CN-117778786-B - Preparation method of ytterbium-containing high-performance magnesium alloy plate

Abstract

The invention discloses a preparation method of a ytterbium-containing high-performance magnesium alloy plate, which comprises the following chemical components, by mass, 5.8-6.0% of zinc, 1.8-2.0% of ytterbium, 0.6% of zirconium and the balance of magnesium, wherein the preparation method comprises smelting, solid solution and hot rolling. The magnesium alloy plate provided by the invention has the advantages that through adding a proper amount of rare earth ytterbium, a uniformly refined microstructure and a special non-basal plane weak texture are formed after common hot rolling, the strength and plasticity of the plate are greatly improved, and the magnesium alloy plate has the characteristics of low cost, short flow and high performance.

Inventors

• LI LU
• ZHANG BAIHAO
• XIA YUFENG

Assignees

• 西南大学

Dates

Publication Date

20260512

Application Date

20240111

Claims (3)

1. 1. A preparation method of a ytterbium-containing high-performance magnesium alloy plate is characterized in that the mass percentage of the prepared alloy components is 5.8-6.0% of Zn, 1.8-2.0% of Yb, 0.6% of Zr and the balance of Mg and unavoidable impurities, the preparation steps comprise alloy smelting, solid solution, hot rolling, annealing, hot rolling, cyclic annealing and hot rolling until a preset rolling thickness, the alloy is rolled at 300 ℃, the rolling reduction of each pass is guaranteed to be 5-8% of the total rolling reduction, the annealing is carried out by furnace return heat preservation for 15-20min at 300 ℃ between every 2 adjacent passes of hot rolling, the total rolling amount is 70-80% of the original thickness of the material, the recrystallization proportion of the final alloy is 75-90%, weak structures with continuous deflection of a base plane in the rolling direction and the transverse direction are formed, the continuous deflection of 30-45 degrees in the rolling direction is 70-85 degrees, the room temperature tensile mechanical property of the alloy in the rolling direction is 10-15% elongation, the yield strength is 230-280 MPa, the tensile strength is 350-280 MPa, the tensile strength of the alloy in the rolling direction is guaranteed to be 15-320 MPa, the tensile strength in the room temperature tensile mechanical property in the rolling direction is equal to 20-320 MPa, the anisotropic mechanical strength of the plate is equal to or less than or equal to the 20-320 MPa after the rolling strength in the transverse tensile strength is equal to the 20-320% of the plane anisotropic mechanical strength.
2. 2. The preparation method of the ytterbium-containing high-performance magnesium alloy plate is characterized in that after magnesium alloy smelting, as-cast metallographic structure is uniform equiaxed grains, the average grain size is 30-35 microns, mg-Zn phases with the diameter of 0.2-0.5 microns, mg-Zn-Yb phases with the diameter of 0.5-1.5 microns and Yb and Zr particles which are not completely dissolved in 1-2 microns are discontinuously distributed on grain boundaries, after solution treatment, the structure is not over-burned, equiaxed grains slightly grow, the average grain size is 35-40 microns, grain boundaries are smooth, a small amount of second phases are not fully dissolved in a matrix, the average size is 0.5-1 microns, the grains are recrystallized and refined after cyclic hot rolling annealing, the recrystallized grain size is 5-8 microns, and a large amount of submicron-level approximately spherical Mg-Zn-Yb phases and short rod-shaped Mg-Zn phases are distributed in the grain boundaries.
3. 3. The preparation method of the ytterbium-containing high-performance magnesium alloy sheet material according to any one of claims 1 to 2, which is characterized by comprising the following preparation steps: 1) Heating and melting a magnesium ingot by using a resistance heating furnace under the protection of SF 6 ＋CO 2 gas, adding Mg-Zr intermediate alloy at 750-760 ℃ to enable the Zr content to be 0.6% of the mass percentage of the final molten alloy, stirring for 1-3 min under the protection of a flux for fluxing, adding Mg-Yb intermediate alloy at 750-760 ℃ to enable the Yb content to be 1.8-2.0% of the mass percentage of the final molten alloy, finally adding pure zinc ingot at 720-730 ℃ to enable the Zn content to be 5.8-6.0% of the mass percentage of the final molten alloy, stirring for 1-3 min, preserving heat at 700-720 ℃ for 8-10 min, adding covering agent sediment, standing at 700-720 ℃ for deslagging, casting the ingot, and immediately quenching water; 2) Solid solution, namely placing the cast ingot into a gas protection heat treatment furnace, preserving heat for 45-48 hours at 400-420 ℃, and immediately cooling to room temperature; 3) And (3) circularly hot rolling and annealing, namely preserving the temperature of the plate subjected to solution treatment at 300 ℃ for 20-30 min, and then circularly hot rolling and annealing, wherein the rotating speed of a roller is 5-10 m/min, the temperatures of an upper roller and a lower roller are 150-200 ℃ and the temperature difference between the upper roller and the lower roller is within +/-6 ℃, rolling is stopped after the rolling is performed to 70-80% of the original thickness of the material, and immediately water-cooling is performed to room temperature.

