High-temperature-resistant and wear-resistant aluminum-magnesium alloy welding wire and preparation process thereof

Abstract

The invention relates to the technical field of alloy processing, and particularly discloses a high-temperature-resistant and wear-resistant aluminum-magnesium alloy welding wire and a preparation process thereof. The alloy welding wire is composed of the following raw material components in percentage by mass: 4%-6% of Mg, 0.2%-0.35% of Cr, 0.1%-0.2% of Ti, 0.05%-0.2% of Mn, 0.02%-0.05% of Zn, 0.1%-0.3% of C, 0.05%-0.15% of Sc and the balance of Al and inevitable impurities, and the content of the impurities is smaller than or equal to 0.03%. In the alloy welding wire preparation process, C is added in the form of graphite powder. The preparation process of the aluminum-magnesium alloy welding wire comprises the following steps: (1) heating and melting an aluminum ingot, sequentially adding all elements, uniformly stirring, degassing, heating, slagging off and pouring to obtain an aluminum-magnesium alloy casting rod; and (2) the aluminum-magnesium alloy casting rod is subjected to drawing and heat treatment, and the aluminum-magnesium alloy welding wire is obtained. Wherein the C element is added into a melting system in the form of graphite powder, and the temperature of the melting system is controlled to be 1000 DEG C or above before the graphite powder is added.

Description

Technical Field

[0001] The present application relates to the technical field of alloy processing, and more specifically, to a high temperature resistant and wear resistant aluminum-magnesium alloy welding wire and a preparation process thereof. Background Art

[0002] With the development of lightweight and high-speed transportation vehicles, aluminum alloys are widely used, and at the same time, higher requirements are put forward for aluminum alloy welding materials and welding technology. Aluminum-magnesium alloy has good plastic fracture toughness, fatigue strength and corrosion resistance, as well as good forming processability and weldability, so it has become the main welding material for aluminum alloy structural parts, and the performance of welding materials is the key to affecting the overall components; under the condition of a certain base material, the performance of welded structural parts mainly depends on the welding process and the composition and performance of the welding wire, so improving the performance of aluminum-magnesium welding wire materials is of great significance to the wide application of aluminum alloy welded structural parts.

[0003] The chemical composition of aluminum alloy welding wire, in addition to aluminum matrix, generally contains various main alloying elements, added trace elements and impurity elements. According to the main alloying elements, it can be divided into pure aluminum welding wire, aluminum copper welding wire, aluminum silicon welding wire, aluminum manganese welding wire and aluminum magnesium welding wire. The main alloying element of aluminum magnesium welding wire is magnesium, and the trace elements are mainly manganese, chromium, titanium, etc.

[0004] As a high-strength and corrosion-resistant welding material, aluminum-magnesium welding wire is widely used in the field of modern industrial manufacturing. Aluminum-magnesium alloy welding wire not only inherits the lightness, corrosion resistance and good plasticity of aluminum, but also combines the high strength and high hardness of magnesium, making it an ideal welding material, especially in situations where high temperature resistance and wear resistance are required.

[0005] The main features of aluminum-magnesium welding wire are high strength, excellent corrosion resistance, good plasticity and toughness, low smoke and spatter, and high temperature resistance. The high strength, high stability and corrosion resistance of aluminum-magnesium alloy welding wire make it used in aerospace, automobile manufacturing, building decoration, electronic appliances, rail transportation and other fields.

[0006] Although aluminum-magnesium welding wire has many advantages, there is still room for improvement in terms of high temperature resistance and wear resistance. Traditional aluminum-magnesium alloy welding wire may experience performance degradation and strength reduction under extreme high temperature and friction environments, affecting the stability and service life of welded parts. Therefore, developing a high-temperature and wear-resistant aluminum-magnesium alloy welding wire and its preparation method to meet the application requirements in high temperature and wear-resistant environments has become the focus of current research. Summary of the invention

[0007] In order to solve the above technical problems, the present application provides a high temperature resistant and wear resistant aluminum-magnesium alloy welding wire and a preparation method thereof.

