ICME 2023: Linkages: Microstructure II
Program Organizers: Charles Ward, AFRL/RXM; Heather Murdoch, U.S. Army Research Laboratory
Wednesday 9:40 AM
May 24, 2023
Room: Caribbean VI & VII
Location: Caribe Royale
Session Chair: Michael Uchic, Air Force Research Laboratory
9:40 AM
Plastic Deformation and Failure Predictions of Al-6061 With Inhomogeneities Using Finite Element Modeling Techniques Across Different Length Scales: Nicole Aragon1; Aashique Rezwan1; Ill Ryu2; Hojun Lim1; 1Sandia National Laboratories; 2The University of Texas at Dallas
The presence of a void or secondary particle generates a stress concentration and plays a crucial role in both the mechanical response and damage evolution of metals. This work presents local stress and strain field predictions in a single crystalline matrix near a spherical void or hard inclusion. To characterize the effect of a material inhomogeneity, different modeling techniques at various length scales are utilized, such as an isotropic J2 plasticity finite element model, a coupled dislocation dynamics-finite element model, a crystal plasticity finite element model, and a phase-field fracture model. In this talk, simulation results from each model will be presented with the aim of correlating the defect microstructure characteristics and the macroscopic material behavior. In addition, results will be compared with the intention of bridging simulation length scales to obtain a better understanding of the influence of crystallographic orientation and its effect on failure predictions.
10:00 AM Cancelled
Numerical Characterization of the Effect of Precipitates on the Creep Responses of Steel Alloys: Arul Kumar Mariyappan1; Laurent Capolungo1; 1Los Alamos National Laboratory
The engineering components of steel alloys in energy sectors are mostly operated at high-temperature and low-to-moderate stresses. Introducing precipitates by prior aging process is one of the strategies to improve the creep resistance, mainly in the dislocation glide-dominated operating condition. However, the available limited experimental observations show that the precipitates can also degrade the creep performances. Thus, understanding and quantifying the role of precipitates on the high-temperature creep behavior is critical. In this work, an advanced constitutive model within the full-field elasto-visco-plastic fast Fourier transform (EVPFFT) framework is developed to capture the effect of precipitate size and density on the creep responses of grade-91 and 347H alloys. The model calculation finds that the annihilation/depletion of dislocations, which is governed by the precipitates, during the primary-to-secondary transition modulates the creep rates. In turn, based on the rate of dislocation annihilation, increasing precipitate content can either increase or decrease the creep responses.
10:20 AM
Nanoscale Precipitation Strengthening Mechanisms in CoCrNi-based Medium Entropy Alloys: Ning Zhang1; Charles Matlock1; 1Baylor University
Precipitation strengthening has been proven to be a very effective method to improve the strength, especially the yield stress of alloys. In this work, uniaxial simulations were conducted on medium-entropy alloy, CrCoNi, under temperatures of 77 K and 298 K. Through precipitating Al, Fe, Cu, and Mn in the grain boundaries (GBs) of polycrystalline CoCrNi alloys, the strength and stiffness were significantly improved. Even with a low content (~0.4%) of dopant, the ultimate strength and stiffness were observed to be enhanced by 28% and 37.5%, respectively. Analysis of the deformed configurations reveals that the doped metallic ions play a role of inhibiting GBs sliding and subsequently lead to fcc to hcp phase transformation, as well as multiple inter and intra dislocations. Types of elements also exhibit an effect on the enhancement behavior due to different binding energies, which was demonstrated by the DFT calculations.
10:40 AM
An ICME workflow to assess the process sensitivity of the heat treatment of IN718: Taiwu Yu1; Thomas Barkar1; Carl-Magnus Lancelot1; Paul Mason1; 1Thermo-Calc Software
In developing workflows to describe the process-structure-property relationships, the first step is to calibrate the models producing the best fit to experimental data. Once this is attained, the value of ICME is the ability to vary the process variables to understand the sensitivity of the simulation to different processing conditions and chemistry variations.In this example, a Python enabled workflow is used to combine thermodynamic, kinetic and precipitation calculations to simulate the microstructure in terms of the nucleation and growth of the secondary phases which are then correlated with a simplified yield strength model to predict the precipitate, grain boundary and solid solution strengthening. Model variables are adjusted to give the best fit to experimental data and the framework is then used to adjust different processing conditions such as solution annealing temperature, aging temperature and holding time to assess the sensitivity to process variables and chemistry variation.
11:00 AM
A Generative Adversarial Network for the Creation of Complex 3D Bimodal Polycrystalline Microstructures: Application to Cold-spray Al7050 Alloy: Brayan Murgas1; Joshua Stickel1; Somnath Ghosh1; 1Johns Hopkins University
A methodology to generate synthetic bimodal polycrystalline microstructures is presented. This work develops a model that couples a Generative Adversarial Network (GAN) and a classic microstructure generator to create statistically equivalent microstructures that match the surface fraction, texture, grain size, aspect ratio, and misorientation angle distributions of the EBSD data. Bimodal microstructures are composed of coarse grains and ultra-fine grains. The proposed methodology can generate bimodal microstructures obtained via rolling and annealing, severe plastic deformation, powder metallurgy, sintering, or cold-sprayed materials. This work presents the reconstruction of a cold-sprayed Al7050 alloy. Computational research is needed to understand the process-microstructure-property relationship with the goal of characterizing the fatigue life of the coatings. The generated microstructures subjected to tension along three orthogonal directions show different local and average mechanical behavior with changes in the yield stress and hardening.