Superalloys 2021: Monday Part I - Alloy Development I
Program Organizers: Sammy Tin, University of Arizona; Christopher O'Brien, ATI Specialty Materials; Justin Clews, Pratt & Whitney; Jonathan Cormier, ENSMA - Institut Pprime - UPR CNRS 3346; Qiang Feng, University of Science and Technology Beijing; Mark Hardy, Rolls-Royce Plc; John Marcin, Collins Aerospace; Akane Suzuki, GE Aerospace Research
Monday 11:10 AM
September 13, 2021
Room: Live Session Room
Location: Virtual Event
Session Chair: Roger Reed, University of Oxford; Tresa Pollock, University of California - Santa Barbara
11:10 AM
Developing Alloy Compositions for Future High Temperature Disk Rotors: Mark Hardy1; 1Rolls-Royce Plc
Two new alloy compositions for possible disk rotor applications have been examined. Both were intended to have higher ' content than the existing alloy, RR1000, and be produced using powder metallurgy and isothermal forging to enable forgings to show a consistent coarse grain microstructure. Small pancake forgings of the new alloys and RR1000 were made and from these, blanks were cut, solution heat treated, cooled at measured rates and aged. Results of screening tests to understand the tensile, creep and dwell crack growth behavior, oxidation resistance and phase stability of these new alloys and coarse grain RR1000 are reported. The development alloys were similar in composition but exhibited different tensile and creep properties, phase stability and resistance to oxidation damage. Despite attempts to minimize variation in microstructure from heat treatment, differences in ' size distribution were found to influence tensile and creep behavior. One of the new alloys (Alloy 2) showed improved yield and tensile strength compared to RR1000. Alloy 2 displayed similar initial creep strain behavior to RR1000 but superior resistance to subsequent creep damage, producing longer creep rupture lives. All of the alloys showed crack retardation at low stress intensity factor ranges (K) from 3600 s dwell cycles at 700 °C in air. This occurred whilst crack growth was intergranular. Alloy 1 was found to precipitate C14 Laves phase from long term exposure at 800 °C. Like RR1000, σ phase was not detected in the new alloys after 750 hours at 800 °C.
11:35 AM
Ni-Co-based Wrought Superalloys Containing High W – Microstructure Design for a Balance of Properties: Akane Suzuki1; Steve Buresh2; Richard DiDomizio2; Scott Oppenheimer2; Soumya Nag2; Ian Spinelli2; PR Subramanian2; Stephen Pope3; Jon Schaeffer3; 1GE Global Research; 2GE Research; 3GE Gas Power
Ni-Co-based γ+γ′ superalloys were explored in a wide range of Co/Ni ratios for designing a wrought superalloy with a combination of superior high temperature strength and environmental resistance at temperatures above 927 °C (1700 °F). While alloys with high Co/Ni ratios possess superior creep resistance, reductions of the Co/Ni ratio and additions of Fe and B are effective in improving ductility in the intermediate temperature range and hold-time low cycle fatigue resistance. A formation of fine, discrete Co2W Laves precipitates covering a large fraction of grain boundaries is responsible for the improvements. The experimental alloys exhibited excellent oxidation resistance at 982 °C (1800 °F) by forming a protective alumina scale during cyclic exposure.
12:00 PM
Development of AGAT, a 3rd Generation Nickel Based Superalloy for Single Crystal Turbine Blade Applications: Jeremy Rame1; Pierre Caron2; Virginie Jaquet3; Didier Locq2; Odile Lavigne2; Mikael Perrut2; Joël Delautre1; Lorena Mataveli Suave3; Amar Saboundji3; Jean-Yves Guedou1; 1Safran Aircraft Engines; 2ONERA; 3SAFRAN Tech
The new third generation single crystal superalloy AGAT has been developed for aircraft engine turbine blade applications. Alloy design procedure is described and AGAT alloy properties are presented and compared with those of respectively 1st, 2nd and 3rd generation AM1, CMSX-4 and CMSX-10 alloys. AGAT alloy exhibits high creep resistance at very high temperature (1200 °C) compared with 1st and 2nd generation superalloys while maintaining moderate density (8870 kg·m-3) and stable microstructure unlike the 3rd generation superalloy. High cycle fatigue (HCF) and low cycle fatigue (LCF) properties of AGAT alloy are similar to 2nd generation CMSX-4 alloy. AGAT solution heat treatment allows suppressing the ã/ã’ interdendritic eutectic pools at a temperature 30 °C lower than for CMSX-10 with a shorter duration. Oxidation resistance of AGAT alloy at 1150 °C is lower than that of 2nd but higher than that of 3rd generation reference superalloys. AGAT shows low sensitivity to secondary reaction zone (SRZ) formation under b-NiPtAl bond coat (BC) and great spallation resistance of YPSZ EB-PVD thermal barrier coating (TBC) compared with reference alloys. Finally, single crystal turbine blades were successfully manufactured through industrial processes to be tested in engine conditions.
12:25 PM Invited
Enhancing the Creep Strength of Next Generation Disk Superalloys via Local Phase Transformation Strengthening: Timothy Smith1; Timothy Gabb1; Katelun Wertz2; Joshua Stuckner1; Laura Evans1; Ashton Egan3; Michael Mills3; 1NASA Glenn Research Center; 2AFRL; 3The Ohio State University
A new disk superalloy has been developed by NASA to improve high temperature creep performance utilizing the recently discovered local phase transformation strengthening mechanism. Creep tests were performed at 760°C and 552MPa, to approximately 0.3% plastic strain, a regime where the formation of ãʹ shearing modes such as superlattice extrinsic and intrinsic stacking faults are active. The new alloy exhibited superior creep performance over the current state-of-the-art superalloys, ME3 and LSHR. High resolution characterization confirmed the formation of the strengthening ç phase along superlattice extrinsic stacking faults and ÷ phase along superlattice intrinsic stacking faults. In addition, creep deformation analysis via scanning transmission electron microscopy appears to show a significant reduction in microtwin formation as compared to LSHR and ME3. This improvement in creep performance was also accompanied by an improvement in both room temperature and high temperature strength.
12:50 PM Question and Answer Period