Welding materials, welding consumables, applications and preparation methods

Abstract

The present invention discloses a kind of welding material, welding material, application and preparation method, wherein welding material, its raw material composition includes, wt%:Si:1‑3%, Mg:1.2‑3.2%, Zn:1‑3.6%, Cu:0.6‑1.6%, Mn:0.5‑0.8%, Cr:0.2‑0.45%, Ti:0.1‑0.25%, Zr:0.05‑0.1%, Sc:0.05‑0.1%, Fe<0.2%, remainder is Al and inevitable impurities. The present invention reduces the precipitation enthalpy of nanoscale strengthening phase by the regulation of Zn, Cu, Mg, Si elemental content, so as to improve the bake hardening effect of weld, to make up for the weld excessive softening problem existing due to the dissolution of nanoscale precipitated phase. In addition, Fe-containing brittle phase characteristics are improved in weld by Mn, Cr element addition, and weld hot crack tendency is reduced in combination with grain refining elements such as Zr, Sc, Ti, so as to further improve weld toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy metal material welding, and in particular relates to a welding material, welding material, application and preparation method. Background Art

[0002] Aluminum alloys offer advantages such as light weight, high specific strength, good formability, and corrosion resistance, helping to reduce energy consumption and pollution emissions, making them a key material for lightweighting in the transportation industry. The rapid development of aluminum alloy applications has posed challenges to the reliability of aluminum alloy component connections in vehicle bodies.

[0003] However, existing welding wire systems are single alloying systems, such as Al-Si systems (CN201910414172.6, CN202110629191.8, CN201810532500.8), Al-Mg systems (CN201910114083.X, CN202211335599.5, CN201310700919.7), etc., which are only suitable for welding low-strength aluminum alloys, such as 6063, 6061, 7003, 7039, etc. However, with the large-scale application of high-performance aluminum alloys, existing welding wires can no longer meet their application needs. The main reason for the softening of high-strength heat-treatable aluminum alloys during fusion welding is that the nanoscale precipitates in the original parent material structure at the weld are remelted to form a cast structure during welding, thereby eliminating the strengthening effect. For example, patent CN202310445098.0 discloses a new type of A1-Si welding wire, which improves weld toughness by adding Ti and Zr elements to refine the structure, but cannot make up for the reduction in strength caused by the lack of nano-scale precipitation phase. For example, patent CN202211342824.8 discloses a new type of A1-Mg welding wire, which hinders the excessive growth and aggregation of Mg2Si phase by adding Sr elements, thereby reducing the harm of Mg2Si to the material structure and properties. However, this patent only refines the Mg2Si phase, and after refinement, it still belongs to the micron level, and the strength cannot achieve the strengthening advantage of the nano phase.

[0004] Therefore, in response to the above technical problems, it is necessary to provide a welding material, welding materials, applications and preparation methods.

[0005] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0006] The object of the present invention is to provide a welding material, welding material, application and preparation method.

[0007] In order to achieve the above object, a specific embodiment of the present invention provides the following technical solutions:

[0008] The welding material comprises raw material compositions including, by weight, Si: 1-3%, Mg: 1.2-3.2%, Zn: 1-3.6%, Cu: 0.6-1.6%, Mn: 0.5-0.8%, Cr: 0.2-0.45%, Ti: 0.1-0.25%, Zr: 0-0.1%, Sc: 0-0.1%, Fe<0.2%, and the balance being Al and unavoidable impurities.

[0009] In one or more embodiments of the present invention, a method for preparing a welding material is characterized by comprising the following steps:

[0010] Prepare raw materials, wherein at least Si, Mn, Cr, Ti, Zr, and Sc are prepared in the form of a master alloy;

[0011] Pure aluminum and master alloys other than those containing Mg, Zn, and Ti are smelted at 730-770°C; after being completely melted, the temperature is lowered to 710-730°C to add Mg and Zn; the temperature is then raised to 730-740°C for refining and degassing; after standing to remove impurities, an Al-Ti-B master alloy is added; the melt is cooled to 690-710°C for casting to obtain qualified ingots.

[0012] In one or more embodiments of the present invention, the ingot is further subjected to a two-stage homogenization heat treatment: the first stage is heated to 400-420°C at a heating rate of 2-4°C / min and kept warm for 8-12 hours; the second stage is heated to 470-520°C at a heating rate of 2-4°C / min and kept warm for 8-12 hours.

