Application of 3D EBSD Technique to Study Crystallographic Texture in Heavily Cold-Rolled and Recrystallized Modified 9Cr–1Mo Steel

Abstract

Automated electron backscatter diffraction (EBSD) technique in a dual-beam field emission gun scanning electron microscope has been successfully used to obtain three-dimensional (3D) orientation mapping of grains in modified 9Cr–1Mo after severe plastic deformation and recrystallization. In this technique, the microstructure and micro-texture across several sections of the material were studied by means of the state-of-the-art “slice and view” methodology using grazing incidence high-energy Ga+ focused ion beam for slicing and electron beam for viewing and EBSD analysis. By combining the data from each slice, a 3D texture map could be generated by means of image reconstruction technique. The orientation map thus generated provided volumetric microstructural and micro-textural information. The 3D EBSD studies on the heavily deformed mod-9Cr–1Mo steel (cold-rolled 88%) revealed that rolled grains were elongated like plates with thickness ≤ 200 nm. Analysis of the fiber texture components in rolled specimen across the sections showed near equal preference for all fiber texture components with some enhancement of the α-fiber texture. However, by recrystallizing at 1023 K for 1 h, elongated grains along rolling direction with large diameters (~ 40 to 100 µm) were observed together with finer (size ~ 0.5 to 2 µm) polygonal grains and γ-fiber texture component dominated over other texture components.