Description

Preparation method of ytterbium-containing high-performance magnesium alloy plate Technical Field The invention relates to the technical field of magnesium alloy materials, in particular to a preparation method of a high-performance magnesium alloy plate containing rare earth ytterbium. Background The magnesium alloy has the advantages of light weight, environmental protection, high specific strength and high specific rigidity. Parts and products prepared by the magnesium alloy plate can be applied to the national and civil fields with important requirements on light weight, such as automobiles, aviation, aerospace, 5G communication, 3C electronics and the like. However, since magnesium alloy has insufficient absolute strength and poor forming capability, and the crystal structure with low symmetry is easy to form a texture structure, mechanical anisotropy severely limits the large-scale application of the magnesium alloy in the above fields, high-performance magnesium alloy plates with good strength plastic matching and mechanical isotropy are needed to be obtained through alloy element optimization and preparation process design. Researches show that the strength of the magnesium alloy plate can be effectively improved by adding alloying elements such as aluminum, zinc, manganese and the like into the magnesium alloy and assisting with a hot rolling deformation process. This is because the hot rolling deformation can compact the casting defect, promote dynamic recrystallization, refine deformed grains, and thereby induce a remarkable fine-grain strengthening effect. Meanwhile, the dynamically precipitated second phase containing the alloy element can pin dislocation and inhibit dislocation slip. After hot rolling, a strong basal plane texture with the c-axis parallel to the normal direction of the plate is formed, and the strength of the plate along the rolling direction is further improved. Although the above factors effectively improve the strength, the plasticity of the matrix is adversely affected, and the formation of the strong basal plane texture also causes anisotropy of the mechanical properties of the plate, which is not beneficial to the implementation of subsequent forming processes such as stamping and the like. Recent studies have shown that by reasonably selecting rare earth elements and amounts of addition in combination with the hot deformation process, weak textures can be formed in deformed samples with a relatively complete degree of recrystallisation, and that such relatively discrete grain orientation features can promote more efficient onset of basal plane slip of the alloy in subsequent deformations, thereby achieving high hardenability and plastic promotion. However, from the prior art, it is often difficult to combine both strength and plasticity in wrought magnesium alloys. Patent 201210461370.6 discloses a magnesium alloy plate with low Gd content and high ductility and a hot rolling process thereof, the plasticity is reported to be up to 50%, however, the highest tensile strength is only 253: 253 MPa, and for example, patent 202110253005.5 discloses a preparation method of a double-layer sandwich rolled high-strength rare earth magnesium alloy, the tensile strength is reported to be up to 548: 548 MPa, and the plasticity is only 2%. Therefore, the problem that the strength, the plasticity and the mechanical isotropy are difficult to balance is common in rolling deformed magnesium alloy, and the large-scale application of the magnesium alloy plate is severely restricted. In view of the above, the invention discloses a preparation method of a ytterbium-containing high-performance magnesium alloy plate. The technology obtains the deformed magnesium alloy sheet with high strength, large plasticity and low mechanical anisotropy by optimizing alloy components and contents and combining a hot rolling deformation process. The method has the characteristics of low cost, short flow and high performance, and can effectively improve the comprehensive mechanical properties of the traditional magnesium alloy plate. Disclosure of Invention The invention aims to overcome the defects of unbalanced strength and plasticity and large anisotropy of mechanical properties of the existing deformed magnesium alloy sheet, and provides a preparation method of a high-performance magnesium alloy sheet. The technical problem to be solved is that the existing magnesium alloy hot rolled plate cannot achieve high strength and high plasticity and has large mechanical anisotropy, so that the defects of insufficient strength or occurrence of indentations, cracks, lugs and the like of parts of the plate after subsequent stamping processing are caused, and the service safety and stability of magnesium alloy plate parts are affected. According to the invention, the comprehensive mechanical properties of the magnesium alloy plate are effectively improved through optimizing rare earth alloying elements and the additi