Mechanical Response of Materials Investigated through Novel In-situ Experiments and Modeling: Session II
Sponsored by: TMS Structural Materials Division, TMS Functional Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Thin Films and Interfaces Committee
Program Organizers: Saurabh Puri, VulcanForms Inc; Amit Pandey, Lockheed Martin Space; Dhriti Bhattacharyya, Australian Nuclear Science and Technology Organization; Dongchan Jang, Korea Advanced Institute of Science and Technology; Shailendra Joshi, University of Houston; Minh-Son Pham, Imperial College London; Jagannathan Rajagopalan, Arizona State University; Robert Wheeler, Microtesting Solutions LLC; Josh Kacher, Georgia Institute of Technology
Tuesday 2:30 PM
March 21, 2023
Room: Aqua 310B
Location: Hilton
Session Chair: Manas Upadhyay, Ecole Polytechnique, Lms, Cnrs; Tijmen Vermeij, Eindhoven University Of Technology
2:30 PM Invited
Directional Hardening in Metals: GND / Bowout Mechanism: Robert Wagoner1; Stephen Niezgoda1; David Fullwood2; Guowei Zhou3; Ehsan Taghipour1; 1Ohio State University; 2Brigham Young University; 3Shanghai Jiao Tong University
Isotropic/scalar work hardening is well understood in concept: plastic deformation induces dislocation multiplication and intersection, with strengthening by higher dislocation density and shorter pin spacing. Directional/tensor metal memory has no simple microstructural interpretation. Manifestations include the Bauschinger effect, ratcheting in fatigue, back stress in creep, and anelasticity. Recent experiments and simulations suggest that anelasticity and other tensor memory effects are the result of the concurrent operation of two mechanisms: 1) development of internal stress by GND evolution and 2) bowout of dislocation segments. Evidence for this hypothesis will be summarized, new and from the literature. Experimental and simulations show that directional hardening is likely significant at all length scales and for all metals. Predictions are compared with measurements. Major References: Dayong Li and Robert H. Wagoner: The Nature of Yielding and Anelasticity in Metals, Acta Materialia, 2021, 206, doi 116625. G. Zhou, W. Jeong, E.R. Homer, D.T. Fullwood, M.G. Lee, J.H. Kim, H. Lim, H. Zbib, R.H. Wagoner: A predictive strain-gradient model with no undetermined constants or length scales, J. Mech. Phys. Solids, 2020, 145, doi 104178.
3:00 PM Invited
Effect of Macrozone Stereology on Crack Growth Rate Predictions in Ti-6Al-4V: Jaylen James1; Reji John2; Sushant Jha3; Adam Pilchak4; Raymundo Arroyave1; Eric Payton2; 1Texas A&M University; 2Air Force Research Laboratory; 3University of Dayton Research Institute; 4MRL Materials Resources, LLC
The fatigue life of near-alpha titanium alloys in service can be reduced by the presence of clusters of alpha phase with similar c-axis orientations, known as micro-textured regions (MTRs) or macrozones. MTRs provide a localenvironment that facilitates initiation and growth of sub-surface cracks. Models exist for prediction of fatigue crack growth rate taking into account both dwell time and microtextured region parameters such as size; however, to date only 2-dimensional measurements have been used as inputs to this inherently 3-dimensional problem. In the present work, the MTR regions are assumed to have the shape of prolate spheroids and the major and minor axis lengths are measured in cross-section. Then, the 3D size and shape distributions are estimated using the expectation-maximization and the Cruz-Orive spheroid unfolding algorithm. The magnitude of uncertainty in the unfolding results and implications for fatigue life models for Ti-6Al-4V will be discussed.
3:30 PM
Explicit Separation of Edge and Screw Dislocation Mobility and Density Evolution Law in BCC Single Crystal Plasticity Model: Cathy Bing1; Philip Eisenlohr1; 1Michigan State University
The plastic behavior of body-centered cubic (BCC) single crystals such as niobium (Nb) depends on the kinetics and structure evolution of lattice dislocations. For BCC symmetry, the two extreme characters of edge and screw dislocations exhibit marked differences in their glide velocities and annihilation kinetics, typically resulting in the dominance of the screw character. The model introduced in this study explicitly separates the mobility and density evolution law of edge and screw dislocation characters in BCC single crystal to investigate their distinct influence on the plasticity response.