[0008] In a first aspect, the present application provides a high temperature resistant and wear resistant aluminum-magnesium alloy welding wire, which adopts the following technical solution: A high temperature and wear resistant aluminum-magnesium alloy welding wire, comprising the following raw material components by mass percentage: Mg 4-6%, Cr 0.2-0.35%, Ti 0.1-0.2%, Mn 0.05-0.2%, Zn 0.02-0.05%, C 0.1-0.3%, Sc 0.05-0.15%, reinforcing phase particles 1-2%, and the rest being Al and unavoidable impurities, wherein the impurities are ≤0.03%; In the process of preparing the aluminum-magnesium alloy welding wire, the C is added in the form of graphite powder.

[0009] When the Mg content exceeds 6%, Mg5Al3 and Mg2Al6 will precipitate at the grain boundaries before Al3Mg2, which will cause intergranular cracks in the aluminum alloy and reduce the stress corrosion resistance. Therefore, the Mg content should not exceed 6%. Mn can inhibit the recrystallization process in magnesium-aluminum alloys, increase the recrystallization temperature, and refine the recrystallized structure; the Mn content should not be too high, otherwise a large amount of brittle MnAl6 will be formed, resulting in a significant reduction in the alloy plasticity and a sharp drop in the material's processing performance.

[0010] Cr is a transition element. Adding a small amount of Cr can effectively improve the structure and properties of aluminum alloys. Similar to Mn, Cr can produce dispersed particles in aluminum alloys, hinder dislocation movement and migration between grain boundaries, inhibit recrystallization, increase recrystallization temperature, and reduce the grain size of alloy casting structure. The mechanical properties and stress corrosion resistance of aluminum alloys are improved. When a small amount of Cr is added to aluminum alloy welding wire, the welding wire will be melted and quickly solidified during welding, which will disperse and precipitate the primary Al7Cr phase on the aluminum matrix, thereby improving the strength of the welded joint and reducing the tendency of welding hot cracks.

[0011] When Zn is added to aluminum alone, it has limited effect on improving the mechanical properties of aluminum alloys. The addition of zinc increases intergranular cracks and reduces stress corrosion resistance. When Zn is added to aluminum-magnesium alloys, the order of precipitation of aging strengthening phases is: supersaturated solid solution, GP zone, metastable precipitation phase, stable precipitation phase MgZn2, which has a good strengthening effect and can be heat treated, making it applicable to aerospace, vehicles, marine engineering and other fields, greatly broadening the application field.

[0012] A small amount of Ti element can not only refine the cast structure of aluminum alloy, but also partially inhibit recrystallization, increase the recrystallization temperature, improve the weldability of aluminum alloy, and significantly reduce the sensitivity to hot cracks, reduce the tendency of hot cracks in welded joints during welding, thereby improving the welding quality of welded joints; the addition of Ti element can cause the aluminum alloy to precipitate primary TiAl3 phase during welding. The TiAl3 particles are very close to the aluminum matrix in unit cell constant, crystal structure and size, and can serve as a good substrate for accumulation, providing a core for heterogeneous nucleation of the aluminum matrix, thereby significantly refining the grain structure of the welded joint during the welding process.

[0013] The trace addition of Sc can form primary Al3 (Sc, Zr) particles during the rapid solidification process of aluminum alloy. The particles are L12-type particles that can provide the core for heterogeneous nucleation of the aluminum matrix, thereby refining the aluminum alloy grains. Al (Sc, Zr) particles have the properties of high melting point, refractoryness and stable structure. During fusion welding, the grain refining effect caused by the addition of scandium and zirconium can still be applied. Therefore, the grains of the welded joints are refined, which can reduce the tendency of welding hot cracks to form in the welded joints, improve the mechanical properties of the welded joints, and improve their stress corrosion resistance.

[0014] The introduction of C element can further strengthen the aluminum-magnesium alloy and improve its heat resistance, wear resistance and impact toughness, but too high carbon content can easily lead to fatigue cracks in the aluminum-magnesium alloy, reduce its strength and plasticity, and then cause cracking. The addition of rare earth element Sc can improve the mechanical properties of aluminum-magnesium alloy welding wire, thus making up for the defect of decreased mechanical properties of aluminum-magnesium alloy welding wire caused by the introduction of carbon element.

[0015] Preferably, the particle size of the graphite powder is 160 to 200 μm. More preferably, the particle size of the graphite powder is 160 to 180 μm.

