Texture Analysis by theMeasurement of IndividualGrain Orientations—Electron Microscopical Methods and Application on Dual-Phase Steel

Abstract

A short review is given on electron microscopical methods for the determination of local textures. Electron microscopy offers the unique facility of diffraction from well defined locations in the sample and high resolution imaging of the microstructure. Standard techniques of orientation determination are the evaluation of electron diffraction spot and—more recently—Kikuchi patterns, which are applicable to electron transparent fine-grain materials. Specimen areas smaller than 500 nm or 50 nm in diameter, respectively, can be selected. Bulk samples with crystallite sizes greater than approximately 1 μm or 5 μm, respectively, can be studied with the SEM using electron backscattering or channelling patterns. For routine work a program has been developed to do on-line determination of orientation of cubic, orthorhombic or hexagonal crystals from Kikuchi, channelling and backscattering patterns.Applications of this technique on dual-phase steel are given. The orientation distribution functions (ODF) of the ferrite and martensite phases from individual grain measurements are compared with X-ray and neutron pole-figure measurements. Misorientation distribution functions (MODF) are discussed for contiguous ferrite-martensite and martensite-martensite grains.