[0013] In one or more embodiments of the present invention, the welding material comprises at least a main body, and the main body is prepared by the welding material according to claim 1.

[0014] In one or more embodiments of the present invention, the ingot is heated to 440-480° C. and then extruded to obtain a rod, which is then drawn to obtain a main body.

[0015] In one or more embodiments of the present invention, the extrusion speed is regulated so that the temperature of the rod at the die outlet is controlled between 470-520°C.

[0016] In one or more embodiments of the present invention, the drawing process further includes an annealing process, and the annealing process conditions are: 390-440° C., 1-3 hours.

[0017] In one or more embodiments of the present invention, welding consumables are used in welding operations.

[0018] In one or more embodiments of the present invention, the welding operation is selected from the group consisting of: laser wire welding, laser-arc hybrid welding, non-metallic inert gas shielded arc welding, and metal inert gas shielded arc welding.

[0019] In one or more embodiments of the present invention, the welding operation further includes post-weld baking, and the process conditions thereof meet the following requirements: 140-180° C., 30-90 min.

[0020] Compared with the prior art, the welding materials, welding materials, applications and preparation methods of the present invention, based on the rapid cooling rate characteristics of the welding molten pool, break through the single-element alloying system of the aluminum alloy welding wire by adding multi-component elements, and improve the lattice distortion of α-Al in the weld to obtain a higher solid solution strengthening effect. At the same time, by regulating the content of Zn and Cu elements to reduce the precipitation enthalpy of the nano-scale precipitation phase, the bake hardening effect of the weld is improved. The combination of solid solution strengthening and precipitation strengthening achieves low-cost and efficient strengthening of high-performance aluminum alloy welds. After welding, the baking heat during the paint baking of the vehicle body or the post-weld aging heat treatment is used to promote the rapid and uniform precipitation of the nano-scale precipitation phase in the α-Al matrix, thereby strengthening the weld structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a hardness test diagram and an average hardness diagram of the laser welding weld and the weld after baking using the welding material of the present invention in Example 1.

[0023] Figure 2 This is a tensile property test curve diagram of the laser welding weld and the weld after baking using the welding material of the present invention in Example 1.

[0024] Figure 3 This is a hardness test diagram and an average hardness diagram of the laser welding weld and the weld after baking using the welding material of the present invention in Example 2.

[0025] Figure 4 This is a tensile property test curve diagram of the laser welding weld and the weld after baking using the welding material of the present invention in Example 2.

[0026] Figure 5 The hardness test diagram and average hardness diagram of the laser welding weld and the weld after baking using the commercial ER4043 welding wire in comparative example 1.

[0027] Figure 6 This is a tensile property test curve of the laser welding weld using the commercial ER4043 welding wire in comparative example 1.

[0028] Figure 7 This is a tensile properties curve of the laser welding weld using the welding material in Comparative Example 2. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0030] The present invention incorporates 1-3% Si, which ensures good fluidity in the molten pool during welding, inhibits cracking, and provides a wide process window for the welding material. Furthermore, an appropriate amount of Si (lower than that found in hypoeutectic Al-Si welding wire) prevents the molten pool from solidifying too quickly, preventing the release of dissolved hydrogen and leading to excessive weld porosity.

[0031] (2) The present invention adds 1.2-3.2% of Mg element. Mg element solid-dissolved in the α-Al matrix has a better solid solution strengthening effect than other elements. During baking, the dissolved Mg element and Si element can form dispersed nano-scale atomic clusters and nano-scale β″ phases to play a precipitation strengthening role. The remaining Mg element and Si element form a Mg2Si second phase to play a certain strengthening role.

[0032] (3) The addition of 0.6-1.6% Cu in the present invention, when dissolved in the α-Al matrix, enhances the solid solution strengthening effect. Furthermore, during baking, Cu combines with Mg and Si to precipitate into dispersed nanoscale atomic clusters and nanoscale Q″ / Q′ strengthening phases.

[0033] (4) The addition of 1-3.6% Zn element in the present invention is important. The solid solution of Zn element in the α-Al matrix can reduce the precipitation enthalpy of nano-scale atomic clusters and precipitated phases during baking, and can increase their precipitation rate and amount under short-term low-temperature baking conditions.

