EFFECT OF COOLING RATE ON GLEEBLE HOT DUCTILITY OF UDIMET ALLOY 720 BILLET

M. Fahrmann1 and A. Suzuki2

1 Special Metals Corporation, 3200 Riverside Drive, Huntington, WV 25705, USA 2 GE Global Research, 1 Research Circle, Niskayuna, NY 12309, USA

Keywords: UDIMET alloy 720, billet, hot ductility, cooling rate, gamma prime, microtwinning

Abstract Conversion of highly-alloyed -hardened disk alloys such as UDIMET alloy 720 from cast ingot into billet requires a detailed knowledge of the hot working process window. Hot workability of billet stock was assessed by Gleeble tension testing. The effects of test temperature and, in particular, cooling rate from the prior annealing temperature to the test temperature on hot ductility were systematically studied. High cooling rates on the order of 30 oC / s as realized in the Gleeble tester resulted in a dramatic drop in hot ductility. Much slower cooling rates, representative of industrial conversion operations, resulted in acceptable ductility of greater than 60 %. Microstructures of the as-supplied billet stock and in the various tested conditions were characterized. The measured significant differences in hot ductility are rationalized by the dominant deformation mechanisms observed microscopically.

Introduction UDIMET alloy 720, a hardenable Ni-base superalloy, is known to be one of the highest alloyed disk materials that can be processed along the traditional cast & wrought route [1]. Thermo-mechanical conversion of the cast ingot to billet stock is often accomplished by press forging at temperatures approximately 50 oC below the solvus temperature (roughly 1160 oC). Owing to the rapid age hardening propensity of this alloy upon cooling while being processed, loss of ductility is a major concern potentially impacting quality and yield. Hot ductility of billet stock is traditionally assessed by various types of Gleeble hot deformation testing schemes that reflect the relatively high strain rates encountered in industrial conversion operations. In the present study, simple Gleeble tension testing was executed. To closely simulate conversion processes, the specimens were heated to a nominal forging temperature, stabilized, and then cooled within a wide range of rates to the actual test temperature. Reduction in area was utilized as a measure of hot ductility. These tests were complemented by detailed analyses of the respective microstructures.

Experiment

Material was made available from 0.15 m diameter billet. The actual chemical composition of this billet stock is listed in Table I. Two alloying elements (Cr and Ti) are slightly outside the specification limits for UDIMET alloy 720. This resulted in a solvus temperature elevated by roughly 10 oC over regular production material. Nonetheless, it is believed that the results and

conclusions of this study are generally applicable to highly alloyed hardened disk materials.

Table I. Chemical composition (in wt.%) of the studied billet material.

C Cr Mo W Al Ti Co Ni

0.013 14.8 3.1 1.3 2.7 5.5 14.2 bal.

Uniformity of the microstructure across the billet diameter was adequate to allow for machining of a significant number of Gleeble specimens without regard to location. All specimens featured an axial orientation. Specimens were mounted in a Gleeble tester, rapidly annealed to a temperature of 1110 oC, and held for 5 min. Cooling rates to the actual test temperature varied between 0.03 and 30 oC / s. The upper bound reflects cooling rates typically encountered in Gleeble tests whereas the lower bound approximates cooling rates experienced by the billet center upon a standard air cool [2]. Once stabilized (1 min) at the test temperature, specimens were pulled rapidly at approximately 0.02 m / s translating into strain rates on the order of 1 / s. Peak loads were used to compute tensile strength, and reduction of area was employed as a measure of hot ductility. Microstructures of the material in the as-supplied as well as in the various tested conditions were characterized by optical microscopy, SEM, and TEM. Seven-acids etch (300 ml hydrochloric acid, 60 ml nitric acid, 60 ml phosphoric acid, 30 ml hydrofluoric acid, 30 ml sulfuric acid, 30 grams anhydrous iron chloride, 60 ml acetic acid, 300 ml water) was employed to reveal the precipitates. In order to gain insight into the operative deformation mechanisms during testing, TEM specimens were prepared from near the fracture surfaces. Discs 0.12 mm in thickness and 3 mm in diameter were cut, mechanically polished, and then subjected to twin-jet electron polishing in a solution of 340 ml methanol, 50 ml perchloric acid, 65 ml butyl cellusolve and 45 ml distilled water. The polishing was conducted at 40 oC and a voltage of 18~22 V.

