3D Computed Tomography Quantifies the Dependence of Bulk Porosity, Surface Roughness, and Re‐Entrant Features on Build Angle in Additively Manufactured IN625 Lattice Struts

Fritsch, Tobias; Farahbod-Sternahl, Lena; Serrano-Muñoz, Itziar; Léonard, Fabien; Haberland, Christoph; Bruno, Giovanni

doi:10.1002/adem.202100689

Cited by 10 publications

(14 citation statements)

References 21 publications

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“…The differences in the obtained RS are small and well within the error bar of the measurements. This corroborates the assumption made by Mishurova et al (2018), Serrano-Munoz, Fritsch et al (2021) and Thiede et al (2018). Most probably, the mild texture of the 311 reflection (maximum 1.6 m.r.d.)…”

Section: Figure 11supporting

confidence: 90%

“…Similar observations have been made for PBF-LB/M/IN625 structures, where the principal direction coincides with the main geometrical axis of the structure (Fritsch et al, 2021). However, Fritsch et al (2021) showed that the determination of the principal stress is only independent of the choice of the measurement directions if one uses nine directions.…”

Section: The Scanning Strategy Determines the Rs Distributionsupporting

confidence: 73%

“…Overall, the increase of the RS magnitudes in the sub-surface region can be linked to the surface roughness of the parts, since the roughness contributes to a stress relaxation in the vicinity of the surface (Serrano-Munoz et al, 2022). In fact, the mean roughness of PBF-LB specimens manufactured without a contouring parameter set is reported to be in the range 10-25 mm (Fritsch et al, 2022;Mishurova et al, 2019;. It is further known that high tensile stresses are usually present in the sub-surface region (Bayerlein et al, 2018;Serrano-Munoz et al, 2022;Busi et al, 2021).…”

Section: Through-thickness Stress Distributionmentioning

confidence: 99%

“…All calculations were repeated 10000 times, selecting a random value within the 95% confidence interval of the leastsquares solution to estimate an error band for the principal stress directions and magnitudes. The procedure is described in more detail by Fritsch et al (2021). Although the choice of d 0 311 as the mean value of all measured d 311 values remains somewhat arbitrary, it may affect the absolute values of the principal stresses but not the principal stress directions.…”

Section: Texture-based Rs Analysismentioning

confidence: 99%

See 3 more Smart Citations

Texture-based residual stress analysis of laser powder bed fused Inconel 718 parts

Schröder¹,

Evans²,

Luzin³

et al. 2023

J Appl Crystallogr

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Although layer-based additive manufacturing methods such as laser powder bed fusion (PBF-LB) offer an immense geometrical freedom in design, they are typically subject to a build-up of internal stress (i.e. thermal stress) during manufacturing. As a consequence, significant residual stress (RS) is retained in the final part as a footprint of these internal stresses. Furthermore, localized melting and solidification inherently induce columnar-type grain growth accompanied by crystallographic texture. Although diffraction-based methods are commonly used to determine the RS distribution in PBF-LB parts, such features pose metrological challenges in their application. In theory, preferred grain orientation invalidates the hypothesis of isotropic material behavior underlying the common methods to determine RS. In this work, more refined methods are employed to determine RS in PBF-LB/M/IN718 prisms, based on crystallographic texture data. In fact, the employment of direction-dependent elastic constants (i.e. stress factors) for the calculation of RS results in insignificant differences from conventional approaches based on the hypothesis of isotropic mechanical properties. It can be concluded that this result is directly linked to the fact that the {311} lattice planes typically used for RS analysis in nickel-based alloys have high multiplicity and less strong texture intensities compared with other lattice planes. It is also found that the length of the laser scan vectors determines the surface RS distribution in prisms prior to their removal from the baseplate. On removal from the baseplate the surface RS considerably relaxes and/or redistributes; a combination of the geometry and the scanning strategy dictates the sub-surface RS distribution.

