SIMPLE GEOMETRY AND CRYSTALLOGRAPHY APPLIED TO FERROUS BAINITES

Conclusions about the morphology and interface structure of ferrous bainite may be drawn from the theory of finite homogeneous deformation combined with the accepted results that a shape change accompanies the formation of bainitic ferrite and that the mobilities of iron and all substitutional solutes are negligible in the temperature range of bainite formation. It is shown that the ferrite particles can have only one macroscopic interface and so must be lath- or plate-shaped with atomic steps in the habit plane interface but no superledges. The motion of the interface must conserve the number of atoms so that its structure is "glissile" or "martensitic." In order to model the interface as a single array of intrinsic dislocations, the orientation relation must be irrational, and, in particular, close-packed planes in the two structures cannot be exactly parallel. © 1990 The Metallurgical of Society of AIME.