阅读说明：本技术 一种铝镁合金焊丝强韧性提高方法 (Method for improving obdurability of aluminum-magnesium alloy welding wire ) 是由 王正军 王子洋 徐建明 刘爱辉 程思瑜 张满 张成绩 郭立侨 于 2020-11-12 设计创作，主要内容包括：本发明公开了一种铝镁合金焊丝强韧性提高方法,包括以下步骤：(1)对铝镁合金焊丝进行三级升温均匀化热处理；(2)进行回火处理；(3)进行气体深冷处理；(4)将经过气体深冷处理后的铝镁合金焊丝进行第二次回火处理；(5)将经过第二次回火处理的铝镁合金焊丝进行第二次气体深冷处理；(6)将经过第二次气体深冷处理的铝镁合金焊丝进行第三次回火处理；(7)将经过第三次回火处理的铝镁合金焊丝进行第三次气体深冷处理。该方法能够有效减少铝镁合金焊丝中的晶格缺陷,并抑制铝镁合金焊丝中部分缺陷的扩散,通过分步3次反复的回火处理及深冷处理,能够提高铝镁合金焊丝的强韧性,相对未处理的提高铝镁合金焊丝伸长率提高1倍。(The invention discloses a method for improving the obdurability of an aluminum-magnesium alloy welding wire, which comprises the following steps: (1) carrying out three-stage heating homogenization heat treatment on the aluminum-magnesium alloy welding wire; (2) tempering treatment is carried out; (3) carrying out gas cryogenic treatment; (4) carrying out secondary tempering treatment on the aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment; (5) carrying out secondary gas cryogenic treatment on the aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment; (6) carrying out third tempering treatment on the aluminum-magnesium alloy welding wire subjected to the second gas cryogenic treatment; (7) and carrying out third gas cryogenic treatment on the aluminum magnesium alloy welding wire subjected to the third tempering treatment. The method can effectively reduce lattice defects in the aluminum magnesium alloy welding wire, inhibit diffusion of partial defects in the aluminum magnesium alloy welding wire, and improve the toughness of the aluminum magnesium alloy welding wire by step-by-step 3-time repeated tempering treatment and cryogenic treatment, and the elongation of the aluminum magnesium alloy welding wire is improved by 1 time compared with that of the untreated aluminum magnesium alloy welding wire.)

1. The method for improving the obdurability of the aluminum-magnesium alloy welding wire is characterized by comprising the following steps of:

(1) carrying out three-stage heating homogenization heat treatment on the aluminum-magnesium alloy welding wire which is drawn to the diameter of 5-6 mm, and sequentially carrying out heat preservation at 230-240 ℃ for 8-10 hours, at 400-410 ℃ for 8-10 hours and at 430-440 ℃ for 8-10 hours;

(2) tempering the aluminum-magnesium alloy welding wire subjected to the homogenization heat treatment;

(3) carrying out gas cryogenic treatment on the tempered aluminum-magnesium alloy welding wire;

(4) carrying out secondary tempering treatment on the aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment;

(5) carrying out secondary gas cryogenic treatment on the aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment in the step (4);

(6) carrying out third tempering treatment on the aluminum-magnesium alloy welding wire subjected to the second gas cryogenic treatment in the step (5);

(7) and (4) carrying out third gas cryogenic treatment on the aluminum magnesium alloy welding wire subjected to the third tempering treatment in the step (6).

2. The method for improving the toughness of the aluminum magnesium alloy welding wire according to claim 1, wherein the aluminum magnesium alloy welding wire is subjected to homogenization heat treatment in the step (1) and then is placed in oil for quenching, and the quenching temperature is 50-80 ℃.

3. The method for improving the toughness of the aluminum-magnesium alloy welding wire according to claim 1 or 2, wherein the tempering treatment in the step (2), the step (4) and the step (6) is carried out at the temperature of 170-180 ℃ for 6-10 h.

4. The method for improving the toughness of the aluminum magnesium alloy welding wire according to claim 3, wherein the aluminum magnesium alloy welding wire is placed in air to be recovered to room temperature after the tempering treatment in the step (2), the step (4) and the step (6).