[0034] (5) The addition of trace elements such as Mn, Cr, Ti, Zr, and Sc can improve the composition of the second phase in the microstructure and refine the grain size. In addition, Zr and Sc can improve the crack sensitivity of alloys with Zn content greater than 2% during welding. The addition of trace elements not only further improves the microstructure and properties, but also widens the welding process window.

[0035] The welding material provided by the present invention comprises the following steps:

[0036] Step 1: Prepare raw materials according to the above-mentioned component ratio requirements. The Al, Mg, and Zn elements in the raw materials are prepared in the form of high-purity metals, and Si, Mn, Cr, Ti, Zr, and Sc are prepared in the form of intermediate alloys.

[0037] Step 2: Place the metals other than Mg, Zn, and Ti in a smelting furnace, and control the furnace temperature at 730-770°C during the metal melting stage; after complete melting, lower the temperature of the melt to 710-730°C, add Mg and Zn to avoid burnout of magnesium and zinc elements; then raise the temperature to 720-740°C for refining and degassing; after standing to remove impurities, measure the hydrogen content of the melt. When the hydrogen content is lower than 0.18 ppm, add Al-Ti-B master alloy to refine the ingot structure; cool the melt to 690-710°C for pouring; and remove defective parts at both ends of the ingot after pouring is completed.

[0038] Step 3: subject the ingot to a two-stage homogenization heat treatment. The first stage is to heat the temperature to 400-420°C at a heating rate of 2-4°C / min and keep it warm for 8-12 hours. The second stage is to heat the temperature to 470-520°C at a heating rate of 2-4°C / min and keep it warm for 8-12 hours.

[0039] Step 4: Heat the ingot to 440-480°C before extrusion, and adjust the extrusion speed so that the temperature of the rod at the die outlet is controlled between 470-520°C to ensure the surface quality of the rod. The diameter of the extruded rod is 7-12mm.

[0040] Step 5: The rod is drawn through 10-22 passes to obtain a welding wire with a diameter of 0.8-3.0 mm. The intermediate annealing process used during the drawing process is 390-440° C. for 1-3 hours, and the number of annealing times is 1-4.

[0041] Step 6: After the wire drawing is completed, the surface is physically scraped with a scraping thickness of 20-60 μm, or a chemical cleaning method such as degreasing, alkali washing, pure water washing, and drying is used to remove surface impurities.

[0042] The welding material provided by the present invention is particularly suitable for welding high-strength heat-treatable aluminum alloy materials with a strength higher than 350 MPa, thereby improving the weld strength and service performance of such alloys.

[0043] The welding material provided by the present invention is suitable for various welding methods such as laser wire welding, laser-arc hybrid welding, non-metallic inert gas shielded arc welding and metallic inert gas shielded arc welding.

[0044] The welding material provided by the present invention is suitable for laser wire welding and laser-arc hybrid welding. The content of Mg, Si, Zn and Cu elements in the weld after welding must reach the following content in mass percentage: Si: 1-2%, Mg: 1-2.2%, Zn: 0.8-3% and Cu: 0.5-3%.

[0045] The welding material provided by the present invention is applicable to non-metallic inert gas shielded arc welding and metallic inert gas shielded arc welding. The content of Mg, Si, Zn and Cu elements in the weld after welding must reach, in terms of mass percentage, the following: Si: 1.2-2%, Mg: 1.2-2.2%, Zn: 1-3% and Cu: 0.6-3%.

[0046] The calculation method for the content of Mg, Si, Zn and Cu elements in the weld of the welding material provided by the present invention after welding is: P=P1×S1+P2×S2.

[0047] Where P is the mass percentage of the calculated element in the weld, P1 is the mass percentage of the calculated element in the base metal, P2 is the mass percentage of the calculated element in the welding wire, S1 is the percentage of the base metal melting area to the molten pool area in the weld cross-sectional morphology, and S2 is the percentage of the welding wire filling area to the molten pool area in the weld cross-sectional morphology, that is, S 1+ S2=1.

[0048] The bake-hardening method for welding materials provided by this invention involves heating the weld seam with heated gas during the vehicle body painting process or post-weld aging heat treatment. The paint bake or aging heat treatment temperature ranges from 140-180°C for 30-90 minutes. This process precipitates a large number of nanoscale atomic clusters and precipitates in the weld structure, further enhancing weld strength.

