Method for improving homogenizing efficiency of 7000 series aluminum alloy cast ingots

Abstract

The invention provides a homogenizing annealing method for 7000 series aluminum alloy cast ingots, and particularly relates to a method for improving the homogenizing efficiency of the 7000 series aluminum alloy cast ingots. The whole process of the method is completed in a variable-temperature environment, and the method is suitable for flat cast ingots with the thickness larger than 200 mm. Research finds that the key factor of coarse primary phase dissolution is temperature, the higher the temperature is, the more thorough the coarse primary phase dissolution is, traditional homogenizing treatment is performed at a constant temperature for a certain time, and in order to avoid overburning, the temperature far lower than the temperature of coarse primary phase dissolution is often selected, and the homogenizing effect is achieved by prolonging the time. However, the inventor of the invention surprisingly discovers that by adopting the method disclosed by the invention, not only the coarse primary phase dissolution can be quickly realized, but also the overburning of the cast ingots at a high temperature can be effectively avoided, and on the premise of obtaining the same homogenizing treatment effect, the time of the homogenizing treatment process can be remarkably shortened, and the production cost is greatly reduced.

Description

technical field [0001] The invention belongs to the technical field of metal materials, and relates to a homogenization annealing method for 7000-series aluminum alloy ingots, in particular to a method for improving the homogenization efficiency of 7000-series aluminum alloy ingots. Background technique [0002] The 7000-series aluminum alloy has high comprehensive properties such as ultra-high strength, high toughness, and corrosion resistance. It is one of the commonly used metal materials in the aviation industry. It is mainly used in important parts such as main load-bearing frame beams and joints of aircraft fuselages. With the increase in the size of the aircraft and the increase in the demand for overall structural parts, the size of aluminum alloy semi-finished products, such as plates and forgings, is also increasing. With the increase in size, the problem of difficulty in uniformity control becomes more and more obvious, and The uniformity of the ingot is the bas...

AI Technical Summary

Problems solved by technology

[0003] The homogenization annealing process of 7000 series aluminum alloy has developed from the initial single-stage and two-stage to the current three-stage, taking the three-stage homogenization annealing treatment as an example, in which the temperature of the first-stage homogenization annealing treatment is relatively low, generally 380℃~420℃, the purpose is to promote Al 3 Zr particles are precipitated; the temperature of the second and third homogenization annealing treatment is generally 450 ° C ~ 470 ° C, the purpose is to gradually dissolve the coarse primary phase in the alloy through a step-by-step method, and the second and third homogenization The temperature of chemical annealing treatment will not exceed 480°C or above, because the 7000 series aluminum alloy will be over-burned at this temperature, resulting in cracking during thermal processing

[0004] In order to further pursue the effect of fully dissolving the coarse primary phase and reduce the content of the residual coarse primary phase to the greatest extent, the conventional practice in this field is to prolong the holding time as much as possible. Since the thickness of the flat cast ingots used in industrial production is all above 200mm, this As a result, the holding time of the homogenization process exceeds 48 hours, and with the increase of the ingot size, the holding time is correspondingly extended. In addition, because the ingot is more sensitive to temperature, the coarse primary phase cannot be achieved by extending the holding time alone. The effect of fully dissolving, and prolonging the holding time also greatly prolongs the preparation time of ingots and increases the production cost

Images