The effect of cooling rate on the solidification of INCONEL 718

Antonsson, Tomas; Fredriksson, Hasse

doi:10.1007/s11663-005-0009-0

Cited by 186 publications

(80 citation statements)

References 12 publications

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“…Amine et al [29] estimated the cooling rates between the newly and previously deposited stainless steel layers, fabricated by laser melting deposition (LMD) process, to be ranging from 200 to 5500 °C/s. Good metallurgical bonding between new and old deposited layers that can be seen in Figure 7 indicates that the instantaneous thermal energy generated from laser power was not only enough to melt the IN718 powder above its melting temperature (1340-1364 °C [30]), but it was also high enough to melt the previously solidified layers. Figure 1a shows the structure of the as SLM-printed IN718 alloy in the center of the cylindrical specimen.…”

Section: Microstructure Of the As-received Powdermentioning

confidence: 97%

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Mostafa

Rubio

Braïlovski

et al. 2017

Metals

194

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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 (Nb 0.78 Ti 0.22 )C carbide phase, with an fcc structure having a lattice parameter a = 4.43 Å, 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.

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Section: Microstructure Of the As-received Powdermentioning

confidence: 97%

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Mostafa

Rubio

Braïlovski

et al. 2017

Metals

194

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“…As the γ growing, segregation of Nb in the remaining liquid would trigger another eutectic reaction L→γ+Laves to terminate solidification, since the available C at this stage is not enough for L→γ+NbC reaction. Antonsson et al [36] compared the effects of cooling rate on IN718's solidification sequence, and suggested that:…”

Section: Solidification Metallurgymentioning

confidence: 99%

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

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Linköping 2018Cover image: A fracture surface of EBM IN718 after tensile test at room temperature.During the course of research underlying this thesis, Dunyong Deng was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. Printed by LiU-Tryck 2018 © Dunyong Deng AbstractAdditive manufacturing (AM), also known as 3D printing, has gained significant interest in aerospace, energy, automotive and medical industries due to its capabilities of manufacturing components that are either prohibitively costly or impossible to manufacture by conventional processes. Among the various additive manufacturing processes for metallic components, electron beam melting (EBM) and selective laser melting (SLM) are two of the most widely used powder bed based processes, and have shown great potential for manufacturing high-end critical components, such as turbine blades and customized medical implants. The futures of the EBM and SLM are doubtlessly promising, but to fully realize their potentials there are still many challenges to overcome.Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties and low cost. Though IN718 is being mostly used as a turbine disk material now, the initial introduction of IN718 was to overcome the poor weldability of superalloys in 1960s, since sluggish precipitation of strengthening phases γ ′ /γ ′′ enables good resistance to strain-age cracking during welding or post weld heat treatment. Given the similarity between AM and welding processes, IN718 has been widely applied to the metallic AM field to facilitate the understandings of process-microstructure-property relationships.The work presented in this licentiate thesis aims to better understand microstructures and mechanical properties EBM and SLM IN718, which have not been systematically investigated. Microstructures of EBM and SLM IN718 have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and correlated with the process conditions. Monotonic mechanical properties (e.g., Vickers microhardness and tensile properties) have also been measured and rationalized with regards to the microstructure evolutions before and after heat treatments.For EBM IN718, the results show the microstructure is not homogeneous but dependant on the location in the components, and the anisotropic mechanical properties are probably attributed to alignment of porosities rather than texture.iii Post heat treatment can slightly increase the mechanical strength compared to the as-manufactured condition but does not alter the anisotropy. SLM IN718 shows significantly different microstructure and mechanical properties to EBM IN718. The as-manufactured SLM IN718 has very fine dendritic microstructure and Laves phases in the interdendrites, and is "work-hardened" by the residual strains and dislocations present in the material. Mechanical properties are different between horizontally and vertically built samples, and heat treatment can m...

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“…The HIPing temperatures used are 1140°C, 1180°C, 1210°C, 1260°C and 1275°C. The first two are respectively below and above the Laves phase incipient melting point (between 1150°C and1160°C) of the as-cast Inconel 718 [19]; the third is below the temperature for carbide to begin to dissolve [20]; the fourth and the last are respectively at and above the solidus [20]. Pressurizing and heating during the HIP operation were conducted simultaneously in a QIH-15 mini-hipper.…”

Section: Materials and Experimentsmentioning

confidence: 99%

Development of Prior Particle Boundary Free Hot-Isostatic-Pressing Process for Inconel 718 Powder

Chang¹,

Yang²,

Sun³

et al. 2014

8th International Symposium on Superalloy 718 and Derivatives (2014)

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Hot isostatic pressed (HIPed) powder metallurgy (PM) Inconel 718 has the potential to be applied in turbine engines. However, the precipitation of high-density carbide particles along the prior particle boundaries (PPBs) leads to its poor ductility and is the main obstacle to be overcome if further and wider applications are pursued. In the past few years, we conducted research aimed at solving this problem, and a HIPing method that could eliminate the PPBs was developed. This paper summarizes the results in three parts: the first is on the influence of HIPing temperature on microstructure and tensile fracture modes of the HIPed alloy; several temperatures ranging from below the Laves incipient temperature to super-solidus were selected. In the second part, typical heat treatments for Inconel 718 were employed for mechanical property optimization of the HIPed alloy. It is found that HIPing at super-solidus temperatures could completely eliminate the PPBs, but the grain size is large and detrimental Laves phase also present. In the third part, a new HIPing process was developed, which consists of a short time holding above the solidus and a long time annealing below the incipient temperature of the Laves phase. This process could produce alloy free of PPBs and Laves phase. After heat treatment, the mechanical properties of the alloy are excellent.

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The effect of cooling rate on the solidification of INCONEL 718

Cited by 186 publications

References 12 publications

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Development of Prior Particle Boundary Free Hot-Isostatic-Pressing Process for Inconel 718 Powder

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