A method for improving the strength and hardness of aluminum-magnesium alloy welding wire

Abstract

This invention discloses a method for improving the strength and hardness of aluminum-magnesium alloy welding wire, comprising the following steps: (1) homogenizing aluminum-magnesium alloy welding wire prepared by melting, extrusion molding, and drawing to a diameter of 5-6 mm; (2) subjecting the homogenized aluminum-magnesium alloy welding wire to deep gas cryogenic treatment; (3) removing the deep-cryogenically treated aluminum-magnesium alloy welding wire and placing it at room temperature, and after it recovers to room temperature, performing a stretching treatment with the stretching rate controlled at 3.0-3.6%; (4) subjecting the stretched aluminum-magnesium alloy welding wire to a second deep gas cryogenic treatment; and (5) finally subjecting the deep-cryogenically treated aluminum-magnesium alloy welding wire to tempering treatment. This method can greatly improve the strength and hardness of aluminum-magnesium alloy welding wire, achieving the effect of strengthening and toughening. It solves the problems that are prone to occur when welding wire is used, such as poor weld formation, low weld strength and hardness, poor weld formation stability, and weld thermal cracking, thereby improving the stability of welding performance.

Description

Technical Field

[0001] This invention relates to a processing technology for aluminum-magnesium alloy welding wire, specifically a method for improving the strength and hardness of aluminum-magnesium alloy welding wire. Background Technology

[0002] 5356 aluminum-magnesium alloy welding wire is a general-purpose welding material containing 4.5%-5.5% Mg and trace alloying elements such as Cr, Mn, and Ti. It is mainly used for welding medium- and high-strength aluminum alloys such as Al-Mg, Al-Mg-Si, and Al-Zn-Mg. Since the quality of the welding wire directly determines the quality of the weld, problems with the material itself during the production process of 5356 aluminum-magnesium alloy welding wire can lead to deviation from the weld seam during welding, even causing arc breakage, resulting in poor weld formation, low weld strength and hardness, and poor arc stability. To mitigate the impact of adverse factors, improve the internal stress distribution of the workpiece, enhance the weld strength, hardness, and other microstructure properties, and ensure the dimensional accuracy of the workpiece, homogenization heat treatment is usually performed. However, the improvement in strength and hardness is limited. Therefore, existing 5356 aluminum-magnesium alloy welding wire cannot meet the needs of high-quality product production. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a method for improving the strength and hardness of aluminum-magnesium alloy welding wire, so that the wire is fed smoothly and the weld formation is stable during welding.

[0004] Technical solution: The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to the present invention includes the following steps:

[0005] (1) Homogenize the aluminum-magnesium alloy welding wire that has been prepared by melting, extrusion molding and drawing to a diameter of 5-6 mm;

[0006] (2) The homogenized aluminum-magnesium alloy welding wire is subjected to deep gas cryogenic treatment.

[0007] (3) Take out the aluminum-magnesium alloy welding wire after gas cryogenic treatment and place it at room temperature. After it returns to room temperature, perform stretching treatment and control the stretching rate at 3.0-3.6%.

[0008] (4) The stretched aluminum-magnesium alloy welding wire is subjected to a second deep gas cryogenic treatment.

[0009] (5) Temper the aluminum-magnesium alloy welding wire after the second gas cryogenic treatment.

[0010] Furthermore, the homogenization treatment in step (1) is carried out at a temperature of 410-420℃ and the holding time is 18-22h. After the homogenization treatment in step (1), the aluminum-magnesium alloy welding wire is cooled to room temperature.

[0011] Furthermore, in steps (2) and (4), the latent heat of vaporization of liquid nitrogen is used to perform gas cryogenic treatment on the aluminum-magnesium alloy welding wire. The treatment temperature is -196℃ and the treatment time is 24-36 hours, and even more specifically, 36 hours.

[0012] Furthermore, the stretching speed of the stretching process in step (3) is 0.5 mm / min.

