Composite squeeze casting method for magnesium alloy special-shaped parts

Abstract

The invention relates to a composite squeeze casting method for magnesium alloy special-shaped parts in order to avoid the situations that in the casting process of the magnesium alloy special-shaped parts, the hole shrinkage phenomenon and the shrinkage loosening phenomenon are serious, and the structural compactness of a metallographic structure is poor. According to the composite squeeze casting method, firstly, a composite squeeze casting mold is prepared; gas protection is performed in the whole process of magnesium alloy liquid; the magnesium alloy liquid is smelted through a vacuum furnace, cast and subjected to composite squeeze casting; and the magnesium alloy special-shaped parts are manufactured. The technology of the preparation method is advanced; data are accurate and detailed; the magnesium alloy special-shaped parts manufactured through composite squeeze casting are accurate in shape, good in metallographic structure compactness and free of the hole shrinkage phenomenon and the shrinkage loosening phenomenon, and the tensile strength can be 180 MPa; and the composite squeeze casting method for the magnesium alloy special-shaped parts is advanced.

Description

technical field [0001] The invention relates to a compound extrusion casting method for magnesium alloy special-shaped parts, which belongs to the technical field of preparation and application of magnesium alloy special-shaped parts. Background technique [0002] Magnesium alloys have extremely important application value and broad application prospects in the fields of automobiles, electronic communications, aerospace, and national defense, and are known as green engineering materials in the 21st century. [0003] At present, most of the magnesium alloy deep-processing products are obtained through casting methods. The casting of magnesium alloys can be made by sand casting, metal casting and pressure casting. The sand casting process has a low yield and is prone to micro-shrinkage, which reduces the mechanical properties. Although metal mold casting overcomes some shortcomings of the sand casting process, its production efficiency is low and it is not suitable for mass pr...

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Problems solved by technology

[0003] At present, most of the magnesium alloy deep-processing products are obtained through casting methods. The casting of magnesium alloys can be made by sand casting, metal casting and pressure casting. The sand casting process has a low yield and is prone to micro-shrinkage, which reduces the mechanical properties. Although metal mold casting overcomes some shortcomings of the sand casting process, the production efficiency is low and it is not suitable for mass production

[0004] Die casting is that liquid or semi-liquid metal fills the mold cavity under pressure, and rapidly solidifies under pressure to obtain castings, which can form thin-walled, complex-shaped, and clear-cut castings; since pressure casting is a high-speed filling of magnesium alloy liquid In the mold cavity, the metal flow in the dispersed state is highly mixed with the air in the cavity, forming diffusely distributed pores in the die casting, which seriously affects the performance of the casting. Therefore, the die casting generally cannot be strengthened by heat treatment

[0005] Squeeze casting technology provides an effective method for forming magnesium alloys. It applies high mechanical pressure to the liquid metal poured into the mold cavity, and makes it shape and solidify to obtain castings; at present, the traditional Squeeze casting technology is divided into direct squeeze casting and indirect squeeze casting. Direct squeeze casting is to pour liquid metal directly into the metal mold, and then close the mold to realize the filling flow of molten metal, so that the molten metal fills all the cavity and continues Boosting and holding pressure make the casting solidify, demold after cooling, and complete the casting; with the development of technology, there are many special-shaped and complex parts of magnesium alloy, and it is difficult for liquid metal to pressurize and solidify during the filling process of casting, especially at the corners , edge parts and special-shaped structure parts, it is difficult to pressurize and solidify, resulting in shrinkage and shrinkage cavities of the castings, which will cause great harm to the quality of the castings; some use indirect extrusion casting, use the forming pressure head, and the magnesium The alloy liquid is squeezed into the mold cavity, and the ingate composed of the indenter and the die transmits the pressure to the casting, but the indenter only partially pressurizes the casting, and the metallographic structure of the casting is less compact, and the metal After the liquid is injected into the mold cavity, the temperature of the molten metal has dropped with the filling and flow of the molten metal, and the runner part has begun to solidify, and the pressure transmission effect is not good, so the castings often have shrinkage cavities and shrinkage porosity; magnesium alloy is a non-ferrous metal Light metal alloy, small specific gravity, easy to oxidize, easy to evaporate during the casting process, which also seriously affects the casting quality

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