5th International Congress on 3D Materials Science (3DMS 2021): Process Microstructure Properties I
Program Organizers: Dorte Juul Jensen, Technical University of Denmark; Erica Lilleodden, Fraunhofer Insitute for Microstructure of Materials and Systems (IMWS); Scott Barnett, Northwestern University; Keith Knipling, Naval Research Laboratory; Matthew Miller, Cornell University; Akira Taniyama, The Japan Institute of Metals and Materials; Hiroyuki Toda, Kyushu University; Lei Zhang, Chinese Academy of Sciences
Tuesday 9:50 AM
June 29, 2021
Room: Virtual D
Location: Virtual
Session Chair: David Rowenhorst, Naval Research Laboratory
Grain Scale Analysis of Deformation in Ti6Al4V Anisotropically Built Using Electron Beam Melting Powder Bed Additive Manufacturing Process: Md Jamal Mian1; Jafar Razmi1; Leila Ladani1; 1Arizona State University
Ti6Al4V alloy, originally developed for aerospace applications, has found wide acceptance in various industries due to its high strength and low density. EB-PBF additive manufacturing is an efficient technique to fabricate complicated geometries with this hard metal. High temperature deformation behavior of Ti6Al4V is very crucial specially to the aircraft engine manufacturers. Therefore, this study focuses on the anisotropic mechanical behaviors at elevated temperatures along with potential reasons for these behaviors. Ti6Al4V alloy is observed to experience flow softening during hot deformation around 600°C temperature. Electron back scattered diffraction (EBSD) analysis is conducted using samples before and after the tensile test to determine possible softening mechanisms and microstructural changes. Microstructural features such as crystallographic texture and grain boundary misorientation angles are investigated via different EBSD maps. Moreover, a 3D X-ray CT analysis is conducted on the samples to investigate the internal defects and their impact on the inherent anisotropic behavior.
Thermal Expansion of Ti-7Al Using High Energy X-ray Diffraction Microscopy: Rachel Lim1; Darren Pagan2; Joel Bernier3; Anthony Rollett1; 1Carnegie Mellon University; 2Cornell High Energy Synchrotron Source; 3Lawrence Livermore National Laboratory
Hexagonal metals have anisotropic coefficients of thermal expansion, and there is little agreement in literature on the CTEs for these metals. High energy x-ray diffraction microscopy, a non-destructive, in situ, microstructural characterization technique, has been used to determine the anisotropic coefficients of thermal expansion (CTEs) for Ti-7Al. Two samples of polycrystalline Ti-7Al were continuously heated from room temperature to 850C while far-field HEDM scans were being taken. The lattice parameters at a given temperature were calculated based on the distribution of lattice parameters of the individual grains. The results showed that the CTEs in were different in the a- and c-directions respectively, and the change in the ratio of these CTEs explained the discrepancies found in literature. It was also found that the equivalent strain and von Mises stress were lower after the thermal cycle with the outliers in the initial state having shifted the most after the thermal cycle.
Three-dimensional Electron Backscatter Diffraction Analysis of Fatigue Crack Propagation in Steel: Mayuko Kikuzuki1; Takanori Kato1; Taizo Makino1; Yukihiko Kimura1; 1Nippon Steel Corporation
Resistance against crack propagation is dominant effective in improving fatigue strength in steel. Identifying the behavior of non-propagating fatigue crack tip which stop growing during cyclic stress test reveals the factors inhibiting fatigue cracks. The conventional cross-sectional observations around the cracks have been performed; however, it was difficult to determine the crystal orientation of the fracture surfaces of fatigue crack tip from such 2D observation.In this study, 3D electron backscatter diffraction (3D-EBSD) analysis using a focused ion beam scanning electron microscope (FIB-SEM) visualized the distribution of crystal grains and the primary crystal orientation of the fracture surface around the non-propagating fatigue crack tip in a ferritic model steel. The result shows that the fatigue crack propagated on the three planes of equivalent {101} slip planes in the steel, and fatigue crack tip stopped not at grain boundary but inner grain.
X-ray Tomography and 3D X-ray Diffraction for Quantifying Particle Rearrangements in Granular Materials: Ryan Hurley1; Chongpu Zhai1; Nahuel Albayrak2; Jonas Engqvist3; Stephen Hall3; Eric Herbold4; 1Johns Hopkins University; 2Chesapeake Science Point High School; 3Lund University; 4Lawrence Livermore National Laboratory
The behavior of granular materials undergoing macroscopic deformation is characterized by local particle rearrangements and other deformation mechanisms, including fracture. Recent advances in X-ray computed tomography (XRCT) and 3D X-ray diffraction (3DXRD) at synchrotron facilities provides a unique approach for quantifying the details of these deformation mechanisms. Previously, access to the type of particle-scale detail that XRCT and 3DXRD can provide in 3D was restricted to photoelasticity in 2D or numerical simulations. Here, we will discuss recent experiments performed on granular materials that combined XRCT and 3DXRD to examine deformation mechanisms occurring during uniaxial and triaxial compression of granular materials. We will focus on deformation mechanisms including local particle strains, non-affine motion, and rotations. We will discuss the application of machine learning to identify and predict the location of such local deformation mechanisms from our X-ray measurements.
Statistical Analysis of Crystal Plasticity on Commercially Pure Titanium by Coupling 4D Testing and Finite Element Simulations: Clement Ribart1; Aldo Marano1; Franck N'Guyen1; Andrew King2; David Ryckelynck1; Wolfgang Ludwig3; Henry Proudhon1; 1MINES ParisTech, PSL Research University, Centre des Materiaux; 2Synchrotron SOLEIL; 3ESRF Synchrotron
This talk will present a multimodal experiment on Grade 2 Titanium for the study of polycrystal plasticity. The data set is composed of 3D and 4D in-situ Diffraction Contrast Tomography (DCT) tests conducted at SOLEIL synchrotron. In addition in-situ SEM tests (high resolution SEM mapping and EBSD scans) have been performed on specimens where the microstructure was previously measured by DCT. Digital twins of the specimens are built using the reference 3D microstructure to access the local stress fields by means of crystal plasticity finite element simulations. The volumes studied are of the order of 1 mm cube and each contains several thousands of grains to be representative of the mesoscopic scale. This allows statistical evaluation of slip system activation and lattice curvature extracted from the data set. The method is an important step towards constitutive behaviour identification at the scale of the grain.