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CN-118086739-B - Low-cost high-corrosion-resistance high-strength magnesium alloy and preparation method thereof

CN118086739BCN 118086739 BCN118086739 BCN 118086739BCN-118086739-B

Abstract

The invention discloses a low-cost high-corrosion-resistance high-strength magnesium alloy and a preparation method thereof. The magnesium alloy comprises, by mass, 0.45-2.1% of aluminum, 0.15-0.9% of calcium, 0.35-0.7% of manganese, 0.1-0.75% of rare earth elements, one or any combination of cerium, yttrium, lanthanum, samarium, gadolinium and neodymium, and unavoidable impurities <0.05% and the balance of magnesium. The preparation method comprises alloy smelting, homogenization treatment, deformation processing and heat treatment. The method is based on a cooperative regulation strategy of rare earth microalloying and thermal coupling, and synchronously improves alloy strength and corrosion resistance. The corrosion rate of the magnesium alloy can reach 0.098-0.133 mm/year, the tensile strength is more than or equal to 280MPa, the corrosion resistance is higher than that of pure Mg (0.25 mm/y), and the corrosion resistance is more than 10 times of that of commercial AZ, AM and ZK magnesium alloys. The invention solves the bottleneck problems of serious micro galvanic couple corrosion and loose and porous film layer of magnesium alloy, realizes the synergy of high strength and high corrosion resistance of low-cost magnesium alloy, and has great commercial application potential.

Inventors

  • WANG HUIYUAN
  • ZHANG KAI
  • JIN SHENBAO
  • HUA ZHENMING
  • Si Wenping
  • XU XINYU

Assignees

  • 河北工业大学

Dates

Publication Date
20260512
Application Date
20240305

Claims (8)

  1. 1. The low-cost high-corrosion-resistance high-strength magnesium alloy is characterized by comprising, by mass, 0.45-2.1% of aluminum, 0.15-0.9% of calcium, 0.35-0.7% of manganese and 0.1-0.75% of rare earth elements, wherein the rare earth elements are one or any combination of cerium, yttrium, lanthanum, samarium, gadolinium and neodymium, unavoidable impurities are less than 0.05%, and the balance is magnesium, and the preparation method comprises the following steps: (1) Under the protection of argon, heating and preserving pure magnesium, pure aluminum, magnesium-manganese intermediate alloy, magnesium-calcium intermediate alloy and magnesium-rare earth intermediate alloy at 700-830 ℃, and rapidly pouring into a metal mold for air cooling after complete melting and full stirring to obtain a magnesium alloy cast ingot, wherein the magnesium-rare earth intermediate alloy is one or any combination of magnesium-cerium intermediate alloy, magnesium-yttrium intermediate alloy, magnesium-lanthanum intermediate alloy, magnesium-samarium intermediate alloy, magnesium-gadolinium intermediate alloy and magnesium-neodymium intermediate alloy; (2) Carrying out multistage step homogenization heat treatment on the magnesium alloy cast ingot obtained in the step (1), carrying out room-temperature water quenching, and carrying out multi-pass rolling treatment or extrusion treatment to obtain a magnesium alloy rolled plate or a magnesium alloy extruded section; The multi-stage step homogenization heat treatment is 2-4-stage step homogenization heat treatment, the heat treatment temperature is 280-520 ℃, the treatment time of each stage is 1-12 h, the rolling treatment comprises 3-16 rolling passes, the reduction of each pass is 5-45%, the temperature is kept at 300-350 ℃ for 5-20 min before each rolling, the rolling temperature is 280-330 ℃, the extrusion treatment comprises 380-540 ℃, the extrusion ratio is 20-80:1, and the extrusion speed is 0.5-20 m/min; (3) Under the protection of argon, carrying out solution heat treatment on the magnesium alloy rolled plate or the magnesium alloy extruded section obtained in the step (2), and then carrying out artificial aging heat treatment after water quenching and cooling to obtain the magnesium alloy with low cost, high corrosion resistance and high strength; The solid solution heat treatment is that the temperature is kept at 490-550 ℃ for 0.5-6 h, and the artificial aging heat treatment is that the temperature is kept at 175-380 ℃ for 0.5-12 h; The low-cost high-corrosion-resistance high-strength magnesium alloy obtained in the step (3) synchronously improves the mechanical property and corrosion resistance of the alloy, realizes that the tensile strength of the alloy is more than or equal to 280MPa, controls the total hydrogen evolution amount to be less than or equal to 0.30mL/cm 2 after being soaked in 3.5wt.% NaCl solution for 7 days, controls the total hydrogen evolution amount to be less than or equal to 0.82mL/cm 2 after being soaked for 14 days, and controls the corrosion rate to be less than or equal to 0.133 mm/year in 3.5wt.% NaCl solution.
  2. 2. The low-cost high-corrosion-resistance high-strength magnesium alloy according to claim 1, wherein the mass percentage of the aluminum is 0.5-1.5%, the mass percentage of the calcium is 0.2-0.4%, and the mass percentage of the manganese is 0.4-0.6%.
  3. 3. The low-cost high-corrosion-resistance high-strength magnesium alloy according to claim 1, wherein the rare earth element is 0.4-0.65% by mass.
  4. 4. The low-cost high-corrosion-resistance high-strength magnesium alloy according to claim 1, wherein in the step (1), pure magnesium, pure aluminum, magnesium-manganese intermediate alloy, magnesium-calcium intermediate alloy and magnesium-rare earth intermediate alloy are heated and kept at 710-810 ℃ under the protection of argon.
  5. 5. The low-cost high-corrosion-resistance high-strength magnesium alloy according to claim 1, wherein the temperature of the multi-stage step homogenization heat treatment in the step (2) is 330-480 ℃, and the treatment time of each stage is 2-8 h.
  6. 6. The low-cost high-corrosion-resistance high-strength magnesium alloy according to claim 1, wherein the rolling pass in the step (2) is 4-14, the reduction per pass is 10-35%, the heat preservation is carried out at 310-340 ℃ for 8-15 min before each rolling, and the rolling temperature is 290-320 ℃.
  7. 7. The magnesium alloy with low cost, high corrosion resistance and high strength according to claim 1, wherein the extrusion temperature in the step (2) is 400-500 ℃, the extrusion ratio is 30-70:1, and the extrusion speed is 1-18 m/min.
  8. 8. The low-cost high-corrosion-resistance high-strength magnesium alloy according to claim 1, wherein the solution heat treatment in the step (3) is carried out by heat preservation at 495-540 ℃ for 1-5h, and the artificial aging heat treatment is carried out by heat preservation at 190-350 ℃ for 1-10 h.

