CRYSTALLOGRAPHY AND SUBSTRUCTURE OF LATH MARTENSITE FORMED IN CARBON STEELS.

Crystallographic observations have been made for two carbon steels containing 0. 2% and 0. 4% C using transmission electron microscopy and diffraction, both steels exhibit the same austenite-martensite orientation relationship, this indicates that there are four possible relative orientations between adjacent laths in a packet. Contrary to earlier reports, adjacent twin-related laths were never observed. Instead, heavy deformation twinning localized to one side of a lath was observed. Retained austenite was observed between adjacent laths, indicating that growth by a self-accommodation process does not occur. It appears that all ferrous lath martensites have common crystallographic features.