Advanced Characterization Techniques for Quantifying and Modeling Deformation Mechanisms: Session VIII
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Shaping and Forming Committee
Program Organizers: Rodney McCabe, Los Alamos National Laboratory; John Carpenter, Los Alamos National Laboratory; Thomas Beiler, Michigan State University; Khalid Hattar, Sandia National Laboratory; Wolfgang Pantleon, DTU; Irene Beyerlein, Los Alamos National Laboratory

Thursday 2:00 PM
March 2, 2017
Room: 33C
Location: San Diego Convention Ctr

Session Chair: Cody Miller, Los Alamos National Laboratory; Fulin Wang, Department of Materials Science and Engineering, University of Virginia

2:00 PM  
Progress on Measuring the Transient Dynamic Strength of Rapidly Heated Plain Carbon Steels: Steven P. Mates1; Sindhura Gangireddy1; Mark Stoudt1; 1National Institute of Standards and Technology
    Plain carbon steels with ferrite-pearlite microstructures can exhibit time-dependent strength owing to austenite nucleation and growth during rapid heating. Such time-dependent mechanical behavior can become important under dynamic, high temperature and high strain deformation conditions encountered during high speed machining or other rapid manufacturing processes. The present work uses a rapidly-heated, high strain rate mechanical test to study the effect of temperature and time on the amount of pearlite dissolved and the resulting transient effect on dynamic strength of a 1045 steel. Dynamic strength measurements are correlated to time, temperature and the amount of transformation observed in tested samples.

2:20 PM  
Parameter Estimation in Crystal Plasticity Based Material Models: Aritra Chakraborty1; Philip Eisenlohr1; 1Michigan State University
    Predicting deformation behavior based on external load relies on constitutive descriptions through material models. To capture the inherent deformation anisotropy, crystal plasticity simulations have proved efficient. Efficacy critically depends on the accurate determination of constitutive parameters used in these models. Generally, such problems are ill-posed due to the strongly non-linear model equations. The direct estimation of such parameters from experiments (such as slip trace analysis) is challenging and results vary with experimental conditions. To overcome such uncertainty, an efficient inverse optimization approach is suggested to estimate constitutive parameters by comparing simulated and experimental responses to single crystal indentation. Robustness of such an approach is tested by applying it to different crystal lattice systems. Success of such a study would not only give us directions for estimating constitutive parameters with confidence but also increase our general understanding of the underlying physics. Support through NSF grant DMR-1411102 is gratefully acknowledged.

2:40 PM  Student
High Resolution Strain Mapping of Proton Irradiated Zirconium Alloy: Rhys Thomas1; David Lunt1; Philipp Frankel1; Michael Preuss1; Aidan Cole-Baker2; 1School of Materials, University of Manchester; 2Rolls-Royce Plc
    During service, zirconium alloys (used as fuel cladding in nuclear reactors) are exposed to a neutron flux due to the fission process. As a result, <a> loops are generated which cause plastic strain localization due to dislocation channeling. The high resolution digital image correlation (HR-DIC) technique allows in-plane strain fields to be quantified at sub-grain scale. The ability to generate a strain map using the technique relies on being able to image a pattern with suitable feature size and spacing for the target resolution. A random, nanoscale (~20 nm) speckle pattern was applied to the surface of ZIRLO (Zr­1.0Sn­1.0Nb­0.1Fe) using the styrene-vapour gold remodeling process. Tensile test on dog-bone samples with and without irradiation damage were performed to progressive macroscopic strain levels before imaging the resultant gold speckle pattern with high resolution FEG-SEM. Using DaVis image correlation software, strain maps were generated which give an insight into the effect of proton irradiation on slip characteristics.

3:00 PM  Student
Modeling of Matrix-precipitate Interactions in NiTi Using FFT-based Constitutive Modeling: Shivram Kashyap Sridhar1; Anthony Rollett1; 1Carnegie Mellon University
    NiTi alloys are used in for biomedical applications such as stents due to its superelastic effect, biocompatibility and favorable mechanical properties. Previous studies have shown that the superelastic effect is affected by precipitate distribution. In the current study we shall be modeling the effects of precipitate distribution, especially Ni4Ti3 precipitates and their effects on the mechanical behavior of NiTi. A Fast Fourier Transform based constitutive model shall be implemented. We shall obtain experimental data of the 3D distribution of the precipitates using the Plasma Focussed Ion Beam (PFIB) dual-beam SEM. We will try to estimate the mechanical properties of material imaged using our model.

3:20 PM Break

3:40 PM  
Microstructural Characterization of Inconel 600 Tubes after Tensile Tests at Various Temperatures and Strain Rates: Cécile Davoine1; Vincent Marcadon1; David Leveque1; Fabienne Popoff1; Nicolas Horezan1; Denis Boivin1; Gerald Portemont1; 1Onera the French Aerospace Lab
    As a first step of studying the mechanical behaviour of cellular material made with tubes assembled by brazing, this work aims at characterizing the elasto-(visco)plastic behavior of Inconel 600 tubes subjected to different annealing pre-treatments representative of brazing process. Tensile tests highlighted rate sensitivity at room temperature and at 800°C that can be attributed to microstructural evolutions occurring both during annealing and during the test at 800°C. Electron BackScattered Diffraction (EBSD) analysis was carried out on post-mortem samples, leading to Kernel Average Misorientation (KAM) and Grain Orientation Spread (GOS) analyses. They highlighted dynamic recrystallization and recovery that occured during tensile test performed at 800°C, whereas a high-strained area is observed near nitrides precipitates for the annealed tubes loaded at room temperature.

