Relative Density Measurement of PBF-Manufactured 316L and AlSi10Mg Samples via Eddy Current Testing

Marvin Aaron Spurek,Adriaan Bernardus Spierings,Viet Hiep Luong,Marc Lany,Gilles Santi,Bernard Revaz,Konrad Wegener

doi:10.3390/met11091376

Abstract

Powder bed fusion (PBF) is the most commonly used additive manufacturing process for fabricating complex metal parts via the layer-wise melting of powder. Despite the tremendous recent technological development of PBF, manufactured parts still lack consistent quality in terms of part properties such as dimensional accuracy, surface roughness, or relative density. In addition to process-inherent variability, this is mainly owing to a knowledge gap in the understanding of process influences and the inability to adequately control them during part production. Eddy current testing (ECT) is a well-established nondestructive testing technique primarily used to detect near-surface defects and measure material properties such as electrical conductivity in metal parts. Hence, it is an appropriate technology for the layer-wise measuring of the material properties of the fused material in PBF. This study evaluates ECT’s potential as a novel in situ monitoring technology for relative part density in PBF. Parts made from SS316L and AlSi10Mg with different densities are manufactured on a PBF machine. These parts are subsequently measured using ECT, as well as the resulting signals correlated with the relative part density. The results indicate a statistically significant and strong correlation (316L: r(8) = 0.998, p < 0.001, AlSi10Mg: r(8) = 0.992, p < 0.001) between relative part density and the ECT signal component, which is mainly affected by the electrical conductivity of the part. The results indicate that ECT has the potential to evolve into an effective technology for the layer-wise measuring of relative part density during the PBF process.

Highlights

In the last decade, additive manufacturing technologies have evolved from rapid prototyping to established manufacturing technologies that are increasingly used in industrial production
Relative part density monitoring systems for Powder bed fusion (PBF) must at minimum be able to detect porosity coming from these causes
This study investigates the feasibility of measuring the relative part density of PBFmanufactured parts by Eddy current testing (ECT)

Summary

Introduction

Additive manufacturing technologies have evolved from rapid prototyping to established manufacturing technologies that are increasingly used in industrial production. Powder bed fusion (PBF) is the most commonly used additive manufacturing process for fabricating metal parts, and has evolved to a state-of-the-art technology adopted in various industrial fields such as aerospace, medical, defence, as well as tool, and mould making [1,2]. The PBF process is characterized by the layer-wise melting of a powder bed using a laser beam; it enables the direct manufacturing of complex-shaped parts. Despite the tremendous recent technological development of PBF, Debroy et al [3] identified the lack of consistent part quality as a major challenge impeding the wider commercial adoption of PBF. Part quality is mainly characterized by mechanical properties such as. Process-inherent variability, a remaining knowledge gap in understanding the influences on part quality, and the inability to adequately control these influences during part production are the main reasons for inconsistent part quality [3]

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Discussion

Conclusion