5. The method for improving the toughness of the aluminum magnesium alloy welding wire according to claim 1, wherein the gas cryogenic treatment in the step (3), the step (5) and the step (7) is carried out by placing the welding wire in liquid nitrogen for 24-36 hours.

6. The method for improving the toughness of the aluminum magnesium alloy welding wire according to claim 5, wherein the aluminum magnesium alloy welding wire is subjected to gas cryogenic treatment by using the latent heat of vaporization of liquid nitrogen in the step (3), the step (5) and the step (7).

7. The method for improving the toughness of the aluminum-magnesium alloy welding wire according to claim 1, wherein the aluminum-magnesium alloy welding wire in the step (1) is 5356 aluminum-magnesium alloy welding wire.

8. The method for improving the obdurability of the aluminum magnesium alloy welding wire according to claim 7, wherein the 5356 aluminum magnesium alloy welding wire comprises the following chemical components in percentage by mass: 4.5 to 5.5 percent of Mg, 0.06 to 0.20 percent of Ti, 0.05 to 0.20 percent of Mn, 0.05 to 0.20 percent of Cr, less than or equal to 0.40 percent of Fe, less than or equal to 0.25 percent of Si, less than 0.10 percent of Cu, less than 0.10 percent of Zn, less than or equal to 0.05 percent of each of the other impurity elements and the balance of Al.

Technical Field

The invention relates to an aluminum magnesium alloy welding wire processing method, in particular to a method for improving the obdurability of an aluminum magnesium alloy welding wire.

Background

5356 an aluminum-magnesium alloy welding wire is a general welding material containing 4.5% -5.5% of Mg4, Cr, Mn, Ti and other trace alloy elements, and is mainly used for welding Al-Mg, Al-Mg-Si, Al-Zn-Mg and other high-strength aluminum alloys, the quality of the welding wire determines the welding quality, but the 5356 aluminum-magnesium alloy welding wire has certain problems in the production process and the material, and the welding wire is easy to crack due to heat during welding, and has low strength and plasticity, poor stability of the welding wire and the like, so the existing 5356 aluminum-magnesium alloy welding wire can not meet the production requirement of high-quality products.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a method for improving the obdurability of an aluminum magnesium alloy welding wire, which can improve the obdurability of the aluminum magnesium alloy welding wire and improve the stability and the quality of a welding seam.

The technical scheme is as follows: the method for improving the obdurability of the aluminum-magnesium alloy welding wire comprises the following steps of:

(1) carrying out three-stage heating homogenization heat treatment on the aluminum-magnesium alloy welding wire which is drawn to the diameter of 5-6 mm, and sequentially carrying out heat preservation at 230-240 ℃ for 8-10 hours, at 400-410 ℃ for 8-10 hours and at 430-440 ℃ for 8-10 hours;

(2) tempering the aluminum-magnesium alloy welding wire subjected to the homogenization heat treatment;

(3) carrying out gas cryogenic treatment on the tempered aluminum-magnesium alloy welding wire;

(4) carrying out secondary tempering treatment on the aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment;

(5) carrying out secondary gas cryogenic treatment on the aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment in the step (4);

(6) carrying out third tempering treatment on the aluminum-magnesium alloy welding wire subjected to the second gas cryogenic treatment in the step (5);

(7) and (4) carrying out third gas cryogenic treatment on the aluminum magnesium alloy welding wire subjected to the third tempering treatment in the step (6).

The method comprises the following steps of (1) placing an aluminum magnesium alloy welding wire in oil for quenching after homogenizing heat treatment, wherein the quenching temperature is 50-80 ℃, the tempering temperature in the step (2), (4) and (6) is 170-180 ℃, the heat preservation time is 6-10 hours, the aluminum magnesium alloy welding wire is placed in the air to be recovered to the room temperature after tempering in the step (2), (4) and (6), the aluminum magnesium alloy welding wire is placed in liquid nitrogen for treatment for 24-36 hours when gas cryogenic treatment is carried out in the step (3), (5) and (7), gas cryogenic treatment is carried out on the aluminum magnesium alloy welding wire by using the gasification latent heat of the liquid nitrogen in the step (3), (5) and (7), the aluminum magnesium alloy welding wire is a 53aluminum magnesium 56 alloy welding wire in the step (1), and the chemical components of the 5356 aluminum magnesium alloy welding wire are calculated according to the mass percentage: 4.5 to 5.5 percent of Mg, 0.06 to 0.20 percent of Ti, 0.05 to 0.20 percent of Mn, 0.05 to 0.20 percent of Cr, less than or equal to 0.40 percent of Fe, less than or equal to 0.25 percent of Si, less than 0.10 percent of Cu, less than 0.10 percent of Zn, less than or equal to 0.05 percent of each of the other impurity elements and the balance of Al.