Results and Discussion

Fig. 1 shows reduction of area (RA) as a function of test temperature for standard Gleeble testing conditions, i.e., cooling rates of approximately 30 oC / s. The two curves represent the test results obtained with two sets of specimens and demonstrate the reproducibility of the results. The dramatic drop in hot

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ductility at around 1040 oC is apparent. Values of less than 20 % in RA are generally considered unacceptable for hot forming operations. Recalling that billet surface temperatures could readily drop below this mark during a forge session, major surface cracking could be anticipated. This projection contradicts forge shop experience with this alloy.

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Figure 1. Reduction of area as a function of test temperature of two sets of specimens. Standard Gleeble testing conditions. Another set of specimens was subsequently tested employing a cooling rate of only 0.03 oC / s to the test temperature. The results are plotted in Figure 2 and contrasted to the outcome of the first test condition employing a cooling rate of 30 oC / s.

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Figure 2. Reduction of area as a function of test temperature for two different cooling rates of 30 oC / s and 0.03 oC / s. Evidently, the drop in hot ductility is no longer present. Ductility over a wide temperature range is quite acceptable, actually suggesting a generous hot working window.

To further explore cooling rate effects, another set of specimens was cooled at varying rates to 1010 oC, and pulled. Figure 3 depicts the measured RA values as a function of cooling rate. Superimposed on this graph is the range of cooling rates from center to surface modeled for air cooling of an intermediate size, 0.38 m diameter billet [2]. Apparently, even the billet surface can be expected to exhibit sufficient hot ductility.

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Figure 3. Reduction of area as a function of cooling rate to a test temperature of 1010 oC. Superimposed is the modeled range of cooling rates of air- cooled 0.38 m diameter billet. Hence, from a conversion point of view, hot cracking should be a rare event. However, above reasoning does not account for the fact that the grain structure of the tested material (fully wrought) is certainly not representative of the grain structure during initial ingot break-down. It is speculated that the initially coarse, oriented grain structure in the cast ingot may be much more important in terms of cracking propensity than any lack of traditional Gleeble hot ductility measured on fully wrought, fine-grained material. This notion is supported by shop floor observations in that the workability of UDIMET alloy 720 billet generally improves throughout the conversion process [3]. In order to gain insight into the different hot ductility behaviors, microstructures of material in the initial and selected tested conditions were examined. Specifically, samples from the standard test runs at 30 oC / s (subsequently referred to as fast cooling condition) and 0.03 oC / s (referred to as slow cooling condition) were chosen for detailed analyses. Test temperature was 1010 oC in either case. Figure 4 depicts the typical assupplied microstructure featuring coarse, blocky primary precipitates of several microns in size. The grain size was read to ASTM 8 or finer. Higher magnification images (Figure 5) revealed the presence of 150 nm-size fine spherical secondary that must have formed during cooling from the hot working temperature. It can be expected that this fine cooling would dissolve upon heating to the 1110 oC annealing temperature in the Gleeble tester.

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Figure 4. SEM micrograph of the as-supplied billet microstructure featuring coarse, blocky primary .

Figure 5. SEM micrograph of the as-supplied billet microstructure revealing fine cooling . A SEM micrograph representative of the fast cooling condition is shown in Figure 6. Notice the presence of the similarly coarse blocky as observed in the as-supplied condition (Figure 4). Evidently, the 1110 oC annealing temperature in the Gleeble tester was well below the -solvus temperature of the material as intended. A higher resolution TEM micrograph (Figure 7) revealed copious amounts of fine, approximately 40 nm-size secondary that precipitated during controlled cooling from the 1110 oC annealing temperature to the 1010 oC test temperature.