[0016] The melting point of graphite is as high as 3650℃, and it is difficult to melt during the preparation of welding wire. The particle size of graphite is controlled between 160 and 200μm, so that the graphite powder is evenly dispersed in the alloy crystal phase without agglomeration.

[0017] Preferably, in the process of preparing the aluminum-magnesium alloy welding wire: The Mn is added in the form of Al-Mn master alloy, wherein the mass content of the Mn is 6-8%; The Cr is added in the form of Al-Cr master alloy, wherein the mass content of the Cr is 6-8%; The Ti is added in the form of an Al-Ti master alloy, wherein the mass content of the Ti is 14-16%; The Ti is added in the form of an Al-Sc master alloy, wherein the mass content of Sc is 8-12%.

[0018] In a second aspect, the present application also provides a method for preparing a high temperature resistant and wear resistant aluminum-magnesium alloy welding wire, which adopts the following technical solution: (1) After heating and melting the aluminum ingot, add each element in turn, stir evenly, degas, heat and slag, and cast to obtain aluminum-magnesium alloy casting rods; (2) drawing and heat treating the aluminum-magnesium alloy cast rod to obtain the aluminum-magnesium alloy welding wire; The C element is added into the molten system in the form of graphite powder. Before the graphite powder is added, the temperature of the molten system is controlled to be above 1000°C.

[0019] In the process of preparing aluminum-magnesium alloy welding wire, the applicant found that no matter how the particle size of graphite is controlled, its dispersibility in the aluminum-magnesium molten system is poor. The prior art shows that at 700°C, the contact angle between aluminum liquid and graphite is above 90°, and the wettability of graphite in aluminum is extremely poor. The applicant believes that this may be the reason for the poor dispersibility of graphite in the molten system. By further increasing the temperature of the aluminum-magnesium molten system before adding graphite powder, when it reaches above 1000°C, the above problem can be effectively solved and the high temperature and wear resistance of the aluminum-magnesium alloy welding wire can be improved.

[0020] Preferably, the order of adding the elements is: aluminum ingot, magnesium ingot, zinc powder, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-Sc master alloy, and graphite powder.

[0021] Preferably, the diameter of the aluminum-magnesium alloy cast rod is 9-12 mm, and the diameter of the aluminum-magnesium alloy welding wire is 0.1-4 mm.

[0022] Preferably, in step (1), the temperature of the heating and melting is 670-750° C., the stirring speed is 450-500 r / min, and the stirring time is 0.5-1 h.

[0023] Preferably, in step (2), the specific steps of drawing and heat treatment are: subjecting the aluminum-magnesium alloy cast rod to a first drawing - a first heat treatment - a second drawing - a second heat treatment in sequence.

[0024] Preferably, during the first drawing, the compression rate of the end section of the aluminum-magnesium alloy cast rod is 30-40%; during the second drawing, the compression rate of the end section of the aluminum-magnesium alloy cast rod is 20-30%.

[0025] Preferably, the temperature of the first heat treatment is 330-360° C., and the time is 1-1.5 h; the temperature of the second heat treatment is 320-350° C., and the time is 1-1.5 h.

[0026] Preferably, the aluminum-magnesium alloy welding wire obtained in step (2) is further post-processed, specifically comprising the following steps: firstly grinding the surface of the aluminum-magnesium alloy welding wire with sandpaper to remove the oxide layer, and then removing the grease on the surface with acetone or alcohol to obtain a finished aluminum-magnesium alloy welding wire.

[0027] In summary, this application has the following beneficial effects: The present application adds Sc and C elements to the aluminum-magnesium alloy system to ensure that the aluminum-magnesium alloy has high wear resistance while having high strength; the C element can significantly improve the high temperature resistance and wear resistance of the aluminum-magnesium alloy, and the addition of Sc can improve the defect of reduced alloy strength due to the addition of the C element.

[0028] The present application introduces the C element into the alloy by using graphite powder, controls the particle size of the graphite powder to be 160-180 μm, and increases the system temperature to above 1000°C before adding the graphite powder into the aluminum-magnesium molten system, thereby significantly improving the wettability and dispersibility of the graphite powder in the alloy, and ensuring that the aluminum-magnesium alloy welding wire has high high temperature resistance and mechanical properties. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the embodiments.

