Correlation between the crystallography and morphology of proeutectoid Widmanstatten cementite precipitates

Electron backscatter diffraction was used in conjunction with deep etching to examine the relationship between the crystallography and three-dimension al morphology of cementite precipitates in an Fe-1.34 wt% C-13.1 wt% Mn ste el. Orientation relationships (ORs) between more than 200 proeutectoid Widm anstatten cementite precipitates and the surrounding austenite were determi ned to be on or very near either the well-known Pitsch OR or the Farooque-E dmonds OR. Scanning electron microscopy of the same specimens after deep et ching was used to determine the three-dimensional morphology of each of the precipitates for which an OR was determined. These precipitates could be i dentified as either monolithic plates or conglomerates of laths. Results sh ow that monolithic plates consistently exhibit the Pitsch OR and conglomera tes of laths have the Farooque-Edmonds OR, indicating that the precipitate morphologies are dictated by their orientation relationships. Published by Elsevier Science Ltd on behalf of Acta Metallurgica Inc.