Welding wire for tailored blank laser welding filler wire welding and preparation method thereof

Abstract

The invention discloses a welding wire for tailored blank laser welding filler wire welding and a preparation method of the welding wire, and relates to the technical field of tailored blank laser welding of automobile plates. The preparation method comprises the following steps: performing diameter pressing treatment on a steel billet to obtain a diameter-pressed steel billet with first density; primary heat treatment is conducted on the diameter-pressed steel billet at the first preset temperature, so that the tensile strength of the diameter-pressed steel billet is 800-1000 MPa, and the wire winding ring diameter of the diameter-pressed steel billet is 400-600 mm; sequentially carrying out peeling treatment and first drawing treatment on the diameter-pressed steel billet subjected to primary heat treatment; carrying out secondary heat treatment on the primarily drawn steel wire under a first preset temperature condition, so that the wire winding ring diameter of the primarily drawn steel wire is any one value of 400-600mm; and the primarily-drawn steel wire subjected to secondary heat treatment is sequentially subjected to secondary drawing treatment and layer winding treatment, and the welding wire is prepared and obtained. The prepared welding wire has high tensile strength, and the preparation cost can be reduced by 30%-40%.

Description

Technical Field

[0001] The present invention relates to the technical field of laser tailor welding of automobile plates, and in particular to a welding wire for laser tailor welding with filler wire and a preparation method thereof. Background Art

[0002] As an efficient and precise advanced welding process, laser welding has been widely used in the automotive, rail, and aerospace industries. While achieving precise connections between plates of varying thicknesses and materials, this technology also places higher quality and performance demands on the welding wire used as filler material. In particular, to enhance the structural strength and reliability of welded joints, the welding wire must possess extremely high mechanical strength to withstand the thermal effects of laser energy input during the welding process; microstructure refinement and uniformity control to ensure weld pool stability and good metal-metal bonding; and high dimensional accuracy and tight diameter tolerance to meet the wire feeding accuracy and weld consistency requirements of automated laser welding.

[0003] However, existing welding wire production typically relies on traditional continuous casting and rolling processes, which primarily include billet smelting, hot rolling, multi-pass drawing, and heat treatment. These processes present the following technical limitations: The billet's microstructure is loose or its elemental distribution is uneven, leading to large fluctuations in material strength during subsequent processing and unstable welding performance. The mismatch between the hot rolling and cold drawing processes results in high residual stress within the welding wire, making it prone to drawing cracking or structural abnormalities during welding. Dimensional control accuracy is low, making it difficult to maintain a stable tolerance within ±0.08mm or even ±0.06mm. The production of high-strength welding wire relies on large-scale equipment and lengthy process flows, making it unsuitable for small- and medium-volume customized production. This is particularly true in automotive laser tailor welding, where the amount of wire used is small but the performance requirements are extremely high. Conventional processes struggle to balance the trade-offs between cost, strength, dimensional accuracy, and consistency.

[0004] Therefore, how to improve the strength and dimensional accuracy of welding wire while constructing a controllable process flow suitable for small-batch, low-cost welding wire preparation has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] An object of the first aspect of the present invention is to provide a method for preparing welding wire for laser tailor welding with filler wire, so as to solve the technical problems in the prior art of low strength and high preparation cost of welding wire for laser tailor welding with filler wire.

[0006] Another object of the first aspect of the present invention is to further improve the strength of the welding wire.

[0007] The second aspect of the present invention aims to provide a welding wire for laser tailor welding with filler wire, which is prepared according to the above preparation method.

[0008] According to the purpose of the first aspect of the present invention, the present invention provides a method for preparing a welding wire for laser tailor welding with filler wire, comprising: preparing a steel billet having a preset density; Performing a caliper treatment on the steel billet to obtain a caliper steel billet having a first density; The sizing steel billet is subjected to a heat treatment at a first preset temperature, so that the tensile strength of the sizing steel billet is any value between 800 MPa and 1000 MPa, and the wire winding diameter of the sizing steel billet is any value between 400 mm and 600 mm; performing a peeling process and a first drawing process on the steel billet after the primary heat treatment to obtain a pre-drawn steel wire; Performing a secondary heat treatment on the initially drawn steel wire under the first preset temperature condition, so that the diameter of the initially drawn steel wire is any value between 1.8 mm and 2.5 mm, and the diameter of the wire winding is any value between 400 mm and 600 mm; performing a second drawing process and a layer winding process on the initially drawn steel wire that has undergone the secondary heat treatment in sequence to prepare the welding wire; Wherein, no coolant is added in the sizing treatment, the first density is greater than the preset density, the first preset temperature is any value between 700°C and 800°C, and the drawing speed of the first drawing treatment is greater than the drawing speed of the second drawing treatment.

