Deformation-induced Phase Transformations: On-Demand Oral Presentations
Program Organizers: Yangyang Zhao, Purdue University; Jonah Klemm-Toole, Colorado School of Mines; Amy Clarke, Los Alamos National Laboratory; Janelle Wharry, Purdue University
Friday 8:00 AM
October 22, 2021
Room: On-Demand Room 7
Location: MS&T On Demand
Engineering Microstructures for Conventionally and Additively Manufactured Ni-based Superalloys: Felix Theska1; Nima Haghdadi1; Sophie Primig1; 1UNSW Sydney
Ni-based superalloys resisting high mechanical workloads in aggressive high-temperature environments are experiencing an increase in demand. Current forecasts project ~30% growth in the commercial aircraft and gas turbine markets. To continue the ongoing technological success of superalloys, multi-scale microstructural design helps to concurrently exploit various strengthening mechanisms. The complex microstructures of advanced superalloys consist of interfaces between phases, micron-sized precipitates, nanoscale precipitates, solute clusters, and interfacial segregation. Targeted engineering of these microstructural features is driven by advances in microscopy to unlock superior mechanical properties. Hot-formability and weldability are some of the current challenges and can be overcome by advanced conventional thermo-mechanical processing or additive manufacturing.In this talk, we present our recent progress in microstructural engineering and microscopy of superalloys. Advanced processing of Alloy 718 and René 41 improve strength and hot workability. Electron-beam powder-bed fusion of Alloy 738 via random point scanning promotes in-situ γ' precipitation.
Influence of 3D Microstructure on Deformation-induced Martensitic Transformation Studied by In Situ High-energy Diffraction Microscopy and Crystal Plasticity Modeling: Ye Tian1; Xiaohui Tu1; He Liu2; Ming Guan1; Peter Kenesei3; Jun-Sang Park3; Robert Suter2; Todd Hufnagel1; 1Johns Hopkins University; 2Carnegie Mellon University; 3Argonne National Laboratory
Transformation-induced plasticity (TRIP) can increase the work-hardening rate and enhance stability of plastic flow in steels through a deformation-induced martensitic transformation. The relationship between microstructure and the martensitic transformation has been extensively investigated, but additional insights can be obtained from high-energy x-ray diffraction microscopy (HEDM) which provides information about 3D microstructure and strain states. These data enable connections to crystal plasticity models representing the evolution of morphology, crystallography, and anisotropy. In this work, we investigate the deformation-induced martensitic transformation in metastable austenitic Fe-Cr-Ni alloys using in situ HEDM during tensile loading. We track the microstructure evolution and grain-averaged strain tensors, and use these data to inform and validate a crystal plasticity model that accounts for the activation of dislocation-driven and transformation-induced deformation mechanisms and volumetric changes. The validated model is used to study the competition between slip and transformation and the influence of microstructure on martensite formation.