Mechanical Properties and In Situ Deformation Imaging of Microlattices Manufactured by Laser Based Powder Bed Fusion.

Anton Du Plessis,Igor Yadroitsev,Dean-Paul Kouprianoff,Ina Yadroitsava

doi:10.3390/ma11091663

Anton Du Plessis, Igor Yadroitsev + Show 2 more

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https://doi.org/10.3390/ma11091663

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Abstract

This paper reports on the production and mechanical properties of Ti6Al4V microlattice structures with strut thickness nearing the single-track width of the laser-based powder bed fusion (LPBF) system used. Besides providing new information on the mechanical properties and manufacturability of such thin-strut lattices, this paper also reports on the in situ deformation imaging of microlattice structures with six unit cells in every direction. LPBF lattices are of interest for medical implants due to the possibility of creating structures with an elastic modulus close to that of the bones and small pore sizes that allow effective osseointegration. In this work, four different cubes were produced using laser powder bed fusion and subsequently analyzed using microCT, compression testing, and one selected lattice was subjected to in situ microCT imaging during compression. The in situ imaging was performed at four steps during yielding. The results indicate that mechanical performance (elastic modulus and strength) correlate well with actual density and that this performance is remarkably good despite the high roughness and irregularity of the struts at this scale. In situ yielding is visually illustrated.

Highlights

Additive manufacturing (AM) is an emerging production technique whereby a part with complex geometry can be produced directly from a design file in a layer-by-layer method [1,2]
In the case of laser-based powder bed fusion (LPBF), a single layer of the part is selectively fused using a laser beam that is scanned across a powder bed surface in a series of tracks, new powder is delivered, and the layer is scanned and fused
Despite the possibility of irregularities in parts, it is possible to produce parts with excellent mechanical properties when process parameters are optimized

Summary

Introduction

Additive manufacturing (AM) is an emerging production technique whereby a part with complex geometry can be produced directly from a design file in a layer-by-layer method [1,2]. In the case of laser-based powder bed fusion (LPBF), a single layer of the part is selectively fused using a laser beam that is scanned across a powder bed surface in a series of tracks, new powder is delivered, and the layer is scanned and fused. Well overlapped with one another, as well as layers to prevent unwanted porosity in solid parts. This has been discussed in some detail in a recent review of the use of X-ray microtomography in additive manufacturing [4]. One of the major benefits brought about by additive manufacturing is the ability to produce complex parts, and this is especially true for lattice structures that are regularly spaced and repeating combinations of struts with spaces between them. The porous nature of the lattice structure is beneficial to lower the elastic

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