Quantification of precipitate fraction in maraging steels by X-ray diffraction analysis

Abstract

Quantification of precipitate fraction, a critical step in modelling precipitation hardening, is difficult to carry out for maraging steels because of the small precipitate size and its low volume fraction. A method is proposed in the present work to estimate the precipitate fraction in an 18 wt-%Ni C250 maraging grade based on simple X-ray diffraction (XRD) analysis. The estimation gives reasonable values of precipitate fraction, which increases when aging proceeds. The precipitate formed at 427°C may be of a type that has not been reported before. The method proposed may be applicable to other precipitate hardened alloys. The amount of reverted austenite formed was also estimated when applicable.