[0049] Example 1:

[0050] The welding material of this embodiment includes, in terms of mass percentage, the following components: Si: 1.5%, Mg: 1.6%, Zn: 2.5%, Cu: 0.75%, Mn: 0.6%, Cr: 0.3%, Ti: 0.2%, Fe: 0.1%, and the remainder is Al and unavoidable impurities.

[0051] The preparation method comprises the following steps:

[0052] Step 1: Prepare the raw materials according to the set composition ratio. Al, Mg, and Zn are prepared as 99.9% high-purity metals. Si, Mn, Cr, and Ti are prepared as a master alloy of Al-20% Si, Al-10% Mn, Al-10% Cr, and Al-5% Ti-1% B. After pouring, remove any defects at the ends of the ingot.

[0053] In step 3, the ingot is subjected to a two-stage homogenization heat treatment. The first stage is heated to 400°C at a heating rate of 3°C / min and kept warm for 8 hours. The second stage is heated to 480°C at a heating rate of 2°C / min and kept warm for 10 hours.

[0054] In order to obtain a certain specification of welding wire, the following further processing can be performed:

[0055] Step 4: Heat the ingot to 450°C before extrusion, adjust the extrusion speed so that the temperature of the rod at the die outlet is controlled between 480-490°C, and the diameter of the extruded rod is 9.5 mm.

[0056] Step 5: After annealing the bar at 410°C for 3 hours, it is drawn through 14 passes, with three annealing passes required. After the wire is drawn, the surface is physically scraped to obtain a wire with a diameter of 1.2 mm.

[0057] The aforementioned welding wire was used to laser weld 370 MPa grade, high-strength 6XXX aluminum alloy T5 sheets with a thickness of 2.5 mm. The specific composition by mass fraction was: Si: 1%, Mg: 0.8%, Cu: 0.5%, Mn: 0.5%, Cr: 0.21%, Ti: 0.05%, Fe < 0.15%, and the balance being Al.

[0058] The process parameters of laser welding are as follows: laser power 2400 W, welding speed 40 mm / s, laser beam circular swing, swing amplitude 1.5 mm, swing frequency 200 Hz, and wire feeding speed 6 m / min.

[0059] After welding, the content of Mg, Si, Zn and Cu elements in the weld was calculated. Through metallographic observation of the weld cross section, S1 and S2 were measured to be 60% and 40% respectively. According to the formula P=P1×S1+P2×S2, Mg: 1.15%, Si: 1.2%, Zn: 1%, Cu: 0.6% were calculated.

[0060] Example 2:

[0061] The welding material of this embodiment includes, in terms of mass percentage, the following components: Si: 1.2%, Mg: 2.8%, Zn: 2%, Cu: 0.6%, Mn: 0.6%, Cr: 0.25%, Ti: 0.15%, Fe: 0.1%, and the remainder is Al and unavoidable impurities.

[0062] The preparation method comprises the following steps:

[0063] Step 1: Prepare the raw materials according to the set chemical composition ratio of the welding wire. Al, Mg, and Zn are prepared as 99.9% high-purity metals. Si, Mn, Cr, and Ti are prepared as a master alloy of Al-20% Si, Al-10% Mn, Al-10% Cr, and Al-5% Ti-1% B. After pouring, remove any defects at the ends of the ingot.

[0064] In step 3, the ingot is subjected to a two-stage homogenization heat treatment. The first stage is heated to 400°C at a heating rate of 3°C / min and kept warm for 8 hours. The second stage is heated to 480°C at a heating rate of 3°C / min and kept warm for 10 hours.

[0065] In order to obtain a certain specification of welding wire, the following further processing can be performed:

[0066] Step 4: Heat the ingot to 460°C before extrusion, adjust the extrusion speed so that the temperature of the rod at the die outlet is controlled between 480-500°C, and the diameter of the extruded rod is 9.5 mm.

[0067] Step 5: After annealing the bar at 400°C for 3 hours, it is drawn through 12 passes, with three annealing passes required during the drawing process. After the wire is drawn, the surface is physically scraped to obtain a wire with a diameter of 1.2 mm.

