. Moreover, we discuss the applications of LMD parts in the aerospace and biomedical industries as well as the potential of LMD techniques for fabrication of more complex parts such as cellular structures. The paper concludes with a summary of the most important findings and suggestions for future research.
Journal of Alloys and Compounds, 2018
Wire þ Arc Additive Manufacturing (WAAM) is a promising manufacturing process for producing large aerospace components. Based on welding technology, the process is highly affordable, has a very high deposition rate and is not limited by chamber size. Ti-6Al-4V is a promising candidate material for this technology given that it is extensively used in aerospace applications and some large, high buy-fly ratio components can be more efficiently produced by WAAM than via the conventional machining from billet approach. There is currently limited knowledge about whether additional post processes including heat treatments and hot isostatic pressing are necessary to unlock the optimal mechanical properties of Ti-6Al-4V components produced by WAAM. This work explores a range of different post process treatments and the effects on the microstructure and tensile properties of Ti-6Al-4V components produced by WAAM. The relatively slow cooling rate (10-20Ks À1) during the b-a transformation produced Wid-manst€ atten-a and offered an optimal balance between strength and ductility. Hot Isostatic Pressing (HIPing) removed gas porosity but was not effective in improving strength or ductility. Residual tensile stresses in as-built components severely impair ductility and should be removed through stress relief treatments.
Additive Manufacturing of Ti6Al4V with Wire Laser Metal Deposition Process
Materials Science Forum, 2021
Additive manufacturing (AM) using wire as an input material is currently in full swing, with very strong growth prospects thanks to the possibility of creating large parts, with high deposition rates, but also a low investment cost compared to the powder bed fusion machines. A versatile 3D printing device using a Direct Energy Deposition Wire-Laser (DED-W Laser) with Precitec Coaxprinter station to melt a metallic filler wire is developed to build titanium parts by optimizing the process parameters. The geometrical and metallurgical of produced parts are analyzed. In the literature, several authors agree to define wire feed speed, travel speed, and laser beam power as first-order process parameters governing laser-wire deposition. This study shows the relative importance of these parameters taking separately as well as the importance of their sequencing at the start of the process. Titanium deposit are obtained with powers never explored in bibliography (up to 5 kW), and wire feed speed up to 5 m.min-1 with a complete process repeatability.
International Journal of Fatigue, 2021
This paper investigates the influence of two different deposition strategies, oscillation and parallel pass, on the tensile and high cycle fatigue properties of a wire + arc additive manufactured Ti-6Al-4V alloy in the as-built condition. In the oscillation build, the plasma torch and the wire feeder continuously oscillated across the wall thickness direction. In contrast, four single layers were deposited consecutively in the same direction along the wall length in the parallel pass build. Test specimens were manufactured in horizontal and vertical orientation with respect to the deposited layers. Compared with the parallel pass build, the oscillation build had lower static strength due to its coarser transformation microstructure. However, the elongation values were similar. The presence of columnar primary β grains has resulted in anisotropic elongation values. The vertical samples with loading axis parallel to the primary β grains showed 40% higher elongation than the horizontal samples. The fatigue strength was comparable with its wrought counterpart and greater than typical material by casting. At 10 7 cycles, fatigue strength of 600 MPa was achieved for the oscillation build vertical samples and the parallel pass build in both orientations. Only the oscillation build horizontal samples had lower fatigue strength of 500 MPa. Fractography analysis showed that most of the samples (about 70%) had crack initiation from pores, about 20% samples had crack initiated from microstructural features and the rest did not failed (runouts at 10 7 cycles).
