ABSTRACT
Significant microstructural changes occur during commercial thermomechanical processing of aluminum alloys. In the so-called non-heat-treatable alloys comprising the 1xxx, 3xxx, and 5xxx alloys, microstructural control essentially involves obtaining the right grain size and crystallographic texture, since there is no scope for hardening these alloys through precipitation. In these alloys, strength is mainly controlled through grain size, and texture plays a major role in controlling the formability of sheet products. In the heat-treatable alloys that include the 2xxx, 6xxx, and 7xxx series, strengthening is mainly due to precipitation phenomena. However, the crystallographic texture and grain size are strongly influenced by the precipitation processes that occur concurrently during recrystallization. Therefore, there is a greater flexibility in processing these alloys to produce a variety of microstructures and properties. In the past, significant progress has been achieved in the process control and product optimization of specific industrial alloys, through the development of empirical models that are either alloy-specific or process-specific or both. The need for developing physically based models that are more fundamental in nature and have predictive capability over a range of alloy chemistries and processing conditions has resulted in the development of several new modeling and simulation tools, which, along with the availability of increased computational power, are beginning to provide fundamental insights into the evolution of 222microstructure during the processing of aluminum alloys. The goal of this chapter is first to provide a brief description of the empirical and analytical models that were developed in the past to understand the microstructure and texture development during deformation, recrystallization, and precipitation in aluminum alloys. This is followed by a description of the more recent developments in microstructure modeling with regard to each of the above phenomena.
