Effect of Cold Deformation on Properties of Aluminum Profiles

A: Physical and chemical properties

1) Density. After cold deformation, the density of aluminum material decreases due to defects such as microcracks or macrocracks and cracks in the grains.

2) Resistance. The destruction of the intergranular material causes the direct contact of the crystal grains, the ordering of the crystal grains, the intergranular and intragranular cracking, and so on, all having a significant influence on the resistance change. The first two reduce the resistance as the degree of deformation increases, and the latter reverses.

3) Chemical stability. After cold deformation, the internal energy of the material can be increased, making its chemical properties more unstable and easily corroded, in particular, it is prone to stress corrosion.

B: Mechanical properties

After cold deformation of aluminum, due to intragranular and intercrystalline damage, the crystal lattice is distorted and the second type of residual stress occurs, which causes the plasticity index to drastically decline and may be close to a completely brittle state in the limit state. On the other hand, due to lattice distortions, increased dislocations, elongated grains, and substructures, their strength indexes are greatly improved, ie, work hardening occurs.

C: Structure and Anisotropy

After a large cold deformation of the aluminum material, the material exhibits anisotropy due to the texture. For example, aluminum alloy thin plates tend to show noticeable ears during deep drawing. The processing conditions should be properly controlled to take full advantage of the favorable aspects of texture and anisotropy while avoiding or eliminating its disadvantageous aspects.