Advanced Characterization Techniques for Quantifying and Modeling Deformation: Session IV
Sponsored by: TMS Extraction and Processing Division, TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Materials Characterization Committee
Program Organizers: Mariyappan Arul Kumar, Los Alamos National Laboratory; Irene Beyerlein, University of California, Santa Barbara; Wolfgang Pantleon, Technical University of Denmark; C. Tasan, Massachusetts Institute of Technology; Olivia Underwood Jackson, Sandia National Laboratories

Tuesday 2:30 PM
March 1, 2022
Room: 207A
Location: Anaheim Convention Center

Session Chair: Carlos Tome, LANL

2:30 PM  Invited
Applications of an Efficient Elasto-visco-plastic Self-consistent Polycrystal Model Interfaced with a Finite Element Framework: Youngung Jeong1; Carlos Tome2; Bohye Jeon1; Mooyeong Joo1; 1Changwon National University; 2Los Alamos National Laboratory
    We present a computationally efficient elasto-visco-plastic self-consistent polycrystal model (EVPSC), based on homogeneous equivalent medium method. The model inherits the predictive capabilities of the well-known visco-plastic self-consistent polycrystal model VPSC and has been recently interfaced with a commercial finite element software (Abaqus) as user material subroutine (EVPSC-FE). The performance and capabilities of EVPSC-FE are demonstrated by comparing with the stand-alone version. For doing so, we applied the model to an FCC 316L stainless steel, a BCC low-carbon steel, and HCP zirconium, respectively. In order to quantify the computational efficiency, the uniaxial tension simulations were repeatedly conducted for simple solid structures consisting of 8, 27, 64, and 512 elements, allowing the use of multiple CPU core units. A four-point beam bending simulation followed by holding and unloading was conducted to demonstrate the unique modelling capabilities of the model. The hereditary effect on spring-forward and backward deformation is discussed.

3:00 PM  
Prismatic Slip Induced Interface Sliding in Alpha/Beta Titanium Alloys: Zachary Kloenne1; Stoichko Antonov2; Gopal Viswanathan1; Michael Loretto3; Hamish Fraser1; 1Ohio State University; 2Max-Planck-Institut fr Eisenforschung GmbH; 3University of Birmingham
    Titanium and its alloys have shown to deform through a combination of dislocation slip and deformation twinning. Grain boundary sliding has also been reported to contribute to the plasticity of CP titanium and Ti-6Al-4V, though these results have been reported far less frequently. More recently, Ti-1Al-4V-0.25Si-0.25Fe-0.15O has been shown to deform through sliding at the alpha/beta interface. Whilst interface sliding appears to be a slip-stimulated event, significant strain gradients were observed in response, thus speculating the presence of GNDs. The nature of these dislocations were studied using a split dislocation density analysis by HR-EBSD. Absolute character of the dislocations involved were confirmed by trace analysis in the TEM. Additionally, the sequence of events, and associated plastic strain, were studied via in-situ straining in the SEM coupled with HRDIC. Interestingly, APT results showed a Si enrichment at the alpha/beta interface. The effect of Si on sliding was studied further.

3:20 PM  
Analysis of RVE Size Based on Slip Activity Using Far-field HEDM Data: Rachel Lim1; Anthony Rollett2; Darren Pagan1; 1Pennsylvania State University; 2Carnegie Mellon University
    Acquisition and analysis of 3D microstructural data takes a significant amount of time and computational resources, driving a need to determine the minimal amount of data necessary to be statistically significant. A new method to evaluate representative volume element (RVE) size, the smallest volume that statistically reflects the macroscopic properties of a material, is presented. Resolved shear stresses (RSS) are calculated from far-field high energy x-ray diffraction microscopy data of a sample of Ti-7Al loaded to 2.5% strain. Analysis of the RSS distributions reveal increasing levels of spatial homogeneity as the strain was increased, indicating that for the Ti-7AL tested, RVE size appears to decrease with the amount of deformation.

3:40 PM  
Strain Accommodation Mechanisms in the Near Alpha Ti-6Al-2Sn-4Zr-2Mo Alloy Studied Using Experiments and Simulations: Samuel Hemery1; Azdine Nat-Ali2; Mikael Gueguen2; Olga Smerdova2; Christophe Tromas2; 1Institute Prime - Ensma; 2Institut Pprime
    In spite of decades long research focused on deformation in Ti alloys, the understanding of the early slip activity regime is still incomplete. In this context, performance prediction under cyclic loadings such as experienced in-service is difficult. In this context, characterization of operating deformation mechanisms was carried out using in-situ SEM tensile tests combined with electron back-scattered diffraction. Additional information about the slip character was obtained using atomic force microscopy. A specific attention was paid on the sequential activation of the different strain accommodation mechanisms including slip and twinning, and the relation to room temperature creep / stress relaxation. A CRSS dataset for the different slip and twinning modes observed is then derived and validated using fast-Fourier transforms based simulations. New insights into the fatigue and dwell-fatigue behaviors are finally discussed.