3:50 PM
Integrated Experimental-numerical Testing of “2D” Steel Microstructures: Tijmen Vermeij1; Job Wijnen1; Ron Peerlings1; Marc Geers1; Johan Hoefnagels1; 1Eindhoven University of Technology
Recent years saw advancement in simulations of plasticity, localizations and damage of various alloys and steels, using crystal plasticity or more advanced models. However, their experimental validation, particularly at the micro- and nanoscale, remains challenging due to (i) the unknown 3D subsurface microstructure, (ii) proper matching of boundary conditions and stress states, and (iii) the intricacy of damage mechanisms. In this work ‘2D’ tensile specimens, a few microns thick over a large area, are extracted from the bulk microstructure, in this case Dual-Phase (DP) steel. Rich data is obtained: (i) the full-field thickness profile by two-sided optical profilometry, (ii) two-sided microstructure maps by BSE and EBSD, (iii) high-resolution strain maps from SEM-DIC, and (iv) careful 3D alignment of all data. The full 3D crystal structure is meshed and the material behavior is modelled using two novel CP models, which can handle discrete plasticity and anisotropic martensite plasticity, closely matching experiments.
4:10 PM Break
4:30 PM Invited
What Happens to a Microstructure after Solidification During Metal Additive Manufacturing? – an Experiment-modeling Synergistic Study: Manas Upadhyay1; 1Institut Polytechnique de Paris
During metal additive manufacturing (AM), just after melting of feedstock, the molten material rapidly solidifies. Then, for the remaining build time, it is subjected to solid-state thermal cycling (SSTC). Until recently, worldwide research efforts were heavily focused on studying the role of solidification to obtain as-built microstructures; much less focus was on studying the role of SSTC. Studying the role of SSTC is important because SSTC-induced thermo-mechanical driving forces can trigger micro-mechanisms (e.g., dislocation dynamics, phase transformations, precipitation, etc.) that can significantly alter the as-solidified microstructure and determine the as-built material’s subsequent response. In my group, we develop and use experiment-modeling synergies to study SSTC-induced microstructure evolution. In this overview talk, I will present some of our latest experiment (in-situ synchrotron XRD and electron microscopy studies) and modeling (dislocation thermo-mechanics and crystal plasticity) work. Details on each of these topics will be given in other presentations at TMS.
5:00 PM Invited
Multiscale Scattering Modeling from Deforming Titanium Alloy Polycrystals: Darren Pagan1; Kenneth Peterson1; Joel Bernier2; Jacob Ruff3; 1Pennsylvania State University; 2Lawrence Livermore National Laboratory; 3Cornell High Energy Synchrotron Source
It is well accepted that distributions of elastic strain (and stress) found in deforming polycrystals have contributions from various features in the microstructure that span length scales and are spatially heterogeneous in 3D. However, to date, efforts to model the effects of these elastic strain distributions on the broadening of X-ray diffraction peaks have primarily focused on a single length scale, likely leading to inaccurate interpretation of experimental results. Here we present a new multiscale scattering framework to capture the effects of both grain interactions and dislocation distributions present. Peak broadening of Ti-6Al-4V during uniaxial deformation, as predicted by the multiscale scattering modeling and crystal plasticity finite element modeling, is compared to experimental peak broadening measured in-situ using new high-dynamic range detection capabilities at the Cornell High Energy Synchrotron Source.
5:30 PM
Micromechanical Experimental-Numerical Study Reveals Martensite Plasticity and Damage Competition in Dual-Phase Steel: Casper Mornout1; Tijmen Vermeij1; Vahid Rezazadeh1; Johan Hoefnagels1; 1Eindhoven University of Technology
We investigate whether soft martensite plasticity mechanisms, attributed to lath morphology or substructure boundary sliding along the Habit Plane (HP), can delay/inhibit damage initiation in DP steel. ‘Damage-sensitive’ martensite notches are analyzed with state-of-the-art experimental methods: nanoscale in-situ deformation tracking, alignment to detailed microstructure maps, and categorization for each martensite variant, into HP or out-of-HP slip. Strong plasticity (>70%) is observed in martensite notches, enabled by slip along a favorably oriented HP, whereas damaged notches have unfavorably oriented HPs with limited pre-damage strains (<10%), carried by out-of-HP slip. Additionally, Crystal Plasticity (CP) simulations are performed, employing an enriched CP approach modeling a soft plasticity mechanism on the variants’ HP. The enriched CP simulations show considerably lower stresses in non-damaged and plastically deforming notches, thereby revealing that the soft HP mechanism is key for introducing the high plastic anisotropy leading to inhibition of martensite damage in highly strained martensite notches.