[0068] The aforementioned welding wire was used to laser-weld 2.5mm thick 400MPa high-strength and tough 6XXX aluminum alloy T5 sheet. The specific composition of the sheet is Si: 1.2%, Mg: 0.95%, Zn: 0.2%, Cu: 0.6%, Mn: 0.65%, Cr: 0.25%, Ti: 0.05%, Fe < 0.15%, and the balance is Al.

[0069] The process parameters of laser welding are as follows: laser power 2400 W, welding speed 40 mm / s, laser beam circular swing, swing amplitude 1.6 mm, swing frequency 200 Hz, and wire feeding speed 6 m / min.

[0070] After welding, the content of Mg, Si, Zn and Cu elements in the weld was calculated. Through metallographic observation of the weld cross section, S1 and S2 were measured to be 55% and 45% respectively. According to the formula P=P1×S1+P2×S2, Mg: 1.8%, Si: 1.2%, Zn: 1%, Cu: 0.6% were calculated.

[0071] Example 3

[0072] The only difference between this embodiment and Example 1 is that the raw material composition of the welding material includes, by weight: Si: 1.5%, Mg: 1.6%, Zn: 2.5%, Cu: 0.75%, Mn: 0.6%, Cr: 0.3%, Ti: 0.2%, Sc: 0.05%, Fe: 0.1%, and the balance is Al and unavoidable impurities.

[0073] Example 4

[0074] The only difference between this embodiment and Example 1 is that the raw material composition of the welding material includes, by weight: Si: 1.5%, Mg: 1.6%, Zn: 2.5%, Cu: 0.75%, Mn: 0.6%, Cr: 0.3%, Ti: 0.2%, Zr: 0.05%, Fe: 0.1%, and the balance is Al and unavoidable impurities.

[0075] Example 5

[0076] The only difference between this embodiment and Example 1 is that the welding material comprises the following raw material compositions by weight: Si: 1%, Mg: 1.2%, Zn: 1%, Cu: 1%, Mn: 0.5%, Cr: 0.2%, Ti: 0.1%, Zr: 0.1%, Sc: 0.1%, Fe0.15%, and the remainder being Al and unavoidable impurities.

[0077] Example 6

[0078] The only difference between this embodiment and embodiment 1 is that the raw material composition of the welding material includes, by weight: Si: 3%, Mg: 3.2%, Zn: 3.6%, Cu: 1.6%, Mn: 0.8%, Cr: 0.45%, Ti: 0.25%, Zr: 0.1%, Sc: 0.1%, Fe0.05%, and the balance is Al and unavoidable impurities.

[0079] Example 7

[0080] The only difference between this embodiment and embodiment 1 is that: pure aluminum and the master alloy other than those containing Mg, Zn, and Ti are smelted at 730-770°C; after complete melting, the temperature is lowered to 710-730°C to add Mg and Zn; the temperature is then raised to 730-740°C for refining and degassing; after standing to remove impurities, the Al-Ti-B master alloy is added; and the melt is cooled to 690-710°C for casting to obtain a qualified ingot.

[0081] Example 8

[0082] The only difference between this embodiment and embodiment 1 is that: pure aluminum and the master alloy other than those containing Mg, Zn, and Ti are smelted at 730-770°C; after complete melting, the temperature is lowered to 710-730°C to add Mg and Zn; the temperature is then raised to 730-740°C for refining and degassing; after standing to remove impurities, the Al-Ti-B master alloy is added; and the melt is cooled to 690-710°C for casting to obtain a qualified ingot.

[0083] Example 9

[0084] The only difference between this embodiment and embodiment 1 is: two-stage homogenization heat treatment: the first stage is heated to 400-420°C at a heating rate of 2-4°C / min and kept warm for 8-12 hours, and the second stage is heated to 470-520°C at a heating rate of 2-4°C / min and kept warm for 8-12 hours.

[0085] Example 10

[0086] The only difference between this embodiment and embodiment 1 is: two-stage homogenization heat treatment: the first stage is heated to 400-420°C at a heating rate of 2-4°C / min and kept warm for 8-12 hours, and the second stage is heated to 470-520°C at a heating rate of 2-4°C / min and kept warm for 8-12 hours.

