Development of a EBSD-FEM data conversion interface and the image-based crystal plasticity analysis

Abstract

Image-based deformation simulation of microstructures in metals is attracting attention; however, the data conversion processes from the images of microstructures into the geometric models for the deformation simulation are now inconvenient, and there is a possibility that it prevents diffusion of the image-based simulation. In order to solve the problem, we developed an interface geometric models for Crystal Plasticity Finite Element (CPFE) analysis. The interface incorporates several functions for data cleaning and coarse graining of the microstructures: functions to narrow down the limits of Eulerian angles presenting crystal orientations, integrate crystal grains with similar crystal orientations, eliminate small crystal grains, select representative crystal orientation in each crystal grain, and so on. The interface was applied to an orientation map of polycrystal microstructure in pure titanium, and the course-grained geometric models were successfully obtained. Image-based CPFE analysis was conducted using the geometric models with different number of finite elements. The numbers of crystal grains were assumed to be around 50 in any geometric models. A dislocation density dependent constitutive equation was employed and uniaxial tensile loading was applied to the geometric models by the forced displacement. The results showed that spatial distributions of stress, strain, and dislocation density were good agreement among geometric models with different number of elements in both elastic and plastic ranges while values of the strain and dislocation density showed quantitatively dependency of the number of elements on their distributions in the plastic ranges. These features indicate that the qualitatively similar results can be obtained using the developed interface on the condition that coarse graining of the microstructures does not occur even though the number of elements is changed.

Crystal Plasticity Analysis of Microscopic Deformation Mechanisms and GN Dislocation Accumulation Depending on Vanadium Content in β Phase of Two-Phase Ti Alloy

“…The data obtained by EBSD measurements are converted into geometric model data for CPFE analysis using the data conversion procedure developed by Kawano et al 18) The maps, comprising hexagonal pixels typically employed in the visualization of EBSD measurement data, are converted into geometric models with cuboid elements. The geometric model obtained is shown in Fig.…”

“…The authors have developed a procedure to convert the data of microstructural maps obtained by electron back scatter diffraction patterns (EBSD) into geometric models for crystal plasticity finite element (CPFE) analysis. 18) The procedure solves the operation complexity in the process of the data conversion, and we can easily obtain geometrical models for CPFE analysis using the procedure. In this study, we adapt the procedure to a microstructure of two-phase titanium alloy, and investigate the distributions of slip strains and density of GNDs in a single ¡-¢ colony depending on the elastic constants as a function of the V ¢ , using a crystal plasticity finite element (CPFE) method.…”