Ferrite: Cementite crystallography in pearlite

Abstract

The interlamellar crystallography of pearlite in iron-carbon alloys is examined in Fe-0.8C and Fe-0.81C-12Mn steels with attention given to the Bagaryatsky, Pitsch-Petch, and Isaichev orientation relationships and their related atomic habit planes. A survey of the overall literature reveals confusion about the crystallographic uniqueness in these orientation relationships. The present article focuses on this uniqueness and on habit planes between the pearlitic ferrite and cementite, from which the crystallography of ferrous pearlite orientation relationships is proposed to emanate. Techniques to characterize and identify orientation relationships unambiguously are developed. Habit planes are shown to be consistently obtained, even during curvature, with all deviations accommodated by microscopic steps. © 1992 The Minerals, Metals and Materials Society, and ASM International.