[0087] Example 11

[0088] The only difference between this embodiment and embodiment 1 is that: the preparation method of the welding material includes heating the ingot to 440°C and then extruding it to obtain a rod, and then drawing the rod to obtain the welding material body. The extrusion speed is adjusted so that the temperature of the rod at the mold outlet is controlled between 470-480°C. The drawing process also includes an annealing process, and the annealing process conditions are: 440°C, 1h.

[0089] Example 12

[0090] The only difference between this embodiment and embodiment 1 is that: the preparation method of the welding material includes heating the ingot to 480°C and then extruding it to obtain a rod, and then drawing the rod to obtain the welding material body. The extrusion speed is adjusted so that the temperature of the rod at the mold outlet is controlled between 500-520°C. The drawing process also includes an annealing process, and the annealing process conditions are: 390°C, 2h.

[0091] Comparative Example 1:

[0092] Commercial ER4043 aluminum alloy welding wire was used to laser weld 2mm thick, 400MPa-grade, high-strength and toughness 6XXX aluminum alloy T5 sheets. The welding wire composition was Si: 5.5%, Mg: 0.05%, Zn: 0.05%, Cu: 0.2%, Ti: 0.15%, Fe: 0.4%, with the balance being Al. The sheet composition was Si: 1.2%, Mg: 0.95%, Zn: 0.2%, Cu: 0.6%, Mn: 0.65%, Cr: 0.25%, Ti: 0.05%, Fe: <0.15%, with the balance being Al.

[0093] The process parameters of laser welding are as follows: laser power 2100 W, welding speed 40 mm / s, laser beam circular swing, swing amplitude 1.2 mm, swing frequency 150 Hz, and wire feeding speed 6 m / min.

[0094] After welding, the contents of Mg, Si, Zn and Cu elements in the weld were calculated. Through metallographic observation of the weld cross section, S1 and S2 were measured to be 43% and 57% respectively. According to the formula P=P1×S1+P2×S2, Mg: 0.37%, Si: 3.61%, Zn: 0.03% and Cu: 0.31% were calculated.

[0095] Comparative Example 2:

[0096] A comparative welding wire was used to laser weld 2 mm thick 370 MPa high-strength and tough 6XXX aluminum alloy T5 sheets. The wire composition was Si: 1.5%, Mg: 1.6%, Zn: 0%, Cu: 0%, Mn: 0.6%, Cr: 0.25%, Ti: 0.15%, Fe: 0.1%, with the balance being Al and unavoidable impurities. The wire, with a diameter of 1.2 mm, was produced through a multi-step process including melting, mean heat treatment, extrusion, drawing, and annealing. The sheet composition was Si: 1.1%, Mg: 0.79%, Cu: 0.45%, Mn: 0.6%, Cr: 0.2%, Ti: 0.05%, Fe: <0.15%, with the balance being Al.

[0097] The process parameters of laser welding are as follows: laser power 2100 W, welding speed 40 mm / s, laser beam circular swing, swing amplitude 1.5 mm, swing frequency 200 Hz, and wire feeding speed 6 m / min.

[0098] After welding, the contents of Mg, Si, Zn and Cu elements in the weld were calculated. Through metallographic observation of the weld cross section, S1 and S2 were measured to be 51% and 49% respectively. According to the formula P=P1×S1+P2×S2, Mg: 1.2%, Si: 1.3%, Zn: 0%, Cu: 0.2% were calculated.

[0099] Test Example 1:

[0100] Microhardness tests were conducted on the welds obtained from the sample of Example 1 and the welds after baking, wherein the baking process was electrophoresis baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The microhardness test results are shown in Figure 2. Figure 1 As shown. Figure 1 It can be seen that the weld hardness has been significantly improved after baking. The average hardness of the weld before baking was 74.8HV. After three coats of baking, the average hardness reached 88.1HV, a 17.8% increase in hardness after baking. This welding wire composition has an excellent bake hardening effect.

