Ageing process for improving strength non-uniformity of quenched large-size 7-series aluminum alloy

Abstract

The invention provides an ageing process for improving strength non-uniformity of quenched large-size 7-series aluminum alloy. According to the ageing process, an aluminum alloy thick plate which is subjected to solid-solution water-quenching treatment is subjected to natural ageing for 15-45 days and is then subjected to double-stage manual ageing treatment. The ageing process belongs to the technical field of preparation and thermal treatment of metals and alloy. By adopting a synergistic effect of natural ageing and subsequent double-stage manual ageing which are combined, the ageing process provided by the invention can effectively refine the size of a precipitated phase under a slow quenching state; thus the precipitation strengthening effect of the alloy under the slow quenching state; the hardness of a core part is improved by about 15% without remarkably reducing the surface performances of a large-size sample so that the strength non-uniformity, caused by quenching, of a large-size component can be effectively improved; compared with research results of formers, the ageing process provided by the invention shortens the natural ageing time by 94% to 98%, namely the naturalageing time is shortened from the original two years (730 days) to 15-45 days.

Description

technical field [0001] The invention discloses an aging heat treatment process for improving the strength inhomogeneity caused by quenching of large-size 7-series aluminum alloys, and belongs to the technical field of preparation and heat treatment of metals and alloys. Background technique [0002] Al-Zn-Mg-Cu alloy has high specific strength and hardness, good corrosion resistance, high toughness and excellent processing performance, and has been widely used as a structural material in the aviation industry. In recent years, aircraft structural parts are developing toward large-scale and integrated, and there is an urgent demand for large-section 7xxx alloy thick plates and forgings. However, with the increase in the size of large-scale structural parts, large-thickness products tend to show higher quenching sensitivity during the quenching process. Currently commonly used 7xxx aluminum alloys such as 7050, 7055, 7075 and other alloys, when the thickness is greater than 1...

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Problems solved by technology

However, although this method is universal, the researchers found that only when the natural aging time reaches 17280 hours (2 years) can the quenching sensitivity be significantly reduced, and the hardness of the core can be increased by 13.5% compared with the state without natural aging. %, but since the natural aging time exceeds two years, obviously this method is not suitable for industrial production

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