The working principle is as follows: the aluminum magnesium alloy welding wire with the thickness of 5-6 mm after drawing treatment has high-density dislocation and a large number of lattice defects inside, many alloy elements are in a saturated state, the alloy has large internal stress, and dendritic crystal reticular beta (Al) enriched in crystal boundaries is reduced inside the aluminum magnesium alloy welding wire after three-stage temperature rise homogenization heat treatment₃Mg₂) Phase and other second phase particles and the like generate intragranular or regional segregation, solid solution at high temperature is kept to room temperature in a supersaturated state through oil quenching, the solid solution is strengthened, the cooling capacity of oil is low, cracking caused by too fast temperature reduction of a welding wire can be avoided, then through first tempering treatment, a crystal lattice of the alloy is recovered to a more stable state, and then gas cryogenic treatment is carried out on the alloy by utilizing gasification latent heat of liquid nitrogen, so that the strength of the interior of the welding wire is smallDissolving out a chemical phase, then carrying out secondary tempering treatment to generate a large amount of new phase cores in the welding wire, promoting the second phase to be uniform and dispersed, promoting the volume fraction of the second phase to be greatly improved, then carrying out secondary gas cryogenic treatment on the second phase by using the latent heat of vaporization of liquid nitrogen, separating out fine and uniform second phase, obtaining higher strength, then carrying out tertiary tempering treatment to reduce the internal stress of the welding wire, partially gathering the particles of the second phase, further decomposing the metastable phase, keeping a strengthening state, improving plasticity, then carrying out tertiary gas cryogenic treatment on the metastable phase by using the latent heat of vaporization of the liquid nitrogen, further stabilizing the internal structure of the welding wire, obtaining better strength and plasticity matching

The gas cryogenic treatment is carried out on the aluminum magnesium alloy welding wire at the temperature of critical gasification of liquid nitrogen, namely about-196 ℃, so that the liquid nitrogen can be prevented from impacting the surface of the aluminum magnesium alloy welding wire, cracks are generated on the surface of the aluminum magnesium alloy welding wire, and the quality of the aluminum magnesium alloy welding wire is influenced.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: 1. the lattice defects in the aluminum magnesium alloy welding wire can be effectively reduced, and the diffusion of partial defects in the aluminum magnesium alloy welding wire is inhibited through cryogenic treatment; 2. al segregated and enriched in grain boundaries and dendritic network can be obtained by stepwise homogenization heat treatment and 3 times of repeated tempering treatment₃Mg₂The phases are dissolved into solid solution, the residual second phase is dissolved into the solid solution as much as possible, but the welding wire is not over-burnt, and 3 times of repeated cryogenic treatment can enable coarse nonequilibrium phases in the alloy to be more fully dissolved and homogenized, and the second phase is uniform and dispersed and precipitated; 3. the toughness of the aluminum magnesium alloy welding wire can be improved, and the elongation of the aluminum magnesium alloy welding wire is improved by 1 time compared with the untreated aluminum magnesium alloy welding wire.

Detailed Description

Example 1

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 4.5 percent of Mg, 0.06 percent of Ti, 0.05 percent of Mn and 0.05 percent of Cr, wherein the content of single unavoidable impurity elements Fe is less than or equal to 0.40 percent, the content of Si is less than or equal to 0.25 percent, the content of Cu is less than 0.10 percent, the content of Zn is less than 0.10 percent, and the balance is Al.