[0030] In the preparation process of the aluminum-magnesium alloy welding wire of the present application, the heating equipment used is a LY1400 pit-type resistance furnace, and the stirring equipment is a Ti6Al4V mechanical stirring paddle.

[0031] Example 1 Preparation of high temperature resistant and wear resistant aluminum-magnesium alloy welding wire: (1) Under argon protection, preheat an alumina crucible to 250°C, add an aluminum ingot and heat it to 700°C to melt the aluminum ingot to obtain aluminum liquid, add zinc powder, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, and Al-Sc master alloy in sequence, stir at a speed of 450 r / min for 0.5 h after melting, then heat it to 1000°C, add graphite powder with a particle size of 160 μm, continue stirring for 0.5 h, put hexafluoroethane into it for degassing, remove slag, stand it for 5 min, and then pour it into a preheated steel mold and cool it to obtain an aluminum-magnesium alloy casting rod with a diameter of 10 mm; (2) The aluminum-magnesium alloy cast rod is drawn for the first time, with the end section compression rate of 30-40%, and heat treated at 350°C for 1h; then it is drawn for the second time, with the end section compression rate of 20-30%, and heat treated at 330°C for 1h to obtain an aluminum-magnesium alloy welding wire with a diameter of 3mm.

[0032] The mass percentage of each element in the aluminum-magnesium alloy welding wire prepared in this embodiment is shown in Table 1.

[0033] Example 2-3 Preparation of high temperature and wear resistant aluminum-magnesium alloy welding wire: The difference from Example 1 is that the amount of raw material added is changed, and the mass percentage of each element in the final aluminum-magnesium alloy welding wire is shown in Table 1. The rest is the same as Example 1.

[0034] Table 1 Composition of high temperature and wear resistant aluminum-magnesium alloy welding wire of Example 1-3 Example 4 Preparation of high temperature resistant and wear resistant aluminum-magnesium alloy welding wire: The difference from Example 1 is that graphite powder with a particle size of 180 μm is added, and the rest is the same as Example 1.

[0035] Example 5 Preparation of high temperature resistant and wear resistant aluminum-magnesium alloy welding wire: The difference from Example 1 is that graphite powder with a particle size of 200 μm is added, and the rest is the same as Example 1.

[0036] Example 6 Preparation of high temperature resistant and wear resistant aluminum-magnesium alloy welding wire: (1) Under argon protection, the alumina crucible was preheated to 250°C, an aluminum ingot was added, the temperature was raised to 730°C to melt the aluminum ingot, and aluminum liquid was obtained. Zinc powder, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, and Al-Sc master alloy were added in sequence. After melting, the mixture was stirred at a speed of 480 r / min for 0.5 h, and then the temperature was raised to 1000°C. Graphite powder with a particle size of 160 μm was added, and stirring was continued for 0.5 h. Hexafluoroethane was added for degassing, slag was removed, and the mixture was placed in a preheated steel mold for heat preservation for 5 min. The mixture was cooled to obtain an aluminum-magnesium alloy casting rod with a diameter of 10 mm. (2) The aluminum-magnesium alloy cast rod is drawn for the first time, the end section compression rate is 30-40%, and the rod is heat treated at 340°C for 1h; then the rod is drawn for the second time, the end section compression rate is 20-30%, and the rod is heat treated at 320°C for 1h to obtain an aluminum-magnesium alloy welding wire with a diameter of 3mm.

[0037] The mass percentage of each element in the aluminum-magnesium alloy welding wire prepared in this embodiment is the same as that in Example 1.

[0038] Comparative Example 1 Preparation of aluminum-magnesium alloy welding wire: The preparation process is the same as that of Example 1. The difference from Example 1 is that no graphite powder and Al-Sc master alloy are added in Comparative Example 1. The mass percentage of the obtained aluminum-magnesium alloy welding wire is shown in Table 1.

[0039] Comparative Example 2 Preparation of aluminum-magnesium alloy welding wire: The preparation process is the same as that of Example 1. The difference from Example 1 is that no graphite powder is added in Comparative Example 1. The mass percentage of the obtained aluminum-magnesium alloy welding wire is shown in Table 1.

