Particle Size of Gamma Prime as a Result of Vacuum Heat Treatment of INCONEL 738 Super Alloy

Guzman, I. Ya.; Granda‐Gutiérrez, E. E.; Méndez, R.; López, Graciela; Acevedo, J.; González, David

doi:10.1007/s11665-012-0385-y

Cited by 9 publications

(4 citation statements)

References 17 publications

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“…Figure 10(c) shows a PWHT of 775°C for 22 h, where the g 0 precipitates have a size of 70 nm and large spherical and polygonal shapes, particularly compared to the g 0 precipitates from the PWHT of 705°C for 22 h. At a PWHT temperature of 845°C and a PWHT time of 24 h, over-aging in the FZ results in coarsening, coalescence, and agglomeration of the primary g 0 precipitate, which causes the lowest hardness value of all tested samples. 22 This phenomenon can be explained using the large g 0 size of 96 nm and polygonal shape of the g 0 precipitates, which is caused by the insufficient PWHT time and temperature for g 0 precipitation and can contribute to the lower hardness, 23 as shown in the SEM image in Figure 10(d).…”

Section: Hardness Analysismentioning

confidence: 99%

Investigation into the influence of post-weld heat treatment on the microstructure and hardness of Inconel X-750

Peasura

Poopat

2015

Advances in Mechanical Engineering

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This work describes a post-weld heat treatment for a precipitation-hardened nickel alloy. Inconel X-750 is a nickel-based superalloy for gas tungsten arc welding processes. The materials were heat-treated in two steps: solution and aging. The post-weld heat treatment variables examined in this study included post-weld heat treatment temperatures of 705°C, 775°C, and 845°C and post-weld heat treatment time of 2-24 h in 2-h increments. The resulting materials were examined using the full factorial design of experiments to determine the resulting material hardness and observed with optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy in the fusion zone and heat-affected zone. The results show that a longer post-weld heat treatment time corresponds to larger g 0 precipitates and a smaller amount of Cr 23 C 6 at the grain boundaries, which can decrease the overall hardness. The post-weld heat treatment analysis indicates that an increase in the amount of g 0 results in better mechanical properties for particles with octagonal shapes and a small size. A factorial analysis, which was conducted on the relationship between the post-weld heat treatment temperature and time to the hardness of the fusion zone, had a 95% confidence level.

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Section: Hardness Analysismentioning

confidence: 99%

Investigation into the influence of post-weld heat treatment on the microstructure and hardness of Inconel X-750

Peasura

Poopat

2015

Advances in Mechanical Engineering

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“…Kwai S. Chan and Giulio Marchese [7,8] predicted crystal growth of Ni-based superalloys Inconel 718 and 718 plus during additive layer-by-layer deposition of laser powder bed fusion process under multi-variant heat treatments. Adelajda Polkowska, Cosimo Monti and I. Guzman [9][10][11] discussed influence of rejuvenation heat treatment cooling conditions on crystal growth of gamma phase, size and distribution of gamma prime phase of Ni-based superalloys Haynes 282 and Inconel738. Fan Yang and Y.F.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis Nucleation and Growth Conditions of Single-Crystallinity Control during Laser Surface Modification of Ni-Based Single-Crystal Superalloy Part I: Thermal and Chemical Determinants

