Effect of Pretreatment after Solid Solution Treatment on the Mechanical and Corrosion Properties of 7055 Alloy Plate

A novel heat treatment process combining cooling pretreatment after artificial aging treatment of a high-temperature solid solution was conducted to coordinate the mechanical properties with the corrosion resistance of 7055 aluminum alloy. In the present investigation, after treatment with a high-temperature solid solution (480 degrees C x 1 h), the alloys were held at 455 degrees C for 0.5 h, quenched in water and then aged at 120 degrees C for 24 h (CPt455+T6). After the CPt455+T6 treatment, the alloy exhibited an ultimate tensile strength and elongation of 623 MPa and 15.7%, respectively, which were similar to those of the SS+T6 state. Moreover, the alloy showed excellent resistance to medium corrosion, which was superior to that of the T74 state. The well-matched strength and plasticity of the CPt455+T6 sample was due to the synergistic effects of intragranular nanosized precipitates and a narrow precipitate-free zone (PFZ). The improvement in corrosion resistance was attributed to the intermittent distribution of the grain boundary eta phase and the high Cu content in the grain boundary eta phase.

Automated summary

This study proposes a novel heat treatment process to improve the mechanical properties and corrosion resistance of 7055 aluminum alloy. The CPt455+T6 treatment results in excellent mechanical properties and corrosion resistance due to the synergistic effects of intragranular nanosized precipitates and a narrow precipitate-free zone.