Microstructure and Mechanical Properties of Long Ti-6Al-4V Rods Additively Manufactured by Selective Electron Beam Melting Out of a Deep Powder Bed and the Effect of Subsequent Hot Isostatic Pressing

Lu, S.L.; Tang, Hongxiao; Ning, Yongquan; Liu, N.; StJohn, David H.; Qian, Ma

doi:10.1007/s11661-015-2976-3

Cited by 108 publications

(53 citation statements)

References 8 publications

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“…This is the typical morphology of prior β grains in cross-sectional planes perpendicular to the EBM layers [19]. In both cases, the microstructure morphology is similar and represents a typical Widmanstätten or basket-weave morphology, reported in literature for Ti6Al4V alloys [22,23]. The microstructure of both EBM-X and EBM-Z consists of alternating layers of acicular α phase separated by thin layers of retained β phase.…”

Section: Microstructuresupporting

confidence: 75%

Sliding Contact Wear Damage of EBM built Ti6Al4V: Influence of Process Induced Anisotropic Microstructure

Ryu

Shrestha

Manogharan

et al. 2018

Metals

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Process-induced directional microstructure is identified as one of the key factors of anisotropic mechanical properties. This directional property significantly affects surface contact fatigue and corrosion of electron beam melting (EBM) built biomedical implants. In the current study, material removal on EBM built titanium (Ti6Al4V) subjected to reciprocating motion of commercially pure titanium spherical slider is investigated to identify the influence of the process-induced layered structure and environments on wear damage. Specimens developed by two different build orientations are mechanically stimulated using different sliding directions with nominally elastic normal load in dry, passivating, and synovial environments. It was noticed that EBM orientation significantly changes wear behavior in ambient environment. Wear resistance of mill-annealed Ti6Al4V was improved in passivating environment. Implications to improve useful life of orthopedic implants are discussed.

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Section: Microstructuresupporting

confidence: 75%

Sliding Contact Wear Damage of EBM built Ti6Al4V: Influence of Process Induced Anisotropic Microstructure

Ryu

Shrestha

Manogharan

et al. 2018

Metals

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“…Those challenges include poor surface finishing [6][7][8], porosity [9,10] and residual stresses [11]. In order to tackle these issues, post-treatments are usually applied to the near-net shape parts, such as machining or chemical etching to improve the surface finish [8,[12][13][14], Hot Isostatic Pressing (HIP) to increase the relative density [6,9,10,15] and improve the fatigue properties, or stress-relief [16]. The fully martensitic microstructure and high residual stresses observed in as-built SLM parts are very detrimental in terms of ductility [17,18].…”

Section: Introductionmentioning

confidence: 99%

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

et al. 2019

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In order to improve the tensile properties of additively manufactured Ti 6Al 4V parts, specific heat treatments have been developed. Previous work demonstrated that a sub-transus thermal treatment at 920°C followed by water quenching generates a dual-phase α+α′ microstructure with a high work-hardening capacity inducing a desirable increase in both strength and ductility. The present study investigates the micromechanical behavior of this α+α′ material as well as the thermal stability of the metastable α' martensite. To that end, annealing of the α+α′ microstructure is performed and the resulting microstructural evolution is analyzed, along with its impact on the tensile properties. A deeper understanding of the micromechanics of the multiphase microstructure both before and after annealing is achieved by performing in-situ tensile testing within a SEM, together with digital image correlation for full-field local strain measurements. This approach allows the strain partitioning to be quantified at a microscale and highlights a significant mechanical contrast between the two phases. In the α+α′ microstructure, the α′ phase is softer than the α phase, which is confirmed by nanoindentation measurements. Partial decomposition of the martensite during annealing induces a substantial hardening of the α′ phase, which is attributed to fine-scale precipitation and solution strengthening. A scale transition model based on the iso-work assumption and describing the macroscopic tensile behavior of the material depending on the individual mechanical behavior of each phase is also proposed. This model enables to provide insights into the underlying deformation and work-hardening mechanisms.

