Search

CN-122013013-A - High-strength and high-toughness die-casting magnesium alloy and preparation method and application thereof

CN122013013ACN 122013013 ACN122013013 ACN 122013013ACN-122013013-A

Abstract

The invention relates to the technical field of magnesium alloy materials, in particular to a high-strength and high-toughness die-casting magnesium alloy, and a preparation method and application thereof. The high-strength and high-toughness die-casting magnesium alloy comprises, by mass, 5% -7.5% of Al, 0.3% -0.65% of Mn, 0.6% -1.2% of RE, 0.2% -0.46% of V, 0.1% -0.48% of Sr, 0.1% -0.32% of Ti and the balance of Mg and unavoidable impurity elements, wherein RE comprises Ce and La, and the mass ratio of Ce to La is (2-2.5): 1. According to the high-strength and high-toughness die-casting magnesium alloy, die-casting magnesium alloy with high strength, high plasticity, corrosion resistance and good casting fluidity is obtained through the diversified synergistic effect of Ce and La mixed rare earth elements and V, sr and Ti micro alloy elements, and the preparation cost is low.

Inventors

  • ZHANG WEI
  • QI DAN
  • LIU KEXIN
  • GAO DONGHONG
  • LIU JINMING

Assignees

  • 中国第一汽车股份有限公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. The die-casting magnesium alloy with high strength and toughness is characterized by comprising the following components in percentage by mass: 5% -7.5% of Al, 0.3% -0.65% of Mn, 0.6% -1.2% of RE, 0.2% -0.46% of V, 0.1% -0.48% of Sr, 0.1% -0.32% of Ti and the balance of Mg and unavoidable impurity elements; wherein RE comprises Ce and La, and the mass ratio of Ce to La is (2-2.5): 1.
  2. 2. The high-strength and high-toughness die-casting magnesium alloy according to claim 1, which comprises the following components in percentage by mass: 5.5% -7% of Al, 0.3% -0.55% of Mn, 0.4% -0.8% of Ce, 0.2% -0.4% of La, 0.25% -0.35% of V, 0.15% -0.35% of Sr, 0.1% -0.2% of Ti and the balance of Mg and unavoidable impurity elements.
  3. 3. The high-strength and toughness die-cast magnesium alloy according to claim 1, wherein said unavoidable impurity elements include at least one of Fe, ni and Cu; And/or, in the high-strength and high-toughness die-casting magnesium alloy, the total content of the unavoidable impurity elements is less than or equal to 0.02wt%.
  4. 4. The high strength and toughness die cast magnesium alloy according to claim 1, comprising at least one of the following features (1) to (5); (1) The yield strength of the high-strength and high-toughness die-casting magnesium alloy is 145-160 MPa; (2) The tensile strength of the high-strength and high-toughness die-casting magnesium alloy is 260-280 MPa; (3) The elongation after fracture of the high-strength and high-toughness die-casting magnesium alloy is 15% -19%; (4) The maximum bending angle of the high-strength and high-toughness die-casting magnesium alloy is 42-48 degrees; (5) The corrosion rate of the high-strength and high-toughness die-casting magnesium alloy under the neutral salt spray test condition is 0.38-0.46 mm/a.
  5. 5. The method for preparing the high-strength and high-toughness die-casting magnesium alloy according to any one of claims 1 to 4, which is characterized by comprising the following steps: and sequentially melting, degassing, refining, deslagging and die casting the raw materials which are mixed according to the composition of each element to obtain the die casting magnesium alloy with high strength and toughness.
  6. 6. The method for preparing a high-strength and high-toughness die-casting magnesium alloy according to claim 5, comprising the following steps: s1, drying magnesium ingots, aluminum ingots, mg-Mn intermediate alloy, mg-30CeLa intermediate alloy, al-55V intermediate alloy, al-10Sr intermediate alloy and Al-10Ti-1B intermediate alloy in a heating furnace for pretreatment; S2, under a protective atmosphere, melting a magnesium ingot, heating to a first temperature, sequentially adding an aluminum ingot, an Mg-30CeLa intermediate alloy and an Al-55V intermediate alloy, and standing after melting to obtain a first alloy melt; s3, cooling the first alloy melt to a second temperature, sequentially adding the Mg-Mn intermediate alloy, the Al-10Sr intermediate alloy and the Al-10Ti-1B intermediate alloy, and standing after melting to obtain a second alloy melt; And S4, sequentially carrying out degassing, refining, cooling and standing, deslagging and die casting molding on the second alloy melt to obtain the high-strength and high-toughness die casting magnesium alloy.
  7. 7. The method for producing a high-strength and toughness die-cast magnesium alloy according to claim 6, comprising at least one of the following features (1) to (5); (1) In the step S1, the temperature of the drying pretreatment is 150-200 ℃ and the time is 10-20 min; (2) In step S2, the protective atmosphere includes at least one of CO 2 、SF 6 and N 2 ; (3) In the step S2, the melting temperature of the magnesium ingot is 660-680 ℃; (4) In the step S2, the first temperature is 720-740 ℃; (5) In the step S2, the standing time is 10-25 min.
  8. 8. The method for producing a high-strength and toughness die-cast magnesium alloy according to claim 6, comprising at least one of the following features (1) to (3); (1) In the step S3, the second temperature is 700-720 ℃; (2) In the step S3, standing for 15-30 min; (3) In the step S4, the temperature of the degassing and the refining is 700-720 ℃.
  9. 9. The method for preparing the high-strength and high-toughness die-casting magnesium alloy according to claim 6, wherein in the step S4, the die-casting molding condition is that the die-casting temperature is 680-700 ℃, the die temperature is 180-230 ℃, the vacuum degree is 50-70 mbar, the injection speed is 2-6 m/S, and the pressurizing is 350-800 bar.
  10. 10. Use of the high-strength and toughness die-cast magnesium alloy according to any one of claims 1 to 4 or the high-strength and toughness die-cast magnesium alloy prepared by the preparation method of the high-strength and toughness die-cast magnesium alloy according to any one of claims 5 to 9 in an automobile integrated die-cast structural member.

