ANALYTICAL MODELING OF GRAIN-GROWTH IN METALS AND ALLOYS IN THE PRESENCE OF GROWING AND DISSOLVING PRECIPITATES .2. ABNORMAL GRAIN-GROWTH

The present investigation is concerned with analytical modelling of gr ain growth in metals and alloys in the presence of growing and dissolv ing precipitates. In Part II the modelling methodology presented in Pa rt I for normal grain growth has been further developed and applied to abnormal grain growth. The judicious construction of the constitutive equations makes full use of both dimensionless parameters and calibra tion techniques to eliminate poorly known kinetic constants. The resul ts are presented in the form of novel ''mechanism'' maps (by utilizing the concept of group variables) which show the competition between th e various processes that lead to abnormal grain growth during heat tre atment. This approach has made it possible to fit many of the apparent ly conflicting results into a more consistent picture and establish a simple criterion for the initiation of abnormal grain growth under dif ferent pinning conditions. It is concluded that the key to a verified, quantitative understanding of the phenomenon of abnormal grain growth lies primarily in the recognition of the important effect of precipit ate stability on the secondary recrystallization kinetics.