Study of Arc-wire and Laser-wire processes for the realization of Ti-6Al-4V alloy parts
MATEC web of conferences, 2020
Arc-wire or laser-wire additive manufacturing seems promising because it allows large parts to be produced with significant deposition rates (ten times higher than powder bed additive manufacturing), for a lower investment cost. These additive manufacturing techniques are also very interesting for the construction or the repair of parts. A versatile 3D printing device using a Wire Arc Additive Manufacturing (WAAM) station or laser device Wire Laser Additive Manufacturing (WLAM) for melting a filler wire is developed to repair and build large titanium parts. The final objectives of the study are to optimize the process parameters to control the dimensional stability, the metallurgical and mechanical properties of the produced parts. In this paper, an experimental study is carried out to determine the first order process parameter ranges (synergic law, laser power, wire feed speed, travel speed) appropriate for these two techniques, for repair or construction parts on Ti-6 Al-4V.
IOP Conference Series: Materials Science and Engineering, 2011
The urge in aeronautics to reduce cost and time to flight of components without compromising safety and performance stimulates the investigation of novel manufacturing routes. Shaped Metal Deposition (SMD) is an innovative time-compression technology, which creates near-net shaped components layer by layer by weld deposition. Especially for Ti alloys, which are difficult to shape by traditional methods such as forging, machining and casting and for which the loss of material during the shaping process is also very expensive, SMD promises great advantages. Applying preliminary SMD parameter, four different tubular components with a square cross section and wall thicknesses of about 9 mm were built. The microstructure of the Ti-6Al-4V components consists of large prior β grains, elongated along the temperature gradient during welding, which transform into a lamellar α/β substructure at room temperature. The ultimate tensile strength was between 880 and 1054 MPa. The strain at failure was between 3.0 and 11.3 % for tensile testing parallel to the deposition plane and between 9.1 and 16.4 % perpendicular to the deposition plane. The micro-hardness (3.1-3.4 GPa), the Young´s modulus (117-121 GPa) and the oxygen and nitrogen content are comparable to cast Ti-6Al-4V material.
Fatigue Behaviour of Additively Manufactured Ti-6Al-4V
Procedia Engineering, 2015
Fatigue behaviour of Ti-6Al-4V specimens additively-manufactured via Laser Engineered Net Shaping (LENS) is investigated in this study. Additive manufacturing provides the opportunity to fabricate complex geometries layer-by-layer from 3D computer aided drawings. As the mechanical behaviour of metallic materials depends on their microstructure, which is affected by the time-temperature history, additive-manufactured components are expected to have different properties than those of their wrought counterparts. Ti-6Al-4V rods were fabricated by LENS using two different sets of process parameters and machined into 'dog-bone' fatigue specimens with dimensions in conformance to ASTM standards. The fatigue behaviour and microstructural features of the LENS Ti-6Al-4V samples were characterized and compared with wrought Ti-6Al-4V. Fractography of the fractured specimen surfaces was performed using Scanning Electron Microscopy (SEM) to determine the failure mechanism and realize the effects of porosity on fatigue resistance and data scatter of LENS Ti-6Al-4V. The fatigue lives of the LENS Ti-6Al-4V materials were found to be lower than those of the wrought Ti-6Al-4V, and driven by the porosity and microstructure of the samples.
Mechanical properties of Ti-6Al-4V specimens produced by shaped metal deposition
Science and Technology of Advanced Materials, 2009
Shaped metal deposition is a novel technique to build near net-shape components layer by layer by tungsten inert gas welding. Especially for complex shapes and small quantities, this technique can significantly lower the production cost of components by reducing the buy-to-fly ratio and lead time for production, diminishing final machining and preventing scrap. Tensile testing of Ti-6Al-4V components fabricated by shaped metal deposition shows that the mechanical properties are competitive to material fabricated by conventional techniques. The ultimate tensile strength is between 936 and 1014 MPa, depending on the orientation and location. Tensile testing vertical to the deposition layers reveals ductility between 14 and 21%, whereas testing parallel to the layers gives a ductility between 6 and 11%. Ultimate tensile strength and ductility are inversely related. Heat treatment within the α + β phase field does not change the mechanical properties, but heat treatment within the β phase field increases the ultimate tensile strength and decreases the ductility. The differences in ultimate tensile strength and ductility can be related to the α lath size and orientation of the elongated, prior β grains. The micro-hardness and Young's modulus are similar to conventional Ti-6Al-4V with low oxygen content.