Description

Low-cost high-corrosion-resistance high-strength magnesium alloy and preparation method thereof Technical Field The invention relates to the field of metal material processing, in particular to a low-cost high-corrosion-resistance high-strength magnesium alloy and a preparation method thereof. Background Magnesium alloy is widely applied to the fields of automobile industry, aerospace, electronic products and the like due to the characteristics of light weight, high specific strength, high specific stiffness and the like. The poor corrosion resistance compared to aluminum alloys has been one of the bottleneck challenges restricting the commercial application of magnesium alloys due to the severe micro-galvanic corrosion and the loose porous surface film layers present in magnesium alloys. In addition, the strength and corrosion resistance of the magnesium alloy are difficult to synchronously improve, mainly because most of second phases with strengthening effect in the magnesium alloy have corrosion potential higher than that of the magnesium alloy, and severe micro-galvanic corrosion can be caused, so that a compact protective film is difficult to form on the surface of the alloy. Therefore, the corrosion resistance and strength of magnesium alloy are often difficult to be simultaneously improved. In view of the urgent need of high-strength high-corrosion-resistance magnesium alloy, the deep exploration of a cooperative lifting mechanism of the strength and corrosion resistance of the magnesium alloy has important significance. In the prior art, the strength of the magnesium alloy is improved by improving the total addition amount of the alloy and the addition amount of rare earth and combining a multistage deformation process and high-temperature long-time treatment by utilizing modes of fine grain strengthening, dislocation strengthening, precipitation strengthening and the like. However, the factors such as precipitated phases, dislocation defects, grain boundaries and the like can lead to preferential corrosion of the magnesium matrix around the magnesium alloy, which is unfavorable for the corrosion resistance of the magnesium alloy. Therefore, how to reduce the cost and simplify the process to obtain the magnesium alloy with high strength and high corrosion resistance is one of the technical problems to be solved in the prior art. Disclosure of Invention In order to solve the technical problems, the invention provides a low-cost high-corrosion-resistance high-strength magnesium alloy, which comprises, by mass, 0.45-2.1% of aluminum, 0.15-0.9% of calcium, 0.35-0.7% of manganese and 0.1-0.75% of rare earth elements, wherein the rare earth elements are one or any combination of cerium, yttrium, lanthanum, samarium, gadolinium and neodymium, unavoidable impurities are less than 0.05%, and the balance is magnesium, and the preparation method comprises the following steps: (1) Under the protection of argon, heating and preserving pure magnesium, pure aluminum, magnesium-manganese intermediate alloy, magnesium-calcium intermediate alloy and magnesium-rare earth intermediate alloy at 700-830 ℃, and rapidly pouring into a metal mold for air cooling after complete melting and full stirring to obtain a magnesium alloy cast ingot, wherein the magnesium-rare earth intermediate alloy is one or any combination of magnesium-cerium intermediate alloy, magnesium-yttrium intermediate alloy, magnesium-lanthanum intermediate alloy, magnesium-samarium intermediate alloy, magnesium-gadolinium intermediate alloy and magnesium-neodymium intermediate alloy; (2) Carrying out multistage step homogenization heat treatment on the magnesium alloy cast ingot obtained in the step (1), carrying out room-temperature water quenching, and carrying out multi-pass rolling treatment or extrusion treatment to obtain a magnesium alloy rolled plate or a magnesium alloy extruded section; The multi-stage step homogenization heat treatment is 2-4-stage step homogenization heat treatment, the heat treatment temperature is 280-520 ℃, the treatment time of each stage is 1-12h, the rolling treatment comprises 3-16 rolling passes, the reduction of each pass is 5-45%, the temperature is kept for 5-20min at 300-350 ℃ before each rolling, the rolling temperature is 280-330 ℃, the extrusion treatment comprises 380-540 ℃, the extrusion ratio is 20-80:1, and the extrusion speed is 0.5-20m/min; (3) Under the protection of argon, carrying out solution heat treatment on the magnesium alloy rolled plate or the magnesium alloy extruded section obtained in the step (2), and then carrying out artificial aging heat treatment after water quenching and cooling to obtain the magnesium alloy with low cost, high corrosion resistance and high strength; The solid solution heat treatment is carried out for 0.5-6h at 490-550 ℃, and the artificial aging heat treatment is carried out for 0.5-12h at 175-380 ℃. Further, the aluminum accounts for 0.5 to 1.5 percent, the calcium