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 3-axis compressive stress state is dominant, thermal deformation can most effectively change the as-cast structure of the aluminum profile. Given an appropriate amount of deformation, the following beneficial changes can occur in the as-cast structure.
(1) Generally, thermal deformation is completed through multiple passes of repeated deformation. Since the hardening and softening processes occur simultaneously in each pass. The deformation of industrial aluminum profiles breaks 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, it can promote the welding of bubbles existing in the cast structure, compaction of shrinkage cavities, loosening and compaction, and turning it into a denser structure.
(3) Due to the enhanced thermal movement ability of high-temperature atoms, under the action of stress, with the help of free diffusion and differential diffusion of atoms, the inhomogeneity of the chemical composition of the ingot is relatively reduced.
Through thermal deformation, the ingot structure improves the deformation structure, making it have higher density, uniform and fine equiaxed grains, and relatively uniform chemical composition. Therefore, the plasticity and resistance indicators are significantly improved.
