Process for producing large-size 7055 aluminum alloy round ingot

Abstract

The invention discloses a process for producing a large-size 7055 aluminum alloy round ingot. The process comprises the following steps of firstly preparing the following raw materials in mass ratio: less than or equal to 0.10% of Si, less than or equal to 0.15% of Fe, 2.0-2.6%b of Cu, less than or equal to 0.05% of Mn, 1.8-2.3% of Mg, less than or equal to 0.04% of Cr, 7.6-8.4% of Zn, less than or equal to 0.06% of Ti, 0.08-0.25% of Zr and the balance of inevitable impurities and aluminum; smelting, refining, skimming slag, standing, carrying out heat preservation, carrying out online degassing and refining and casting by virtue of stepped casting process parameters, wherein the casting speed is 15-25mm / min and the water flow is 600-1300l / min. By the process for producing the large-size 7055 aluminum alloy round ingot, the casting composition segregation can be avoided and the generation of casting cracks can be solved, the finished product rate is high and the thickness of the coarse-grained layer is much lower than conventional levels.

Description

technical field [0001] The invention belongs to the field of metal material forming, and relates to an aluminum alloy casting method, in particular to a production process of a large-size 7055 aluminum alloy round ingot. Background technique [0002] With the development of the aviation industry, high-strength aluminum alloys, one of the commonly used materials for aeronautical structures, are widely used. Al-Zn-Mg-Cu alloy is a widely used aeronautical structural material, and its average content of alloying element w(Cu+Mg+Zn) can reach 12.75%, which is currently the highest strength alloy among wrought aluminum alloys. Due to the high w(Zn) / w(Mg) ratio and w(Cu) / w(Mg) ratio of this alloy, the aluminum alloy has high strength, good fracture toughness and strong resistance to fatigue crack growth. and other good overall performance. [0003] However, although the Al-Zn-Mg-Cu alloy has high comprehensive properties, its production and processing technology is difficult, an...

AI Technical Summary

Problems solved by technology

[0003] However, although the Al-Zn-Mg-Cu alloy has high comprehensive properties, its production and processing technology is difficult, and domestic aluminum processing enterprises still lack the ability to cast large-diameter (diameter> 400mm) Al-Zn-Mg-Cu alloys. Alloy experience, which is especially prominent for this series of aluminum alloys with a diameter > 500mm. At present, no domestic company has successfully developed a casting process for this series of aluminum alloys with a diameter > 500mm

The reason for this phenomenon is that on the one hand, there are fewer large-scale extrusion machines in China, and on the other hand, the stress in the casting process of large-diameter Al-Zn-Mg-Cu series aluminum alloys is relatively large, the tendency of cracks is very large, and the yield very low

[0004] Traditional large-diameter hard alloy casting mostly adopts low liquid level or same-level casting, that is, the casting tooling is a copper sheath crystallizer, which needs to be laid at the beginning of casting, which causes a lot of waste and low production efficiency; in addition, traditional casting Due to the one-stop process (casting speed and water flow rate does not change during the entire casting process), the coarse-grained layer on the surface of the hard alloy round rod is very thick, and the surface segregation is serious, and the casting speed of this process is relatively slow, so it is easy to Severe chemical composition segregation, internal quality defects such as porosity, pores, and slag inclusions

The round bar produced by this process has to be turned and milled before the next process, that is, extrusion, which causes a lot of waste of manpower, material resources and financial resources.