[0013] Furthermore, in step (5), the tempering temperature is 160-170℃ and the holding time is 6-8 hours.

[0014] Furthermore, in step (1), the aluminum-magnesium alloy welding wire is 5356 aluminum-magnesium alloy welding wire; the chemical composition of 5356 aluminum-magnesium alloy welding wire is calculated by mass percentage as follows: Mg is 4.5%-5.5%, Ti is 0.06%-0.20%, Mn is 0.05%-0.20%, Cr is 0.05%-0.20%, Fe≤0.40%, Si≤0.25%, Cu<0.10%, Zn<0.10%, and the content of each of the remaining impurity elements is not greater than 0.05% and the total amount is not greater than 0.20%, with the balance being Al.

[0015] Working Principle: The 5-6mm aluminum-magnesium alloy welding wire, after drawing, contains high-density dislocations and numerous lattice defects, with many alloying elements in a saturated state, resulting in significant internal stress. After homogenization heat treatment, the strengthening phases within the aluminum-magnesium alloy welding wire are fully dissolved into the matrix. Prolonged heat treatment allows for rapid atomic diffusion at high temperatures, significantly reducing the chemical composition inhomogeneity and inclusion aggregation caused by severe dendrite segregation during the drawing process. While solution treatment can relatively uniformly dissolve the solid solution phases in a solid solvent, reducing segregation and defects, rapid cooling of the alloy leaves the dissolved components within the matrix as a supersaturated solid solution. While this can improve the strength and hardness of the welding wire, the improvement is limited. Homogenization annealing, through prolonged high-temperature treatment, eliminates grain deviations in the aluminum alloy, resulting in a more uniform crystal structure, strengthening the wire, and achieving higher hardness and strength. Finally, deep cryogenic treatment using the latent heat of liquid nitrogen promotes the precipitation of fine strengthening phases within the wire. Tensile testing causes deformation of the welding wire, reducing internal defects such as porosity and shrinkage cavities, increasing wire density, refining grain size, and significantly reducing internal stress, thus improving the wire's mechanical properties. However, when the tensile rate is too low, below 3.0%, the micro-second-phase reinforcing particles are not significantly broken down into granular or short rod-like shapes, leading to unsatisfactory final wire strength and hardness. Conversely, when the tensile rate is too high, above 3.6%, the internal stress increases significantly, causing subgrains to nucleate and grow under localized stress, also resulting in unsatisfactory final wire strength and hardness. Therefore, after extensive experimentation, this application selected a tensile rate of 3.0-3.6%. Then, a second cryogenic treatment is performed using the latent heat of liquid nitrogen vaporization. This causes more fine and uniform second-phase particles to precipitate inside the welding wire, further enhancing its strength and hardness. Finally, tempering is performed, which generates a large number of new phase nuclei inside the welding wire, ensuring uniform and dispersed precipitation of the second phase. This significantly increases the integral number of second-phase particles, further stabilizing the microstructure and achieving a better balance of strength and hardness, greatly improving the quality of the 5356 aluminum-magnesium alloy welding wire. Cryogenic treatment before tempering greatly improves the alloy's machinability. As the strength and hardness of the 5356 aluminum alloy welding wire increase, the winding force required when winding it onto the wire spool increases, and the degree of elastic deformation of the wire increases. When the external binding force is released, the wire rebounds due to the elastic deformation that occurs during winding, and its outward expansion under the internal force increases. This ensures the wire reaches a straight state before winding, allowing for smooth wire feeding during welding, thereby improving the stiffness and stability of the welding arc.