Figure 6. SEM micrograph of the gage section of a Gleeble specimen in the fast cooling condition.

Figure 7. TEM dark field image of fast cooling specimens featuring copious amounts of secondary precipitates in matrix (B=001, g=100). In order to examine the deformation mechanisms operative during Gleeble tests, TEM foils were prepared from near the fracture surface. A bright field image (Figure 8a) exhibits a high density of planar faults with a couple of 100 nm in spacing. These faults are continuous across entire grains. The diffraction pattern taken from the [011] direction shows weak reflection spots that have a twin relationship with the matrix as indicated with circles. A higher magnification micrograph (Figure 8b) shows thin twin plates 10-30 nm thick. The twin interfaces are indicated with arrowheads, and they are (111) planes. The twin plates seem to penetrate precipitates. Other deformation activities, such as dislocation gliding, are rarely observed in this specimen. These features are similar to "microtwins" observed in polycrystalline Ni-base superalloys with fine precipitates during creep deformation at low temperature and high stress condition [4]. Therefore, microtwinning is surmised to be the dominant deformation mechanisms in the "fast cooling" condition.

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Figure 8. TEM bright field images of the region near fracture surface of Gleeble specimens in the fast cooling condition, showing microtwins (B=011). A SEM micrograph representative of the slow cooling condition is shown in Figure 9. In addition to the retained primary coarse , secondary of dendritic morphology is evident. Such morphologies are likely growth morphologies as reported in a number of -hardened alloys. They typically result from slow cooling (on the order of 1 oC / min) through the precipitation range [5]. In the present study, they are surmised to have formed during slow cooling from the 1110 oC annealing temperature to the 1010 oC test temperature. Precipitate-free zones around the primary precipitates are also apparent, indicative of the exhausted hardener levels in the vicinity of these larger particles.

Figure 9. SEM micrograph of the gage section of Gleeble specimens in the slow cooling condition.

Figure 10. TEM bright field images of the region near fracture surface of Gleeble specimens

in the slow cooling condition (B=001).

Figure 10(a) shows a TEM bright field image taken from near fracture surface of the specimen in "slow cooling" condition. Large precipitates with a size larger than 200 nm are present in the matrix. Different from the "fast cooling" condition, microtwins were absent. Instead, dislocations gliding in the matrix phase were observed (Figure 10(b)). They were identified as 1/2 type dislocations via gB analysis. Therefore, normal

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dislocation gliding appears to be the dominant deformation mechanism in the "slow cooling" condition. Based on the examinations of the various microstructures, the Gleeble results can be rationalized. Upon cooling from the 1110 oC annealing temperature to the actual test temperature, a significant supersaturation of the -matrix in the -forming elements Al and Ti will build up (Figure 11).

Figure 11. JMatPro predictions [6] of the temperature-dependent volume fraction in the studied billet material. Then, the cooling rate dictates the interplay between nucleation of secondary and its growth high cooling rates favor nucleation, hence, large amounts of very fine secondary precipitates are formed. Their size and tight spacing greatly impede dislocation motion during the actual Gleeble test. In + alloys, mode of shearing depends on the size of precipitates. Generally, when precipitates are small (less than 100 nm), the precipitates are sheared by 1/6 partial dislocations, rather than 1/2 dislocations, and microtwins [4] or stacking faults [7] are observed. This is thought to be the case of the "fast cooling" condition. Interestingly, it apparently takes a significant amount of supersaturation (or undercooling) in solute for this mechanism to become operative since the ductility deficit did not materialize for small amounts of undercooling (see Figure 1). In the slow cooling case, precipitate growth (either of pre-existing, retained primary or newly created secondary nuclei) dominates. Hence, nucleation number densities are low and precipitate spacing is significantly greater. Such microstructures enable the classical (111) slip systems in the matrix, and result in much improved ductility. The ramifications of the different microstructures for specimen mechanical behavior are also reflected in their tensile strengths fine secondary resulted in significantly higher strength levels than coarser dendritic secondary (Figure 12).