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Section: Figure 11supporting

confidence: 90%

Section: The Scanning Strategy Determines the Rs Distributionsupporting

confidence: 73%

Section: Through-thickness Stress Distributionmentioning

confidence: 99%

Section: Texture-based Rs Analysismentioning

confidence: 99%

See 2 more Smart Citations

Texture-based residual stress analysis of laser powder bed fused Inconel 718 parts

Schröder¹,

Evans²,

Luzin³

et al. 2023

J Appl Crystallogr

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“…A detailed study of the roughness is, however, beyond the scope of the present work, as it would require many more data. [ 30 ] The results in Figure 7 and 8 show that the major portion of the damage is initially caused by the hydrogen charging procedure and little additional damage is introduced during plastic deformation (specimen B). However, a significant amount of damage (observed by SXRCT) arises at large elongations, i.e., shortly before failure (specimen C).…”

Section: Resultsmentioning

confidence: 99%

Quantitative Analysis of Hydrogen‐Assisted Microcracking in Duplex Stainless Steel through X‐Ray Refraction 3D Imaging

et al. 2022

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While the problem of the identification of mechanisms of hydrogen‐assisted damage has and is being thoroughly studied, the quantitative analysis of such damage still lacks suitable tools. In fact, while, for instance, electron microscopy yields excellent characterization, the quantitative analysis of damage requires at the same time large field‐of‐views and high spatial resolution. Synchrotron X‐ray refraction techniques do possess both features. Herein, it is shown how synchrotron X‐ray refraction computed tomography (SXRCT) can quantify damage induced by hydrogen embrittlement in a lean duplex steel, yielding results that overperform even those achievable by synchrotron X‐ray absorption computed tomography. As already reported in the literature, but this time using a nondestructive technique, it is shown that the hydrogen charge does not penetrate to the center of tensile specimens. By the comparison between virgin and hydrogen‐charged specimens, it is deduced that cracks in the specimen bulk are due to the rolling process rather than hydrogen‐assisted. It is shown that (micro)cracks propagate from the surface of tensile specimens to the interior with increasing applied strain, and it is deduced that a significant crack propagation can only be observed short before rupture.

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Quantitative surface characterisation and stress concentration of additively manufactured NiTi lattice struts

Zheng,

Ghabraie,

Yang

et al. 2024

Int J Adv Manuf Technol

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With the advancement of metal additive manufacturing (AM), lattice structures become a promising solution to situations that require lightweight design and yet maintain adequate mechanical strength. Limited by the quality of feedstock materials, the layer-wise process characteristic and the dynamic nature of thermal environment, lattice structures made by AM often suffer from process-induced imperfections such as poor surface finish and notable geometric deviation. In this study, systematic quantitative characterisation methods are developed to address surface quality and geometric discrepancy of NiTi lattice struts made by laser powder bed fusion (LPBF), with a special focus on fatigue-related features such as stress concentration factors. The results show that for the examined strut diameters and inclination angles, the strut diameter plays a significant role in geometry inaccuracy and the inclination angle has a greater effect on surface texture and stress concentration factor distribution on the surface. Lattice struts with diameters greater than 0.7 mm and inclination angles over 40° with respect to the platform exhibit superior manufacturing quality among all configurations of the struts. The proposed approach not only opens a new avenue to evaluate μ-CT data in a more quantitative way but also offers opportunities to develop guidelines for lattice structure design.

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3D Computed Tomography Quantifies the Dependence of Bulk Porosity, Surface Roughness, and Re‐Entrant Features on Build Angle in Additively Manufactured IN625 Lattice Struts

Cited by 10 publications

References 21 publications

Texture-based residual stress analysis of laser powder bed fused Inconel 718 parts

Texture-based residual stress analysis of laser powder bed fused Inconel 718 parts

Quantitative Analysis of Hydrogen‐Assisted Microcracking in Duplex Stainless Steel through X‐Ray Refraction 3D Imaging

Quantitative surface characterisation and stress concentration of additively manufactured NiTi lattice struts

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