An analytical model to ascertain the fragmentation of cementite lamella at lamellar fault sites

Abstract

ABSTRACT An analytical model is conceptualised and implemented for the first time to study the kinetics of cementite lamella fragmentation at the lamellar fault site occurring at an early stage of austenitisation in eutectoid steel. The model is conceived on the basis of two prime diffusion phenomena; namely, the curvature-dependent diffusion within cementite lamella and the diffusion-assisted dissolution in austenite. Both these diffusion phenomena are observed to have adequate significance in view of respective kinetic factors ascertained therein. The model is validated with necessary experimental work pertaining to the progress of lamellar fragmentation during isothermal holding at an austenitisation temperature of 775°C. The experimental result is closely followed by the developed model. A lamellar fragmentation time of 260 s is predicted accordingly for the incomplete austenitisation-based heat treatment of eutectoid steel.