7075 aluminum alloy is an Al Zn mg Cu alloy, which is widely used in modern aerospace industry and some civil transportation
It has the advantages of low density, high strength, corrosion resistance and good processing performance. In recent years, the integration and large-scale of aircraft components require the use of high-performance thick section aluminum alloy materials (such as large forgings and ultra thick plates) to reduce weight, reduce cost and improve reliability.
As a typical heat treatable strengthened aluminum alloy, 7075 aluminum alloy produces components with large thickness. When the thick section materials are quenched after solid solution, it is often difficult for the central layer to obtain a sufficiently high cooling rate, resulting in great differences in internal and external microstructure and properties of forgings. The external surface is cold too fast, and the longitudinal yield strength exceeds the index, Due to insufficient solid solution, the core performance leads to heat treatment repair and even scrap of forgings.
The effect of quenching water temperature on
7075 aluminum die forgings was studied by means of conductivity test, metallographic structure and room temperature tensile test
The results show that:
(1) 7075 material is highly sensitive to water temperature. The cooling speed of 7075 aluminum die forging quenching affects the internal and external performance differences of forgings. The performance difference after two-stage aging in the three directions of solution quenching water temperature 60 ~ 85 ℃ is small, and the difference between high strength and contrast water temperature 60 ~ 85 ℃ after two-stage aging is about 13 ~ 17ksi.
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7075 aluminum die forgings
The solution quenching water temperature is 60 ~ 85 ℃, compared with the water temperature of 20 ~ 35 ℃, the conductivity is increased by 2% IACS after two-stage aging, the metallographic structure is uniform after two-stage aging, and there is a certain directionality in three directions.
(3) the effective thickness of
7075 aluminum die forgings is about 140mm, and the hardenability of solution quenching water temperature of 20 ~ 35 ℃ is about 55mm.