[0040] Comparative Example 3 Preparation of aluminum-magnesium alloy welding wire: The preparation process is the same as that of Example 1. The difference from Example 1 is that no Al-Sc master alloy is added in Comparative Example 1. The mass percentage of the obtained aluminum-magnesium alloy welding wire is shown in Table 1.

[0041] Comparative Example 4 (1) Under argon protection, preheat an alumina crucible to 250°C, add an aluminum ingot and heat it to 700°C to melt the aluminum ingot to obtain aluminum liquid, add zinc powder, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, and Al-Sc master alloy in sequence, stir at a speed of 450 r / min for 0.5 h after melting, then heat it to 1000°C, add chromium carbide, continue stirring for 0.5 h, put hexafluoroethane into it for degassing, remove slag, stand it for 5 min, and then pour it into a preheated steel mold and cool it to obtain an aluminum-magnesium alloy casting rod with a diameter of 10 mm; (2) The aluminum-magnesium alloy cast rod is drawn for the first time, with the end section compression rate of 30-40%, and heat treated at 350°C for 1h; then it is drawn for the second time, with the end section compression rate of 20-30%, and heat treated at 330°C for 1h to obtain an aluminum-magnesium alloy welding wire with a diameter of 3mm.

[0042] The mass content of each element in the finally obtained aluminum-magnesium alloy welding wire is the same as that in Example 1. The difference from Example 1 is that in Comparative Example 4, the C element is introduced by adding chromium carbide.

[0043] Comparative Example 5 The mass content of each element in the finally obtained aluminum-magnesium alloy welding wire is the same as that in Example 1. The difference from Example 1 is that before adding the graphite powder, the temperature of the molten system is controlled to be 950°C.

[0044] Performance Test: The surface of the welding wire prepared in each embodiment and comparative example was polished with sandpaper to remove the oxide layer, and then the grease was washed off with acetone, and welding was performed. The obtained welding layer was tested. The test results are shown in Table 2 below.

[0045] Welding parameters: Tangshan Panasonic YC-500WX AC standard TIG welding machine and Panasonic TA-1400 robot arm were used. The welding current was 200A, the welding voltage was 25V, the welding speed was 2.5mm / s, the argon gas flow rate was 15L / min, the groove was 0°, the blunt edge was 0.5-1.0mm, the thickness was 10mm, and the welding substrate was Q235 steel plate.

[0046] Hardness test: Use HR-150A Rockwell hardness tester, load 150Kg, take 5 points of hardness for each test sample and calculate the average value.

[0047] Wear resistance test: Dry abrasive wear test was conducted according to ASTM G65A, using an ABT-3 abrasive wear tester with a quartz sand particle size of 40 to 70 meshes.

[0048] Table 2 Test results The welding wires prepared in Examples 1-6 have good joint formation after welding, high width consistency, fish scale-like excess height surface, and no cracks or pores on the surface. From the test results in Table 2, it can be seen that the weld layer has high hardness, small wear, and the test data distribution of each embodiment is narrow and has high repeatability.

[0049] Compared with Example 1, in Comparative Example 1, no C and Sc elements were added, the wear resistance of the aluminum-magnesium alloy welding wire decreased, and the hardness remained basically unchanged; in Comparative Example 2, no C element was added, but Sc element was added, the wear resistance of the aluminum-magnesium alloy welding wire decreased greatly, and the hardness was slightly improved; in Comparative Example 3, C element was added, but Sc element was not added, the wear resistance of the aluminum-magnesium alloy welding wire remained basically unchanged, and the hardness decreased significantly. From the test results of Comparative Examples 1-3, it can be seen that the introduction of C element can improve the wear resistance of the aluminum-magnesium alloy welding wire, but it will have a negative impact on the hardness of the aluminum-magnesium alloy welding wire, and the introduction of the rare earth element Sc can make up for this defect.

