Strain Transfer across the Ferrite/Cementite Interface in Carbon Steels with Coarse Lamellar Pearlite

Abstract

A crystal geometry analysis was performed of strain transfer mechanisms across the ferrite/cementite interface in coarse lamellar pearlite. The possibility of strain transfer was evaluated using LRB criteria, which were developed by Lee, Robertson, and Birnbaum to describe the slip transfer mechanism across grain boundaries. Dislocation reactions at the Fe/Fe₃C interface were studied according to the Pitsch–Petch orientation relationships between ferrite and cementite, which are valid for coarse lamellar pearlite. Slip planes and Burgers vectors of partial and full dislocations in cementite were proposed based on the results of atomistic simulation of stacking faults in close-packed planes of cementite. It was determined that the strain transfer across the Fe/Fe₃C interface is possible only for two slip systems 1/2〈111〉{110}_F and one slip system 1/2〈111〉{112}_F of ferrite. The other slip systems of ferrite do not cross the interface and are involved in the hardening of the ferrite phase of pearlite.