[0101] Similarly, the tensile properties of the welds in Example 1 and the welds after baking were tested. The baking process was a three-step process of electrophoresis baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joint was conducted using the transverse displacement velocity method with a tensile speed of 2 mm / min. The results are shown in Figure 2. Figure 2 The tensile strength of the welds before baking was 313.7MPa and 315.9MPa respectively. After three baking processes, the welds were significantly improved, reaching 338.6MPa and 335.2MPa respectively. Test Example 2:

[0102] Microhardness tests were conducted on the welds obtained from the sample of Example 2 and the welds after baking. The baking process was three baking steps: electrophoresis baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The microhardness test results are shown in Figure 2. Figure 3 The hardness of the weld seam after baking is significantly higher than that before baking. The average hardness of the weld seam before baking is 75.2HV. After three baking processes, the average hardness of the weld seam is increased to 90.7HV, and the bake hardening value reaches 15.5HV. The weld seam hardness is increased by 20.6% compared with the pre-baking process.

[0103] Similarly, the tensile properties of the welds in Example 2 and the welds after baking were tested. The baking process was a three-step process of electrophoresis baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joint was conducted using the transverse displacement velocity method with a tensile speed of 2 mm / min. The results are shown in Figure 2. Figure 4 The tensile strength of the welds before baking was 341.0MPa and 333.1MPa respectively. After three baking processes, the welds were significantly improved, reaching 373.2MPa and 369.2MPa respectively. Test Example 3:

[0104] Microhardness tests were conducted on the welds obtained from the sample of Comparative Example 1 and the welds after baking. The baking process was a three-step process: electrophoresis baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The microhardness test results are shown in Figure 2. Figure 5 As shown in the figure, the hardness of the weld after baking is not significantly improved compared to the unbaked weld. The average hardness before baking is 75.7 HV, while the hardness after baking is only 77.4 HV. The hardness after baking is only increased by 2.2%, which is far lower than the bake hardening value of more than 15% in the present invention.

[0105] Similarly, the tensile performance test was carried out on the weld after baking in comparative example 1. The tensile test of the weld joint was carried out using the transverse displacement velocity method with a tensile speed of 2 mm / min. The results are shown in Figure 2. Figure 6 The tensile strength of the welds using the commercial ER4043 welding wire only reached 277.9 MPa and 280.6 MPa, which were significantly lower than those in the examples.

[0106] Test Example 4:

[0107] The tensile properties of the welds obtained from the sample of Comparative Example 2 and the welds after baking were tested. The baking process was electrophoresis baking at 175℃ for 35min, primer baking at 140℃ for 25min, and topcoat baking at 140℃ for 25min. The tensile test of the weld joint was carried out using the transverse displacement velocity method with a tensile speed of 2mm / min. The results are as follows: Figure 7 The tensile strength of the welds using the welding wire of Comparative Example 2 before baking was 268.8 MPa and 262.2 MPa respectively, and the tensile strength of the welds after baking was only 270.2 MPa and 274.3 MPa, which was significantly lower than the weld strength in the embodiment.

[0108] Test Example 5:

[0109] Tensile properties were tested for the welds obtained using the sample from Example 3 and the welds after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joint was conducted using the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 3 before baking were 318.8 MPa and 316.1 MPa, respectively. After baking, the tensile strengths of the welds increased to 340.2 MPa and 337.1 MPa.

[0110] Test Example 6:

[0111] Tensile properties were tested on the welds obtained using the sample from Example 4 and after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The weld joint tensile test used the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the wire from Example 4 before baking were 314.3 MPa and 310.4 MPa, respectively. After baking, the tensile strengths of the welds reached 337.6 MPa and 332.7 MPa.

[0112] Test Example 7:

[0113] Tensile properties were tested on the welds obtained using the sample from Example 5 and after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The weld joint tensile test used the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the wire from Example 5 before baking were 308.9 MPa and 306.1 MPa, respectively. After baking, the tensile strengths of the welds reached 321.8 MPa and 326.9 MPa.

[0114] Test Example 8:

[0115] Tensile properties were tested for the welds obtained using the sample from Example 6 and the welds after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joints was conducted using the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 6 before baking were 339.9 MPa and 336.4 MPa, respectively. After baking, the tensile strengths of the welds increased to 374.2 MPa and 379.1 MPa.

[0116] Test Example 9:

[0117] Tensile properties were tested for the welds obtained using the sample from Example 7 and the welds after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joints was conducted using the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 7 before baking were 309.4 MPa and 316.3 MPa, respectively. After baking, the tensile strengths of the welds increased to 334.6 MPa and 339.2 MPa.