[0016] Beneficial Effects: Compared with existing technologies, this invention has the following advantages: By homogenizing, cryogenically heating, stretching, secondary cryogenic heating, and tempering the aluminum-magnesium alloy welding wire, the tensile strength is increased by 63.0-71.1%, the yield strength by 81.6-87.1%, and the hardness by 56.5-61.9%, which greatly improves the strength and hardness of the aluminum-magnesium alloy welding wire, achieving a toughening effect. It solves problems such as poor weld formation, low weld strength and hardness, poor weld formation stability, and weld thermal cracking that easily occur during the use of welding wire, improving the stability of welding performance and possessing high engineering application value. Detailed Implementation

[0017] Example 1

[0018] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 5mm, has the following chemical composition (by mass percentage): Mg 4.5%, Ti 0.06%, Mn 0.05%, Cr 0.05%, with unavoidable impurity elements individually ≤0.40%, ≤0.25%, Cu <0.10%, Zn <0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0019] The specific methods for improving the strength and hardness of aluminum-magnesium alloy welding wire include the following steps:

[0020] (1) Homogenize the 5356 aluminum-magnesium alloy welding wire at a temperature of 410℃ for 18 hours. After homogenization, remove the aluminum-magnesium alloy welding wire and cool it to room temperature.

[0021] (2) The homogenized 5356 aluminum-magnesium alloy welding wire was placed in nitrogen at -196℃ for the first gas cryogenic treatment for 24 hours, and then placed in air to recover to room temperature.

[0022] (3) Take out the aluminum-magnesium alloy welding wire after the first gas cryogenic treatment and place it at room temperature. After it returns to room temperature, perform a stretching treatment. The stretching speed is 0.5 mm / min and the stretching rate is controlled at 3.0%.

[0023] (4) The stretched aluminum-magnesium alloy welding wire was subjected to deep gas cryogenic treatment in nitrogen at -196℃ for 24 hours, and then placed in air to recover to room temperature.

[0024] (5) After the second gas cryogenic treatment, the 5356 aluminum-magnesium alloy welding wire is tempered at 160°C for 6 hours and then placed in the air to recover to room temperature.

[0025] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0026] Example 2

[0027] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 5mm, has the following chemical composition (by mass percentage): Mg 5.0%, Ti 0.13%, Mn 0.12%, Cr 0.12%, with unavoidable impurity elements individually ≤0.40% Fe, ≤0.25% Si, <0.10% Cu, <0.10% Zn, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0028] The specific methods for improving the strength and hardness of aluminum-magnesium alloy welding wire include the following steps:

[0029] (1) Homogenize the 5356 aluminum-magnesium alloy welding wire at a temperature of 415℃ for 20 hours. After homogenization, remove the aluminum-magnesium alloy welding wire and cool it to room temperature.

[0030] (2) The homogenized 5356 aluminum-magnesium alloy welding wire was placed in nitrogen at -196℃ for the first gas cryogenic treatment for 30 hours, and then placed in air to recover to room temperature.

[0031] (3) Take out the aluminum-magnesium alloy welding wire after the first gas cryogenic treatment and place it at room temperature. After it returns to room temperature, perform a stretching treatment. The stretching speed is 0.5 mm / min and the stretching rate is controlled at 3.3%.

[0032] (4) The stretched aluminum-magnesium alloy welding wire is placed in nitrogen at -196℃ for deep gas cryogenic treatment for 30 hours, and then placed in air to recover to room temperature.

[0033] (5) After the second gas cryogenic treatment, the 5356 aluminum-magnesium alloy welding wire is tempered at a temperature of 170°C and a holding time of 7 hours. Then it is placed in the air to recover to room temperature.

[0034] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0035] Example 3

[0036] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%. Among these, the unavoidable impurity elements are individually Fe≤0.40%, Si≤0.25%, Cu<0.10%, Zn<0.10%, and the content of each of the remaining impurity elements is not greater than 0.05% and the total amount is not greater than 0.20%, with the balance being Al.

[0037] The specific methods for improving the strength and hardness of aluminum-magnesium alloy welding wire include the following steps:

[0038] (1) Homogenize the 5356 aluminum-magnesium alloy welding wire at a temperature of 420℃ for 22 hours. After homogenization, remove the aluminum-magnesium alloy welding wire and cool it to room temperature.