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“…An X-ray CT study by Tammas-Williams et al (2016) have shown that HIPing on Ti-6Al-4V parts manufactured by selective electron beam melting eliminated all internal porosities, considering the limiting factor for the detectable nominal size of porosities (i.e., undetectable below 5 μm), which coincided with the detection limits of the equipment. Not surprisingly, HIP has also been shown to increase the density in components by reduction or elimination of porosity (Lu et al, 2015;Ordas et al, 2015) and decrease scatter in fatigue and tensile properties often seen in AM components (Tammas-Williams et al, 2016;Lu et al, 2015).…”

Section: Effect Of Defects On Design Consideration and Materials Applimentioning

confidence: 99%

“…Several studies discuss the mechanical behaviour of different AM parts (Leuders et al, 2013;Song et al, 2015;Shifeng et al, 2014), including orientation-induced variations in the mechanical properties (Brice et al, 2016). There has also been work that reported the influence of different types of defects on final part mechanical performance (Liu et al, 2014;Lu et al, 2015).…”

Section: Influence Of Process Parameters and Inhomogeneities On Mechamentioning

confidence: 99%

“…HIP which was originally developed for diffusion bonding of nuclear reactor components in 1955 (Saller et al, 1956), is the application of high isostatic pressure (via an inert gas) at elevated temperature on the final AM part (Atkinson and Davies 2000). Currently, HIP is widely used for consolidation of metal powders and quality improvement in additively manufactured parts (Gaytan et al, 2009;Lu et al, 2015). HIP is generally used to reduce porosity in the final parts.…”

Section: Effect Of Defects On Design Consideration and Materials Applimentioning

confidence: 99%

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Powder-based additive manufacturing - a review of types of defects, generation mechanisms, detection, property evaluation and metrology

Taheri

Shoaib

Koester³

et al. 2017

IJASMM

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Powder-based additive manufacturing (AM) technologies have been evaluated for use in different fields of application (aerospace, medical, etc.). Ideally, AM parts should be at least equivalent, or preferably better quality than conventionally produced parts. Manufacturing defects and their effects on the quality and performance of AM parts are a currently a major concern. It is essential to understand the defect types, their generation mechanisms, and the detection methodologies for mechanical properties evaluation and quality control. We consider the various types of microstructural features or defects, their generation mechanisms, their effect on bulk properties and the capability of existing characterisation methodologies for powder based AM parts in this work. Methods of in-situ non-destructive evaluation and the influence of defects on mechanical properties and design considerations are also reviewed. Together, these provide a framework to understand the relevant machine and material parameters, optimise the process and production, and select appropriate characterisation methods.Abstract: Powder-based additive manufacturing (AM) technologies have been evaluated for use in different fields of application (aerospace, medical, etc.). Ideally, AM parts should be at least equivalent, or preferably better quality than conventionally produced parts. Manufacturing defects and their effects on the quality and performance of AM parts are a currently a major concern. It is essential to understand the defect types, their generation mechanisms, and the detection methodologies for mechanical properties evaluation and quality control. We consider the various types of microstructural features or defects, their generation mechanisms, their effect on bulk properties and the capability of existing characterisation methodologies for powder based AM parts in this work. Methods of in-situ non-destructive evaluation and the influence of defects on mechanical properties and design considerations are also reviewed. Together, these provide a framework to understand the relevant machine and material parameters, optimise the process and production, and select appropriate characterisation methods.Reference to this paper should be made as follows: Taheri, H., Shoaib, M.R.M., Koester, L., Bigelow, T.A., Collins, P.C. and Bond, L.J. (2017) 'Powder-based additive manufacturing -a review of types of defects, generation mechanisms, detection, property evaluation and metrology', Int. Institute of Aviation Technology conducting research on UAVs and designing and printing 3D parts for UAVs. His research interest areas include engineering mechanics, additive manufacturing and non-destructive testing.Lucas W. Koester received his PhD from the University of Nebraska at Lincoln studying wave propagation and scattering in polycrystalline media. His current and past research interests include wave propagation in polycrystalline media, defect scattering, and modelling with emphasis on additive manufacturing processes and materials.Powder-based additive...

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Microstructure and Mechanical Properties of Long Ti-6Al-4V Rods Additively Manufactured by Selective Electron Beam Melting Out of a Deep Powder Bed and the Effect of Subsequent Hot Isostatic Pressing

Cited by 108 publications

References 8 publications

Sliding Contact Wear Damage of EBM built Ti6Al4V: Influence of Process Induced Anisotropic Microstructure

Sliding Contact Wear Damage of EBM built Ti6Al4V: Influence of Process Induced Anisotropic Microstructure

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

Powder-based additive manufacturing - a review of types of defects, generation mechanisms, detection, property evaluation and metrology

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