THE EFFECT OF INITIAL GRAIN-SIZE DISTRIBUTION ON ABNORMAL GRAIN-GROWTH IN SINGLE-PHASE MATERIALS

A model that describes the temporal evolution of an initial grain size distribution (GSD) has been used to analyze the effect of initial GSD on grain growth. Based upon the work of Hillert, and Hunderi and Ryum , this model uses a finite difference technique to numerically solve t he continuity equation. A formal method has been developed to create s ynthetic GSDs. The model is used to study the evolution of both contin uous and discontinuous GSDs. For either case, two parameters describe the deviation from steady state: u(max) is the ratio of the largest gr ain radius to the critical grain radius, and F-o is the initial fracti on of grains larger than twice the critical radius. The analysis is ap plied to lognormal GSDs obtained from experimental results. It is show n that, for all initial GSDs with nonzero F-o, a transient period of a bnormal grain growth characterizes the initial stages of growth. F-o a nd u(max) allow approximate prediction of the duration and extent of a bnormal grain growth. (C) 1998 AL ra Metallurgica Inc. Published bl El sevier Science Ltd. All rights reserved.