[0039] (2) The homogenized 5356 aluminum-magnesium alloy welding wire was placed in nitrogen at -196℃ for the first gas cryogenic treatment for 36 hours, and then placed in air to recover to room temperature.

[0040] (3) Take out the aluminum-magnesium alloy welding wire after the first gas cryogenic treatment and place it at room temperature. After it returns to room temperature, perform a stretching treatment. The stretching speed is 0.5 mm / min and the stretching rate is controlled at 3.6%.

[0041] (4) The stretched aluminum-magnesium alloy welding wire was subjected to deep gas cryogenic treatment in nitrogen at -196℃ for 36 hours, and then placed in air to recover to room temperature.

[0042] (5) After the second gas cryogenic treatment, the 5356 aluminum-magnesium alloy welding wire is tempered at 180°C for 8 hours and then placed in the air to recover to room temperature.

[0043] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0044] Comparative Example 1

[0045] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%. Among these, the unavoidable impurity elements are individually Fe≤0.40%, Si≤0.25%, Cu<0.10%, Zn<0.10%, and the content of each of the remaining impurity elements is not greater than 0.05% and the total amount is not greater than 0.20%, with the balance being Al.

[0046] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0047] Comparative Example 2

[0048] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%, with unavoidable impurity elements individually comprising Fe ≤ 0.40%, Si ≤ 0.25%, Cu < 0.10%, Zn < 0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0049] The 5356 aluminum-magnesium alloy welding wire was homogenized at 420℃ for 22 hours. After homogenization, the aluminum-magnesium alloy welding wire was removed and cooled to room temperature.

[0050] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0051] Comparative Example 3

[0052] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%, with unavoidable impurity elements individually comprising Fe ≤ 0.40%, Si ≤ 0.25%, Cu < 0.10%, Zn < 0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0053] The 5356 aluminum-magnesium alloy welding wire was homogenized at 420℃ for 22 hours. After homogenization, the wire was removed and cooled to room temperature. The homogenized wire was then subjected to a first cryogenic treatment in nitrogen at -196℃ for 36 hours, followed by exposure to air to restore to room temperature. After the first cryogenic treatment, the wire was removed and allowed to return to room temperature. Once at room temperature, a tensile treatment was performed at a speed of 0.5 mm / min, with the elongation controlled at 3.6%.

[0054] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0055] Comparative Example 4

[0056] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%, with unavoidable impurity elements individually comprising Fe ≤ 0.40%, Si ≤ 0.25%, Cu < 0.10%, Zn < 0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0057] The 5356 aluminum-magnesium alloy welding wire underwent homogenization treatment at 420℃ for 22 hours. After homogenization, the wire was removed and cooled to room temperature. The homogenized wire was then subjected to a first cryogenic treatment in nitrogen at -196℃ for 36 hours, followed by air exposure to allow it to return to room temperature. After the first cryogenic treatment, the wire was removed and allowed to return to room temperature. Once at room temperature, a stretching treatment was performed at a speed of 0.5 mm / min, with a stretching rate controlled at 3.6%. The stretched wire was then subjected to a second cryogenic treatment in nitrogen at -196℃ for 36 hours, followed by air exposure to allow it to return to room temperature.

[0058] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0059] Comparative Example 5

[0060] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%, with unavoidable impurity elements individually comprising Fe ≤ 0.40%, Si ≤ 0.25%, Cu < 0.10%, Zn < 0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0061] The aluminum-magnesium alloy welding wire is processed according to the following steps:

[0062] (1) Homogenize the 5356 aluminum-magnesium alloy welding wire at a temperature of 420℃ for 22 hours. After homogenization, remove the aluminum-magnesium alloy welding wire and cool it to room temperature.

[0063] (2) The homogenized 5356 aluminum-magnesium alloy welding wire was placed in nitrogen at -196℃ for the first gas cryogenic treatment for 36 hours, and then placed in air to recover to room temperature.

