Nondestructive quantitative characterisation of material phases in metal additive manufacturing using multi-energy synchrotron X-rays microtomography

Abstract

Metal additive manufacturing (MAM) has found emerging application in the aerospace, biomedical and defence industries. However, the lack of reproducibility and quality issues are regarded as the two main drawbacks to AM. Both of these aspects are affected by the distribution of defects (e.g. pores) in the AM part. Computed tomography (CT) allows the determination of defect sizes, shapes and locations, which are all important aspects for the mechanical properties of the final part. In this paper, data-constrained modelling (DCM) with multi-energy synchrotron X-rays is employed to characterise the distribution of defects in 316L stainless steel specimens manufactured with laser metal deposition (LMD). It is shown that DCM offers a more reliable method to the determination of defect levels when compared to traditional segmentation techniques through the calculation of multiple volume fractions inside a voxel, i.e. by providing sub-voxel information. The results indicate that the samples are dominated by a high number of small light constituents (including pores) that would not be detected under the voxel size in the majority of studies reported in the literature using conventional thresholding methods.

Determination of the elastoplastic properties of Ti-6Al-4V alloy manufactured by electron beam melting

“…It is a non-destructive observation method and is widely used in the additive manufacturing industry. Defects and their sizes, shapes and locations, which affect the mechanical properties of the final part, can be determined by the micro computerized tomography (microCT) method (Xavier et al , 2020). As the reproducibility of parts by additive manufacturing is not well-known, microCT provides information about each manufactured part’s internal structure.…”

Multimetal Research in Powder Bed Fusion: A Review

“…Techniques such as hot isostatic pressing (HIP) or hot forging can help to promote diffusion and bonding between the particles, which can reduce the formation of oxide inclusions. HIP involves subjecting the printed part to high temperatures and pressures to compress and bond the particles, while hot forging involves pressing and shaping the printed part at high temperatures to promote bonding [ 84 ].…”

Algorithmic detection and categorization of partially attached particles in AM structures: a non-destructive method for the certification of lattice implants

“…For example; optical microscopy methods are restricted to line-of-sight observations and are incompatible with three-dimensional (3D) lattice structures. Similarly, radiographic testing and eddy current inspection can also be challenging for complex structures including patient-specific medical implants; these non-destructive methods are typically used in conjunction with destructive methodologies (Xavier et al , 2020). Of the available NDT technologies, x-ray CT is the most compatible with particle inspection for LB-PBF lattice structures, as it enables evaluation of 3D structures with high-geometric resolution ( Petrick and Simpson, 2016; Senck et al , 2020).…”