Heat-treatment-free aluminum alloy material for die casting

Abstract

The invention relates to a heat treatment-free aluminum alloy material for die casting in the technical field of die-casting aluminum alloy materials, which comprises the following components in percentage by mass: 6.5 to 8.5 percent of Si, 0.1 to 0.25 percent of Fe, 0.1 to 0.4 percent of Mg, 0.35 to 0.75 percent of Mn, 0.03 to 0.05 percent of Sr and the balance of Al. According to the method, the morphology of eutectic Mg2Si and Si particles in an as-cast structure is converted from a coarse Chinese character shape to a fine fiber shape, the morphology of an Al8Mg3FeSi6 iron-rich phase in the structure is improved, the morphology of primary Mg2Si is sequentially converted from a dendritic crystal shape to a polygon and a quadrangle, a coarse second phase in the alloy is remarkably reduced, and the plasticity of the alloy is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of die-casting aluminum alloy materials, in particular to a heat-treatment-free aluminum alloy material for die-casting. Background Art

[0002] Traditional aluminum alloys must be heat treated (solid solution-quenching-aging) before use. Integrated die-casting technology integrates dozens or even hundreds of single parts into a large or extra-large structural part. Some parts are thin and some are thick. The thin parts are only 2mm or 3mm thick and cannot be heat treated. Otherwise, they will deform violently and produce bubbles and have to be scrapped. The development of heat-treatment-free die-casting aluminum alloy materials is the key to integrated die-casting technology.

[0003] Elements such as Mg, Si, Mn and impurity Fe in the alloy form a large number of crystalline phases during the alloy crystallization process, resulting in serious composition and structural inhomogeneity in the alloy ingot, which increases the deformation resistance. Among them, impurity Fe is easy to form hard and brittle intermediate compounds during the solidification process of the alloy, such as needle-shaped β-Al5FeSi and other phases. These hard and brittle phases can become stress concentration sources, significantly reducing the deformation plasticity of the alloy and deteriorating the cutting performance. From the perspective of production technology, it is hoped that the deformed metal has high plasticity to meet the needs of production. Summary of the invention

[0004] The purpose of the present invention is to solve the above defects and provide an aluminum alloy material with high cost performance and suitable for large-scale thin-walled integrated die-casting and heat-treatment-free.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A heat-treatment-free aluminum alloy material for die casting comprises Si, Fe, Mg, Mn, Sr and Al, wherein the mass percentage content of each component is 6.5-8.5% Si, 0.1-0.25% Fe, 0.1-0.4% Mg, 0.35-0.75% Mn and 0.03-0.05% Sr, and the rest is Al.

[0006] In the above description, as a further solution, the mass percentage content of each component is 6.5% Si, 0.25% Fe, 0.4% Mg, 0.75% Mn, 0.02% Sr, 91.08% Al and 1% inevitable trace impurities.

[0007] In the above description, as a further solution, the mass percentage content of each component is 6.5% Si, 0.2% Fe, 0.4% Mg, 0.75% Mn, 0.02% Sr, 91.13% Al and 1% inevitable trace impurities.

[0008] The beneficial effects produced by the present invention are as follows: The present application discloses a heat-treatment-free aluminum alloy material for die casting, in which the addition of a very small amount of Sr element can significantly change the nucleation and precipitation process of the aluminum alloy, which can not only control the grain structure, but also eliminate the harmful effects of Fe and Si in the alloy, which is beneficial to improving the performance of the alloy. By adding a small amount of Sr to the Al-15Si-14Mg alloy, the morphology of the eutectic Mg2Si and Si particles in the cast structure changes from a coarse Chinese character shape to a fine fiber shape, and the morphology of the Al8Mg3FeSi6 iron-rich phase in the structure is improved, so that the morphology of the primary Mg2Si changes from a dendrite shape to a polygon and a quadrilateral in turn, significantly reducing the coarse second phase in the alloy and greatly improving the plasticity of the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The present invention is a flow chart of the preparation process of a heat-treatment-free aluminum alloy material for die casting. DETAILED DESCRIPTION

[0010] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the embodiments are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0011] Embodiment 1: A heat-treatment-free aluminum alloy material for die casting comprises Si, Fe, Mg, Mn, Sr and Al, wherein the mass percentage contents of the components are 7% Si, 0.15% Fe, 0.4% Mg, 0.75% Mn, 0.02% Sr, 90.68% Al and 1% inevitable trace impurities.

