Quantification of complex-phase steel microstructure by using combined EBSD and EPMA measurements

We combined electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) techniques to characterize the microstructure of industrial produced complex-phase CP800 steel. First, three major constituents (ferrite, martensite and bainite) are characterized. Then, transformation-induced dislocation zones in ferrite and bainitic regions consisting of different sub-structures are quantified and segmented. A final digitalized component map including plenty of microstructural features including crystal structures, orientations and elemental distribution are successfully achieved. The precise carbon content is measured in bainite and martensite utilizing EPMA line scans, which is around 0.2 wt% and 0.4 wt%, respectively. In the bainite phase of CP800, a typical Bagaryatski orientation relationship between cementite and lath-like bainitic ferrite is revealed based on the select diffraction patterns of transmission electron microscopy measurements.