Aging heat treatment method for 7-series aluminum alloy

Abstract

The invention discloses an aging heat treatment method for a 7-series aluminum alloy, and belongs to the field of non-ferrous metal materials and heat treatment thereof. The aging heat treatment method is used for the 7-series aluminum alloy after solid solution treatment, and comprises the following steps that (1) first-stage aging is performed, specifically, a 7-series aluminum alloy workpiece is placed in a heating furnace of 90-120 DEG C for heat preservation for 10-30h; (2) second-stage aging is performed, specifically, the temperature is raised to a second-stage predetermined aging temperature of 165 DEG C-185 DEG C along with the furnace, and after the heat preservation is performed for 1-5h, the 7-series aluminum alloy workpiece is subjected to water cooling to the room temperature; (3) third-stage aging is performed, specifically, the 7-series aluminum alloy workpiece is then placed at a third-stage predetermined aging temperature of 60-90 DEG C for heat preservation for 20-30h; and (4) fourth-stage aging is performed, specifically, the temperature is raised to a fourth-stage predetermined aging temperature of 90-110 DEG C along with the furnace, and after the heat preservation is performed for 10-30h, the 7-series aluminum alloy workpiece is subjected to air cooling to the room temperature. In the second-stage high-temperature aging process, a method of lowering the temperature than the RRA temperature and increasing the heat preservation time is adopted, and the problem of uneven structure and performance caused by the temperature gradient due to rapid heating and cooling of large components is solved.

Description

technical field [0001] The invention belongs to the field of nonferrous metal materials and thermal processing thereof, and in particular relates to a heat treatment method for 7 series aluminum alloys. Background technique [0002] The 7-series aluminum alloy is a typical age-strengthened aluminum alloy, which has many advantages such as low density, high strength and good corrosion resistance. It is widely used in aerospace, marine and rail transportation and other fields, especially in shafts and rings. , Supports and other load-bearing components, these components have high requirements for strength, corrosion resistance and fatigue resistance. [0003] This series of alloys often adopts the method of aging treatment to obtain comprehensive performance requirements. The sequence of precipitated phases during the aging process of 7 series aluminum alloys is: supersaturated solid solution → GP area → η′(MgZn 2 )→η(MgZn 2 ). It initially adopts T6 peak aging. After the a...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a heat treatment method for 7-series aluminum alloys, which is especially suitable for large-scale components of 7-series aluminum alloys, and solves the problem that the surface layer and internal structure of the material are not uniform due to the temperature difference caused by high temperature and short-term aging problems, and can greatly improve the corrosion resistance while maintaining the strength of the alloy

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