Influence of the Delta Phase in the Microstructure of the Inconel 718 subjected to “Delta-processing” Heat Treatment and Hot Deformed

Kañetas, Pedro Jacinto Páramo; Osorio, L.A. Reyes; Guerrero‐Mata, Martha Patricia; Garza, Maribel de la Garza; Lopez, V.

doi:10.1016/j.mspro.2015.04.180

Cited by 34 publications

(12 citation statements)

References 6 publications

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“…The top surface of Sample I3, as previously seen in Figure 8d, is heavily deformed to the point at which it is no longer possible to distinguish the grains (see Figure 9d). In the case of Sample I4 (see Figure 9e), the δ phase is more concentrated in the UNSM region, which implies that the volume fraction covered by γʹʹ phase is lower, as shown by previous authors [12,46,51]. Besides the δ phase formation, the microstructure of Sample I4 resembles that previously seen of Sample I3, having higher twin boundaries in the transition region and scattered carbides in the grain boundary triple junctions.…”

Section: Microstructure Characterizationsupporting

confidence: 77%

“…The composition of Inconel 718 presents a Ni equivalent value (Ni eq ) high enough to promote a single-phase microstructure (γ phase) as seen in the Schaeffler diagram [11]. Besides the γ phase, Inconel 718 precipitates other phases, the most common are: γ being a face centered cubic (FCC), with a Ni 3 (Al, Ti) composition; γ" being a body centered tetragonal (BCT) with a Ni 3 Nb composition, and δ phase with an orthorhombic crystal structure having a Ni 3 Nb composition [4,[12][13][14]. The γ" phase confers most of the hardening to the Inconel 718 γ-phase matrix; however, it is a metastable phase the more stable form of which is the δ phase.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718

Martin

Ress

Bosch

et al. 2020

Metals

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In this work, influence of ultrasonic nanocrystal surface modification (UNSM) on the degree of sensitization (DOS) in Inconel 718 has been studied and correlated with the resulting microstructure. The UNSM processed samples decreased their grain size from 11.9 µm to 7.75 µm, increasing the surface of grain boundaries, and thus enhancing the area where δ phase and niobium carbides precipitate. The effect of the UNSM process on the DOS of Inconel 718 was studied by the double loop electrochemical potentiokinetic reactivation (DL−EPR) test. The DL−EPR showed that for UNSM processed samples with no thermal treatment, the DOS increased up to 59.6%, while for UNSM treated samples that were post-annealed at 1000 °C for 10 min and water quenched the DOS decreased down to 40.9%. The increase of grain boundaries surface area and triple junctions after the UNSM process enables the formation of twice the amount of δ phase compared to the as-received Inconel 718 bulk sample. The area fraction of the grain boundary covered by δ phase was of 9.87% in the UNSM region while in the bulk the area fraction was 4.09%. In summary, it was found that after UNSM process, the annealing at 1000 °C for 10 min and water quenching promoted the transformation of γ″ to form δ phase on the grain boundaries, which reduces the intergranular corrosion susceptibility.

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Section: Microstructure Characterizationsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718

Martin

Ress

Bosch

et al. 2020

Metals

View full text Add to dashboard Cite

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“…This treatment includes an intentional δ-phase precipitation cycle as a preparation for the subsequent thermomechanical processing. It has been reported that DP718 can produce uniform fine grains [17][18][19][20][21][22][23][24]. Although DP718 is derived from a process known as "mini grain" mainly used in ingot-billet conversion [25][26][27], it also finds an opportunity as a possible industrial forging process.…”

