Aluminum alloy semisolid secondary combined extrusion casting method

Abstract

The invention relates to an aluminum alloy semisolid secondary combined extrusion casting method to overcome the defects that in the current aluminum alloy semisolid extrusion casting technology, the quality of a sizing agent is extremely hard to control, meanwhile, close connection between sizing agent preparing and forming is very difficult to achieve, and the stability is poor. By adopting the aluminum alloy semisolid secondary combined extrusion casting method, semisolid sizing agent preparing and extrusion casting forming integration is achieved through the secondary combined extrusion casting technology. The preparation method is advanced, data is accurate and detailed, formed parts cast in a secondary combined extrusion manner are precise in shape, the metallographic structure compactness is good, primary alpha-Al is composed of spherical grains and nearly-spherical grains, the number of rose grains is small, the grain size is obviously reduced, the extension strength reaches 235 Mpa, the ductility reaches 8.5 %, and the aluminum alloy semisolid secondary combined extrusion casting method is advanced.

Description

technical field [0001] The invention relates to an aluminum alloy semi-solid secondary compound extrusion casting method, which belongs to the technical field of aluminum alloy semi-solid forming. Background technique [0002] Aluminum alloy semi-solid forming technology includes rheological forming and thixoforming. The semi-solid metal blank used in thixoforming has a high solid phase fraction, which is more convenient in transportation and heating, and is easy to realize automatic operation. Therefore, the industrial application of the early semi-solid forming technology mainly focused on the thixoforming process; with the application and promotion of the thixoforming technology, the equipment cost is high, the processing residue cannot be recovered quickly, and secondary remelting Oxidation of the surface of the billet, long production cycle, and high energy consumption have restricted the development of thixoforming technology; therefore, rheological forming technology ...

AI Technical Summary

Problems solved by technology

[0003] The preparation process of aluminum alloy semi-solid slurry is divided into two types, one is that the melt is stirred by an external field, and the other is that the melt does not need to be stirred by an external field; the former method is to apply an external field during the solidification of the alloy. Strong stirring, the convection caused by stirring inhibits the growth of dendrites, and in the case of high stirring shear rate and low cooling rate, the dendrites eventually evolve into spherical or nearly spherical, such as mechanical stirring, electromagnetic stirring, ultrasonic Vibration method; however, the common feature of the method of using external field stirring is that special equipment needs to be added during the preparation of semi-solid slurry, the process is complicated, and the cost is high, which restricts the industrial application of semi-solid forming technology; another process is to control the temperature. , alloy elements, nucleation and other internal factors to prepare semi-solid slurry, such as low superheat casting method, chemical grain refinement method, controlled nucleation method, strain-induced melt activation method; however, the disadvantage of this method is Precise control of external conditions such as temperature and composition is required, so the current non-external field stirring method is still in the laboratory research stage and is rarely used in industrial production

[0004] Squeeze casting technology is a new type of metal processing method with potential application prospects in the field of semi-solid processing. This technology applies high mechanical pressure to the liquid or semi-liquid metal or alloy injected into the mold cavity to make the solidified The plastic deformation of the shell occurs, and the liquid or semi-liquid metal is fed in time under the action of isostatic pressure, so as to obtain a casting with dense structure and high mechanical properties; squeeze casting technology mainly includes direct squeeze casting and indirect squeeze casting. One method, direct squeeze casting, is that the pressure directly acts on the surface of the liquid metal, and the pressure transmission distance is short, but the molten metal must be filled accurately and quantitatively. Therefore, it is only suitable for the production of castings with simple shape and symmetrical structure; indirect squeeze casting is that the pressure is transmitted to the metal melt in the mold cavity through the runner, so the pressure transmission distance is long, and defects such as shrinkage and porosity are prone to occur.

[0005] How to efficiently and stably combine semi-solid molding technology with squeeze casting technology and realize precise control of the molding process has become the key to semi-solid molding. That is, the use of external fields such as electromagnetic stirring and ultrasonic waves, or through external devices such as inclined plates and serpentine runners to prepare semi-solid slurry, then pour the slurry into the mold cavity, and realize extrusion casting on a hydraulic extrusion machine. It is extremely difficult to control the quality of the pulp in the process, and it is difficult to achieve a close connection between pulping and molding, so there is a lack of stable and dedicated molding technology and equipment

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