Inconel 625 lattice structures manufactured by selective laser melting (SLM): Mechanical properties, deformation and failure modes

doi:10.1016/j.matdes.2018.06.010

Materials & Design

Volume 157, 5 November 2018, Pages 179-199

https://doi.org/10.1016/j.matdes.2018.06.010 Get rights and content

Highlights

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A comprehensive reference of the mechanical response of Inconel 625 (IN625) lattice structures made by Selective Laser Melting (SLM) is provided.
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Mechanical performance was measured including yield strength, Young’s Modulus and associated density specific properties for mass limited design.
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IN625 lattice structures display exceptional ductility presenting attractive opportunities for energy absorption applications.
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Adjustment of topology and cell size can enable coarse and fine tuning of lattice mechanical properties.
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This previously unavailable IN625 lattice experimental data provides a reference for design application and numerical models validation.

Abstract

Additive Manufacture (AM) enables the fabrication of highly complex lattice structures with exceptional engineering properties. Inconel is a technically useful material in that it provides high resistance to oxidisation, creep and loss of mechanical properties at elevated temperatures. The combination of Inconel material properties and the geometric freedom of AM provides a unique opportunity for the fabrication of engineered structures with exceptional strength and stiffness at elevated temperatures, as for example is required for high temperature turbomachinery. Despite the associated technical opportunities, there exists no design data on the mechanical response, deformation characteristics and failure modes of AM Inconel 625 lattice structures. This research provides a comprehensive reference for the mechanical response of Inconel 625 lattice structures fabricated by Selective Laser Melting (SLM). Furthermore, the high ductility of Inconel 625 lattice enables novel insight into the structural mechanics of AM lattice, and the associated deformation photography provides a reference for the validation and verification of numerical models of AM lattice behaviour.

Graphical abstract

Section snippets

Additive manufacture

Additive manufacturing (AM) refers to the process of “joining materials to make objects from 3D model data” [1], and typically occurs in a layer-wise manner [2]. AM enables a fundamentally different set of economic and technical production attributes in comparison to traditional manufacturing processes, in particular, the design of engineered structures with enhanced technical performance [3].

Additive manufacture occurs by the sequential joining of material layers [2]. This fabrication method

Fabrication of SLM Inconel 625 lattice structures

Inconel is fundamentally compatible with the SLM process as it is challenging to fabricate with traditional methods, and is applicable for high-value applications. Despite the significant commercial and technical opportunities, there appears to be no comprehensive resource for the design of Inconel lattice structures for load bearing applications. This research responds to this identified deficiency by characterising the manufacturability and associated mechanical response of IN625 lattices

Mechanical testing

Manufactured lattice specimens (Table 8) in the as-built condition were subject to quasi-static uniaxial compression at room temperature to quantify mechanical properties and associated failure modes. Specimen strain was determined from machine crosshead displacement, and a strain rate of 1 × 10⁻³ s⁻¹ was used according to ASTM standards [56]. The compressive stress was calculated based on applied compression force and the initial XY plane cross-sectional base area of each lattice specimen. As

Concluding remarks

Inconel alloys provide an exceptional commercial opportunity for additive manufacture due to their poor manufacturability by traditional methods, and their appeal for high-value applications as engineered lattice structures. Despite this opportunity, insufficient data exists for engineering design of IN625 lattice structures. This research provides a robust design reference for IN625 lattice structures, as well as providing fundamental insights into AM lattice behaviour.

Manufacturability limits

Acknowledgements

This research was conducted by the Australian Research Council Industrial Transformation Training Centre in Additive Biomanufacturing (IC160100026) http://www.additivebiomanufacturing.org.

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¹: www.additivebiomanufacturing.org.

View full text

Inconel 625 lattice structures manufactured by selective laser melting (SLM): Mechanical properties, deformation and failure modes

Highlights

Abstract

Graphical abstract

Section snippets

Additive manufacture

Fabrication of SLM Inconel 625 lattice structures

Mechanical testing

Concluding remarks

Acknowledgements

Mater. Des.

Mater. Des.

Mater. Des.

J. Mater. Process. Technol.

Procedia Technol.

Phys. Procedia

Phys. Procedia

Mater. Des.

Int. J. Heat Mass Transf.

Int. J. Mach. Tools Manuf.

Mater. Sci. Eng. A

Mater. Lett.

J. Alloys Compd.

Mater. Sci. Eng. A

J. Alloys Compd.

Opt. Laser Technol.

J. Mater. Process. Technol.

Appl. Surf. Sci.

CIRP Ann.

J. Mech. Phys. Solids

Acta Mater.

ASTM Standard F2792-12a, D., F2792-12a. Standard Terminology for Additive Manufacturing Technologies

Additive manufacturing: making imagination the major limitation

JOM

Additive Manufacturing Technologies

Additive manufacturing of metallic cellular materials via three-dimensional printing

Int. J. Adv. Manuf. Technol.

Metal Foams: A Design Guide: A Design Guide

Cellular Solids: Structure and Properties

Design for additive manufacturing of cellular structures

Comput.-Aided Des. Applic.

Metal additive manufacturing: a review

J. Mater. Eng. Perform.

Generative Design Rationale: Beyond the Record and Replay Paradigm