Unified rationalization of the Pitsch and T-H orientation relationships between Widmanstatten cementite and austenite

This work demonstrates that understanding the habit planes of cementite pla tes is an important step to gain an insight into the irrational orientation relationships (ORs) between Widmanstatten cementite and austenite, i.e. th e Pitsch and T-H ORs. A reproducible irrational OR in this system is attrib uted to a unique correspondence between the OR and the habit plane, under t he condition that the habit plane is a quasi-invariant plane. The OR is con strained by two parallelism conditions: parallelism of [0 1 0](C) and < 1 1 0 >(A); parallelism of a group of Delta g's in the zone axis of [0 1 0](C) . The calculated ORs and habit planes are Fully consistent with the experim ental results from the literature. (C) 2000 Acta Metallurgica Inc. Publishe d by Elsevier Science Ltd AN rights reserved.