Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales III: Session II
Program Organizers: Arul Kumar Mariyappan, Los Alamos National Laboratory; Irene Beyerlein, University of California, Santa Barbara; Levente Balogh, Queen's University; Caizhi Zhou, University of South Carolina; Lei Cao, University of Nevada; Josh Kacher, Georgia Institute of Technology
Monday 2:00 PM
October 18, 2021
Room: B246
Location: Greater Columbus Convention Center
Session Chair: M Arul Kumar, Los Alamos National Laboratory; Aaron Tallman, Los Alamos National Laboratory
2:00 PM Invited
Developing Surrogate Models for Crystal Plasticity-based Creep by Leveraging Macroscale Constitutive Relations: Aaron Tallman1; Laurent Capolungo1; 1Los Alamos National Laboratories
Simulations of metal creep are critical to the design of next-generation powerplants. In candidate material systems, material performance can be tied to precipitate strengthening, dynamic strain aging, and other mechanisms that act at the length scale of individual dislocations. Models of creep that include these mechanisms in a crystal plasticity framework are necessarily complex--compared to traditional materials models used at the component-scale. Approximation or model reduction can be used to deliver the mechanistic response of these advanced materials in a quick-to-execute material model for component scale finite element simulations. Data-driven, regression-based surrogate models can address this need, yet they may behave unpredictably in simulations of complex material responses. We propose a hybrid approach that repurposes kinematic and mechanistic constitutive formulations in a data-driven calibration scheme to generate component-scale surrogate constitutive material models that can provide consistent predictions of transient and steady-state creep and response to changes in load and temperature.
2:30 PM
Weldment Finite Element Modeling and Validation for Integration with CALPHAD Tools: Daniel Bechetti1; Jacob Steiner1; Charles Fisher1; 1Naval Surface Warfare Center, Carderock Division
Arc welding is an essential fabrication process that should be considered when computationally designing materials in order to increase the likelihood of successful adoption. Welding involves temporal and spatial variations in temperature ranging from above the melting temperature during initial deposition to repeated sub-solidus thermal excursions in the weld metal and base metal heat affected zones (HAZs) during subsequent weld passes. As such, an integrated approach that enables design for both desirable solidification behavior and microstructural stability during reheating should be considered for novel base and welding filler material combinations. This work discusses a methodology for finite element analysis (FEA) of multipass weldments via the SYSWELD software package, automated post-processing to extract location-dependent thermal history metrics, and input of those data into CALculation of PHAse Diagrams (CALPHAD)-based models for prediction of weld metal and HAZ microstructure. It presents a workflow aimed at combining continuum and thermodynamic models to enable compositional down selection and optimization. Application of the method to a novel austenitic steel alloy will be discussed.
2:50 PM
Now On-Demand Only: Rapid Screening of High-throughput Ground State Predictions: Sayan Samanta1; Axel van de Walle1; 1Brown University
High-through computational thermodynamic approaches has been gaining popularity in the field of novel alloy design. However, traditional techniques are often limited to stability predictions of stoichiometric phases calculated at 0 K. There is an inherent risk in these methods such as identifying an excess of possible phases that are not stable at temperatures of practical relevance. We demonstrate how the Calphad formalism, informed by simple first-principles input can be simply used to overcome this problem at a low computational cost and deliver quantitatively useful phase diagram predictions at all temperatures. We illustrate the method by re-assessing prior compound formation predictions on the Iridium-Ruthenium binary alloy system and reconcile these findings with long-standing experimental evidence to the contrary.
3:10 PM Invited
Lab-based Diffraction Contrast Tomography: Achieving Large Volume Grain Statistics for Full Field Modeling of Polycrystalline Materials: Jun Sun1; Jette Oddershede1; Florian Bachmann1; Hrishikesh Bale2; William Harris3; Erik Lauridsen1; 1Xnovo Technology; 2Carl Zeiss X-ray Microscopy; 3Carl Zeiss Microscopy, LLC
Computational modeling of polycrystalline materials on the mesoscopic scale is a powerful tool to examine, interpret, as well as predict the dynamic behaviors of polycrystalline materials. Compared to synthetic grain structure, a full field experimentally acquired 3D grain map has an unprecedented advantage as it represents the inherent materials anisotropy, such as texture and abnormal grain size distribution that can be challenging to synthetize through simulation. Lab-based diffraction contrast tomography (LabDCT), with the recent advancements in data acquisition approaches, allows recording and reconstructing of large representative volumes seamlessly. We will present different acquisition strategies with emphasis on how to approach a given acquisition problem inherent to the sample and provide examples of how such experimental data can be used for either validation or as input for simulation. Moreover, with its nondestructive nature, LabDCT enables time resolved studies of the response of the materials when exposed to various external stimuli.
