Densification and microstructural investigation of Inconel 718 parts fabricated by selective laser melting
TL;DR: In this paper, the densification behavior and microstructural development of Inconel 718 parts fabricated by selective laser melting (SLM) were investigated with variation of the applied laser scanning speed.
About: This article is published in Powder Technology.The article was published on 2017-04-01. It has received 190 citations till now. The article focuses on the topics: Selective laser melting & Inconel.
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TL;DR: A comprehensive understanding of the interrelation between the various aspects of the subject, as this is essential to demonstrate credibility for industrial needs, is presented in this paper, which highlights some key topics requiring attention for further progression.
761 citations
TL;DR: Inconel 718 is one of the most commonly employed alloys for metal additive manufacturing (MAM) and has a wide range of applications in aircraft, gas turbines, turbocharger rotors, and a variety of other corrosive and structural applications involving temperatures of up to ∼700°C as discussed by the authors.
Abstract: Inconel 718 is one of the most commonly employed alloys for metal additive manufacturing (MAM) and has a wide range of applications in aircraft, gas turbines, turbocharger rotors, and a variety of other corrosive and structural applications involving temperatures of up to ∼700 °C. Numerous studies have investigated different aspects of the mechanical behaviour of additively manufactured (AM) Inconel 718. This study analyses the observations from more than 170 publications to provide an unbiased engineering overview for the mechanical response of AM Inconel 718 (and its variations and spread among different reports). First, a brief review of the microstructural features of AM Inconel 718 is presented. This is followed by a comprehensive summary of tensile strength, hardness, fatigue strength, and high-temperature creep behaviour of AM Inconel 718 for different types of MAM techniques and for different process and post-process conditions.
306 citations
TL;DR: The metal additive manufacturing (metal-AM) has undergone a remarkable evolution over the past three decades as mentioned in this paper, and it has moved into the mainstream of the industrialised field such as biomedicine.
231 citations
30 May 2017
TL;DR: In this paper, the structure, texture and phase evolution of the as-printed and heat treated IN718 superalloy Cylindrical specimens, printed by powder-bed additive manufacturing technique, were subjected to two post-treatments: homogenization (1100 °C, 1 h, furnace cooling) and hot isostatic pressing (HIP)
Abstract: 3D printing results in anisotropy in the microstructure and mechanical properties The focus of this study is to investigate the structure, texture and phase evolution of the as-printed and heat treated IN718 superalloy Cylindrical specimens, printed by powder-bed additive manufacturing technique, were subjected to two post-treatments: homogenization (1100 °C, 1 h, furnace cooling) and hot isostatic pressing (HIP) (1160 °C, 100 MPa, 4 h, furnace cooling) The Selective laser melting (SLM) printed microstructure exhibited a columnar architecture, parallel to the building direction, due to the heat flow towards negative z-direction Whereas, a unique structural morphology was observed in the x-y plane due to different cooling rates resulting from laser beam overlapping Post-processing treatments reorganized the columnar structure of a strong {002} texture into fine columnar and/or equiaxed grains of random orientations Equiaxed structure of about 150 µm average grain size, was achieved after homogenization and HIP treatments Both δ-phase and MC-type brittle carbides, having rough morphologies, were formed at the grain boundaries Delta-phase formed due to γ″-phase dissolution in the γ matrix, while MC-type carbides nucleates grew by diffusion of solute atoms The presence of (Nb078Ti022)C carbide phase, with an fcc structure having a lattice parameter a = 443 A, was revealed using Energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) analysis The solidification behavior of IN718 alloy was described to elucidate the evolution of different phases during selective laser melting and post-processing heat treatments of IN718
184 citations
Cites background or methods from "Densification and microstructural i..."
...[15] studied the grain orientation in the x-y plane of an SLM-built IN718 alloy using optical microscopy and EBSD analysis....
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...The formation of these cellular substructures occur due to the high cooling rates during the SLM process [15] that are ranging between 105 and 108 °C/s [32,33], depending on the material and processing parameters....
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...The change in melt pool morphology and microstructure was attributed to the steep thermal radient betw en the older newer deposited layers during SLM process [15]....
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...The formation of these cellular substructures occur due to the high cooling rates during the SLM process [15] that are ranging between 105 and 108 ◦C/s [32,33], depending on the material and processing parameters....