[0118] Test Example 10:

[0119] Tensile properties were tested on the welds obtained using the sample from Example 8 and after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The weld joint tensile test used the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the wire from Example 8 before baking were 310.4 MPa and 315.2 MPa, respectively. After baking, the tensile strengths of the welds reached 332.2 MPa and 329.8 MPa.

[0120] Test Example 11:

[0121] Tensile properties were tested for the welds obtained using the sample from Example 9 and the welds after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joints was conducted using the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 9 before baking were 319.7 MPa and 325.4 MPa, respectively. After baking, the tensile strengths of the welds increased to 334.7 MPa and 336.3 MPa.

[0122] Test Example 12:

[0123] Tensile properties were tested on the welds obtained using the sample from Example 10 and the welds after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The weld joint tensile test used the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 10 before baking were 323.1 MPa and 317.3 MPa, respectively. After baking, the tensile strengths of the welds increased to 338.2 MPa and 329.1 MPa.

[0124] Test Example 13:

[0125] Tensile properties were tested on the welds obtained using the sample from Example 11 and after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joints was conducted using the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 11 before baking were 309.8 MPa and 316.1 MPa, respectively. After baking, the tensile strengths of the welds increased to 333.2 MPa and 328.5 MPa.

[0126] Test Example 14:

[0127] Tensile properties were tested for the welds obtained using the sample from Example 12 and the welds after baking. The baking process consisted of three baking steps: electrophoretic baking at 175°C for 35 minutes, primer baking at 140°C for 25 minutes, and topcoat baking at 140°C for 25 minutes. The tensile test of the weld joints was conducted using the transverse displacement velocity method at a tensile speed of 2 mm / min. The tensile strengths of the welds using the welding wire from Example 12 before baking were 311.2 MPa and 316.9 MPa, respectively. After baking, the tensile strengths of the welds increased to 337.1 MPa and 329.7 MPa.

[0128] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0129] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A welding material for achieving bake-hardening of welds, the raw material composition of which includes, by mass percentage: Si: 1-3%, Mg: 1.2-3.2%, Zn: 1-3.6%, Cu: 0.6-1.6%, Mn: 0.5-0.8%, Cr: 0.2-0.45%, Ti: 0.1-0.25%, Zr: 0-0.1%, Sc: 0-0.1%, Fe<0.2%, and the balance being Al and unavoidable impurities.

2. The method for preparing the welding material according to claim 1, characterized in that: The steps include: Prepare raw materials, wherein at least Si, Mn, Cr, Ti, Zr, and Sc are prepared in the form of a master alloy; Pure aluminum and master alloys other than those containing Mg, Zn, and Ti are smelted at 730-770°C; after being completely melted, the temperature is lowered to 710-730°C to add Mg and Zn; the temperature is then raised to 730-740°C for refining and degassing; after standing to remove impurities, an Al-Ti-B master alloy is added; the melt is cooled to 690-710°C for casting to obtain qualified ingots.

3. The method for preparing the welding material according to claim 2, characterized in that: The method further comprises subjecting the ingot to a two-stage homogenization heat treatment: the first stage is heating the temperature to 400-420°C at a heating rate of 2-4°C / min and keeping the temperature for 8-12 hours; the second stage is heating the temperature to 470-520°C at a heating rate of 2-4°C / min and keeping the temperature for 8-12 hours.

4. Welding material, comprising at least a main body, wherein the main body is obtained by the method for preparing the welding material according to claim 2.

5. The welding material according to claim 4, characterized in that The method comprises the steps of heating the ingot to 440-480° C. and then extruding the ingot to obtain a rod, and then drawing the rod to obtain a main body.

6. The welding material according to claim 5, characterized in that The extrusion is performed by regulating the extrusion speed so that the temperature of the rod at the die outlet is controlled between 470-520°C.

7. The welding material according to claim 5, characterized in that The drawing process also includes an annealing process, and the annealing process conditions are: 390-440° C., 1-3 hours.

8. Use of the welding material according to claim 4 in welding operations.

9. The use according to claim 8, characterized in that The welding operation is selected from the group consisting of: laser wire welding, laser-arc hybrid welding, non-metallic inert gas shielded arc welding and metallic inert gas shielded arc welding.

10. The use according to claim 9, characterized in that The welding operation also includes post-weld baking, and the process conditions meet the following requirements: 140-180° C., 30-90 minutes.

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