Grain size control method for enhancing high-temperature durability of Al–Cu–Mg–Ag alloy

Abstract

Reducing the grain boundary density (obtaining larger grain size) is beneficial for improving high-temperature durability of the heat-resistant aluminum alloys, and thus for extending their service life. In this paper, a grain size control method was proposed to enhance high-temperature durability of an Al–Cu–Mg–Ag alloy. A relationship formula between grain size, holding time, and annealing temperature was obtained through theoretical analysis. The recrystallization curve of a deformed Al–Cu–Mg–Ag alloy under different heating rates was determined through three-point bending thermal relaxation experiments. Based on the above relationship formula, the recrystallization kinetics parameters were obtained. Subsequently, based on actual processing conditions, the annealing temperature with the maximum grain size under a given annealing time was calculated. After the annealed sample underwent solution-aging (T6) treatment, the grain size increased by more than 60% compared with that of the directly solution-aging treated sample. This method can increase the duration by more than 60% at conditions of 210 °C/190 MPa without significantly reducing the room-temperature mechanical properties.

Keywords

• Al-Cu-Mg-Ag alloy
• Annealing
• Recrystallization
• Grain size