A re-solution and re-aging treatment process method to improve formability of 2219-T6 aluminum alloy

The aerospace components are usually formed in age-hardened states. However, the cold deformation of age-hardening aluminum alloy is highly difficult. In this paper, a novel process route is proposed, i.e. re-solution and re-aging (RSRA) applied before and after the hole-flanging process, respectively. The re-solution (RS) treatment softens the material and improves its formability. Re-aging (RA) is performed to restore the strength of the deformed material. After RS treatment, the yield strength of 2219-T6 aluminum alloy decreased from 294 to 171 MPa, the hardness decreased from 128 to 86 HV. The elongation increased by approximately 33%. The primary mechanism for enhancing plasticity was the dissolution of fine θ precipitates. The RS treatment reduced the flanging coefficient and lowered the required forming temperature during the flanging process. In the ring-expansion test, the fracture load of the RA-treated samples increased by 18%. Microhardness was restored to 96% of the original material’s value.