CN-117363942-B - Mg-Gd-Y-Zn-Zr alloy and die casting fluidity improvement method thereof

Abstract

The invention discloses a method for improving die casting fluidity of Mg-Gd-Y-Zn-Zr alloy, which is characterized in that Ca element accounting for 0.5 to 1.5 percent of the mass percentage is added into a VW92 alloy, so that the die casting fluidity of the alloy is improved. The invention also discloses a high-fluidity Mg-Gd-Y-Zn-Zr alloy with good die casting fluidity, namely, the alloy is formed by adding 0.5 to 1.5 mass percent of Ca element on the basis of the prior VW92 alloy. The invention can better improve the flow property of the Mg-Gd-Y-Zn-Zr alloy during die casting and improve the product quality.

Inventors

• SONG JIANGFENG
• PAN FUSHENG
• GUO XIN
• WANG JING
• Xie Hecong
• ZHAO HUA
• XIE WENLONG
• JIANG BIN
• DONG ZHIHUA
• WU SUJUAN

Assignees

• 重庆大学

Dates

Publication Date

20260512

Application Date

20231026

Claims (4)

1. 1. The high-fluidity Mg-Gd-Y-Zn-Zr alloy with good die casting fluidity is characterized by comprising 1-1.5% by mass of Ca element based on a VW92 alloy, wherein the VW92 alloy comprises 9.0% -10.0% by mass of Gd, 1.5% -2.50% by mass of Y, 0.8% -1.5% by mass of Zn, 0.4% -0.5% by mass of Zr, and the balance of Mg and unavoidable impurities, and the content of the impurities is less than or equal to 0.05%; Or 9.12% of Gd, 2.05% of Y, 1.05% of Zn, 0.51% of Zr, 0.96% of Ca and the balance of Mg and unavoidable impurities, wherein the content of the impurities is less than or equal to 0.05%; Or 9.44% of Gd, 2.4% of Y, 1.21% of Zn, 0.44% of Zr, 1.54% of Ca and the balance of Mg and unavoidable impurities, wherein the content of the impurities is less than or equal to 0.05%; the casting is carried out by adopting the following casting steps: 1) Preparing materials, namely preparing materials of VW92 alloy and Mg-Ca intermediate alloy according to the proportion of alloy components, wherein the total amount of impurity elements Si and Fe is ensured to be less than 0.05%; 2) Removing impurities from the raw materials, removing an oxide layer on the metal surface of the raw materials, and drying for later use; 3) Smelting raw materials and obtaining a melt; 4) Purifying the melt, namely preparing casting after slag dragging and purifying of the melt; 5) Spraying a release agent into the inner cavity of the die, casting, cooling and demolding to obtain a target magnesium rare earth alloy product; In the step 2), the specific operation steps are that firstly, a grinding wheel grinder is used for removing the oxide layer on the surface of the material, then VW92 alloy and Mg-Ca intermediate alloy are put into a drying oven, the temperature is set to 250 ℃, and the material is preheated for 30min for later use after removing water; in the step 3), the specific operation steps are that the smelting furnace is preheated for 30min at 500 ℃. Preparing boron nitride and alcohol into a solution according to the mass ratio of 1:2, uniformly coating the solution on the inner wall of a low-carbon steel crucible by using a brush, drying the solution, placing the VW92 alloy after water removal into an air-dried iron crucible, heating a smelting furnace to 730 ℃ under the protection of CO 2 +SF 6 mixed gas, preserving heat, adding the dried Mg-Ca intermediate alloy after the VW92 alloy is melted, and smelting to obtain a melt.
2. 2. The high-fluidity Mg-Gd-Y-Zn-Zr alloy according to claim 1, wherein in the step 4), the concrete operation steps are that the mixed solution of boron nitride and alcohol is evenly coated on a slag removing ladle and the inner and outer surfaces of a stirring rod, after the materials are melted, the scum on the surface of the melt is fished out by using the steel ladle, the stirring rod is used for 5min to stir, the target alloy melt is obtained, and the casting is prepared after the mixture is kept stand for 30min at the temperature of 730 ℃.
3. 3. The high-fluidity Mg-Gd-Y-Zn-Zr alloy according to claim 1, wherein in the step 5), the specific operation steps are that a magnesium alloy release agent is uniformly sprayed on the inner wall of a single spiral fluidity test die, cooling and releasing are facilitated, the die is heated to 250 ℃ in advance, after the heat preservation of a target alloy melt is completed, the target alloy melt is cast into a 250 ℃ die at the temperature of 730 ℃, and after cooling, the target magnesium alloy product is obtained.
4. 4. A method for improving die casting fluidity of Mg-Gd-Y-Zn-Zr-based alloy, characterized by adding Ca element to VW92 alloy, improving die casting fluidity of the alloy, and producing the high fluidity Mg-Gd-Y-Zn-Zr-based alloy according to any one of claims 1 to 3.