[0064] (3) Take out the aluminum-magnesium alloy welding wire after the first gas cryogenic treatment and place it at room temperature. After it returns to room temperature, perform a stretching treatment. The stretching speed is 0.5 mm / min and the stretching rate is controlled at 2.9%.

[0065] (4) The stretched aluminum-magnesium alloy welding wire was subjected to deep gas cryogenic treatment in nitrogen at -196℃ for 36 hours, and then placed in air to recover to room temperature.

[0066] (5) After the second gas cryogenic treatment, the 5356 aluminum-magnesium alloy welding wire is tempered at 180°C for 8 hours and then placed in the air to recover to room temperature.

[0067] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0068] Comparative Example 6

[0069] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%, with unavoidable impurity elements individually comprising Fe ≤ 0.40%, Si ≤ 0.25%, Cu < 0.10%, Zn < 0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0070] The aluminum-magnesium alloy welding wire is processed according to the following steps:

[0071] (1) Homogenize the 5356 aluminum-magnesium alloy welding wire at a temperature of 420℃ for 22 hours. After homogenization, remove the aluminum-magnesium alloy welding wire and cool it to room temperature.

[0072] (2) The homogenized 5356 aluminum-magnesium alloy welding wire was placed in nitrogen at -196℃ for the first gas cryogenic treatment for 36 hours, and then placed in air to recover to room temperature.

[0073] (3) Take out the aluminum-magnesium alloy welding wire after the first gas cryogenic treatment and place it at room temperature. After it returns to room temperature, perform a stretching treatment. The stretching speed is 0.5 mm / min and the stretching rate is controlled at 3.7%.

[0074] (4) The stretched aluminum-magnesium alloy welding wire was subjected to deep gas cryogenic treatment in nitrogen at -196℃ for 36 hours, and then placed in air to recover to room temperature.

[0075] (5) After the second gas cryogenic treatment, the 5356 aluminum-magnesium alloy welding wire is tempered at 180°C for 8 hours and then placed in the air to recover to room temperature.

[0076] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0077] Comparative Example 7

[0078] The 5356 aluminum-magnesium alloy welding wire, prepared by melting, extrusion, and drawing to a diameter of 6mm, has the following chemical composition (by mass percentage): Mg 5.5%, Ti 0.2%, Mn 0.20%, Cr 0.20%, with unavoidable impurity elements individually comprising Fe ≤ 0.40%, Si ≤ 0.25%, Cu < 0.10%, Zn < 0.10%, and the content of other impurity elements not exceeding 0.05% each and not exceeding 0.20% in total, with the balance being Al.

[0079] The aluminum-magnesium alloy welding wire is processed according to the following steps:

[0080] (1) The 5356 aluminum-magnesium alloy welding wire was subjected to solution treatment at a temperature of 420℃ and a holding time of 6 hours. It was then taken out and placed in 60℃ water for quenching, and then cooled to room temperature.

[0081] (2) The solution-treated 5356 aluminum-magnesium alloy welding wire was placed in nitrogen at -196℃ for the first gas cryogenic treatment for 24 hours, and then placed in air to recover to room temperature.

[0082] (3) Temper the 5356 aluminum-magnesium alloy welding wire after gas cryogenic treatment at a tempering temperature of 160°C and a holding time of 6 hours, and then place it in the air to restore it to room temperature.

[0083] (4) The 5356 aluminum-magnesium alloy welding wire that has been tempered is placed in nitrogen at -196℃ for a second deep gas cryogenic treatment for 24 hours, and then placed in air to recover to room temperature.

[0084] The samples were tested for room temperature strength and hardness in accordance with the national standard for tensile testing and hardness testing. The average value of three sets of mechanical properties was taken for each set. The test results are shown in Table 1.

