Evaluation of the stiffness characteristics of square pore CoCrMo cellular structures manufactured using laser melting technology for potential orthopaedic applications

Hazlehurst, Kevin Brian; Wang, Changjiang; Stanford, Mark

doi:10.1016/j.matdes.2013.05.009

Cited by 103 publications

(85 citation statements)

References 21 publications

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“…However, due to the high stiffness of CoCr, stress shielding and bone resorption have been a concern. Constructing a open cellular structure has been proved to lower the stiffness of CoCr and provide better match with the human bones [84,85]. Customized open cellular CoCr strctures have been successfully manufactured with EBM for load-bearing applications with comparable biological response of Ti6Al4V [86].…”

Section: Materials Manufactured With Ebmmentioning

confidence: 99%

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

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Linköping 2018Cover image: A fracture surface of EBM IN718 after tensile test at room temperature.During the course of research underlying this thesis, Dunyong Deng was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. Printed by LiU-Tryck 2018 © Dunyong Deng AbstractAdditive manufacturing (AM), also known as 3D printing, has gained significant interest in aerospace, energy, automotive and medical industries due to its capabilities of manufacturing components that are either prohibitively costly or impossible to manufacture by conventional processes. Among the various additive manufacturing processes for metallic components, electron beam melting (EBM) and selective laser melting (SLM) are two of the most widely used powder bed based processes, and have shown great potential for manufacturing high-end critical components, such as turbine blades and customized medical implants. The futures of the EBM and SLM are doubtlessly promising, but to fully realize their potentials there are still many challenges to overcome.Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties and low cost. Though IN718 is being mostly used as a turbine disk material now, the initial introduction of IN718 was to overcome the poor weldability of superalloys in 1960s, since sluggish precipitation of strengthening phases γ ′ /γ ′′ enables good resistance to strain-age cracking during welding or post weld heat treatment. Given the similarity between AM and welding processes, IN718 has been widely applied to the metallic AM field to facilitate the understandings of process-microstructure-property relationships.The work presented in this licentiate thesis aims to better understand microstructures and mechanical properties EBM and SLM IN718, which have not been systematically investigated. Microstructures of EBM and SLM IN718 have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and correlated with the process conditions. Monotonic mechanical properties (e.g., Vickers microhardness and tensile properties) have also been measured and rationalized with regards to the microstructure evolutions before and after heat treatments.For EBM IN718, the results show the microstructure is not homogeneous but dependant on the location in the components, and the anisotropic mechanical properties are probably attributed to alignment of porosities rather than texture.iii Post heat treatment can slightly increase the mechanical strength compared to the as-manufactured condition but does not alter the anisotropy. SLM IN718 shows significantly different microstructure and mechanical properties to EBM IN718. The as-manufactured SLM IN718 has very fine dendritic microstructure and Laves phases in the interdendrites, and is "work-hardened" by the residual strains and dislocations present in the material. Mechanical properties are different between horizontally and vertically built samples, and heat treatment can m...

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Section: Materials Manufactured With Ebmmentioning

confidence: 99%

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

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“…Other methods, in particular, electron beam melting (EBM), are widely used in addition to selective laser melting (SLM). Their suitability for the manufacture of components for applications with a bio-medical background has in many cases been confirmed [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Single Ti6Al4V Struts Made Using Selective Laser Melting and Electron Beam Melting Subject to Part Orientation

Weißmann

Drescher

Bader

et al. 2017

Metals

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Abstract:The use of additive manufacturing technologies to produce lightweight or functional structures is widespread. Especially Ti 6 Al 4 V plays an important role in this development field and parts are manufactured and analyzed with the aim to characterize the mechanical properties of open-porous structures and to generate scaffolds with properties specific to their intended application. An SLM and an EBM process were used respectively to fabricate the Ti 6 Al 4 V single struts. For mechanical characterization, uniaxial compression tests and hardness measurements were conducted. Furthermore, the struts were manufactured in different orientations for the determination of the mechanical properties. Roughness measurements and a microscopic characterization of the struts were also carried out. Some parts were characterized following heat treatment (hot isostatic pressing). A functional correlation was found between the compressive strength and the slenderness ratio (λ) as well as the equivalent diameter (d) and the height (L) of EBM and SLM parts. Hardness investigations revealed considerable differences related to the microstructure. An influence of heat treatment as well as of orientation could be determined. In this work, we demonstrate the influence of the fabrication quality of single struts, the roughness and the microstructure on mechanical properties as a function of orientation.

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“…In order to reduce the risk of stress shielding, metal alloy implant components can be fabricated for instance with open-porous structures that provide an elastic modulus low enough for this specification [9][10][11][12][13][14]. Open porous structures were generated and tested as irregular [15][16][17][18] and regular or non-stochastic scaffolds [9,10,[19][20][21][22][23][24][25][26]. Since trabecular bone is irregular, irregular structures may be a more authentic imitation than regular ones.…”

Section: Introductionmentioning

confidence: 99%

“…Additive manufacturing (AM) methods, such as selective laser melting (SLM), are widely used for fabricating open-porous metals and alloys [22,25,27]. They afford the means for the development and manufacturing of structures with defined mechanical and geometrical properties, e.g., with an elastic modulus in the range of that of human bone [4,[28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Specific Yielding of Selective Laser-Melted Ti6Al4V Open-Porous Scaffolds as a Function of Unit Cell Design and Dimensions

Weißmann

Wieding

Hansmann

et al. 2016

Metals

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Bone loss in the near-vicinity of implants can be a consequence of stress shielding due to stiffness mismatch. This can be avoided by reducing implant stiffness, i.e., by implementing an open-porous structure. Three open-porous designs were therefore investigated (cubic, pyramidal and a twisted design). Scaffolds were fabricated by a selective laser-melting (SLM) process and material properties were determined by conducting uniaxial compression testing. The calculated elastic modulus values for the scaffolds varied between 3.4 and 26.3 GP and the scaffold porosities between 43% and 80%. A proportional linear correlation was found between the elastic modulus and the geometrical parameters, between the elastic modulus and the compressive strengths, as well as between the strut width-to-diameter ratio (a/d) and elastic modulus. Furthermore, we found a power-law relationship between porosity and the modulus of elasticity that characterizes specific yielding. With respect to scaffold porosity, the description of specific yielding behaviour offers a simple way to characterize the mechanical properties of open-porous structures and helps generate scaffolds with properties specific to their intended application. A direct comparison with human bone parameters is also possible. We generated scaffolds with mechanical properties sufficiently close to that of human cortical bone.

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Evaluation of the stiffness characteristics of square pore CoCrMo cellular structures manufactured using laser melting technology for potential orthopaedic applications

Cited by 103 publications

References 21 publications

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Comparison of Single Ti6Al4V Struts Made Using Selective Laser Melting and Electron Beam Melting Subject to Part Orientation

Specific Yielding of Selective Laser-Melted Ti6Al4V Open-Porous Scaffolds as a Function of Unit Cell Design and Dimensions

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