Widmanstatten ferrite plate formation in low-carbon steels

The mechanism by which Widmanstatten ferrite plates nucleate and grow in low-carbon steels has been studied. In-situ laser scanning confocal microscopy (LSCM) observations, optical microscopy, and electron backscattered diffraction (EBSD) techniques have been used to characterize the relationship between grain boundary allotriomorphs and Widmanstatten ferrite plates. The issue of where Widmanstatten ferrite plates nucleate is one of some debate, with theories including morphological instability and sympathetic nucleation. Evidence has been found that supports the theory of a sympathetic nucleation mechanism being responsible for the formation of Widmanstatten ferrite plates. The EBSD measurements have shown that low-angle misorientations of between 5 and 10 deg exist between ferrite allotriomorphs and Widmanstatten ferrite plates.