Concurrent precipitation in continuous cast Al alloys

This paper deals with concurrent precipitation and its effccts on the development of recrystallization texture and microstructure, and mechanical properties in continuous cast Al alloys. Concurrent precipitation often takes place during annealing of plastically deformed continuous cast Al alloys, especially 3000 series Al alloys, due to their high levels of solid solution of mainly Mn or Cr. As a result, uncommonly occurring recrystallization textures, such as P ({011}<566>) and {113}<110> orientations, arc often developed, and the grain structure beeomcs significantly coarsc and elongated in the rolling direction in the continuous cast Al alloys. A strong uncommon texture usually leads to inferior formability of the alloys. Recent observation of strong uncommon textures in continuous cast Al alloys without occurrence of concurrent precipitation during crystallization indicates that the formation of these textures is not necessarily associated with concurrent precipitation but precipitates pinning dislocations and subgrain boundaries during recrystallization. They arc likely to be formed by lattice rotation in the deformed grains in the vicinity of coarsc particles, due to sudden release of a large number of dislocations which break free from fine precipitates at a temperature higher than the onset temperature for recrystallization without the influence of precipitate pinning.