Description

High-strength and high-toughness die-casting magnesium alloy and preparation method and application thereof Technical Field The invention relates to the technical field of magnesium alloy materials, in particular to a high-strength and high-toughness die-casting magnesium alloy, and a preparation method and application thereof. Background The magnesium alloy has the advantages of low density, high specific strength, good heat and electric conductivity, good damping and vibration reduction performance, electromagnetic shielding performance, recycling and the like, and is a high-quality lightweight material. The die-casting magnesium alloy has good fluidity, can obtain die-casting parts with complex structure, thin wall and higher surface quality, and has higher production efficiency, so that the die-casting magnesium alloy has wide application prospect in the automobile industry and accounts for more than 80 percent of the magnesium alloy quantity for the automobile. The traditional die-casting magnesium alloy mainly comprises AZ91D, AM B and other alloys, has lower strength, plasticity, heat resistance, corrosion resistance and other performances, is only used for low-bearing parts such as automobile interior skeletons, instrument panel skeletons and the like, and limits the further expansion application of the die-casting magnesium alloy. Along with the development trend of automobile light weight, the application of the die-casting magnesium alloy is expanded from interior parts to large-size and high-bearing key parts such as automobile body parts and chassis parts, and higher requirements are put on the strength, plasticity, casting fluidity and other properties of the die-casting magnesium alloy. Therefore, the die-casting magnesium alloy with high strength, high plasticity, high fluidity and low cost and the preparation method thereof are developed, the comprehensive performance requirement of the automobile integrated die-casting structural part on the die-casting magnesium alloy is met, and the die-casting magnesium alloy has important significance for further expanding application and realizing the weight reduction of the automobile. At present, the performance of the die-casting magnesium alloy is improved by means of optimizing alloy components, improving a die-casting process and the like. The mechanical property of the die-casting magnesium alloy can be improved by adding a single rare earth element, but the improvement range of the mechanical property is not obvious, and when the addition content of the rare earth element is too high, adverse effect is caused on the plasticity of the magnesium alloy, and meanwhile, the preparation cost of the magnesium alloy is improved. The rare earth elements are of various types and contents, so that the alloy cost is high, and meanwhile, the process control difficulty is extremely high in the actual die casting production. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a high-strength and high-toughness die-casting magnesium alloy, which separates out a plurality of dispersed second phases through the diversified synergistic effect of Ce and La mixed rare earth elements and V, sr and Ti microalloy elements, refines microcosmic morphology characteristics such as alpha-Mg matrix grains, coarse dendrite structures and the like, reduces micro-couple corrosion between a matrix and the second phases, finally obtains the die-casting magnesium alloy with high strength, high plasticity, corrosion resistance and good casting fluidity, solves the problems of low strength and plasticity, insufficient casting fluidity and the like of the existing die-casting magnesium alloy, and meets the comprehensive performance requirements of an automobile integrated die-casting structural member on the high strength, high plasticity and high fluidity of the die-casting magnesium alloy. The second aim of the invention is to provide a preparation method of the die-casting magnesium alloy with high strength and toughness, and the preparation cost is low. The third object of the invention is to provide the high-strength and toughness die-casting magnesium alloy or the application of the high-strength and toughness die-casting magnesium alloy prepared by the preparation method of the high-strength and toughness die-casting magnesium alloy in an automobile integrated die-casting structural part. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: The invention provides a high-strength and high-toughness die-casting magnesium alloy, which comprises the following components in percentage by mass: 5% -7.5% of Al, 0.3% -0.65% of Mn, 0.6% -1.2% of RE, 0.2% -0.46% of V, 0.1% -0.48% of Sr, 0.1% -0.32% of Ti and the balance of Mg and unavoidable impurity elements; wherein RE comprises Ce and La, and the mass ratio of Ce to La is (2-2.5): 1. Further, the high-streng