[0009] Optionally, the drawing speed of the first drawing process is any value between 25 m / min and 30 m / min, and the drawing speed of the second drawing process is any value between 15 m / min and 20 m / min.

[0010] Optionally, the number of drawing times in the first drawing process is any value between 6 and 12.

[0011] Optionally, the number of drawing times in the second drawing process is any value between 3 and 9.

[0012] Optionally, a drawing tolerance of the first drawing process is less than ±0.08 mm, and a drawing tolerance of the second drawing process is less than ±0.06 mm.

[0013] Optionally, the steel billet comprises the following elements in weight percentages: Carbon: 0.15%-0.6%, Silicon: 0.2%-0.5%, Manganese: 0.3%-2.0%, Phosphorus: ≤0.025%, Sulfur: ≤0.025%, Nickel: 0.1%-0.4%, Chromium: 0.01%-0.2%, Niobium: 0.01%-0.1%, Titanium: 0.01%-0.1%, Molybdenum: 0.01%-0.3%, Boron: 0.0005%-0.005%.

[0014] Optionally, the step of preparing a steel billet having a preset density includes: Adding the plurality of elements into a smelting furnace for smelting to prepare molten steel; The molten steel is cast into a steel billet body, and the steel billet body is cooled to a second preset temperature to obtain the steel billet.

[0015] Optionally, the second preset temperature is any value between 20°C and 30°C.

[0016] Optionally, the smelting temperature of the smelting treatment is any value between 1600° C. and 1700° C., and the smelting time is any value between 40 min and 90 min.

[0017] According to the purpose of the second aspect of the present invention, the present invention further provides a welding wire for laser tailor welding with filler wire, wherein the welding wire is prepared according to any one of the preparation methods described above.

[0018] The present invention introduces a process system that combines calibrating, two-stage heat treatment, and a two-stage drawing process to form a controlled path for the evolution of the steel billet from low density to high density, and from coarse grains to a refined wire winding diameter structure. Under cold deformation without the addition of coolant, a moderate work hardening effect is introduced, and a subcritical heat treatment at 700°C-800°C achieves synergistic structural recovery and strengthening, thereby constructing a high-performance welding wire with high strength, good ductility, and excellent dimensional stability. The prepared wire has a tensile strength of up to 2000MPa. The overall preparation process is simple and energy-efficient, and the preparation cost is reduced by 30%-40%.

[0019] Furthermore, the present invention sets the drawing speed of the first drawing process to any value between 25m / min-30m / min and the drawing speed of the second drawing process to any value between 15m / min-20m / min, which helps to achieve rapid plastic deformation of the material and induce strain hardening in the first drawing process stage, and achieve fine dimensional control, residual stress release and surface defect suppression in the second drawing process stage, so that the prepared welding wire has high strength, high dimensional accuracy and excellent surface quality, meeting the welding consistency and stability requirements of laser tailor welding with filler wire.

[0020] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings: Figure 1 is a schematic flow chart of a welding wire preparation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It will be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some, rather than all, structures related to the present application are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0025] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] It should be noted that in the automotive laser welding industry, the filler wire welding between sheet metals places extremely high demands on wire strength, dimensional tolerance, and uniformity of the wire winding diameter. However, traditional large-scale welding wire production lines (targeted at scaled output) struggle to meet the demands of small batches, high quality, and low costs. To address this, the applicant conducted extensive experiments based on existing wire drawing technology. For example, to improve wire strength, the applicant increased the elemental composition, but this resulted in an increase in the raw material volume, meaning the elemental density within the billet per unit volume remained unchanged. While the applicant's use of a sizing treatment to sizing the billet improved the strength of the welding wire to some extent, it also made the wire brittle and prone to breakage, hindering the subsequent wire feeding and layer winding packaging processes for the drawing process, resulting in a low wire yield. Furthermore, adding a heat treatment after sizing can alleviate these issues to some extent, but this heat treatment can cause prominent oxide scale to form on the surface of the sizing billet, compromising the subsequent drawing quality and ultimately the quality of the welding wire.