[0085] Table 1 Mechanical properties of 5356 aluminum-magnesium alloy welding wires with different processing techniques

[0086]

[0087] As shown in Table 1, the tensile strength, yield strength, and hardness of the aluminum-magnesium welding wires in Examples 1-3 are significantly improved compared to those in Comparative Examples 1-7. In Comparative Examples 3-6, the strength and hardness of the welding wires increased substantially after stretching treatment, indicating that stretching treatment can greatly reduce the stress caused by cryogenic gas treatment. However, in Comparative Examples 5 and 6, the room temperature stretching rates were above and below 3.0% and 3.6%, respectively, and the improvement in strength and hardness was not as significant as that of a room temperature stretching rate of 3.0-3.6%. The method of this invention can effectively improve the mechanical properties of untreated aluminum-magnesium alloys, increasing tensile strength by 63.0-71.1%, yield strength by 81.6-87.1%, and hardness by 56.5-61.9%. Furthermore, the method of this invention also yields higher strength and hardness than the welding wires in Comparative Example 7 that underwent solution treatment, cryogenic gas treatment, tempering, and further cryogenic gas treatment.

[0088] In summary, by employing the method of this invention, after homogenization treatment, initial gas cryogenic treatment, tensile treatment, re-gas cryogenic treatment, and tempering treatment, the tensile strength, yield strength, and hardness of the welding wire are significantly improved compared to single-stage or two-stage treatment. This solves the problems of poor weld formation, low weld strength and hardness that are easily encountered when using welding wire, resulting in better and more reliable welding performance stability.

Claims

1. A method of increasing strength and hardness of an aluminum magnesium alloy welding wire, characterized by, Includes the following steps: (1) Homogenize the aluminum-magnesium alloy welding wire that has been prepared by melting, extrusion molding and drawing to a diameter of 5-6 mm; (2) The homogenized aluminum-magnesium alloy welding wire is subjected to deep gas cryogenic treatment; (3) The aluminum-magnesium alloy welding wire after gas cryogenic treatment is stretched, and the stretching rate is controlled at 3.0-3.6%; (4) The stretched aluminum-magnesium alloy welding wire is subjected to a second deep gas cryogenic treatment; (5) Temper the aluminum-magnesium alloy welding wire after the second gas cryogenic treatment.

2. The method of increasing strength and hardness of an aluminum magnesium alloy welding wire of claim 1, wherein, The homogenization treatment temperature in step (1) is 410~420℃, and the heat preservation time is 18-22 h.

3. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 1, characterized in that, After homogenization in step (1), the aluminum-magnesium alloy welding wire is cooled to room temperature.

4. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 1, characterized in that, The gas cryogenic treatment in steps (2) and (4) involves using the latent heat of vaporization of liquid nitrogen to perform gas cryogenic treatment on the aluminum-magnesium alloy welding wire. The treatment temperature is -196℃ and the treatment time is 24-36 hours.

5. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 4, characterized in that, The gas cryogenic treatment time in steps (2) and (4) is 36 hours.

6. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 1, characterized in that, The stretching treatment in step (3) is performed after the aluminum-magnesium alloy welding wire has naturally recovered to room temperature.

7. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 1, characterized in that, The stretching speed in step (3) is 0.5 mm / min.

8. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 1, characterized in that, In step (5), the tempering temperature is 160~170℃ and the holding time is 6-8 hours.

9. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 1, characterized in that, The aluminum-magnesium alloy welding wire used in step (1) is 5356 aluminum-magnesium alloy welding wire.

10. The method for improving the strength and hardness of aluminum-magnesium alloy welding wire according to claim 9, characterized in that, The chemical composition of the 5356 aluminum-magnesium alloy welding wire, calculated by mass percentage, is as follows: Mg 4.5%-5.5%, Ti 0.06%-0.20%, Mn 0.05%-0.20%, Cr 0.05%-0.20%, Fe≤0.40%, Si≤0.25%, Cu<0.10%, Zn<0.10%, and the content of each of the remaining impurity elements is not greater than 0.05% and the total amount is not greater than 0.20%, with the balance being Al.

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