Static and dynamic response of titanium alloy produced by electron beam melting

Mirone, Giuseppe; Barbagallo, Raffaele; Corallo, D.; Bella, Santo Di

doi:10.1016/j.prostr.2016.06.295

Cited by 20 publications

(11 citation statements)

References 3 publications

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“…The best tensile properties, both at room temperature and in the range between 400 and 600 • C, were measured in the first type of specimens, thanks to grain alignment with the tensile direction; this kind of specimen showed the best creep performance at 400 and 600 • C as well. At room temperature, the same difference in tensile behaviour has been detected not only at the conventional quasi-static strain rate conditions, but also at dynamic ones [26].…”

Section: Introductionsupporting

confidence: 56%

Tensile and Creep Properties Improvement of Ti-6Al-4V Alloy Specimens Produced by Electron Beam Powder Bed Fusion Additive Manufacturing

Aliprandi

Giudice

Guglielmino

et al. 2019

Metals

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Thanks to their excellent mechanical strength in combination with low density, high melting point, and good resistance to corrosion, titanium alloys are very useful in many industrial and biomedical fields. The new additive manufacturing methods, such as Electron Beam Powder Bed Fusion based on the deposition of metal powders layers progressively molten by electron beam scanning, can overcome many of the machining problems concerning the production of peculiar shapes made of Ti alloys. However, the processing route is strictly determinant for mechanical performance of products, especially in the case of Ti alloys. In the present work flat specimens made of Ti-6Al-4V alloy produced by Electron Beam Powder Bed Fusion (or Electron Beam Melting) have been built and post-processed with the purpose of obtaining good tensile and creep performance. Preliminarily, the process parameters were set according to literature evidence and machine producer recommendations, validated by the results of a thermal analysis, aimed at satisfying the best processing conditions to reduce defects, as unmelted regions, microstructure coarsening or porosity, that are detrimental to mechanical behavior. Subsequently, Hot Isostatic Pressing and surface smoothing were considered, respectively, in order to reduce any internal porosity and lower roughness. Microstructure of the investigated specimens was characterized by optical and scanning electron microscopy observations and by X-ray diffraction measurements. Results show enhanced tensile behavior after the hot pressing treatment that allows to relieve stresses and reduce defects detrimental to mechanical properties. The best ductility was obtained by the combined effects of machining and densification. Creep test results verify the beneficial effects of surface smoothing.

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Section: Introductionsupporting

confidence: 56%

Tensile and Creep Properties Improvement of Ti-6Al-4V Alloy Specimens Produced by Electron Beam Powder Bed Fusion Additive Manufacturing

Aliprandi

Giudice

Guglielmino

et al. 2019

Metals

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“…2c just magnifying the vertical axis for making visible the lower rate histories. All tests exhibit the typical surge of the strain rate beginning at the necking onset, already analysed by the authors in previous works [10][11] [12][13] and by Zhang et al [14] and Zhang et al [15], leading to very large strain rates at failure, nearly ten times greater than the strain rate values at the plateau.…”

Section: Dynamic Tests At Initial Room Temperaturesupporting

confidence: 52%

Modelling the influence of strain and strain rate on the thermal softening during dynamic loading of ductile metals

Mirone

Barbagallo

2021

EPJ Web Conf.

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Although the combined effect of strain rate and temperature on the behaviour of metals is widely recognized, no universally accepted viewpoints are available about the physical phenomena. Experiments on a highly ductile A2-70 steel, performed at moderate dynamic rates (10 s-1) and different initial temperatures (20 to 150 °C), are firstly aimed here at assessing whether the thermal softening previously verified at static rates on the same steel is also suitable for describing now the mixed effect of dynamic rates and consequent variable temperatures, or further contributions to the thermal softening are necessary for describing such mixed effects. A general multiplicative model of the dynamic hardening is proposed, based on a static flow curve at room temperature to be increased by the dynamic amplification and to be decreased by the thermal softening, the latter incorporating the known “static component” depending on both strain and constant temperatures, together with a new “dynamic component” incorporating the dependence on the temperature variation and promoted by fast straining. The dynamic amplification of the stress is then obtained from another series of dynamic tests ran at initial room temperature and four nominal strain rates between 1 and 1800 s-1. The trend obtained is compatible with the seizing of the strain rate effect beyond necking onset, already found for other metals in previous works. All the experiments are based on the acquisition of the current load (by load cells for the testing machine and by strain gauges for the Hopkinson bar) and of the current cross section through optical diameter measurements by a fast camera; then, the effective current values of true stress-true strain-true strain rate are measured on a semi-local basis over the neck section at different instants during the test.

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“…Products made of polymeric materials are obtained with such techniques as fused deposition modeling (FDM), where the material is a thermoplast in a circular wire; stereolitography (SLA), where the material is a light-cured resin; and selective laser sintering (SLS), where the batch material is a powdered polymer [2,3]. For metal alloys, techniques including powder bed fusion (PBF), selective laser melting (SLM), electron beam melting (EBM) and direct energy deposition (DED), for instance, laser engineered net shaping (LENS) [4,5,6,7] are used.…”

Section: Introductionmentioning

confidence: 99%

“…A proper selection of technological parameters and their impact on the obtained microstructure and mechanical properties [13,19,36,37] is also discussed. During the investigations, the relationship between the assumed wall thickness and the obtained microstructure [37,38], defect analysis, and fatigue strength of the samples [4,12,13,39] was analyzed.…”

Section: Introductionmentioning

confidence: 99%

Identification of Mechanical Properties for Titanium Alloy Ti-6Al-4V Produced Using LENS Technology

et al. 2019

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This paper presents a characterization study of specimens manufactured from Ti-6Al-4V powder with the use of laser engineered net shaping technology (LENS). Two different orientations of the specimens were considered to analyze the loading direction influence on the material mechanical properties. Moreover, two sets of specimens, as-built (without heat treatment) and after heat treatment, were used. An optical measurement system was also adopted for determining deformation of the specimen, areas of minimum and the maximum principal strain, and an effective plastic strain value at failure. The loading direction dependence on the material properties was observed with a significant influence of the orientation on the stress and strain level. Microstructure characterization was examined with the use of optical and scanning electron microscopes (SEM); in addition, the electron backscatter diffraction (EBSD) was also used. The fracture mechanism was discussed based on the fractography analysis. The presented comprehensive methodology proved to be effective and it could be implemented for different materials in additive technologies. The material data was used to obtain parameters for the selected constitutive model to simulate the energy absorbing structures manufactured with LENS technology. Therefore, a brief discussion related to numerical modelling of the LENS Ti-6Al-4V alloy was also included in the paper. The numerical modelling confirmed the correctness of the acquired material data resulting in a reasonable reproduction of the material behavior during the cellular structure deformation process.

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Static and dynamic response of titanium alloy produced by electron beam melting

Cited by 20 publications

References 3 publications

Tensile and Creep Properties Improvement of Ti-6Al-4V Alloy Specimens Produced by Electron Beam Powder Bed Fusion Additive Manufacturing

Tensile and Creep Properties Improvement of Ti-6Al-4V Alloy Specimens Produced by Electron Beam Powder Bed Fusion Additive Manufacturing

Modelling the influence of strain and strain rate on the thermal softening during dynamic loading of ductile metals

Identification of Mechanical Properties for Titanium Alloy Ti-6Al-4V Produced Using LENS Technology

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