Influence of laser powder bed fusion scanning pattern on residual stress and microstructure of alloy 718

Čapek, Jan; Polatidis, Efthymios; Casati, Nicola; Pederson, Robert; Lyphout, Christophe; Ströbl, Markus

doi:10.1016/j.matdes.2022.110983

Cited by 9 publications

(1 citation statement)

References 53 publications

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“…However, for the applicability of the stress balance method it must be ensured that no spatial variation of d 0 hkl exists within the cross section of interest (Withers et al, 2007). In the case of PBF-LB it has been shown that no large variations of d 0 hkl across the specimen occur (Serrano-Munoz et al, 2022;Bayerlein et al, 2018), at least when significant heat concentrations are avoided (Capek et al, 2022). This has also been observed for the specimens in this work (Fig.…”

Section: On the Choice Of The Stress-free Referencesupporting

confidence: 74%

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: On the Choice Of The Stress-free Referencesupporting

confidence: 74%

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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Characterization of Fe-6Si Soft Magnetic Alloy Produced by Laser-Directed Energy Deposition Additive Manufacturing

Adamczyk,

Birchall,

Rothermel

et al. 2023

JOM

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Commercial electrical steels, Fe-Si alloys with < 4 wt.% Si, are inexpensive and efficient materials for electrical power conversion. Further efficiency improvements require increasing the silicon concentration to 6 wt.%, at which point the material becomes brittle and difficult to form by conventional rolling and sheet fabrication methods. Additive manufacturing stands to overcome challenges with commercial manufacturing techniques by leveraging near-net-shape fabrication. The wide array of process conditions provides additive manufacturing with increased flexibility, enabling control over the microstructure and mechanical properties. This work explores the microstructures and magnetic properties of ring-shaped Fe-Si alloys produced using concentric and cross-hatch tool paths on a laser-directed energy deposition additive manufacturing system. Concentric-built samples exhibit elongated grain structures while cross-hatch-built samples comprise lower aspect ratio grain structures. Thermal finite element analysis simulations model the stress conditions produced by the different scan path geometries. Microhardness measurements probe the mechanical properties as a function of anneal temperature, providing a qualitative understanding of the intergranular defect density. Soft magnetic properties measured under quasistatic and AC conditions show frequency- and microstructure-dependent coercivity and permeability. Finally, analysis of the core loss quantifies how the build strategies and thermal treatments influence efficiency in electrical power conversion applications. Understanding the influences of scan path geometry and thermal treatment provides a pathway towards application of additively manufactured soft magnetic materials.

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Fatigue performance in additively manufactured metal alloys

Butt,

Laieghi,

Kvvssn

et al. 2024

Prog Addit Manuf

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Influence of laser powder bed fusion scanning pattern on residual stress and microstructure of alloy 718

Cited by 9 publications

References 53 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

Characterization of Fe-6Si Soft Magnetic Alloy Produced by Laser-Directed Energy Deposition Additive Manufacturing

Fatigue performance in additively manufactured metal alloys

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