Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

Bartłomiej Wysocki,Ryszard Sitek,Joseph Buhagiar,Wojciech Święszkowski,Piotr Maj,Krzysztof Kurzydłowski

doi:10.3390/app7070657

Bartłomiej Wysocki, Ryszard Sitek + Show 4 more

Open Access

https://doi.org/10.3390/app7070657

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Abstract

Additive Manufacturing (AM) methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering. The direct fabrication of metallic implants can be achieved by methods, such as Selective Laser Melting (SLM) or Electron Beam Melting (EBM). This work compares the SLM and EBM methods used in the fabrication of titanium bone implants by analyzing the microstructure, mechanical properties and cytotoxicity. The SLM process was conducted in an environmental chamber using 0.4–0.6 vol % of oxygen to enhance the mechanical properties of a Ti-6Al-4V alloy. SLM processed material had high anisotropy of mechanical properties and superior UTS (1246–1421 MPa) when compared to the EBM (972–976 MPa) and the wrought material (933–942 MPa). The microstructure and phase composition depended on the used fabrication method. The AM methods caused the formation of long epitaxial grains of the prior β phase. The equilibrium phases (α + β) and non-equilibrium α’ martensite was obtained after EBM and SLM, respectively. Although it was found that the heat transfer that occurs during the layer by layer generation of the component caused aluminum content deviations, neither methods generated any cytotoxic effects. Furthermore, in contrast to SLM, the EBM fabricated material met the ASTMF136 standard for surgical implant applications.

Highlights

A significant growth of interest in the use of Additive Manufacturing (AM) techniques for rapid prototyping and fabrication of various components has been noticed [1]
Method (Figure 4a), in the optimized sample with a side length of 5 mm produced by the Selective Laser Melting (SLM) method (Figure 4b), as well as in heat-treated wrought Ti-6Al-4V sample, which was fabricated conventionally (Figure 4d)
From the previous research of the authors [37], the results suggest that oxygen addition plays a significant role in solution hardening of technical-grade titanium

Summary

Introduction

A significant growth of interest in the use of Additive Manufacturing (AM) techniques for rapid prototyping and fabrication of various components has been noticed [1]. AM is a process that fuses materials layer by layer, to produce items based on 3D model data. Various AM methods differ in terms of the raw materials used and in the ways for material consolidation [2,3]. This work focuses on AM techniques where a raw material is delivered in a form of powder and is consolidated via a laser beam or an electron beam. Laser or electron beams heat and melt the powder in order to.

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