Description

Mg-Gd-Y-Zn-Zr alloy and die casting fluidity improvement method thereof Technical Field The invention relates to the technical field of casting of magnesium rare earth alloys of automobiles, in particular to an Mg-Gd-Y-Zn-Zr alloy and a method for improving the die casting fluidity of the Mg-Gd-Y-Zn-Zr alloy. Background The magnesium alloy has the characteristics of light weight, high specific strength, good vibration damping performance, good electric conduction and heat conduction performance and the like, and is widely applied to the fields of aerospace, automobile manufacturing, 3C and the like at present. With the deep advancement of energy conservation and emission reduction, the magnesium alloy is used as the lightest commercial metal structural material at present, plays an important role in the light-weight design of automobiles, not only can remarkably reduce carbon emission, but also can bring higher economic benefit. With the continuous improvement of the application requirements of magnesium alloy and the continuous development of material processing equipment, cast magnesium alloy components are gradually developed from small to large, ultra-large and structural integration towards more and more complex shapes, and the cast magnesium alloy components have high requirements on the fluidity of magnesium alloy. In the casting process of the magnesium alloy, the solution solidification can generate huge solidification shrinkage force, and when the critical resistance of the alloy is exceeded, the magnesium alloy is extremely easy to generate fatal defects such as hot cracking and the like, and the formability and the application of the magnesium alloy are seriously hindered. The magnesium alloy has good fluidity, and the residual liquid phase at the final stage of alloy solidification can effectively feed generated hot cracks, so that the hot cracking tendency of the magnesium alloy is obviously reduced. In addition, the main casting method of the magnesium alloy is die casting at present, and the alloy fluidity has important influence on the quality of die castings for the formation of complex and ultra-large magnesium alloy castings. In die casting, high fluidity of the magnesium alloy melt is required to ensure rapid melt filling, especially for structures with small holes and uneven wall thickness. Therefore, improving the fluidity of the magnesium alloy has important significance for improving the quality of complex oversized magnesium alloy castings and developing the key technology of magnesium alloy casting. The VW92 alloy is used as a high-strength cast magnesium alloy in Mg-Gd-Y-Zn-Zr magnesium alloy, and has huge application scene. However, the alloy has a high rare earth element content, so that the fluidity is poor, the hot cracking tendency is high, the die casting formability is poor, and the application of the alloy is seriously hindered. Therefore, how to improve the defect of the VW92 magnesium alloy and improve the fluidity of the alloy, thereby reducing the defect of alloy casting products and improving the quality of the products is a problem to be considered to be solved by the person skilled in the art. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide the Mg-Gd-Y-Zn-Zr alloy and the die casting fluidity improving method thereof, so that the fluidity of the Mg-Gd-Y-Zn-Zr alloy in die casting can be better improved, and the product quality is improved. In order to solve the technical problems, the invention adopts the following technical scheme: a method for improving the die casting fluidity of Mg-Gd-Y-Zn-Zr alloy is characterized in that 0.5-1.5% of Ca element by mass percent is added into a VW92 alloy, so that the die casting fluidity of the alloy is improved. In the scheme, the VW92 alloy, namely the Mg-9Gd-2Y-1Zn-0.5Zr alloy, comprises the following components in percentage by mass, 9.0% -10.0% of Gd, 1.5% -2.50% of Y, 0.8% -1.5% of Zn, 0.4% -0.5% of Zr, and the balance of Mg and unavoidable impurities, wherein the content of the impurities is less than/equal to 0.05%. Therefore, after a small amount of Ca element is added into the VW92 alloy, on one hand, the low-melting point eutectic phase of Mg2Ca with relatively large diffusion coefficient can be introduced to drive the flow of the magnesium rare earth phase with small diffusion coefficient, so that the cavity of a casting mould is fully filled before the eutectic alloy is crystallized, on the other hand, the magnesium alloy with high rare earth element content always has the problem of high melt viscosity, after the Mg2Ca phase with relatively low viscosity is introduced, the Mg2Ca phase can be distributed between the magnesium rare earth phases before the melt is solidified, the binding force between the magnesium rare earth phases is reduced, and the characteristic of high overall melt viscosity is reduced, so that the fluidity of the magnesium rare earth alloy can be g