Multi-stage Solution Heat Treatment Of 7150 Aluminum Alloy And Performance

In ultra-high strength Al-Zn-Mg-Cu aluminum alloys, the increase in yield strength is accompanied by the decrease in the fracture toughness and stress corrosion resistance, which is highly related to a high density of precipitates concentrate in the grain boundaries after temper and lead to the intercrystalline cracking. This limits the extensive utilization of ultra-high strength aluminum alloy, so we need to find ways to regulate the structure of grain boundary and the characteristic of precipitate in the grain boundary.Stepped solution treatment and solution pre-precipitation re-solution treatment was explored to regulate the structure of grain boundary and the structure of grain boundary of 7150 aluminum alloys, respectively. The effects of stepped solution treatment and solution pre-precipitation re-solution treatment on regulating the structure of grain boundary and the structure of grain boundary, and improving the mechanical properties and the resistance of corrosion of 7150 aluminum alloys have been investigated by means of optical microscopy, SEM analysis and the measurement of mechanical properties, electrical conductivity and corrosion properties (intergranular corrosion, exfoliation corrosion and stress corrosion).The recrystallization and growth of the grains have been effectively inhibited and recrystallization fractions have been reduced by stepped solution treatment in 7150 aluminum alloys. Compared to the current solution treatment,7150 aluminum alloys with stepped solution treatment has an enhanced strength, fracture toughness and resistance to intergranular corrosion, exfoliation corrosion and stress corrosion in T6 and T77 condition.The considerable second-phase dispersions have been reserved by solution pre-precipitation re-solution treatment in 7150 aluminum alloys and induce precipitation in the grain boundary, which favors to the formation of coarser and discrete precipitates in grain boundaries of T6-tempered.Compared to the current solution treatment,7150 aluminum alloys with solution pre-precipitation re-solution treatment has an enhanced resistance to intergranular corrosion, exfoliation corrosion and stress corrosion in T6 and T77 condition with the same hardness and strength.