Parent grain reconstruction from partially or fully transformed microstructures in MTEX

Abstract

A versatile generic framework for parent grain reconstruction from fully or partially transformed child microstructures has been integrated into the open-source crystallographic toolbox MTEX. The framework extends traditional parent grain reconstruction, phase transformation and variant analysis to all parent–child crystal symmetry combinations. The inherent versatility of the universally applicable parent grain reconstruction methods and the ability to conduct in-depth variant analysis are showcased via example workflows that can be programmatically modified by users to suit their specific applications. This is highlighted by three applications, namely α′-to-γ reconstruction in a lath martensitic steel, α-to-β reconstruction in a Ti alloy, and a two-step reconstruction from α′ to ɛ to γ in a twinning and transformation-induced plasticity steel. Advanced orientation relationship discovery and analysis options, including variant analysis, are demonstrated via the add-on function library ORTools.

Efficient reconstruction of prior austenite grains in steel from etched light optical micrographs using deep learning and annotations from correlative microscopy

“…The crystallographic reconstruction of the PAG, needed for the ground truth for the training data set, has been done using the MATLAB R2021b toolbox MTEX 5.7 (Bachmann et al, 2010;Niessen et al, 2022) provide a workflow, which loads the raw EBSD data and reconstructs the PAG using different preprocessing steps and filters. For the final reconstruction, similarly oriented child grains within the PAG with a tolerance of 12.5 °have been filtered, using the function mergeSimilar.…”

“…PAG reconstruction by EBSD has become widespread in the last years and is readily available in various commercial or open-source software packages. Approaches for reconstructing PAG include (Cayron, 2007;Germain et al, 2012;Nyyssönen et al, 2016;Niessen et al, 2022). Disadvantages are the time-consuming EBSD measurement and computationally expensive reconstruction.…”

Insights into a dual-phase steel microstructure using EBSD and image-processing-based workflow

“…Parent-grain reconstruction algorithms have been extensively developed recently. In the following, the method proposed by Niessen et al (2022) and implemented in MTEX was used. The algorithm starts from an initial guess of the orientation relationship between the two phases and then optimizes it iteratively.…”

Ex situ analysis of high-strength quenched and micro-alloyed steel during austenitising bending process: numerical simulation and experimental investigation

“…Electron backscattered diffraction (EBSD) experiments were carried out on a JEOL JSM-7001F field emission gun scanning electron microscope for the microstructural observation with a scanning area of 200 × 90 μm and a step size of 0.18 μm; then, the obtained data was post-processed by HKL Channel 5 software. The parent grain reconstruction was achieved by the MTEX toolbox, which enables the traditional phase transformation, prior austenite grain, and variant investigation to extend to all crystal symmetry combinations [30].…”

“…In the current work, reconstructed EBSD data with PA grain boundaries was successfully integrated into crystallographic toolbox MTEX from completed or partially transformed microstructures (see Fig. 7) when applying the technique proposed by Frank et al [30]. This enables to list the child α-grains belonging to a specific parent γ-grain and is crucial for analysing subsequent variants.…”