Combined application of electron backscatter diffraction and stereo-photogrammetry in fractography studies

The main aim of this paper is to report on recent experimental developments that have succeeded in combining electron back-scatter diffraction (EBSD) with stereophotogrammetry, compared with two other methods for study of fra cture surfaces, namely visual fractography analysis in the scanning electro n microscope (SEM) and EBSD directly from facets. These approaches will be illustrated with data relating to the cleavage plane orientation analysis i n a ferritic and C-Mn steel. It is demonstrated that the combined use of EB SD and stereophotogrammetry represents a significant advance in the methodo logy for facet crystallography analysis. The results of point counting from fractograph characterization determined that the proportions of intergranu lar fracture in C-Mn and ferritic steels were 10.4% and 9.4%, respectively. The crystallographic orientation was determined directly from the fracture surface of a ferritic steel sample and produced an orientation distributio n with a clear trend towards the {001} plane. A stereo-photogrammetry techn ique was validated using the known geometry of a Vickers hardness indent. T he technique was then successfully employed to measure the macroscopic orie ntation of individual cleavage facets in the same reference frame as the EB SD measurements. Correlating the results of these measurements indicated th at the actual crystallographic orientation of every cleavage facet identifi ed in the steel specimens is {001}.