Gao

2022

SSP

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Nucleation and growth conditions of single-crystallinity control are convincingly elaborated by multi-scale mathematical modeling of heat and mass transport to totally abate undesirable weld defects, e.g. disoriented crystal and hot cracking inside molten pool of nonequilibrium crystallization, in order to illustrate the usefulness of predictive capability through theory and experiment procedures. Crystal growth is complicated by crystallinity-dependent thermal and chemical driving forces in front of dendrite tip during viable laser surface modification of Ni-based single-crystal superalloy. These two thermal metallurgical determinants play crucial role in crack-insusceptible columnar crystal growth, which is favorably oriented throughout weld depth. There is particular challenge in complete elimination of disoriented crystal, i.e. stray grain formation, for acceptable surface quality. Conservative (001)/[100] crystalline orientation is desired to diminish Al concentration and supersaturation, and morphologically satisfy epitaxial growth kinetics to successfully lessen central cracking with satisfactory variability of laser power and welding speed. Comparatively, (001)/[110] crystalline orientation is disadvantageous to asymmetrically augment Al concentration and supersaturation and aggressively increase interface instability, microstructure heterogeneity and hot cracking vulnerability along disoriented crystal boundaries. Disoriented crystal is increasingly withstood if the Al concentration and supersaturation in front of dendrite tip are low enough and crack-unsusceptible part is relatively large enough in case of attractive (001)/[100] crystalline orientation with optimal range of heat input to ameliorate microstructure homogeneity. Crystalline orientation region varies with diverse welding configurations, and epitaxy across solid/liquid interface is also sensitive to heat input of laser processing, which necessitate high efficient welding conditions optimization. Considerable effort is made to distinguish diffusion-driven crystal growth between a series of combinations of multiple welding conditions, such as critical welding configuration and heat input. Metallographically, the morphologies of crystal growth and hot cracking are experimentally observed to consistently support kinetics calculation result and well explain correlation between solidification behavior and crystal growth.

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“…Although IN-738 emerged in the aerospace industry, it has been primarily adapted for power gas turbines [9]. IN-738 is a vacuum investment cast, polycrystalline, nickel-based superalloy [3,12,15,16]. The nominal composition is provided in Table 2.…”

Section: In-738 211mentioning

confidence: 99%

“…This heat treatment results in partial dissolution of the primary γ' precipitates producing a microstructure consisting of cuboidal primary γ' with an average size of ~0.7 μm and re-precipitated fine secondary γ' precipitates ( Figure 4) [17]. The solutionizing heat treatment is followed by an aging heat treatment at 845°C for 24h [18] to promote the precipitation of a relatively high volume fraction [16] of fine, ordered L12 intermetallic γ'-Ni 3 Al and γ'-Ni 3 Ti phases [12,15], which confer additional strength to the alloy.…”

Section: In-738 211mentioning

confidence: 99%

Effect of Pre-Oxidation and Thermal Exposure on the Microstructure of Superalloys and Thermal Barrier Coating Systems

Walker¹

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Thermal barrier coatings (TBCs) enable the nickel-base superalloy gas turbine blades of modern gas turbine engines to run at their highest possible temperatures. Currently, a bond coat (BC) is utilized to adhere the yttria-stabilized zirconia (YSZ) top coat to the nickel-base superalloy substrate. However, the addition of this manufacturing step increases cost. In this study, three nickel-based superalloys: IN-738, CMSX-4 and Rene N5 are considered. Isothermal oxidation studies were conducted at 1150°C in atmosphere for holding times ranging from 30 minutes to 16 hours. YSZ top coats were applied directly to the nickel-base superalloy René N5 isothermally oxidized for 2hrs at 1150°C in atmosphere. Rene N5 oxidized at this time and temperature produced the most adherent, dense and uniform α-Al 2 O 3 scale which was anticipated to enhance YSZ adhesion. YSZ coatings were then applied using suspension plasma spraying technology (SPS). Coatings of dense vertically cracked (DVC) and columnar morphologies were applied. Following YSZ application, the samples were subjected to a diffusion heat treatment in vacuum at 1080°C to promote YSZ/substrate adhesion. These samples were then cyclically and isothermally tested in atmosphere at 1150°C. Both SPS DVC and SPS Columnar coatings were found to have poor adhesion (delaminated in less than 25 cycles). The lack of adequate α-Al 2 O 3 coverage, the rapid formation of spinel and grit blasting prior to coating deposition were determined to be the primary causes of poor performance.

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Particle Size of Gamma Prime as a Result of Vacuum Heat Treatment of INCONEL 738 Super Alloy

Cited by 9 publications

References 17 publications

Investigation into the influence of post-weld heat treatment on the microstructure and hardness of Inconel X-750

Investigation into the influence of post-weld heat treatment on the microstructure and hardness of Inconel X-750

Numerical Analysis Nucleation and Growth Conditions of Single-Crystallinity Control during Laser Surface Modification of Ni-Based Single-Crystal Superalloy Part I: Thermal and Chemical Determinants

Effect of Pre-Oxidation and Thermal Exposure on the Microstructure of Superalloys and Thermal Barrier Coating Systems

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