Superalloys 2024: General Session 12: Disk Alloy Mechanical Behavior III
Program Organizers: Jonathan Cormier, ENSMA - Institut Pprime - UPR CNRS 3346

Thursday 10:30 AM
September 12, 2024
Room: Exhibit Hall
Location: Seven Springs Mountain Resort

Session Chair: Michael Mills, Ohio State University; Jonathan Cormier, ENSMA - Institut Pprime - UPR CNRS 3346

10:30 AM
Modeling Microstructural Development During Hot Working of Ni-based Superalloy 680: Jose Gonzalez Mendez¹; Will Heffern²; Spencer Hagaman²; Matias Troper²; Victoria Tucker²; Austin Dicus¹; Mario Epler¹; Matthew Krane²; Mike Titus²; Stephane Forsik¹; ¹Carpenter Technology; ²Purdue University
    In this work, dynamic recrystallization kinetics for a nickel alloy are characterized during hot deformation. Gleeble compression testing within a temperature range from 927 °C to 1149 °C is employed to replicate typical forging conditions with strain rate varying from 0.1 s^-1 to 10 s^-1. Microstructural and flow stress results were analyzed via the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model that describes the mechanisms triggering recrystallization during forging operations. This model considers the significant variables of hot deformation such as temperature, strain, strain rate, and initial structure. The developed model illustrates the dynamic recrystallization fraction and dynamically recrystallized grain diameter within defined temperature ranges based on the JMAK configuration. Results indicate that deformation above 1093 °C yields high dynamic recrystallization. Conversely, at lower temperatures grain structure is highly dependent on strain and strain rate. Validation tests coupling Gleeble compression tests and FE modeling comparisons covering the forging conditions are included in this study.

10:55 AM
Microstructurally Informed Material Model for Haynes® 282: Monica Soare¹; Vito Cedro III²; Vipul Gupta¹; Mallikarjun Karadge¹; Reddy Ganta³; Alon Mazor⁴; ¹GE Research; ²National Energy Technology Laboratory; ³The Energy Industries of Ohio; ⁴GE Aerospace
    The precipitation strengthened alloy Haynes® 282 possesses very good strength, creep resistance and corrosion resistance at high temperatures. It is one of the best candidates for a range of high temperature components for next generation of power systems as Advanced Ultra-Supercritical (A-USC) boilers and steam turbines, Supercritical carbon dioxide (sCO₂) power cycles as well for aerospace gas turbine parts (combustor lines, nozzles, exhaust sections). Some of these components operate for very long time (30-40 years) during which they are subjected to high temperature (up to 60% of the Liquidus Temperature, Tm) creep as well as cyclic loading (cyclic temperature and stress variations). Assessing long term material behavior through combined accelerated testing and model predictions, is an important step in the material qualification process. Towards this goal, a material constitutive model was developed capturing long term creep as well as cyclic plasticity, with and without hold time at two temperatures: 593 °C and 760 °C. The model was calibrated on creep and low cycle fatigue tests performed on smooth specimens. The model predictions were compared with experimental data performed on smooth circular and on notched specimens, in terms of stress-strain response and number of cycles to failure.

11:20 AM
Cyclic- and Dwell-fatigue Crack Growth Behavior in a Phase Transformation Strengthened Disk Superalloy: Christopher Kantzos¹; Timothy Smith¹; Jack Telesman²; Ian Dempster³; Timothy Gabb¹; ¹NASA Glenn Research Center; ²HX5 LLC; ³Wyman Gordon
    A follow-on study was performed on NASA’s recently developed Nickel-based P/M TSNA-1 disk alloy to evaluate the influence of processing on the alloy’s mechanical properties. The composition of the alloy was tailored to improve the high temperature creep strength through transformation strengthening of precipitate phases. Initial alloy development was done utilizing HIP processing. The follow-on study evaluated the properties of the forged version of the alloy which provided for a more realistic processing history similar to that utilized in the engine industry. The creep performance of the forged material significantly exceeded the original HIP material, and outperformed alloys like LSHR and ME3 by an order of magnitude. The TSNA-1 alloy’s cyclic and dwell FCG behavior was also characterized. While the HIP condition the alloy exhibited very poor dwell FCG resistance in comparison to the LSHR P/M disk alloy, the forging processed TSNA-1 drastically improved the crack growth behavior. In the forged condition both cyclic and dwell FCG behavior of the alloy were equivalent to a current LSHR P/M alloy.

11:45 AM
Formation of the γ'''-Ni2(Cr, Mo, W) phase during a two-step aging heat treatment in HAYNES® 244® Alloy: Thomas Mann¹; Victoria Tucker²; Peter Kenesei³; Jun-Sang Park³; Reza Roumina⁴; Emmanuelle Marquis⁴; Michael Fahrmann¹; Michael Titus²; ¹Haynes Intl.; ²Purdue University; ³Argonne National Laboratory; ⁴University of Michigan
    Precipitation hardening is the dominant method of achieving high strength in most Ni-based superalloys. The formation of nanoscale precipitates during thermal exposure is often studied to determine the optimal methods of attaining high strength. The commercial Ni-based superalloy, HAYNES® 244® alloy, is strengthened through a novel γ'''-Ni₂(Cr,Mo,W) intermetallic phase that forms during a two-step aging cycle. The precipitation kinetics of this intermetallic γ''' phase are sluggish for single-step aging in comparison to the γ' phase in precipitation strengthened Ni-based alloys, but a two-step aging treatment has shown to reliably harden the alloy and improve high temperature properties compared to a single-step aging heat treatment. To investigate the formation and coarsening of this phase, heat treated samples of the 244 alloy were analyzed with high energy in situ and ex situ X-ray techniques such as small angle X-ray scattering and wide angle X-ray scattering as well as Vickers microhardness, electron microscopy, and atom probe tomography. The relationship between hardness, aging parameters, and microstructure evolution are discussed. The enthalpy of formation and precipitate solvus temperature were determined with high temperature differential scanning calorimetry and dilatometry analysis.