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Figure 12. Gleeble tensile strengths as a function of test temperature for fast cooling and slow cooling testing regimes. Above reasoning should be generally applicable to highly alloyed Ni-base superalloys that exhibit a sufficient variation in volume fraction within the hot working window. Indeed, quite similar debits in hot ductility were reported for UDIMET alloy 700 in the fast cooling condition [8].

Summary and Conclusions

Hot workability of highly-alloyed -hardened billet stock of UDIMET alloy 720 type was assessed by Gleeble testing. Gleeble hot ductility was found to be sensitive to cooling rate from the prior annealing temperature. High cooling rates on the order of 30 oC / s resulted in poor ductility of less than 20 %. Lower cooling rates of 3 oC / s or less resulted in ductility exceeding 60 %. The observed differences in hot ductility could be rationalized by the precipitation kinetics of during cooling from the prior annealing temperature to the actual test temperature. High cooling rates caused very fine, 40 nm-size secondary which triggered micro-twinning in the course of Gleeble testing. In contrast, slow cooling yielded much coarser (even dendritic) secondary that enabled the classical (111) slip. As for industrial conversion operations, it seems that even surface chill rates would ordinarily fall into the slow cooling regime. Hence, lack of workability is likely be caused by factors other than precipitation kinetics.

Acknowledgment

The authors would like to thank Mr. Steve Gosnay (Special Metals Corp.) for conducting the Gleeble tests and Prof. Tresa Pollock (University of Michigan) for supporting the microscopy work.

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References

[1] D. J. Bryant and G. McIntosh, The manufacture and evaluation of a large turbine disc in cast and wrought alloy 720LI, Proceedings of the Eighth International Symposium on Superalloys, ed. R. D. Kissinger et al., (TMS, 1996), 713 - 722. [2] Ch. Rock, personal communication with author, Special Metals Corporation, 2006. [3] D. Borowski, personal communication with author, Special Metals Corporation, 2007. [4] G.B. Viswanathan, P.M. Sarosi, M.F. Henry, D.D. Whitis, W.W. Milligan, and M.J. Mills, "Investigation of creep deformation mechanisms at intermediate temperatures in Ren 88 DT," Acta Mater., 53 (2005), 3041-3057. [5] M. F. Henry, Y. S. Yoo, D. Y. Yoon, and J. Choi, The dendritic growth of g precipitates and grain boundary serration in a model Ni-base superalloy Met. Trans., 24A (1993) 1733 1738. [6] N. Saunders, Z. Guo, X. Li, and J.-Ph. Schille, JOM, 55 (2003), 60. [7] S. Shinharoy, P. Virro-Nic, and W.W, Milligan, "Deformation and Strength Behavior of Two Nickel-Base Turbine Disk Alloys at 650C," Metall. Mater. Trans., 32A (2001), 2021-2032. [8] L. A. Jackman and T. P. Dressel, Hot workability of U-720 as determined by Gleeble testing (Report TR-78-003, Special Metals, 1978).

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WelcomeRelated PublicationsCopyright InformationPrefaceDedicationBest Paper AwardCommittee MembersTable of ContentsSuperalloys 2008Symposium Keynote AddressChallenges for High Temperature Materials in the New Millennium

Latest Advances in Alloy Development INASA and Superalloys: A Customer, a Participant, and a RefereeDevelopment of a New Fatigue and Creep Resistant PM Nickel-Base Superalloy for Disk ApplicationsA New Ni-Base Superalloy for Oil and Gas ApplicationsStructure Control of a New-Type High-Cr Superalloy

