A NEW ORIENTATION RELATIONSHIP BETWEEN WIDMANSTATTEN CEMENTITE AND AUSTENITE

Abstract

Many previous studies have shown that there is a definite crystallographic orientation relationship (OR) between Widmanstatten cementite and austenite. In the present paper, the ORs between Widmanstatten cementite and austenite have been determined using a convergent beam Kikuchi lines diffraction pattern (CBKLDP) technique with an accuracy of {+-}0.5{degree}. This compares with the accuracy of conventional selected area diffraction (SAD), which may be as large as {+-}5{degree}. Here, convergent beam Kikuchi line diffraction patterns have been used to determine the ORs between Widmanstatten cementite and austenite with an accuracy of approximately {+-}5{degree}. A new OR has been observed between Widmanstatten cementite and austenite in more than 20 cases, no matter whether the cementite was in the form of intergranular precipitates or sideplates. The Pitsch OR was not observed in the present work. Analysis of the OR matrices has shown that the F-E OR and the Z-S OR are very close to this new OR, at least within the experimental error associated with the SAD technique, and that the Pitsch OR and the T-H OR are twin related.