© 2017 Informa UK Limited, trading as Taylor & Francis Group Correlative atom probe tomography (APT) and transmission electron microscopy (TEM) are used to characterise the microstructure and chemistry of carbide precipitation in M50 bearing steel. This is a prerequisite in establishing relationships between the microstructure and hydrogen embrittlement (HE) resistance. Secondary carbides are the focus of this study, as they play a major role in improving HE-resistance. Secondary carbides are observed in APT, with compositions close to M 4 C 3, M 2 C and M 3 C. Correlative TEM measured orientation relationships between the martensite matrix and carbides, enabling the confirmation of M 3 C cementite precipitates in the corresponding APT reconstruction. Additionally, other precipitates observed in TEM were correlated to the M 2 C carbides in APT data. The M 4 C 3 carbides are found to have a significantly lower volume fraction than the M 2 C carbides.
