Application of EBSD to analysis of microstructures in commercial steels

Abstract

Electron backscatter diffraction (EBSD) is a very powerful technique for microstructural characterisation and analysis of crystalline materials. Many of the structural parameters that control the properties and performance of the material can be derived from EBSD data, e.g. grain size, phase constituents, mechanical anisotropy and residual strain. This should make EBSD a valuable tool to control and develop microstructures of commercial metallic materials but technique has mainly been used in basic research at universities and not to the same extent for research and development in industry. The development in scanning electron microscopes and EBSD equipment in recent years makes it possible to measure 'difficult' structures, e.g. with higher dislocation content, but can it manage the complexity of the structures of commercial materials and achieve reliable data? During 2004 an EBSD round robin test on industrial metallic materials was coordinated by KIMAB to test the current status of the technique and most of the results presented here are from that project and participants in that test. The results and conclusions from the test will be published when it is accepted by the financing organisation but the present paper will focus on common problems or difficult tasks that appear during EBSD measurements of some complex or mixed structures in steel and how they can be solved. All participants experienced difficulties despite being familiar with the EBSD technique, which demonstrated the need for a comparative study of this sort and need for guidance in these topics.