Microstructures and mechanical behavior of Inconel 718 fabricated by selective laser melting
TL;DR: In this paper, the Inconel 718 cylinders were fabricated by selective laser melting in either argon or nitrogen gas from a pre-alloyed powder, and they exhibited columnar grains and arrays of oblate ellipsoidal precipitates oriented in a strong [2.0.0] texture determined by combined optical metallography, transmission electron microscopy, and X-ray diffraction analysis.
About: This article is published in Acta Materialia.The article was published on 2012-03-01. It has received 868 citations till now. The article focuses on the topics: Grain boundary & Inconel.
Citations
More filters
TL;DR: A review of the emerging research on additive manufacturing of metallic materials is provided in this article, which provides a comprehensive overview of the physical processes and the underlying science of metallurgical structure and properties of the deposited parts.
4,192 citations
Cites background from "Microstructures and mechanical beha..."
...Inconel 718 PBF-L AD Oblate spheroids/ellipsoids c00 in c-matrix [412]...
[...]
...As an example for PBF-L, depending on the material type and process used to produce the powder (10–60 mm powder), powder flow and spreading by roller or blade, the surface roughness may be adversely effected at the lower range of PSD....
[...]
...PBF-L [31–35] begins with a solid or surface CAD model, orienting it within a build volume to include support structures, slicing into planar layers, defining a scan path and build-file based upon a pre-specified set of material specific parameters and the specific machine configuration (Fig....
[...]
...AD: as deposited, ST: solution treatment, DA: double aging, TSRHT: thermal stress relief heat treatment c: Ni (fcc) solid solution, c0: Ni3Al and Ni3Ti, cubic (ordered face-centered) Ll2 crystal structure, c00: Ni3Nb, metastable coherent in c-matrix, body-centered tetragonal (bct) (DO22) crystal structure, d: Ni3Nb, stable incoherent in c-matrix, orthorhombic crystal structure [412]....
[...]
...Some nickel based alloys such as IN 718 do not readily develop the c0 phase during PBF-L [412] The c0 and c00 phases are precipitated during post processing heat treatment....
[...]
TL;DR: In this article, a review of additive manufacturing (AM) techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy.
Abstract: Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.
1,713 citations
TL;DR: Selective laser melting (SLM) is a particular rapid prototyping, 3D printing, or additive manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders as mentioned in this paper.
Abstract: Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following a...
1,455 citations
TL;DR: The potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications is demonstrated, with austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibiting a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels.
Abstract: Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.
1,385 citations
TL;DR: In this paper, the influence of selective laser melting (SLM) process parameters (laser power, scan speed, scan spacing, and island size) on the porosity development in AlSi10Mg alloy builds has been investigated, using statistical design of experimental approach, correlated with the energy density model.
854 citations
Cites background from "Microstructures and mechanical beha..."
...Aerospace manufacturers are focusing on the SLM powder-bed technology for Ti-alloy and Ni-superalloy components [7, 8] where the potential cost reduction, fewer steps in the production process and designfreedom are among the factors driving this technology....
[...]
References
More filters
TL;DR: In this article, the development of the microstructure of the Ti-6Al-4V alloy processed by selective laser melting (SLM) was studied by light optical microscopy.
2,201 citations
01 Jan 1973
TL;DR: In this article, the precipitation microstructure varies rapidly with aging temperature and composition, and the influence of composition and aging temperature on the conditions that bring about this compact morphology has been investigated.
Abstract: The precipitation of the γ’ (Ll2) and γ" (DO22) phases has been studied in four alloys Fe-Ni-Cr-Ti-Al-Nb containing a higher Ti + Al/Nb ratio than that of the INCONEL 718 alloy. For these alloys, the precipitation microstructure varies rapidly with aging temperature and composition. Bct γ"particles have always been found to precipitate on γ’ phase. Moreover, by aging three alloys above a critical temperature, a “compact ntorphology” has been observed: cube-shaped γ’ particles coated on their six faces with a shell of γ" precipitate. This microstructure has proved to be very stable on prolonged aging. A thermal stability better than that encountered in nominal INCONEL 718 alloy can thus be achieved. The influence of composition and aging temperature on the conditions that bring about this “compact morphology” has been investigated. A minimal Ti + Al/Nb ratio between 0.9 and 1 has been determined, allowing the “compact morphology” to be obtained.
428 citations
TL;DR: In this article, precipitation and dissolution kinetics of the δ-phase were studied in three wrought versions and one spray-formed (SF) version of the nickel alloy, Inconel 718.
382 citations
TL;DR: In this article, the authors investigated the precipitation of the metastable intermetallic phases (γ and γ) in the commercial nickel base superalloy, INCONEL 718, over a wide range of aging temperatures.
Abstract: Some aspects of the precipitation of the metastable intermetallic phases —γ″ and γ″—in the commercial nickel base superalloy, INCONEL 718, have been investigated over a wide range of aging temperatures. It has been confirmed that the spherical γ″ particles and the ellipsoidal γ″ particles evolve predominantly through homogeneous nucleation. Precipitation of the former does not appear to precede that of the latter in this alloy. The tetragonal distortion associated with the γ″ particles has been found to increase with increasing precipitate size. It has been observed that at certain temperatures, physical association between precipitates of the two types occurs frequently, leading to the development of different composite precipitate morphologies. During coarsening, the precipitate size has been found to depend linearly on the cube root of the aging time for γ′ as well as γ″ particles.
258 citations
TL;DR: In this article, a microstructures and a columnar architecture as well as mechanical behavior of as-fabricated and processed INCONEL alloy components produced by additive manufacturing using electron beam melting (EBM) of prealloyed precursor powder are examined.
Abstract: Microstructures and a microstructural, columnar architecture as well as mechanical behavior of as-fabricated and processed INCONEL alloy 625 components produced by additive manufacturing using electron beam melting (EBM) of prealloyed precursor powder are examined in this study. As-fabricated and hot-isostatically pressed (“hipped”) [at 1393 K (1120 °C)] cylinders examined by optical metallography (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive (X-ray) spectrometry (EDS), and X-ray diffraction (XRD) exhibited an initial EBM-developed γ″ (bct) Ni3Nb precipitate platelet columnar architecture within columnar [200] textured γ (fcc) Ni-Cr grains aligned in the cylinder axis, parallel to the EBM build direction. Upon annealing at 1393 K (1120 °C) (hot-isostatic press (HIP)), these precipitate columns dissolve and the columnar, γ, grains recrystallized forming generally equiaxed grains (with coherent {111} annealing twins), containing NbCr2 laves precipitates. Microindentation hardnesses decreased from ~2.7 to ~2.2 GPa following hot-isostatic pressing (“hipping”), and the corresponding engineering (0.2 pct) offset yield stress decreased from 0.41 to 0.33 GPa, while the UTS increased from 0.75 to 0.77 GPa. However, the corresponding elongation increased from 44 to 69 pct for the hipped components.
241 citations