(1) Three-stage heating homogenization treatment: homogenizing heat treatment is carried out on the 5356 aluminum-magnesium alloy welding wire, the heat preservation time is firstly 10 hours at 230 ℃, then the heat preservation time is 10 hours after the temperature is raised to 400 ℃, finally the heat preservation time is 10 hours at 430 ℃, and then the welding wire is taken out and placed in oil at 60 ℃ for quenching;

(2) then taking out the quenched 5356 aluminum magnesium alloy welding wire for carrying out first tempering treatment: tempering temperature is 180 ℃, and heat preservation time is 10 hours;

(3) placing the 5356 aluminum-magnesium alloy welding wire subjected to tempering treatment in liquid nitrogen at the temperature of-196 ℃ for primary gas cryogenic treatment, keeping the temperature for 36 hours, and then taking out and placing in air to recover to room temperature;

(4) carrying out secondary tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment at 180 ℃, preserving heat for 10 hours, and then putting the welding wire in air to recover to room temperature;

(5) placing the 5356 aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment in liquid nitrogen at the temperature of-196 ℃ for secondary cryogenic treatment, keeping the temperature for 36 hours, and then taking out and placing in air to recover to room temperature;

(6) carrying out tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to the secondary cryogenic treatment for the third time, wherein the tempering temperature is 180 ℃, the heat preservation time is 10 hours, and then, placing the welding wire in air to recover to the room temperature;

(7) placing the 5356 aluminum magnesium alloy welding wire subjected to the third tempering treatment in liquid nitrogen at the temperature of 196 ℃ below zero for third cryogenic treatment, keeping the temperature for 36 hours, taking out the welding wire, placing the welding wire in air to recover to room temperature,

the samples were taken to test the tensile mechanical properties at room temperature according to the national standard tensile test regulations, and the tensile rate was 0.05mm/min on a WE-10 type hydraulic tensile tester, and the average value of 3 groups of mechanical properties was obtained for each group, and the test results are shown in Table 1.

Example 2

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 5.5 percent of Mg, 0.20 percent of Ti, 0.20 percent of Mn and 0.20 percent of Cr, wherein the single Fe of inevitable impurity elements is less than or equal to 0.40 percent, the single Si is less than or equal to 0.25 percent, the single Cu is less than 0.10 percent, the single Zn is less than 0.10 percent, and the balance is Al.

(1) Three-stage heating homogenization treatment: homogenizing heat treatment is carried out on the 5356 aluminum-magnesium alloy welding wire, the heat preservation time is firstly carried out for 8 hours at 240 ℃, then the heat preservation time is increased to 400 ℃ for 8 hours, finally the heat preservation time is carried out for 8 hours at 430 ℃, and then the welding wire is taken out and placed in oil at 60 ℃ for quenching;

(2) then taking out the quenched 5356 aluminum magnesium alloy welding wire for carrying out first tempering treatment: tempering temperature is 180 ℃, and the heat preservation time is 8 hours;

(3) placing the 5356 aluminum-magnesium alloy welding wire subjected to tempering treatment in liquid nitrogen at the temperature of-196 ℃ for primary gas cryogenic treatment, preserving heat for 24 hours, and then taking out and placing in air to recover to room temperature;

(4) carrying out secondary tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment at the temperature of 170 ℃ for 6 hours, and then putting the welding wire in air to recover to room temperature;

(5) placing the 5356 aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment in liquid nitrogen at the temperature of 196 ℃ below zero for secondary cryogenic treatment, keeping the temperature for 24 hours, and then taking out and placing in air to recover to room temperature;

(6) carrying out third tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to the second subzero treatment at the tempering temperature of 170 ℃ for 6 hours, and then putting the welding wire in air to recover to the room temperature;

(7) placing the 5356 aluminum magnesium alloy welding wire subjected to the third tempering treatment in liquid nitrogen at the temperature of 196 ℃ below zero for third cryogenic treatment, keeping the temperature for 24 hours, taking out the welding wire, placing the welding wire in air to recover to the room temperature,

the samples were taken to test the tensile mechanical properties at room temperature according to the national standard tensile test regulations, and the tensile rate was 0.05mm/min on a WE-10 type hydraulic tensile tester, and the average value of 3 groups of mechanical properties was obtained for each group, and the test results are shown in Table 1.

Example 3

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 5 percent of Mg, 0.13 percent of Ti, 0.125 percent of Mn and 0.125 percent of Cr, wherein the single Fe of inevitable impurity elements is less than or equal to 0.40 percent, the Si is less than or equal to 0.25 percent, the Cu is less than 0.10 percent, the Zn is less than 0.10 percent, and the balance is Al.

