Aluminum profiles have high plasticity and low resistance at high temperatures. In addition, the atomic diffusion process is intensified, accompanied by complete recrystallization, which is conducive to the improvement of the structure. When the compressive stress state is dominant, thermal deformation can most effectively change the cast structure of aluminum profiles. Given an appropriate amount of deformation, the cast structure can undergo the following favorable changes.
(1) Generally, thermal deformation is accomplished through repeated deformation in multiple passes. Since hardening and softening processes occur simultaneously in each pass, the deformation of industrial aluminum profiles breaks up the coarse columnar grains. At the same time, it can also heal some tiny cracks.
(2) Due to the effect of hydrostatic pressure in the stress state, the bubbles in the cast structure can be welded, the shrinkage cavities can be compacted, and the loose structure can be compacted to form a denser structure.
(3) Due to the enhanced thermal motion of high-temperature atoms, under the action of stress, with the help of free diffusion and heterodiffusion of atoms, the heterogeneity of the chemical composition of the ingot is relatively reduced.
Through thermal deformation, the ingot structure improves the deformed structure (or processed structure) so that it has higher density, uniform and fine equiaxed grains and relatively uniform chemical composition, so the plasticity and resistance indicators are significantly improved.