Interactive Session A: Alloy DevelopmentDevelopment of Ni-Co-Base Alloys for High-Temperature Disk ApplicationsThe Microstructure and Mechanical Properties of EP741NP Powder Metallurgy Disc MaterialEffects of a Tantalum Addition on the Morphological and Compositional Evolution of a Model Ni-Al-Cr SuperalloyLinking the Properties, Processing and Chemistry of Advanced Single Crystal Ni-Base SuperalloysEffect of Ruthenium on Microstructure and Stress Rupture Properties of a Single Crystal Nickel-Base SuperalloyOptimizing SC Ren N4 Alloy for DS Aft-Stage Bucket Applications in Industrial Gas TurbinesThe Influence of Ruthenium and Rhenium on the Local Properties of the gamma- and gamma'-Phase in Nickel-Base Superalloys and Their Consequences for Alloy BehaviorThe Effects of Heat Treatment and Microstructure Variations on Disk Superalloy Properties at High TemperatureA 5th Generation SC Superalloy with Balanced High Temperature Properties and ProcessabilityP/M Alloy 10 - A 700C Capable Nickel-Based Superalloy for Turbine Disk ApplicationsThe Effect of Composition, Misfit, and Heat Treatment on the Primary Creep Behavior of Single Crystal Nickel Base Superalloys PWA 1480 and PWA 1484Influence of the gamma' Fraction on the gamma/gamma' Topological Inversion during High Temperature Creep of Single Crystal Superalloys

Latest Advances in Alloy Development IIEvaluation of Ruthenium-Bearing Single Crystal Superalloys - A Design of ExperimentsDevelopment of High Temperature Capability P/M Disk SuperalloysDevelopment of a Fabricable Gamma Prime Strengthened SuperalloyElevated Temperature Mechanical Behavior of New Low CTE Superalloys

Latest Advances in Processing INew Boron and Silicon Free Single Crystal-Diffusion Brazing AlloysCreep-Fatigue and Thermo-Mechanical Fatigue of Friction-Welded IN 718/MarM247 Dissimilar JointGas Turbine Blade Made of FG75-Investment Casting Technology for Complex, Hollow, Fibre-Reinforced NiAl-Components

Interactive Session B: Advances in ProcessingA Study of HAZ Microfissuring in a Newly Developed Allvac 718 Plus SuperalloyAdvancement in Fast Epitaxial High Temperature Brazing of Single Crystalline Nickel Based SuperalloysAn Analysis of Solidification Path in the Ni-Base Superalloy, CMSX10KPost-Fabrication Vapor Phase Strengthening of a Nickel-Based Sheet Alloy for Thermostructural PanelsSolute Redistribution during Planar and Dendritic Growth of Directionally Solidified Ni-Base Superalloy CMSX-10The Effects of Withdrawal and Melt Overheating Histories on the Microstructure of a Nickel-Based Single Crystal SuperalloyInfluence of TLP Bonding on Creep Deformation of a Nickel-Base Single Crystal Superalloy at High TemperatureDesign of Solutionizing Heat Treatments for an Experimental Single Crystal SuperalloysEffect of Cooling Rate on Gleeble Hot Ductility of UDIMET Alloy 720 BilletCompetitive Grain Growth in Directional Solidification of a Nickel-Base SuperalloySevere Thermomechanical Processing as an Effective Method for Preparation of Bulk and Sheet Nanostructured Semifinished Products from Nickel Alloys 718 and 718plusInvestigation of the Partition Coefficient in the Ni-Fe-Nb Alloys: A Thermodynamic and Experimental ApproachEffect of Thermal History on the Properties and Microstructure of a Large HIPed PM Superalloy Billet

Latest Advances in Processing IIProcess Development and Microstructure and Mechanical Property Evaluation of a Dual Microstructure Heat Treated Advanced Nickel Disc AlloyA Statistical Analysis of Variations in Hot Tear Performance and Microporosity Formation Versus Composition in Investment Cast FSX-414Grain Selection during Solidification in Spiral Grain Selector

