30%冷間圧延したAl–0.7%Mg–0.4%Si–0.2%Cr合金の再結晶組織

Recrystallization behaviors in an Al–Mg–Si alloy have been intermittently observed by means of SEM-EBSD in detail. A specimen of Al–0.73 Mg–0.38 Si–0.26 Cr (mass%) alloy was cold-rolled with reduction rate of 30%, then annealed at 673 K. Annealing, ion-polishing and EBSD measurement were repeated and changes in microstructures were observed on the same area in the specimen during annealing up to 4.8 ks. At the early stage of annealing, crystallites (subgrains) formed near grain boundaries, and they grew into recrystallized grains without changing their orientations. The orientation of the crystallite is in the range of lattice rotation due to cold-rolling. Prior grains in which {100} planes were parallel to the specimen surface tend to form crystallites with {100} and {110} orientations. While prior grains with {110} orientation tend to form {100} oriented crystallites. Crystallite invaded neighboring prior grains with the strain induced boundary migration mechanism. The invaded grain was separated from the mother grain by other invading grains. Grain boundary migration and mutual intersection resulted in formation of recrystallized grains surrounded by large angle grain boundary in the neighboring prior grain. Orientations of the prior grains are maintained in the recrystallized grains with changing in the range of lattice rotation.