| 7A04 ultra-high strength aluminum alloy is applied extensively in the domains of aviation and spaceflight,which is one of the most important structure materials.Heat treatment of high strength and toughness aluminum alloy has already been studied extensively by internal and external reseachers. Seeking high strength and high toughness aluminum alloy is a hot subject.In this paper,heat treatment crafts impacting on the microstructure and mechanical properties of 7A04 ultra-high strength aluminum alloy had been researched,two heat treatment crafts including T6a-17(485℃/50min/water quench+100℃/36h/aging)and T6a3-21(485℃/50min/water quench +160℃/10min+120℃/10min+60℃/240h/aging)which can markedly improve the mechanical properties of 7A04 alloy were found;The results obtained by testing the mechanical properties,impact toughness and fracture toughness of alloy in room temperature,were used to analyze their relationship;and the reason why the capabilities of 7A04 alloys were increased were found by observing the diversification of the micro-structure in 7A04 alloys.Some conclusions of the study are as follow:1.Comparing with a present heat treatment craft T6a-10(485℃/50min /water quench+100℃/36h/aging)craft,the appliance of new heat treatment crafts T6a- 17(485℃/50min/water quench+100℃/36h/aging)and T6a3-21(485℃/50min/ water quench +160℃/10min+120℃/10min+60℃/240h/aging)increased the toughness of 7A04 alloy more markedly with the premise of a little increasing or unmarkedly dropping of the alloy strength,αk is increased by 25.1%and 54.5%,KICis increased by 20.8%and 29.4%.2.The corresponding connection among mechanical properties,impact toughness and fracture toughness of the alloy were assured.Especially,there existed close pertinence between impact toughness and fracture toughness.3.Comparing with precipitates of T6a-10 craft,T6a-17 crafts are smaller, which distributed more uniformly and dispersedly;The alloys treated by T6a-10 craft separated out precipitates of different sizes,the sizes of precipitates were altered in group.Accordingly,the impact toughness and fracture toughness of alloys were markedly improved.
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