Microdeformation and Macroscopic Properties IDeformation Mechanisms in Ni-Base Disk Superalloys at Higher TemperaturesGrain Boundary and Intragranular Deformations during High Temperature Creep of a PM Nickel-Based SuperalloyGrain Scale Straining Processes during High Temperature Compression of a PM Disk AlloyThe Effect of gamma' Particle Size on the Deformation Mechanism in an Advanced Polycrystalline Nickel-BaseSuperalloy

Interactive Session C: Physical MetallurgySurface Effects on Low Cycle Fatigue Behavior in IN718 AlloyThe Characterisation and Prediction of LCF Behaviour in Nickel Single Crystal Blade AlloysTension/Compression Asymmetry in Yield and Creep Strengths of Ni-Based SuperalloysEffects of Low Angle Boundaries on the Mechanical Properties of Single Crystal Superalloy DD6High Temperature Creep of Directionally Solidified Ni Base Superalloys Containing Local RecrystallizationThe Effect of Thermomechanical Processing on the Microstructure and Creep Behavior of Udimet Alloy 188Failure Analysis of Weld-Repaired B-1900 Turbine Blade ShroudsHigh Temperature Microstructural Degradation of Haynes Alloy 230The Effect of Carbide Morphologies on Elevated Temperature Tensile and Fatigue Behavior of a Modified Single Crystal Ni-Base SuperalloyGamma Prime Morphology and Creep Properties of Nickel Base Superalloys with Platinum Group Metal AdditionsElevated-Temperature Creep-Fatigue Crack-Growth Behavior of Nickel-Based HAYNES R-41, HAYNES 230 and HASTELLOY X AlloysA New Hyperbolic Tangent Modelling Approach for the Creep Behavior of the Single Crystal Nickel-Based Superalloy CMSX4Assessment on the Thermo-Mechanical Fatigue Properties of 98 Ni-Base Single Crystal SuperalloysComparison of Low Cycle (Notch) Fatigue Behaviour at Temperature in Single Crystal Turbine Blade MaterialsFatigue Behavior in Monocrystalline Ni-Based Superalloys for Blade ApplicationsMicrostructural Conditions Contributing to Fatigue Variability in P/M Nickel-Base SuperalloysA TEM Investigation on Precipitation Behavior of AEREX350 SuperalloyElastic Microstrains during Tension and Creep of Superalloys: Results from In Situ Neutron Diffraction

Microdeformation and Macroscopic Properties IIMean vs. Life-Limiting Fatigue Behavior of a Nickel Based SuperalloyAssessment of Lifetime Calculation of Forged IN718 Aerospace Components Based on a Multi-Parametric Microstructural EvaluationEvaluation of the Influence of Grain Structure on the Fatigue Variability of WaspaloyFatigue Crack Initiation in Nickel-Based Superalloy Ren 88 DT at 593C

Coatings and Environmental Effects ISuperalloys for Ultra Supercritical Steam TurbinesOxidation BehaviorEffects of Oxidation and Hot Corrosion in a Nickel Disc AlloyDevelopment of Si-Bearing 4th Generation Ni-Base Single Crystal SuperalloysThe Development and Performance of Novel Pt+Hf-Modified gamma'-Ni3Al+gamma-Ni Bond Coatings for Advanced Thermal Barrier Coatings Systems

