Mechanical Response of Materials Investigated Through Novel In-Situ Experiments and Modeling: Session IV
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, Microstructure Engineering; 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; Josh Kacher, Georgia Institute of Technology; Minh-Son Pham, Imperial College London; Jagannathan Rajagopalan, Arizona State University; Robert Wheeler, Microtesting Solutions LLC

Wednesday 8:30 AM
March 2, 2022
Room: 206B
Location: Anaheim Convention Center

Session Chair: David Rowenhorst, Naval Research Laboratory; Ashley Bucsek, University of Michigan

8:30 AM  Invited
High Energy X-ray Diffraction – Seeing Data through a Model: Matthew Miller1; 1Cornell University
    High Energy X-ray Diffraction (HEXD) experiments - conducted at a synchrotron x-ray beamline - have evolved enormously since their introduction over two decades ago. Enhanced area detectors and greatly increased x-ray flux at the x-ray beamline have made seemingly impossible experiments possible. Raw HEXD data, which are literally a list of intensities associated with each detector pixel number, are encoded with valuable structural and mechanical information from multiple size scales and locations within a sample. Material modeling results are often compared to HEXD data but many times models are needed for even the most basic interpretation of the HEXD data. This talk describes several model/HEXD data scenarios from experiments conducted on polycrystalline metals over the past several years at the Cornell High Energy Synchrotron Source (CHESS) and the Advanced Photon Source (APS) examining processes such as plasticity, fatigue, residual stress and hydrogen embrittlement.

9:00 AM  Invited
In Situ 3D Characterization and Crystal Plasticity Modeling of Martensite Formation in Austenitic Steels : Todd Hufnagel1; Ye Tian1; 1Johns Hopkins University
    The martensitic transformation under mechanical loading can have an important effect on plastic deformation of austenitic steels and is expected to be sensitive to microstructure in polycrystalline alloys, and in particular on the local grain orientations and grain boundary character. In this talk, we will describe the use of high-energy diffraction microscopy to track microstructure evolution in situ during uniaxial tensile loading of austenitic Fe-Cr-Ni alloys. The first martensite we observe is the hcp epsilon phase, and as the strain increases we observe formation of the bcc alpha-prime phase in close proximity to the previously-formed epsilon martensite. We used the HEDM data to validate a crystal plasticity model that accounts for dislocation slip as well as deformation-induced formation of both martensite phases, including the effect of dilatation due to the transformation, and used this model to investigate the effect of microstructure on the transformation.

9:30 AM  
Modeling In-situ X-ray Diffraction of Dislocation Evolution during Selective Laser Melting of 316L Stainless Steels with Discrete Dislocation Dynamics and GPU-accelerated Raytracing: Dylan Madisetti1; Markus Sudmanns1; Christopher Stiles2; Jaafar El-Awady1; 1Johns Hopkins University; 2Johns Hopkins University Applied Physics Laboratory
    Large-scale, three-dimensional (3D) discrete dislocation dynamics (DDD) simulations are used to capture the in-situ evolution of predicted X-ray diffraction (XRD) measurements: specifically, dislocation cell-wall formation during the cooling stage of selective laser melting of 316L. These simulations enable the simultaneous study of temperature, dislocation microstructure, alloy composition, interstitial concentration, and solute stresses. The atomic representations of 316L from density functional theory calculations are used in a GPU-accelerated X-ray ray-tracing method. The resultant reflected X-ray is captured by a virtual sensor resulting in micro-Laue or Debye-Scherrer images. Using supercomputing resources, this ray-tracing process can be performed continuously as the dislocation microstructure evolves. These in-situ simulations exhibit peak broadening, peak shift, and spread of select Laue spots, which are phenomena observed in experimental measurements. Microstructures from DDD are utilized to understand spot distortion, providing insight into experimental in-situ XRD and observed underlying microstructure evolution.

9:50 AM Break

10:10 AM  Invited
The Development of a Laboratory-scale High-energy Diffraction Microscopy Instrument: Ashley Bucsek1; Reza Roumina1; Anasuya Adibhatla2; Robert Drake3; 1University of Michigan; 2Excillum Inc.; 3Proto Mfg.
    The synchrotron-based 3D X-ray diffraction technique known as high-energy diffraction microscopy (HEDM) can be used to nondestructively measure 3D microscale information including the elastic strain tensor, crystallographic orientation, location, and volume of each grain for many hundreds to thousands of grains. For this reason, HEDM is arguably one of the most powerful experimental tools we have for mapping the interplay between micro- and macroscale material behavior. Currently, HEDM is only available at select synchrotrons around the world. Here, we present a laboratory-scale HEDM instrument that utilizes an indium liquid-metal jet X-ray source to produce a monochromatic 24 keV parallel box beam suitable for near-field and far-field HEDM measurements on bulk (~1 mm) single crystal, polycrystalline, or granular materials, particularly those composed of light elements (e.g., Al, Mg, Li). We discuss the design and construction of this instrument and present preliminary results.

10:40 AM  Invited
Using High Energy X-rays to Investigate the Evolution of Plastic Strain and Damage in Additively Manufactured 316L Stainless Steel: David Rowenhorst1; Aeriel Leonard2; 1Naval Research Laboratory; 2Ohio State University
    Additive manufacturing (AM) has presented a new processing route for structural alloys, but also leads to highly complex microstructure and defect populations. In this study we examine the behavior of the evolution of damage, texture, and strain in additive manufactured (AM) 316L stainless steel produced via laser powder bed fusion using in-situ tensile loading using high energy X-rays at the Cornell High Energy Synchrotron Source (CHESS). A combination of computed tomography and diffraction tomography was used to reconstruct the defect structure, texture, and strain in the material as it was loaded in tension. The results showed considerable changes in the crystallographic texture during loading. Additionally the inhomogeneous distribution of porosity near the as-built surface played a significant role in the failure of the material as voids and cracks initiated at pre-existing pores coalesced, leading to the eventual failure of the sample.