Unified rationalization of the Pitsch and T–H orientation relationships between Widmanstätten cementite and austenite Original Research Article

This work demonstrates that understanding the habit planes of cementite plates is an important step to gain an insight into the irrational orientation relationships (ORs) between Widmanstätten cementite and austenite, i.e. the Pitsch and T–H ORs. A reproducible irrational OR in this system is attributed to a unique correspondence between the OR and the habit plane, under the condition that the habit plane is a quasi-invariant plane. The OR is constrained by two parallelism conditions: parallelism of [0 1 0]C and 〈1 1 0〉A; parallelism of a group of Δg’s in the zone axis of [0 1 0]C. The calculated ORs and habit planes are fully consistent with the experimental results from the literature.