4:00 PM  Cancelled
Formability Enhancement and Damage Initiation Mechanisms under Static and Dynamic Loading Conditions in Bainitic Steels: Behnam Shakerifard1; Jesus Galan Lopez2; Denis Jorge Badiola3; Frank Hisker4; Stefan Van Bohemen5; Kangying Zhu6; Viktoria Savran2; Leo Kestens7; 1TU Delft; 2M2i; 3CEIT; 4Thyssenkrupp Steel Europe AG; 5TATA steel; 6AMMR; 7UGent
    The goal of this research is to optimize the microstructure of a bainitc advanced high-strength steel in order to improve cold formability and edge-cracking behavior. This will enable enhanced energy absorption due to higher yield strength, higher elongation and favorable crash folding behavior because of improved bending properties. To approach this goal, two batches of bainitic steel with low and high silicon contents were produced. Several annealing treatments were carried out to provide a bainitic matrix with various morphologies of second phase constituents (martensite, retained austenite and carbides). Static mechanical tests were performed in order to evaluate the mechanical behavior. The microstructures and their textures were analyzed quantitatively by X-ray diffraction and orientation contrast microscopy. The correlation between microstructural features such as grain size and second phase constituents with mechanical properties has been studied.

4:20 PM  Cancelled
Multi-scale Modeling of Microstructural Spin in Crystal Plasticity for Phenomenological Models: Christopher Kohar1; John Bassani2; Raja Mishra3; Kaan Inal1; 1University of Waterloo; 2University of Pennsylvania; 3General Motors Research & Development Center
    Crystal plasticity is a micromechanics-based model that is regularly used to simulate microstructural evolution during large deformation. Although these models provide an accurate description of local deformation behaviour, they are often computationally expensive and are often replaced by flow rule-based phenomenological models that do not capture microstructural spin. Bassani and Pan (2012) proposed a phenomenological-based texture evolution (PBTE) model that allows for the enhancement of flow rule-based models to capture microstructural spin in a phenomenological manner. In this work, a framework is presented for multi-scale modeling of microstructural spin in single crystal textures of aluminum using the PBTE Model. Representative volume elements (RVEs) of various single crystal in aluminum are simulated using the Crystal Plasticity Finite Element Method (CPFEM) for uniaxial tension. The PBTE Model is calibrated and used to predict the macroscopic mechanical response and microstructural spin of simulated RVEs during uniaxial tension and other strain paths.

4:40 PM  
Physics Based-crystal Plasticity Modeling of Single Crystal Niobium: Tias Maiti1; Philip Eisenlohr1; Di Kang1; Thomas Bieler1; 1Michigan State University
    Constitutive models based on thermally-activated stress-assisted dislocation kinetics have been successful in predicting deformation behavior of crystalline materials, particularly in face-centered cubic (FCC) metals. In body-centered cubic (BCC) metals success has been more or less limited, owing to ill-defined nature of slip planes and non-planar spreading of 1/2<111> screw dislocation cores leading to a strong dependence of flow stress on temperature and strain-rate. We present high resolution full-field crystal plasticity deformation simulations of single crystal Niobium under tensile and compressive loading with an emphasis on multi-stage hardening, orientation dependence, and the violation of non-Schmid behavior. A physics based material model with atomistically derived parameters for non-Schmid flow rule and kink-pair mechanism (kink-pair nucleation and their lateral propagation) is used for this purpose. The results are then compared with in-situ measurements under tensile and compressive loading.

5:00 PM  
Effect of 3D Crystallographic Orientation on Evolution of Corrosion in Aluminum Alloys: Hrishikesh Bale1; Tyler Stannard2; Jeff Gelb1; Erik Lauridsen3; Leah Lavery1; Arno Merkle1; Nikhilesh Chawla2; 1Carl Zeiss X-ray Microscopy, Inc.; 2Arizona State University; 3Xnovo Technology ApS
    To investigate the effects of corrosion and fatigue on peak-aged 7475 aluminum alloy, we imaged the corroded samples using laboratory based non-destructive 3D X-ray microscopy. In combination with the conventional absorption contrast tomography we collected an additional dataset using Diffraction Contrast Tomography which enabled reconstruction of the three dimensional crystallographic information of the grains. The samples were mechanically polished, then soaked in covered 3.5 wt.% NaCl and simultaneously subjected to a constant load to initiate stress corrosion cracking. The combined diffraction contrast tomography and absorption tomography provides comprehensive information of the grains within the samples before and after corrosion, enabling a detailed analysis of damage initiation and propagation. The effect of the microstructure on corrosion cracking and whether the crack follows a path adjacent to preferred orientation of grains will be discussed.