[0027] Figure 1 FIG. 1 is a schematic flow chart of a method for preparing a welding wire according to an embodiment of the present invention. Figure 1 As shown, the present invention provides a method for preparing a welding wire for laser tailor welding with filler wire, the welding wire preparation method comprising: Step S100: preparing a steel billet with a preset density; Step S200: performing a diameter-pressing process on the steel billet to obtain a diameter-pressed steel billet having a first density; Step S300: performing a heat treatment on the sizing steel billet at a first preset temperature, so that the tensile strength of the sizing steel billet is any value between 800 MPa and 1000 MPa, and the wire winding diameter of the sizing steel billet is any value between 400 mm and 600 mm; Step S400: performing a peeling process and a first drawing process on the steel billet that has undergone the primary heat treatment to obtain a pre-drawn steel wire; Step S500: performing a secondary heat treatment on the initially drawn steel wire under a first preset temperature condition, so that the diameter of the initially drawn steel wire is any value between 1.8 mm and 2.5 mm, and the diameter of the wire winding is any value between 400 mm and 600 mm; Step S600: The primary drawn steel wire, which has undergone secondary heat treatment, is sequentially subjected to a second drawing process and a layer winding process to produce a welding wire. No coolant is added during the calibrating process, the first density is greater than a preset density, the first preset temperature is any value between 700°C and 800°C, and the drawing speed of the first drawing process is greater than the drawing speed of the second drawing process. The diameter of the primary drawn steel wire can be 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, or 2.5 mm, or any other value between 1.8 mm and 2.5 mm. The first preset temperature can be 700°C, 720°C, 740°C, 760°C, 780°C, or 800°C, or any other value between 700°C and 800°C.

[0028] In this embodiment, a steel billet of a preset density is first prepared, and then the steel billet is subjected to a calibrating treatment to obtain a calibrated steel billet with a first density. Thereafter, the calibrated steel billet is subjected to a heat treatment at a first preset temperature so that the tensile strength of the calibrated steel billet is any value between 800MPa and 1000MPa, and the wire winding diameter of the calibrated steel billet is any value between 400mm and 600mm. Then, the calibrated steel billet that has undergone the one-time heat treatment is subjected to a peeling treatment and a first drawing treatment in sequence to obtain an initially drawn steel wire. Thereafter, the initially drawn steel wire is subjected to a secondary heat treatment under the first preset temperature condition so that the wire winding diameter of the initially drawn steel wire is any value between 400mm and 600mm. Finally, the initially drawn steel wire that has undergone the secondary heat treatment is subjected to a second drawing treatment and a layer winding treatment in sequence to prepare a welding wire. Here, the tensile strength of the pressed steel billet can be 800MPa, 850MPa, 900MPa, 950MPa or 1000MPa, or any other value between 800MPa and 1000MPa, and the wire winding diameter of the pressed steel billet can be 400mm, 450mm, 500mm, 550mm or 600mm, or any other value between 400mm and 600mm.

[0029] In this embodiment, by introducing a process system combining calibrating, two-stage heat treatment, and a two-stage drawing process, a controlled path is formed for the evolution of the steel billet from low density to high density, and the microstructure from coarse grains to a refined wire winding diameter structure. Under cold pressing without the addition of coolant, a moderate work hardening effect is introduced, and a subcritical heat treatment at 700°C-800°C is used to achieve synergistic microstructure recovery and strengthening, thereby constructing a high-performance welding wire with high strength, good ductility, and excellent dimensional stability. The prepared wire has a tensile strength of up to 2000MPa. The overall preparation process is simple and energy-efficient, and the preparation cost is reduced by 30%-40%.

[0030] In this embodiment, the steel billet is subjected to a sizing process in step S200 to obtain a sizing steel billet having a first density, wherein the first density is greater than a predetermined density. That is, step S200 is essentially a cold working process at room temperature. Through plastic compression, the steel billet shrinks in volume and the atoms within the unit volume are arranged more tightly, thereby introducing a work hardening effect, significantly increasing the internal dislocation density of the material, improving the structural density, effectively reducing the porosity and risk of microcracks, and pre-establishing a deformation foundation that is conducive to subsequent recrystallization and grain refinement. Furthermore, by not using a coolant under cold working conditions, thermal stress shock and surface cracks can be avoided, which is beneficial for protecting the rolls and controlling surface oxidation defects. Furthermore, the increased density after sizing provides structural support for subsequent drawing, ensuring uniform stress distribution during the deformation process and improving the strength of the welding wire from the source.

