Advancing Current and State-of-the-Art Application of Ni- and Co-based Superalloys: Poster Session
Sponsored by: TMS Structural Materials Division, TMS: High Temperature Alloys Committee, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Chantal Sudbrack, National Energy Technology Laboratory; Mario Bochiechio, Pratt & Whitney; Kevin Bockenstedt, ATI Specialty Materials; Katerina Christofidou, University of Sheffield; James Coakley, Chromalloy; Martin Detrois, National Energy Technology Laboratory; Laura Dial, Ge Research; Bij-Na Kim; Victoria Miller, University of Florida; Kinga Unocic, Oak Ridge National Laboratory
Monday 5:30 PM
February 24, 2020
Room: Sails Pavilion
Location: San Diego Convention Ctr
G-1 (Invited): The Role of Heteroepitaxial Recrystallization in the Determination of the Grain Size Distribution during Thermomechanical Processing of Ni Base Superalloys: Cameron Hale1; Eric Payton2; Victoria Miller1; 1University of Florida; 2Air Force Research Laboratory
The recently discovered heteroepitaxial recrystallization (HeRX) mechanism was originally described as a curiosity that only happened under narrow conditions. However, this experimental and characterization work illustrates that it is active under a much wider range of conditions. Furthermore, the activity of this mechanism can be controlled via changes to the processing schedule, resulting in substantial changes to the shape of the grain size distribution. Further controlling this mechanism offers a new avenue for the control of grain size and the resulting mechanical performance of superalloys.
G-2: Application of Computed Tomography as Non-destructive Test in Development Process of Aircraft Ni Superalloys Castings: Dorota Wyrobek1; Rafal Cygan1; Grzegorz Labaj1; 1Consolidated Precision Products Poland
The reduction of quantity of destructive tests on castings for aircraft engines in development process become very important issue in fast process implementation. The aim is to maintain high product quality using minimum time for development, especially when parts are needed for new engine tests, while no hard tooling is available. Computed tomography (CT) as relatively fast, however still not cheap method, can support new products implementation. Thanks to using CT, it is possible to define in short time dimensions, including wall thickness, internal features for complicated cored castings, as well as determine discontinuity of the material such as porosity. To be able to quantify it, correlation between image and real parts from examined alloy have to be known. The polycrystalline turbine blades and multi vane segments made from nickel-base superalloys are subject of the study. CT tests were performed using various tomography systems to obtain desirable effects.
G-3: Evaluating the Hydrogen Environment-assisted Cracking Susceptibility of a Next-generation Co-Ni Alloy for Marine Fastener Applications: Zachary Harris1; Charles Demarest1; Brendy Rincon Troconis2; John Scully1; James Burns1; 1University of Virginia; 2University of Texas at San Antonio
Due to the in-service failures of Monel K-500 components from hydrogen environment-assisted cracking (HEAC), there has been significant interest in identifying a replacement alloy for use in marine fastener applications. One candidate system is the Co-Ni alloy MP98T, which exhibits an excellent combination of toughness, strength, and corrosion resistance. However, minimal evaluation of MP98T’s HEAC susceptibility has been performed. In this study, a slow-rising stress intensity (K) testing framework was utilized to measure HEAC kinetics for MP98T immersed in 0.6 M NaCl and polarized to electrochemical potentials ranging from -1000 to -1300 mVSCE, where Monel K-500 is known to be susceptible to HEAC. Results indicate a clear decrease in HEAC susceptibility for MP98T over Monel K-500, with HEAC not observed in MP98T until -1300 mVSCE. The mechanistic underpinnings for this improvement are explored based on an assessment of pertinent mechanical properties, hydrogen-metal interactions, and differences in alloy microstructure.
Cancelled
G-6: Phase-field Informed DDD Study: Dependence of Microstructural Evolution on the Crystallographic Orientations in Ni-based Single Crystal Superalloys: Harikrishnan Rajendran1; Jean- Briac le Graverend1; Amine Benzerga1; 1Texas A&M University
Single-crystalline turbine blades, made of Ni-based superalloys, are cast in <001> direction. While crystalline misorientations up to 5-degree are within accepted tolerance, the complex blade geometries result in slight deviations from perfect orientations resulting in mistuning among blades. In this study, we first utilize a phase-field model for generating cuboidal and rafted microstructures in <001>, <011> and <111> crystal orientations. The orientation of γ’ precipitates and direction of rafting is at 45-degrees to the load axis in <011> but is parallel/ perpendicular to the load in <001>. Perhaps, the 45-degree rafts may not be a significant obstacle for the dislocations trying to shear the strong precipitates as compared to the perpendicular rafts. Therefore, to investigate the plastic activity and the evolution of dislocation networks in various crystalline orientations, a discrete dislocation dynamics (DDD) study will be carried out in a high-temperature 2.5 D framework using the phase-field informed γ/γ’ realizations.
G-7: The Role of Microstructural Homogenization on Tensile and Stress-rupture Behavior of Selective Laser Melted Nickel Based 718 Alloy: Shahzad Salam1; Ichiro Mitama1; Takuma Sakata1; 1Sumitomo Heavy Industries LTD.
The effects of homogenization and HIP treatment on tensile and stress-rupture properties of selective laser melted 718 alloy were investigated. Samples were homogenized at 1065°C/4h or 1140°C/4h prior to industrial solution (982°C/1h) and double aging treatment (718°C/8h+621°C/8h) specified in AMS5663. Additional samples were subjected to hot-isostatic-pressing (HIP) at 1065°C/4h or 1140°C/4h under uniform stress of 100MPa prior to solution and aging. Tensile properties were determined at 25°C and 649°C in air, and stress-rupture tests were conducted at 649°C under a constant stress of 689MPa. Specimen without homogenization/HIP treatment exhibited inferior high-temperature ductility and rupture-life. Ductility improved significantly with homogenization/HIP treatments in both horizontal and vertical orientations due to grain recrystallization and interdendritic δ-phase dissolution. Specimen homogenized/HIP treated at 1140°C/4h exceeded the minimum high-temperature tensile requirements specified in AMS5663. Although the rupture-life also improved by homogenization/HIP treatments, minimum requirement of 23h of rupture life was not realized.