A study of a new type of deviation from the Kurdjumov–Sachs orientation relationship in face-centered-cubic/body-centered-cubic transformation system

Slight deviations from the Kurdjumov–Sachs orientation relationship (KS OR) are often observed in the face-centered-cubic/body-centered-cubic (fcc/bcc) transformation systems, and some can be explained on the premise of the parallelism of either the close-packed planes (CPPs) or the close-packed directions (CPDs), as suggested in many models. This work investigates a new OR which deviates from the KS OR in both the CPPs and the CPDs. This OR is determined by requiring the habit plane to contain a single set of periodic dislocations along the invariant line lying in the CPPs. The angles of the double deviation, as a function of the lattice parameter ratio, are proved to be identical. The calculated results for a stainless steel are in good agreement with the experimental observations. The habit plane for the new OR is associated with slightly lower interfacial energy than those with the ORs of single deviation, which might explain the preference by nature in the present case.