An improved X-ray diffraction analysis method to characterize dislocation density in lath martensitic structures

Abstract

An improved X-ray diffraction line profile analysis method is developed to determine dislocation density of lath martensitic steels. This method combines the modified Warren–Averbach (MWA) and the modified Williamson–Hall (MWH) methods. The developed method is robust and leads to unique values for the dislocation density, the effective outer cut-off radius of the dislocations (Re) and the dislocations distribution parameter (M). Dislocation structures of lath martensite in a steel, in the as-quenched condition as well as in tempered conditions, are characterized by using the proposed method. The calculated dislocation density is compared with the values obtained from the MWH method by considering a constant value for M. It was found that both methods provide dislocation densities in the range of the values calculated from the dislocation strengthening component of the yield strength.