Material Science and Engineering

Biography

Biography: Tu Le Manh

Abstract

Electron Backscatter Diffraction (EBSD) is a powerful technique for the microstructural characterization of materials. This paper shows evidence of the capability of EBSD to accurately estimate magnetocrystalline energy (MCE) of API 5L steels. The crystallographic texture of six circular samples extracted from different out-of-service pipelines was characterized through X-ray global texture and EBSD microtexture measurements. The average MCE of each sample was estimated from the set of individual grain orientations measured by EBSD. The angular dependence of EBSD-derived MCE was compared with predictions made from X-ray-measured texture and Barkhausen Noise (BHN) measurements. The average EBSD-derived MCE shows a good agreement with the prediction from X-ray and BHN measurements for all the studied samples both qualitatively and quantitatively. This agreement can be explained by the fact that number of grains used to estimate the average MCE from EBSD data was statistically sufficient to reproduce the predictions by the other two methods. The EBSD measurement strategy for the accurate estimation of MCE was established in terms of parameters such as the number of individual grain orientations to be measured, the sample's texture acuity and grain size, and the use of equivalent orientations given by the statistical orthorhombic symmetry of the studied samples. These results also highlight the fact that EBSD-derived MCE has some advantages with respect to the determination of this energy from X-ray texture as MCE can be calculated directly from raw EBSD data for reduced sample sizes, while other microstructural parameters can be incorporated into the analysis of such the impact of grain boundary character distribution on the average MCE of the polycrystal.