Interactive Session D: Coatings, Environmental/Microstructural DegradationThe Performance of Pt-Modified Alumina-Forming Coatings and Model AlloysOxidation of MCrAlY Coatings on Ni-Based SuperalloysOxidation and Coating Evolution in Aluminized Fourth Generation Blade AlloysD5, Formation of gamma'-Ni3Al via the Peritectiod Reaction: gamma; + beta (+ Al2O3) = gamma' (+ Al2O3)Analysis of Surface Chemical Contamination on Ex-Service Industrial Gas Turbine ComponentsLong-Term Cyclic-Oxidation Behavior of Selected High Temperature AlloysHigh Temperature Corrosion Behavior of DS GTD-111 in Oxidizing and Sulfidizing EnvironmentsThe Influence of Hot-Deformation Parameters on the Mechanical Properties and Precipitation Process in Nickel Based SuperalloyCreep Behavior of Thick and Thin Walled Structures of a Single-Crystal Nickel-Base Superalloy at High Temperatures Experimental Method and ResultsMicrostructural Degradation of CMSX-4: Kinetics and Effect on Mechanical PropertiesLong Term Coarsening of Ren 80 Ni-Base SuperalloyTemperature and Dwell Dependence of Fatigue Crack Propagation in Various Heat Treated Turbine Disc Alloys

Coatings and Environmental Effects IIDevelopment of Improved Bond Coat for Enhanced Turbine DurabilityEQ Coating: A New Concept for SRZ-Free Coating SystemsAn Investigation of the Compatibility of Nickel-Based Single Crystal Superalloys with Thermal Barrier Coating SystemsSecondary Reaction Zones in Coated 4th Generation Ni-Based Blade Alloys

High Temperature Behavior IThermal Stability Characterization of Ni-Base ATI 718Plus SuperalloyThe Precipitation and Strengthening Behavior of Ni2(Mo,Cr) in HASTELLOY C-22HS Alloy, a Newly Developed High Molybdenum Ni-Base SuperalloyEffect of Microstructure on Time Dependent Fatigue Crack Growth Behavior in a P/M Turbine Disk Alloy

Interactive Session E: Modelling, Simulation and ValidationPhase-Field Modeling of gamma' Precipitation in Multi-Component Ni-Base SuperalloysEvolution of Size and Morphology of gamma' Precipitates in UDIMET 720 Li during Continuous CoolingQuantitative Characterization of Features Affecting Crack Path in a Directionally Solidified SuperalloyModeling Topologically Close-Packed Phases in Superalloys: Valence-Dependent Bond-Order Potentials Based on Ab-Initio CalculationsMicrostructure Modeling of the Dynamic Recrystallization Kinetics during Turbine Disc Forging of the Nickel Based Superalloy Allvac 718 PlusHigh Temperature Nanoindentation of Ni-Base SuperalloysA New Analytical Method of gamma/gamma' Morphology in Single Crystal Ni-Base Superalloys: For New Orientation of Damage and Remaining Life AssessmentCharacterization of Three-Dimensional Dendritic Structures in Nickel-Base Single Crystals for Investigation of Defect Formation

High Temperature Behavior IIAtom Probe Tomography Analysis of Possible Rhenium Clustering in Nickel-Based SuperalloysDesigning of High-Rhemium Single Cristal Ni-Based Supealloy for Gas Turbine BladesNumerical Modelling of Creep Deformation in a CMSX-4 Single Crystal Superalloy Turbine Blade

Modeling, Simulation and Validation IPrecipitation Model Validation in 3rd Generation Aeroturbine Disc AlloysA Modeling Tool for the Precipitation Simulations of Superalloys during Heat TreatmentsNon-Isothermal Creep Behavior of a Second Generation Ni-Based Single Crystal Superalloy: Experimental Characterization and ModelingDevelopment of a Simulation Approach to Microstructure Evolution during Solidification and Homogenisation Using the Phase Field Method

Modeling, Simulation and Validation IIA Coupled Creep Plasticity Model for Residual Stress Relaxation of a Shot Peened Nickel-Base SuperalloyIntegration of Simulations and Experiments for Modeling Superalloy Grain GrowthPolycrystalline Modelling of Udimet 720 ForgingStudies on Alloying Element Partitioning in DMS4 Nickel Base Superalloy Using Monte Carlo Simulations and 3D Atom Probe

Author IndexSubject IndexAlloys IndexPrintSearchExit

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