[0050] Compared with Example 1, Comparative Example 4 changes the method of adding element C, and introduces element C in the form of chromium carbide. It can be seen that the hardness of the weld layer obtained in Comparative Example 4 is slightly reduced, while the wear resistance is greatly reduced; compared with Example 1, in Comparative Example 5, before adding graphite powder, the temperature of the molten system of the alloy is controlled to 950°C, and the hardness and wear resistance of the obtained weld layer are significantly reduced; This indicates that the present application adopts the method of adding graphite powder to introduce element C, and at the same time combines the process of heating the alloy molten system to 1000°C before adding, so as to obtain an aluminum-magnesium alloy welding wire with high hardness and high wear resistance.

[0051] The above is only the preferred implementation of the present application. The protection scope of the present application is not limited to the above embodiments. All technical solutions under the concept of the present application belong to the protection scope of the present application. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present application should also be regarded as the protection scope of the present application.

Claims

1. A high temperature and wear resistant aluminum-magnesium alloy welding wire, characterized in that: The aluminum-magnesium alloy welding wire is composed of the following raw material components in terms of mass percentage: Mg 4-6%, Cr 0.2-0.35%, Ti 0.1-0.2%, Mn 0.05-0.2%, Zn 0.02-0.05%, C 0.1-0.3%, Sc 0.05-0.15%, and the rest are Al and unavoidable impurities, wherein the impurities are ≤0.03%; in the process of preparing the aluminum-magnesium alloy welding wire, the C is added in the form of graphite powder.

2. The high temperature and wear resistant aluminum-magnesium alloy welding wire according to claim 1, characterized in that: The particle size of the graphite powder is 160-200 μm.

3. The high temperature and wear resistant aluminum-magnesium alloy welding wire according to claim 1, characterized in that: In the process of preparing the aluminum-magnesium alloy welding wire: the Mn is added in the form of Al-Mn master alloy, wherein the mass content of the Mn is 6-8%.

4. The high temperature and wear resistant aluminum-magnesium alloy welding wire according to claim 1, characterized in that: In the process of preparing the aluminum-magnesium alloy welding wire: the Cr is added in the form of Al-Cr master alloy, wherein the mass content of the Cr is 6-8%.

5. The high temperature and wear resistant aluminum-magnesium alloy welding wire according to claim 1, characterized in that: In the process of preparing the aluminum-magnesium alloy welding wire: the Ti is added in the form of Al-Ti master alloy, wherein the mass content of the Ti is 14-16%.

6. The high temperature and wear resistant aluminum-magnesium alloy welding wire according to claim 1, characterized in that: In the process of preparing the aluminum-magnesium alloy welding wire: the Sc is added in the form of an Al-Sc master alloy, wherein the mass content of the Sc is 8-12%.

7. A process for preparing the high temperature resistant and wear resistant aluminum-magnesium alloy welding wire according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) After heating and melting the aluminum ingot, add each element in turn, stir evenly, degas, heat and slag, and cast to obtain aluminum-magnesium alloy casting rods; (2) drawing and heat treating the aluminum-magnesium alloy cast rod to obtain the aluminum-magnesium alloy welding wire; The C element is added into the molten system in the form of graphite powder. Before the graphite powder is added, the temperature of the molten system is controlled to be above 1000°C.

8. The process for preparing the high temperature resistant and wear resistant aluminum-magnesium alloy welding wire according to claim 7, characterized in that: The order of adding the elements is: aluminum ingot, magnesium ingot, zinc powder, Al-Mn master alloy, Al-Cr master alloy, Al-Ti master alloy, Al-Sc master alloy, and graphite powder.

9. The process for preparing the high temperature resistant and wear resistant aluminum-magnesium alloy welding wire according to claim 7, characterized in that: In step (1), the temperature of the heating and melting is 670-750°C, the stirring speed is 450-500 r / min, and the stirring time is 0.5-1 h; In step (2), the specific steps of drawing and heat treatment are: subjecting the aluminum-magnesium alloy cast rod to a first drawing-a first heat treatment-a second drawing-a second heat treatment in sequence; During the first drawing, the compression rate of the end section of the aluminum-magnesium alloy casting rod is 30-40%; during the second drawing, the compression rate of the end section of the aluminum-magnesium alloy casting rod is 20-30%; The temperature of the first heat treatment is 330-360°C, and the time is 1-1.5h; the temperature of the second heat treatment is 320-350°C, and the time is 1-1.5h.

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