Influences of solution treatment on microstructure and mechanical properties of 7021 aluminum alloy plate were investigated with the help of microstructure observation and tensile testing.The results reveal that with the increase of solution temperature and holding time

the un-dissolved particles are dissolved gradually in the alloy matrix.After artificial aging at 120℃for 24 h

the strength of 7021 is enhanced increasingly.With the solid solution treatment at 380 ℃for 40 min

the strength of 7021 alloy reaches the maxium value.With the further increase of the solution temperature or time

fiber tissue in the alloy is recrystallized

so the grain is grown continuously

resulting in the decrease of strength and the increase of elongation.The optimum solution treatment for 7021 alloy plate is at 380 ℃for 40 min.