The microstructural changes and their effect on CCGR after long time thermal exposure in DA718 and STD718

Wang, Gailian; Wu, Cuiwei; Zhang, Maicang; Dong, Jie; Xie, Xiangyu; Radavich, J.F.; Lindsley, Bruce; Shen, G.

doi:10.1016/s0921-5093(03)00245-4

Cited by 17 publications

(7 citation statements)

References 5 publications

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“…They are most likely associated with large (5-15 mm) primary complex TiC/NbC carbides, which have been formed as spherical-shaped particles. 55,56 These carbides are hard and brittle and have a tendency to interact with the environment at elevated temperatures within the cutting zone. 57 The presence of hard abrasive TiC/NbC carbides may result in intensive abrasive tool wear, which will be taken into account in the machining experiments.…”

Section: Da718 Microstructure Evaluationmentioning

confidence: 99%

Tool wear and chip formation during dry high speed turning of direct aged Inconel 718 aerospace superalloy using different ceramic tools

Shalaby

Veldhuis

2019

Proceedings of the Institution of Mechanical Engineers, Part J:

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Section: Da718 Microstructure Evaluationmentioning

confidence: 99%

Tool wear and chip formation during dry high speed turning of direct aged Inconel 718 aerospace superalloy using different ceramic tools

Shalaby

Veldhuis

2019

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…The main strengthening particles in Inconel 718 are precipitates of the metastable Ni 3 Nb γ phase with an ordered body centered tetragonal (BCT) lattice structure [1]. Rapid coalescence of γ and the transformation of γ to the stable orthorhombic δ phase can result in reduced mechanical properties above 650…”

Section: Introductionmentioning

confidence: 99%

“…The precipitation of α-Cr and sigma after long-time thermal exposure at high temperature can be another factor that affects the mechanical properties [3].…”

Section: Introductionmentioning

confidence: 99%

Effect of thermal exposure on microstructure and nano-hardness of broached Inconel 718

Chen

Peng

Avdovic

et al. 2014

MATEC Web of Conferences

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Abstract. Inconel 718 is a high strength, heat resistant superalloy that is used extensively for components in hot sections of gas turbine engines. This paper presents an experimental study on the thermal stability of broached Inconel 718 in terms of microstructure and nano-hardness. The broaching process used in this study is similar to that used in gas turbine industries for machining fir-tree root fixings on turbine discs. Severe plastic deformation was found under the broached surface. The plastic deformation induces a work-hardened layer in the subsurface region with a thickness of ∼50 µm. Thermal exposure was conducted at two temperatures, 550• C and 650• C respectively, for 300 h. Recrystallization occurs in the surface layer during thermal exposure at 550• C and α-Cr precipitates as a consequence of the growth of recrystallized δ phases. More recrystallized grains with a larger size form in the surface layer and the α-Cr not only precipitates in the surface layer, but also in the sub-surface region when the thermal exposure temperature goes up to 650• C. The thermal exposure leads to an increase in nano-hardness both in the work-hardened layer and in the bulk material due to the coarsening of the main strengthening phase γ .

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“…The corresponding XED spectrum shown in Figure 2 indicates this precipitate is Cr-rich but also contains Fe, in addition to Mo, Ni and Si. In multicomponent alloys, this phase has been reported to form after long-term aging in several morphologies (intra and intergranular modes) and in the vicinity of δ-phase [4]. However, lamellae of the α-Cr phase that has constituted these DP colonies have only been reported to form in binary Ni-Cr alloys [5] [6].…”

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confidence: 99%

Discontinuous Precipitation of α-Cr Phase in Alloy 33 (Cr-Fe-Ni-N)

2019

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Discontinuous precipitation (DP) reactions is a grain boundary (GB) diffusion-controlled phenomenon generating lamellar or rod-type equilibrium precipitates driven by a migrating GB that acts as a fast reaction path under the action of chemical and capillary forces, leaving behind a regularly spaced array of precipitates growing cooperatively from the supersaturated matrix. In multicomponent alloy systems containing both substitutional and interstitial solutes, DP usually is constituted of either Cr-rich M23C6 or Cr2N lamellae [1,2]. Recently, σ-phase has been observed as the main precipitate comprising a DP colony in superaustenitic stainless steel [3]. The DP reactions are of practical interest because of its effect on corrosion and mechanical properties of alloys under service conditions [1,2]. The present investigation deals with the DP reaction in Alloy 33 with an austenitic matrix and nominal composition (wt. %) 33Cr-32Fe-31Ni-1.6Mo-0.6Cu-0.4N. In order to understand the DP behavior upon isothermally aging at 800°C, an experimental study has been conducted using scanning electron microscopy (SEM), scanning and transmission electron microscopy (STEM/TEM) with X-ray energy dispersive spectroscopy (XEDS), and electron backscatter diffraction (EBSD). Detailed microstructural analysis was performed using an FEI Talos F200A with Super X (4 Si Drift Detectors) and X-FEG for high sensitivity STEM-EDX spectrum imaging and analysis on electron-transparent thin-foil specimens prepared by the twin-jet electropolishing technique.

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The microstructural changes and their effect on CCGR after long time thermal exposure in DA718 and STD718

Cited by 17 publications

References 5 publications

Tool wear and chip formation during dry high speed turning of direct aged Inconel 718 aerospace superalloy using different ceramic tools

Tool wear and chip formation during dry high speed turning of direct aged Inconel 718 aerospace superalloy using different ceramic tools

Effect of thermal exposure on microstructure and nano-hardness of broached Inconel 718

Discontinuous Precipitation of α-Cr Phase in Alloy 33 (Cr-Fe-Ni-N)

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