Superalloys 2021: Wednesday Part II - Alternative Materials
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
Wednesday 11:10 AM
September 15, 2021
Room: Live Session Room
Location: Virtual Event
Session Chair: Qiang Feng, University of Science and Technology Beijing; Mathias Goken, Friedrich-Alexander-University Erlangen-Nürnberg
11:10 AM
Microstructure and Tensile Properties of a CoNi-based Superalloy Fabricated by Selective Electron Beam Melting: Sean Murray1; Kira Pusch1; Andrew Polonsky1; Chris Torbet1; Gareth Seward1; Peeyush Nandwana2; Michael Kirka2; Ryan Dehoff2; Ning Zhou3; Stéphane Forsik3; William Slye3; Tresa Pollock1; 1University of California, Santa Barbara; 2Oak Ridge National Laboratory; 3Carpenter Technology Corporation
Successful application of selective electron beam melting to a novel CoNi-based superalloy named SB-CoNi-10 is demonstrated. Crack-free as-printed microstructures exhibit excellent ductilities above 30% and ultimate tensile strengths above 1.1 GPa at room temperature in tension. Conventional post-processing consisting of a super-solvus hot isostatic pressing (HIP), a solution heat treatment (SHT), and a low-temperature aging has been applied to remove microstructural inhomogeneities present in the as-printed microstructure. The microstructures of the as-printed and HIP+SHT+Aged alloys have been investigated to determine the effect of post-processing heat treatments on the nanoscale γγ/γ′γ′ microstructure and the mesoscale grain structure. Tensile tests have been conducted at room temperature and elevated temperatures above 850 ° C to investigate mechanical properties in both the as-printed and HIP+SHT+Aged conditions. The high-temperature ductility and strength are strongly affected by the microstructure, with a mostly columnar-grained microstructure in the as-printed condition exhibiting superior ductility to the fully recrystallized microstructure in the HIP+SHT+Aged condition.
11:35 AM
Recent Developments in the Design of Next Generation γ’-strengthened Cobalt-nickel Superalloys: Stephane Forsik1; Ning Zhou1; Tao Wang1; Alberto Polar Rosas1; Gian Colombo1; Andrea Ricci1; Austin Dicus1; Mario Epler1; 1Carpenter Technology Corporation
A new ă′-strengthened Co-Ni-base superalloy was developed using a combination of computational thermodynamics and lab-scale experimental heats. Multiple 18 kg and 180 kg ingots were melted under vacuum and forged to study the composition-process-property relationship. Several heat treatments were developed to evaluate the balance between strength and creep resistance. In the fine-grain condition, the superalloy exhibits a yield strength of almost 1300 MPa at room temperature, 1071 MPa at 704 °C and 766 MPa at 816 °C. In the coarse-grain condition, the creep resistance is superior to that of Waspaloy and comparable to that of alloy 720. Sulfidation and cyclic oxidation tests show better resistance to environmental damage than Waspaloy and alloy 720 due to the formation of a protective alumina layer. We also show that this superalloy can be atomized and processed via powder metallurgy. Potential applications include discs and casings in land-based and jet engine turbines, fasteners, bolts and studs in automotive exhaust systems, and exhaust valves in internal combustion engines.
12:00 PM
The Effect of Alloying on the Thermophysical and Mechanical Properties of Co–Ti–Cr-Based Superalloys: Christopher Zenk1; Nicklas Volz1; Andreas Bezold1; Laura-Kristin Huber1; Yolita Eggeler1; Erdmann Spiecker1; Mathias Göken1; Steffen Neumeier1; 1FAU Erlangen-Nürnberg
The system Co–Ti–Cr was recently identified as a very promising base for low mass-density Co-based superalloys. This study presents the influence of quaternary alloying additions on the thermo-physical and mechanical properties of a Co–11Ti–15Cr model superalloy. Al, Ta, Re and W were selected as a starting point for alloy development as they represent important alloying elements in both Ni-based and Co–Al–W-based superalloys. Microstructure analysis reveals that the addition of only 1 at.% of either of these elements causes the formation of different undesired intermetallic phases in addition to ă and ă′ phases, which is in agreement with thermodynamic calculations. However, a diffusion-couple between the Co–Ti–Cr and a Co–Al–W–Ta alloy suggests that the tolerance for alloying elements without destabilizing the ă/ă′ two-phase microstructure is higher when they are present in a certain ratio. Energy-dispersive X-ray spectroscopy shows that Cr and Re are enriched in the ă phase whereas Ti and W preferentially partition to ă′. All alloying elements increase the yield strength at room temperature, but are disadvantageous at 1000 °C. Re and W retain their strengthening effect up to 900 °C.
12:25 PM Question and Answer Period