3:50 PM Break
4:10 PM
Physics-based Full-Field Fast Fourier Transform Modeling of Creep Behavior: Application to 347H Steel: Arul Kumar Mariyappan1; Ricardo Lebensohn1; Laurent Capolungo1; 1Los Alamos National Laboratory
Austenitic stainless-steels are widely used in energy sectors including nuclear and fossil industries for many engineering components, and mostly operating at high temperature regime. Developing a numerical framework to capture creep and strain hardening behavior of steels is important to predict the life and certify the materials for desired applications. In this work, a mechanistic constitutive model with explicit stress and temperature dependence is developed and implemented within a full-field elasto-visco-plastic Fast Fourier Transform (EVPFFT) framework. Thermally-activated glide and climb of dislocations, and vacancy diffusional creep mechanisms are considered. Using this framework, uniaxial stress-strain responses and thermal creep responses of 347H stainless steel as a function of temperature are simulated. The model predicted results are validated against the experimental measurements and the relative roles of the different deformation mechanisms (dislocation glide, climb and diffusional creep) are discussed.
4:30 PM
A Physics-based Crystal Plasticity Constitutive Model Incorporating the Dynamic Strain Aging: Application to 347H Steel: Veerappan Prithivirajan1; Nathan Beets1; M Arul Kumar1; Bjorn Clausen1; Ricardo Lebensohn1; Laurent Capolungo1; 1Los Alamos National Laboratory
Dynamic strain aging (DSA) is a process in which solute atoms diffuse toward the mobile dislocations, temporarily pinned at the obstacles. DSA causes additional drag on the dislocations, potentially leading to jerky dislocation motion, abrupt decrease in strain hardening, and eventually leading to instability in plastic flow. DSA depends on the temperature, strain rate, and the loading scenario. In this work, we develop a physics-based constitutive model for DSA within the crystal plasticity modeling framework to capture the DSA effect on mechanical behavior. To guide and validate the model, we performed in-situ neutron diffraction experiments during continuous mechanical loading with stress-hold (i.e., strain relaxation) at two different temperatures. Using the developed model, we simulate both simple thermal creep and complex stress-hold loading conditions in 347H steel at different temperatures to quantify the role of DSA.
4:50 PM
Full-field Modeling of Vacancy Diffusion in a Crystal Plasticity Framework: Aritra Chakraborty1; Nathan Beets1; Mariyappan Arul Kumar1; Ricardo Lebensohn1; Laurent Capolungo1; 1Los Alamos National Laboratory
At high homologous temperature and low-to-moderate stresses vacancy diffusion-mediated plasticity can dominate the creep response of the material. In practice, diffusional flow can occur either by Coble creep (grain boundary diffusion), Nabarro–Herring creep (lattice diffusion) or dislocation creep. In this work, we aim to develop and validate a three-dimensional fully coupled mechanistic diffusion model that can accurately capture these phenomena and predict creep rates observed at such conditions of temperature and stress. Kinematic coupling between dislocation glide and diffusion occurs through the diffusion strain rate tensor that is incorporated into the total strain rate assuming additive decomposition in a small-strain framework. Subsequently, we modulate the different adjustable parameters of the model to gauge their relative influence. Finally, we compare our results to a simplistic one-dimensional diffusional model to determine the importance of having a proper physical description of the diffusion phenomena.
5:10 PM
Simulation of Creep and Uniaxial Strain in 316H Steel via a Fully Mechanistic Fast Fourier Transform Based Crystal Plasticity Constitutive Model: Nathan Beets1; Laurent Capolungo1; Arul Kumar Mariyappan1; Ricardo Lebensohn1; 1Los Alamos National Laboratory
Modeling the mechanical response of materials from the dynamic interplay of different microstructural phenomena is critical for material response prediction and development. We present a mechanistic crystal plasticity constitutive model, which is used to simulate thermal creep and uniaxial stress strain conditions. A dislocation kinetics law defines local plastic slip with latent hardening evolution which includes a contribution from precipitate concentration. Diffusion is modeled with a Coble creep law. Dislocation climb is modeled via activation law dependent on the concentration and diffusivity of vacancies. This framework is incorporated into a full field, Fast Fourier Transform (FFT) parallelized solver that predicts the local and global material response while also capturing microstructural evolution. The creep response for 316H steel under various conditions of temperature, stress, and precipitate content is predicted and compared to experimental measurements. The relative contribution of various mechanisms is analyzed and is represented with an Ashby Weertman map.