Superalloys 2021: Monday Part II - Alloy Development II
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 1:30 PM
September 13, 2021
Room: Live Session Room
Location: Virtual Event
Session Chair: John Marcin, Collins Aerospace; Eric Huron, GE Aviation (Retired)
1:30 PM
Segregation of Solutes at Dislocations: A New Alloy Design Parameter for Advanced Superalloys: Lola Lilensten1; Philipp Kürnsteiner1; Jaber Mianroodi1; Alice Cervellon2; Johan Moverare3; Mikael Segersäll3; Stoichko Antonov4; Paraskevas Kontis1; 1Max-Planck-Institut für Eisenforschung GmbH; 2University of California Santa Barbara; 3Linköping University; 4University of Science and Technology Beijing
The interactions of solutes with crystal defects at near atomic level were investigated in five single crystal Ni-based superalloys deformed at temperatures between 850 and 1160 °C and various deformation conditions. These interactions, and consequently the composition of a particular solute that segregates at a crystal defect, are controlled by the type of the crystal defect, the deformation conditions, i.e. temperature and stress, and the overall alloy composition. Atomistic phase field simulations also reveal the effect of dislocation velocity on the amount of solutes that can segregate on dislocations. The observed plasticity-assisted redistribution of interacting solutes phenomena result in microstructural and chemical alterations, which are associated with recrystallization, rafting and the formation of topologically close-packed phases. Deciphering these interactions by enabling quantitative three-dimensional imaging of solutes at crystal defects with high sensitivity and spatial resolution, will allow to develop a solute-defect database that can be used as a key-design parameter for advanced superalloys.
1:55 PM
A New Co-free Ni Based Alloy for Gas Turbine and Exhaust Valve Applications: Karl Heck1; Ning Zhou1; Samuel Kernion1; Danielle Rickert1; Filip Van Weereld1; 1Cartech
A new Ni based cast-and-wrought alloy designed for high temperature strength, stability, notch ductility and minimal elevated temperature dwell fatigue crack growth rate has been laboratory developed and scaled up in the mill. Based on studies of a relatively wide compositional space, a Co-free composition was selected. Other properties, including tensile strength, stress rupture, creep, low cycle fatigue, oxidation and sulfidation resistance, as well as hot workability were also studied. Several heat treatments were developed to achieve property balances as appropriate for various end-user applications such as those limited by damage tolerance, creep, fatigue or tensile strength. Microstructural stability after extended exposure at temperatures ranging from 704 °C to 871 °C was studied. Multiple 12-tonne heats have been successfully processed as VIM/VAR and VIM/ESR ingots converted into forged billets, rolled bar and strip products. Potential applications for this alloy include turbine disks, gas turbine engine casings, high temperature fasteners, heavy duty diesel engine exhaust valves and high temperature gaskets. This paper discusses alloy and process development as well as microstructure-property relationships of the alloy.
2:20 PM
Alloying Effects on the Competition between Discontinuous Precipitation vs. Continuous Precipitation of δ/η Phases in Model Ni Based Superalloys: Satoru Kobayashi1; 1Tokyo Institute of Technology
Alloying effects on the competition between discontinuous and continuous precipitation of d-Ni3Nb (D0a) phase and h-Ni3Ti (D024) phase were investigated in model Ni-Cr-Fe-Nb and Ni-Ti based alloys, respectively, to aim at designing polycrystalline Ni based superalloys with better temperature capability. Discontinuous precipitation tends to occur at lower temperatures while continuous precipitation dominates at higher temperatures in the two alloy systems. The addition of Mo promotes continuous precipitation with respect to discontinuous precipitation while that of Ti promotes discontinuous precipitation rather than continuous precipitation in d phase precipitation alloys. A replacement of Ti with Mo promotes continuous precipitation with respect to discontinuous precipitation in h phase precipitation alloys at 800 C. The observed alloying effects are discussed in terms of chemical driving force, interfacial energy between the matrix phase and the d(h) phases, and coherency strain caused by the formation of the metastable phases prior to the formation of d/h phases.
2:45 PM Question and Answer Period