Heating processing process for improving ageing strengthening type Al-Mg-Zn alloy intergranular corrosion performance

Abstract

The invention relates to a heating processing process for improving ageing strengthening type Al-Mg-Zn alloy intergranular corrosion performance, and belongs to the field of nonferrous metal and preparation of the nonferrous metal. According to the heating processing process, after an ageing strengthening type Al-Mg-Zn alloy is subject to solution hardening treatment, high temperature preageing treatment is carried out, in other words, heat preservation is carried out for 10 min to 3 h at the temperature ranging from 380 DEG C to 450 DEG C, quick quenching is carried out to the room temperature, then T6 peak aging treatment is carried out, two-step aging is carried out, heat preservation is firstly carried out for 12 h to 36 h at the temperature ranging from 60 DEG C to 100 DEG C, then heat preservation is carried out for 10 h to 40 h at the temperature ranging from 110 DEG C to 160 DEG C, and cooling is carried out to the room temperature. According to the heating processing process, alloy crystal boundary and crystal interior microstructures are changed, on the premise that the alloy strength and the extending rate are basically not lost, and the alloy intergranular corrosion resistance is remarkably improved; and in addition, compared with a traditional retrogression and reaging process, the process flow is greatly shortened, and industrial production is facilitated. The heating processing process has the important reference value on developing the novel high-strength corrosion-resistant ship and armored vehicle ageing strengthening type Al-Mg-Zn alloy.

Description

technical field [0001] The invention belongs to the technical field of heat treatment of aluminum alloys, and in particular relates to a heat treatment method for improving the intergranular corrosion performance of an aging-strengthened Al-Mg-Zn alloy and ensuring that its strength and elongation are not substantially reduced. Background technique [0002] It is an inevitable development trend to improve the fuel efficiency of large vehicles and reduce their structural weight. 5xxx aluminum alloys are aluminum alloys with Mg as the main alloying element. This series of alloys cannot be strengthened by heat treatment. The alloy can only be strengthened by solid solution strengthening and cold work hardening of Mg element. High Mg 5xxx series aluminum alloy has good corrosion resistance, formability, weldability and medium strength, and is one of the best choices for armor and ship weight reduction plates. For example, the 5xxx series aluminum alloys in the state of H321 and...

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Problems solved by technology

Invention patent (Patent No. ZL201410577461.5) on the basis of AA5059 alloy, further increases the content of Zn in the alloy, changes the strengthening method of traditional 5xxx alloys, that is, transforms from traditional solid solution strengthening and work hardening to precipitation strengthening, and ensures that the alloy The strength of the alloy is significantly improved under the premise of elongation, but the intergranular corrosion resistance of the alloy decreases

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