The effect of martensite volume fraction on topography of dual phase steels

•Digital holographic microscopy can characterize topography of dual phase steels.•Mean height difference is reduced for higher martensite volume fractions.•Selective ferrite/martensite regions can be analyzed for statistical classification. Digital holographic microscopy in reflection mode provides 3D visualization of metallographic surfaces within an adjustable field of view, a lateral resolution close to diffraction limit, and a sub-wavelength axial accuracy. In this paper, we utilize reflective digital holographic microscopy (rDHM) to evaluate the mean height between ferrite and martensite phases in dual phase steel (DPS) samples. The data extracted from processing of several digital holograms show that the mean height difference between the phases is reduced for the samples of higher martensite volume fraction. rDHM has the potential to be used for the multi-phase samples that are difficult to be analyzed by conventional metallographic methods.