[0031] In this embodiment, the primary heat treatment in step S300 is performed in the range of 700°C-800°C, i.e., a subcritical or low-temperature intermediate annealing treatment. This not only softens the pressed steel billet and reduces the degree of work hardening during the subsequent drawing process, but also stabilizes the microstructure, allowing partial recovery / recrystallization of the deformed microstructure and grain refinement. Simultaneously, the tensile strength of the pressed steel billet and the wire winding diameter are regulated to maintain a tensile strength between 800MPa and 1000MPa, providing the welding wire with a high plasticity state with moderate work hardening. The wire winding diameter is controlled within the range of 400mm-600mm, providing a metastable structural foundation for final microstructure densification.

[0032] In this embodiment, the slab in step S400 is first peeled after the primary heat treatment to remove scale, surface cracks, and inclusions. This effectively improves the surface integrity and appearance of the wire during the subsequent drawing process, while preventing die wear and surface cracking. The subsequent first drawing process is a cold drawing process with a relatively high deformation rate. This process, drawing at a moderate strength after the primary heat treatment, facilitates initial wire reduction. By controlling the drawing speed of the first drawing process to be higher than that of the second drawing process, this process facilitates the full introduction of plastic deformation, stimulating deformation-inducing mechanisms within the structure, while maintaining a stable drawing process.

[0033] In this embodiment, the second heat treatment in step S500 continues within the first preset temperature range, that is, the temperature range of the secondary heat treatment is 700°C-800°C. This temperature range can partially recrystallize or dynamically recover the strengthened structure in the initially drawn steel wire, releasing residual stress. At the same time, it stabilizes the fine wire winding diameter structure in the internal structure, controlling it between 400mm and 600mm, improving structural uniformity, providing a good plastic foundation for fine drawing, and preventing cracking or brittle failure of the fine wire. In addition, because the wire winding diameter structure has characteristics similar to nanotwins / subgrains, it can improve strength while maintaining plasticity, providing microscopic support for the subsequent high-strength welding wire performance.

[0034] In this embodiment, the second drawing process in step S600 is performed with higher precision and slower speed, ensuring the final wire dimensional accuracy within ±0.06 mm, with good surface finish and high roundness, which promotes wire feeding stability and melt consistency during laser welding. The subsequent layer winding process ensures that the wire is neatly wound with stable tension, preventing springback and tangling, providing process assurance for finished product packaging, transportation, and automated wire feeding.

[0035] In a further embodiment, the drawing speed of the first drawing process is any value between 25 m / min and 30 m / min, and the drawing speed of the second drawing process is any value between 15 m / min and 20 m / min, that is, the drawing speed of the first drawing process can be 25 m / min, 26 m / min, 27 m / min, 28 m / min, 29 m / min or 30 m / min, or any other value between 25 m / min and 30 m / min, and the drawing speed of the second drawing process can be 15 m / min, 16 m / min, 17 m / min, 18 m / min, 19 m / min or 20 m / min, or any other value between 15 m / min and 20 m / min. In this embodiment, by setting the drawing speeds of the first drawing process and the second drawing process within the above-mentioned range, it is helpful to achieve rapid plastic deformation of the material and induce strain hardening in the first drawing process stage, and to achieve fine dimensional control, residual stress release and surface defect suppression in the second drawing process stage, so that the prepared welding wire has high strength, high dimensional accuracy and excellent surface quality at the same time, meeting the welding consistency and stability requirements of laser tailor welding with filler wire.

[0036] In a further embodiment, the number of drawing times in the first drawing process is any value between 6 and 12, that is, the number of drawing times in the first drawing process can be 6, 7, 8, 9, or 12, or any other value between 6 and 12. In this embodiment, by setting the number of drawing times in the first drawing process within the above range, that is, by controlling the drawing deformation through multiple passes, the risk of cracks or wire breakage caused by a single drawing can be effectively avoided, thereby improving the stability of the wire making process. At the same time, the segmented deformation is conducive to grain refinement and uniform microstructure, and cooperates with the subsequent heat treatment step to release internal residual stress, thereby significantly improving the strength retention rate, dimensional consistency, and welding suitability of the finished welding wire.