(1) Three-stage heating homogenization treatment: homogenizing heat treatment is carried out on the 5356 aluminum-magnesium alloy welding wire, the heat preservation time is firstly carried out for 8 hours at 240 ℃, then the heat preservation time is increased to 410 ℃, the heat preservation time is carried out for 8 hours, finally the heat preservation time is carried out for 8 hours at 440 ℃, and then the aluminum-magnesium alloy welding wire is taken out and placed in oil at 60 ℃ for quenching;

(2) then taking out the quenched 5356 aluminum magnesium alloy welding wire for carrying out first tempering treatment: tempering temperature is 175 ℃, and the heat preservation time is 8 hours;

(3) placing the 5356 aluminum-magnesium alloy welding wire subjected to tempering treatment in liquid nitrogen at the temperature of-196 ℃ for primary gas cryogenic treatment, preserving heat for 30 hours, and then taking out and placing in air to recover to room temperature;

(4) carrying out secondary tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment at 175 ℃, preserving heat for 8 hours, and then putting the welding wire in air to recover to room temperature;

(5) placing the 5356 aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment in liquid nitrogen at the temperature of 196 ℃ below zero for secondary cryogenic treatment, keeping the temperature for 30 hours, and then taking out and placing in air to recover to room temperature;

(6) carrying out third tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to the second subzero treatment at the tempering temperature of 175 ℃ for 8 hours, and then putting the welding wire in air to recover to the room temperature;

(7) placing the 5356 aluminum magnesium alloy welding wire subjected to the third tempering treatment in liquid nitrogen at the temperature of 196 ℃ below zero for third cryogenic treatment, keeping the temperature for 30 hours, taking out the welding wire, placing the welding wire in air to recover to the room temperature,

the samples were taken to test the tensile mechanical properties at room temperature according to the national standard tensile test regulations, and the tensile rate was 0.05mm/min on a WE-10 type hydraulic tensile tester, and the average value of 3 groups of mechanical properties was obtained for each group, and the test results are shown in Table 1.

Comparative example 1

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 5 percent of Mg, 0.13 percent of Ti, 0.125 percent of Mn and 0.125 percent of Cr, wherein the single Fe of inevitable impurity elements is less than or equal to 0.40 percent, the Si is less than or equal to 0.25 percent, the Cu is less than 0.10 percent, the Zn is less than 0.10 percent, and the balance is Al. The samples were taken to test the tensile mechanical properties at room temperature according to the national standard tensile test regulations, and the tensile rate was 0.05mm/min on a WE-10 type hydraulic tensile tester, and the average value of 3 groups of mechanical properties was obtained for each group, and the test results are shown in Table 1.

Comparative example 2

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 5 percent of Mg, 0.13 percent of Ti, 0.125 percent of Mn and 0.125 percent of Cr, wherein the single Fe of inevitable impurity elements is less than or equal to 0.40 percent, the Si is less than or equal to 0.25 percent, the Cu is less than 0.10 percent, the Zn is less than 0.10 percent, and the balance is Al. The 5356 aluminum-magnesium alloy welding wire is subjected to homogenization heat treatment, the heat preservation time is firstly 8 hours at 240 ℃, then the heat preservation time is 8 hours after the temperature is raised to 410 ℃, finally the heat preservation time is 8 hours at 440 ℃, then the welding wire is taken out and placed in oil at 60 ℃ for quenching, the room temperature tensile mechanical property test is carried out by sampling according to the national standard tensile experiment regulation, the test is carried out on a WE-10 type hydraulic tensile tester, the tensile rate is 0.05mm/min, 3 groups of mechanical properties are taken as the average value, and the test results are shown in the table 1.