Section: Introductionmentioning

confidence: 99%

EBSD Study of Delta-Processed Ni-Based Superalloy

Kañetas

Calvo

Calvillo

et al. 2020

Metals

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Nickel-based superalloys are extensively used in the aerospace and power generation industries due to their excellent mechanical properties at elevated temperatures and good corrosion resistance. Typically, these alloys require accomplishing critical standards during their manufacturing process. In this study, an Inconel 718 (IN718) Ni-based superalloy was subjected to a delta-processing treatment (DP718) and subsequently deformed at high temperature. Samples were compressed below and above the δ-solvus temperature at two different strain rates of 0.001 s−1 and 0.01 s−1. A detailed microstructural characterization was carried out by the electron backscattered diffraction technique (EBSD). Kikuchi patterns and the orientation relationship of the δ-phase were identified. For samples deformed above the δ-solvus at 0.01 s−1, an increase in the percentage of low angle grain boundaries (LAGB) within deformed grains and a decrease in high angle grain boundaries (HAGB) were observed. Comprehensive observation of the microstructural evolution of IN718 subjected to DP718 using orientation map images was also performed.

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“…It is important to control the thermomechanical processing (TMP) for obtaining the superior performance of Inconel 718. Microstructure evolution, including dynamic recrystallization and grain growth of Inconel 718, has been extensively studied during hot working [7][8][9] and post heating processes [2,[10][11][12]. Owing…”

Section: Introductionmentioning

confidence: 99%

Microstructure Heredity of Inconel 718 Nickel-Based Superalloy during Preheating and Following Deformation

et al. 2020

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Preheating and compression tests of Inconel 718 superalloy double cone specimens were carried out to investigate the microstructure heredity during hot working. Optical microscopy, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to characterize the microstructure evolution. The results show that intense microstructure heredity can be found at the temperature 960~990 • C. During the preheating process, δ phase precipitation or grain growth could increase the fraction of high angle grain boundary (HAGBs) and Σ3 n boundaries. Otherwise, the generation or spread of annealing twin could increase the fraction of LAGBs, Volume fraction of recrystallized grains was evaluated at the whole hot working process. At the temperature of 960~990 • C, the volume fraction of recrystallized grains increases with effective strain increasing. At the super solution temperature of δ phase, the volume fraction of recrystallized grains decreases and then increases with the increase of the effective strain. The unimodal grain size distribution and fully recrystallized grains can be obtained at low strains at 960~990 • C. The twin boundary length fraction of deformed specimens is always lower than that of preheated ones. Discontinuous dynamic recrystallization (DDRX) was considered as the dominant nucleation mechanism, and continuous dynamic recrystallization (CDRX) was strengthened with the increasing grain size. Twin introduced deformation will be the main deformation mode for alloy 718 with larger grain.Crystals 2020, 10, 303 2 of 17 to the relatively low stacking fault energy of nickel-based superalloy, the recovery induced by dislocation climb and cross slip is weak [13]. Hence, recrystallization is one of the most significant mechanisms for microstructure evolution during hot working process. The recrystallization mechanism comprises the following three categories: dynamic recrystallization (DRX), meta-dynamic recrystallization (MDRX), and static recrystallization (SRX) [14]. Due to the difficulty of refining the grain size of superalloy by SRX, extensive studies have been conducted to investigate the dynamic recrystallization during hot working process [15][16][17][18][19][20][21][22][23][24][25][26][27]. It has been well accepted that the nucleation of dynamic recrystallization for superalloy includes discontinuous DRX (DDRX) and continuous DRX (CDRX) δ phase shows clearly the pinning effect on the grain growth and stimulated the nucleation of dynamic recrystallization. Otherwise, few studies have been carried out to investigate microstructure evolution right after preheating which is more consistent with actual production.The detailed investigation of microstructure evolution during TMP is usually conducted using isothermal tests based on uniaxial compression [2,[28][29][30], uniaxial tensile [31,32], torsion [33][34][35], and plane strain compression [36][37][38][39]. Workpieces are firstly annealed to ensure the initial homogeneous microstructure [...

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Influence of the Delta Phase in the Microstructure of the Inconel 718 subjected to “Delta-processing” Heat Treatment and Hot Deformed

Cited by 34 publications

References 6 publications

Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718

Evaluation of the DOS by DL−EPR of UNSM Processed Inconel 718

EBSD Study of Delta-Processed Ni-Based Superalloy

Microstructure Heredity of Inconel 718 Nickel-Based Superalloy during Preheating and Following Deformation

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