[0012] See also Figure 1 ; A preparation process flow chart of heat-treatment-free aluminum alloy material for die casting.

[0013] S1. Melting: Preheat the melting furnace, slag removal tools and raw materials at 250℃ for 2h, put the treated aluminum ingot into the melting furnace, and heat it to completely melt into aluminum water at a melting temperature of 740-760℃. Use tools to gently remove the surface coating of the liquid, add the intermediate alloy with Sr, wait for the intermediate alloy to be completely melted in the aluminum water, use tools to continuously stir until the intermediate alloy is completely melted, and then slowly remove the coating on the liquid.

[0014] After the temperature is lowered to 720-735°C, magnesium and other intermediate alloys are added in proportion, and tools are used to stir until the alloys are completely melted to obtain the first alloy melt.

[0015] S2. Refining treatment: The first alloy melt is degassed in a converter for 40-50 minutes. Modifiers and super refiners are added during the degassing process (the amount of super refiner added is 0.15-0.25% of the total mass of the melt). Nitrogen is then used for a refining treatment. The refining temperature is 710-720°C for 7-12 minutes. Then, a slag removal treatment is performed to reduce the temperature to 700°C. After standing for 30 minutes, a second alloy melt is obtained.

[0016] S3, insulation treatment: After the second alloy melt is heated to 710℃, it is transferred to the machine-side furnace, and the second alloy melt is heated to 730℃ in the machine-side furnace for insulation treatment, and the insulation time is 20-25min. After insulation, the temperature is raised to 740℃ and argon gas is introduced for secondary refining treatment for 15min.

[0017] After the secondary refining treatment, a secondary slag removal treatment is performed. After the secondary refining treatment is qualified, the alloy is allowed to stand for 15 minutes to obtain a third alloy melt.

[0018] S4. Die-casting treatment: first use a heating furnace to heat the die-casting mold to 240-260°C. The die-casting mold is equipped with a heat-insulating barrel. During die-casting, the barrel temperature is maintained at 215-265°C. When the temperature of the third alloy melt reaches 720°C, the molten third alloy melt is passed through the barrel for auxiliary die-casting to obtain an aluminum alloy ingot.

[0019] S5. Post-processing: remove the residue and oxide on the surface of the aluminum alloy ingot to make the surface of the aluminum alloy ingot smooth and beautiful.

[0020] In the above embodiment, the addition of a very small amount of Sr element can significantly change the nucleation and precipitation process of the aluminum alloy, not only can control the grain structure, but also can eliminate the harmful effects of Fe and Si in the alloy, which is beneficial to improve the performance of the alloy. Adding a small amount of Sr to the Al-15Si-14Mg alloy, the morphology of the eutectic Mg2Si and Si particles in the cast structure is transformed from a coarse Chinese character shape to a fine fiber shape, and the morphology of the Al8Mg3FeSi6 iron-rich phase in the structure is improved, so that the morphology of the primary Mg2Si is transformed from a dendrite shape to a polygon and a quadrilateral in turn, which significantly reduces the coarse second phase in the alloy and greatly improves the plasticity of the alloy.

[0021] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. A heat-treatment-free aluminum alloy material for die casting, the formula of which includes: Si, Fe, Mg, Mn, Sr and Al, characterized in that the mass percentage content of each component is: 6.5-8.5% Si, 0.1-0.25% Fe, 0.1-0.4% Mg, 0.35-0.75% Mn and 0.03-0.05% Sr, and the rest is Al.

2. The heat-treatment-free aluminum alloy material for die casting according to claim 1, characterized in that: The mass percentage contents of the components are 6.5% Si, 0.25% Fe, 0.4% Mg, 0.75% Mn, 0.02% Sr, 91.08% Al and 1% inevitable trace impurities.

3. The heat-treatment-free aluminum alloy material for die casting according to claim 1, characterized in that: The mass percentage contents of the components are 6.5% Si, 0.2% Fe, 0.4% Mg, 0.75% Mn, 0.02% Sr, 91.13% Al and 1% inevitable trace impurities.

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