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...Accordingly, small equiaxed grains of around 10 μm average size were seen around the melt pool boundaries and their formation was referred to the grain partial melting due to laser track overlapping and/or presence of impurities [15]....
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04 Mar 2019-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The influence of annealing at different temperatures (573, 873, 1273, 1373 and 1673 K) on the stability of 316L stainless steel fabricated by SLM has been investigated and the changes induced by the heat treatment have been used to understand the corresponding variations of the mechanical properties of the specimens under tensile loading as mentioned in this paper.
Abstract: The influence of annealing at different temperatures (573, 873, 1273, 1373 and 1673 K) on the stability of phases, composition and microstructure of 316L stainless steel fabricated by SLM has been investigated and the changes induced by the heat treatment have been used to understand the corresponding variations of the mechanical properties of the specimens under tensile loading. Annealing has no effect on phase formation: a single-phase austenite is observed in all specimens investigated here. In addition, annealing does not change the random crystallographic orientation observed in the as-synthesized material. The complex cellular microstructure with fine subgrain structures characteristic of the as-SLM specimens is stable up to 873 K. The cell size increases with increasing annealing temperature until the cellular microstructure can no longer be observed at high temperatures (T ≥ 1273 K). The strength of the specimens decreases with increasing annealing temperature as a result of the microstructural coarsening. The excellent combination of strength and ductility exhibited by the as-synthesized material can be ascribed to the complex cellular microstructure and subgrains along with the misorientation between grains, cells, cell walls and subgrains.
172 citations
References
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Book•
01 Jan 2009
TL;DR: Gibson et al. as discussed by the authors presented a comprehensive overview of additive manufacturing technologies plus descriptions of support technologies like software systems and post-processing approaches, and provided systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing.
Abstract: Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing deals with various aspects of joining materials to form parts. Additive Manufacturing (AM) is an automated technique for direct conversion of 3D CAD data into physical objects using a variety of approaches. Manufacturers have been using these technologies in order to reduce development cycle times and get their products to the market quicker, more cost effectively, and with added value due to the incorporation of customizable features. Realizing the potential of AM applications, a large number of processes have been developed allowing the use of various materials ranging from plastics to metals for product development. Authors Ian Gibson, David W. Rosen and Brent Stucker explain these issues, as well as: Providing a comprehensive overview of AM technologies plus descriptions of support technologies like software systems and post-processing approaches Discussing the wide variety of new and emerging applications like micro-scale AM, medical applications, direct write electronics and Direct Digital Manufacturing of end-use components Introducing systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing is the perfect book for researchers, students, practicing engineers, entrepreneurs, and manufacturing industry professionals interested in additive manufacturing.
3,087 citations
TL;DR: Additive manufacturing implies layer by layer shaping and consolidation of powder feedstock to arbitrary configurations, normally using a computer controlled laser as discussed by the authors, which is based on a novel materials incremental manufacturing philosophy.
Abstract: Unlike conventional materials removal methods, additive manufacturing (AM) is based on a novel materials incremental manufacturing philosophy. Additive manufacturing implies layer by layer shaping and consolidation of powder feedstock to arbitrary configurations, normally using a computer controlled laser. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defence, automotive and biomedical industries. Laser sintering (LS), laser melting (LM) and laser metal deposition (LMD) are presently regarded as the three most versatile AM processes. Laser based AM processes generally have a complex non-equilibrium physical and chemical metallurgical nature, which is material and process dependent. The influence of material characteristics and processing conditions on metallurgical mechanisms and resultant microstructural and mechanical properties of AM proc...
2,402 citations
TL;DR: In this paper, the high thermal gradients occurring during SLM lead to a very fine microstructure with submicron-sized cells, which can be modified to a weak cube texture along the building and scanning directions when a rotation of 90° of the scanning vectors within or between the layers is applied.
1,431 citations
TL;DR: In this article, the authors describe which types of laser-induced consolidation can be applied to what type of material, and demonstrate that although SLS/SLM can process polymers, metals, ceramics and composites, quite some limitations and problems cause the palette of applicable materials still to be limited.
1,241 citations
TL;DR: In this article, a systematic material dependent classification of layer manufacturing and process oriented metal part manufacturing techniques are proposed, mainly for metallic parts, polymer parts and tooling, and the generic and the major specific process characteristics and materials are described.
1,080 citations