Comparative example 3

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 5 percent of Mg, 0.13 percent of Ti, 0.125 percent of Mn and 0.125 percent of Cr, wherein the single Fe of inevitable impurity elements is less than or equal to 0.40 percent, the Si is less than or equal to 0.25 percent, the Cu is less than 0.10 percent, the Zn is less than 0.10 percent, and the balance is Al. Homogenizing heat treatment is carried out on the 5356 aluminum-magnesium alloy welding wire, the heat preservation time is firstly carried out for 8 hours at 240 ℃, then the heat preservation time is increased to 410 ℃, the heat preservation time is carried out for 8 hours, finally the heat preservation time is carried out for 8 hours at 440 ℃, and then the aluminum-magnesium alloy welding wire is taken out and placed in oil at 60 ℃ for quenching; then taking out the quenched 5356 aluminum magnesium alloy welding wire for tempering treatment: tempering temperature is 175 ℃, and the heat preservation time is 8 hours; and (3) placing the 5356 aluminum-magnesium alloy welding wire subjected to tempering treatment in liquid nitrogen at the temperature of-196 ℃ for cryogenic treatment, preserving heat for 30 hours, and then taking out and placing in air to recover to the room temperature.

Comparative example 4

The 5356 aluminum magnesium alloy welding wire with the diameter of 5.25mm is obtained by drawing in multiple passes, and the welding wire comprises the following chemical components (by mass percent): 5 percent of Mg, 0.13 percent of Ti, 0.125 percent of Mn and 0.125 percent of Cr, wherein the single Fe of inevitable impurity elements is less than or equal to 0.40 percent, the Si is less than or equal to 0.25 percent, the Cu is less than 0.10 percent, the Zn is less than 0.10 percent, and the balance is Al.

(1) Three-stage heating homogenization treatment: homogenizing heat treatment is carried out on the 5356 aluminum-magnesium alloy welding wire, the heat preservation time is firstly carried out for 8 hours at 240 ℃, then the heat preservation time is increased to 410 ℃, the heat preservation time is carried out for 8 hours, finally the heat preservation time is carried out for 8 hours at 440 ℃, and then the aluminum-magnesium alloy welding wire is taken out and placed in oil at 60 ℃ for quenching;

(2) then taking out the quenched 5356 aluminum magnesium alloy welding wire for carrying out first tempering treatment: tempering temperature is 175 ℃, and the heat preservation time is 8 hours;

(3) placing the 5356 aluminum-magnesium alloy welding wire subjected to tempering treatment in liquid nitrogen at the temperature of-210 ℃ for primary gas cryogenic treatment, preserving heat for 30 hours, and then taking out and placing in air to recover to room temperature;

(4) carrying out secondary tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to gas cryogenic treatment at 175 ℃, preserving heat for 8 hours, and then putting the welding wire in air to recover to room temperature;

(5) placing the 5356 aluminum-magnesium alloy welding wire subjected to the secondary tempering treatment in liquid nitrogen at the temperature of-210 ℃ for secondary cryogenic treatment, keeping the temperature for 30 hours, and then taking out and placing in air to recover to the room temperature;

(6) carrying out third tempering treatment on the 5356 aluminum-magnesium alloy welding wire subjected to the second subzero treatment at the tempering temperature of 175 ℃ for 8 hours, and then putting the welding wire in air to recover to the room temperature;

(7) placing the 5356 aluminum magnesium alloy welding wire subjected to the third tempering treatment in liquid nitrogen at the temperature of-210 ℃ for third cryogenic treatment, keeping the temperature for 30 hours, taking out the welding wire, placing the welding wire in the air to recover to the room temperature,

the samples were taken to test the tensile mechanical properties at room temperature according to the national standard tensile test regulations, and the tensile rate was 0.05mm/min on a WE-10 type hydraulic tensile tester, and the average value of 3 groups of mechanical properties was obtained for each group, and the test results are shown in Table 1.

TABLE 1 mechanical properties of 5356 Al-Mg alloy welding wire treated by different processes

As can be seen from the table, the tensile strength, the yield strength and the elongation after fracture of the mechanical properties of the welding wires in the comparative examples 1-4 are different from those of the welding wires in the embodiments 1-3, after the tempering treatment and the liquid cryogenic treatment are repeated for 3 times step by step in the comparative example 4, the thermal shock of the liquid cryogenic treatment on the welding wires is large, so that microcracks are generated on the surfaces of the welding wires, and the mechanical property index of the welding wires is lower than that of the aluminum magnesium alloy welding wires in the application. Therefore, after the tempering treatment and the gas cryogenic treatment are repeated step by step for 3 times, the tensile strength, the yield strength and the elongation after fracture of the welding wire are greatly improved compared with the single-stage treatment or the secondary treatment and even the liquid cryogenic treatment.