High-pressure harmonization processing method of eliminating 700 line aluminium alloy cast ingot crystallization phase
A technology of homogenization treatment and aluminum alloy ingot casting, which is applied in the field of homogenization heat treatment to achieve high aging strength, increase homogenization temperature, and eliminate adverse effects
Active Publication Date: 2009-07-08
溧阳常大技术转移中心有限公司
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Problems solved by technology
[0005] The present invention is aimed at the problem that the casting crystal phase of 7000 series aluminum alloy with high alloying degree is difficult to be fully eliminated through the existing homogenization treatment process. Heat treatment, so as to achieve the purpose of quickly and fully eliminating the crystalline phase of the ingot
[0008] The main purpose of preheating is to properly improve the plasticity of the ingot and prevent the ingot from cracking when the top pressure mold is pressurized.
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example 1
[0027] The experimental material is a chilled cast 7000 series aluminum alloy ingot, and its chemical composition is Al-12Zn-3.5Mg-3.0Cu-0.14Zr (mass percentage). figure 2 It is a scanning electron micrograph of the as-cast structure. It can be seen from the figure that there are a lot of non-equilibrium crystalline phases in the matrix. These non-equilibrium crystalline phases mainly appear as layered eutectic. X-ray diffraction analysis shows that these crystalline phases are η phases, such as image 3 Shown.
[0028] The ingot was machined into round rod-shaped specimens with a diameter of 10 mm and a height of 12 mm. A 420-bore six-face top synthesis device was used to preheat the sample to 350°C for 30 minutes, then apply an isostatic pressure of 5 GPa, then heat to 750°C, hold for 45 minutes, and then cool to room temperature under pressure. The microstructure after high pressure homogenization is as Figure 4 Shown. At this time, the crystalline phase in the matrix is fu...
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The invention relates to a homogenization heat treatment method for eliminating crystal phases of 7000 series aluminum alloy casting ingots, that is, performing homogenization treatment while applying high isostatic pressure to the ingots. It is carried out in four stages: ingot preheating, pressurization, homogenization treatment, and cooling. The preheating temperature ranges from 250 to 450°C, the holding time is about 10min to 2h, the lower limit of the applied pressure is above 500MPa, and the homogenization temperature At 500°C to 850°C, the holding time is between 15min and 2h. There are two different ways to maintain the uniform pressure until the ingot is cooled under pressure, or to cool under pressure to below the melting temperature of the aluminum alloy at normal pressure, and then perform pressure relief cooling. According to the characteristic that the melting temperature of aluminum alloy rises under high pressure, the present invention adopts a higher temperature for homogenizing heat treatment, so as to realize the purpose of quickly and fully eliminating the crystal phase of the ingot.
Description
Technical field [0001] The invention relates to a homogenization heat treatment method for eliminating the crystalline phase of a 7000 series aluminum alloy ingot, that is, the homogenization treatment is performed while applying high isostatic pressure to the ingot. Background technique [0002] 7000 series aluminum alloy is a kind of deformed aluminum alloy that can obtain the highest aging strengthening effect. It has the characteristics of low density, high strength, and good processing performance. It has become an important structural material in the aviation field. This series of alloys mainly contain Zn, Mg, Cu and other elements. Among them, Zn and Mg aging precipitate fine and dispersed GP zone, η'metastable phase and η equilibrium phase, which directly determine the strength performance; the main function of Cu is to improve the stress corrosion resistance And intensity. In order to further increase the strength of the 7000 series ultra-high-strength aluminum alloy, th...
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IPC IPC(8): C22F1/04
Inventor 李海曹大呼王芝秀
Owner 溧阳常大技术转移中心有限公司