[0037] In a further embodiment, the number of drawing passes in the second drawing process is any value between 3 and 9, i.e., the number of drawing passes in the second drawing process can be 3, 5, 6, or 9, or any other value between 3 and 9. In this embodiment, by setting the number of drawing passes in the second drawing process within the aforementioned range, i.e., by adopting a multi-pass, small deformation finishing drawing control strategy in the second drawing process, the dimensional consistency, surface quality, and stress balance of the finished welding wire are improved, thereby further enhancing the straightness control and feeding stability of the welding wire during the laser tailor welding process with filler wire, thereby ensuring the weld joint formation quality and weld performance.

[0038] In a further embodiment, the drawing tolerance of the first drawing process is less than ±0.08 mm, and the drawing tolerance of the second drawing process is less than ±0.06 mm, that is, the diameter tolerance of the initially drawn steel wire in the first drawing process needs to meet the requirements of being less than 0.08 mm, 0.06 mm, 0.04 mm, 0.02 mm, -0.02 mm, -0.04 mm, -0.06 mm or -0.08 mm, and may also be less than any other value from -0.08 mm to 0.08 mm, and the diameter tolerance of the welding wire in the second drawing process needs to meet the requirements of being less than 0.06 mm, 0.04 mm, 0.02 mm, -0.02 mm, -0.04 mm or -0.06 mm, and may also be less than any other value from -0.06 mm to 0.06 mm. In this embodiment, the first drawing control tolerance is within ±0.08mm, which helps to improve the consistency and dimensional controllability of the intermediate wire, laying a good foundation for subsequent fine drawing. Moreover, through the gradually fine-controlled drawing tolerance matching strategy, the dimensional consistency and roundness of the finished welding wire can be effectively improved, thereby improving the wire feeding stability, weld formation consistency and welding reliability during the laser filling wire welding process, and significantly reducing the risk of welding defects such as bias burning and weld collapse.

[0039] In a further embodiment, the steel billet includes the following weight percentages of various elements: carbon: 0.15%-0.6%, silicon: 0.2%-0.5%, manganese: 0.3%-2.0%, phosphorus: ≤0.025%, sulfur: ≤0.025%, nickel: 0.1%-0.4%, chromium: 0.01%-0.2%, niobium: 0.01%-0.1%, titanium: 0.01%-0.1%, molybdenum: 0.01%-0.3%, and boron: 0.0005%-0.005%. In this embodiment, by configuring the steel billet to contain each component element within the aforementioned ranges, a welding wire that meets strength and cost requirements can be produced after sizing, secondary heat treatment, and two drawing processes. Furthermore, the composition can be adjusted based on the welding wire requirements to fine-tune the welding wire properties. In a preferred embodiment, the steel billet includes the following elements in the following weight percentages: carbon: 0.3467%, silicon: 0.2572%, manganese: 1.21%, phosphorus: 0.009%, sulfur: 0.001%, nickel: 0.1738%, chromium: 0.0218%, niobium: 0.0478%, aluminum: 0.034%, titanium: 0.0299%, molybdenum: 0.007%, boron: 0.00303%, and nitrogen: 0.0036%.

[0040] In a further embodiment, step S100 further includes: Adding multiple elements into a smelting furnace for smelting to prepare molten steel; The molten steel is cast into a steel billet body, and the steel billet body is cooled to a second preset temperature to obtain a steel billet.

[0041] In this embodiment, multiple elements are added into a smelting furnace for smelting, so that the elements are fully and evenly mixed to form molten steel with uniform composition, and the elements are evenly distributed in the steel billet.

[0042] In a further embodiment, the second preset temperature is any value between 20°C and 30°C, that is, the second preset temperature can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C, or any other value between 20°C and 30°C. In this embodiment, by setting the second preset temperature within the above range, moderate work hardening is introduced by applying plastic deformation at room temperature, thereby improving the density and strength of the steel billet, while avoiding oxidation, decarburization, or dimensional instability caused by high-temperature operation, thereby ensuring the stability and reliability of subsequent wire drawing and welding performance.

[0043] In a further embodiment, the smelting temperature of the smelting process is any value between 1600°C and 1700°C, and the smelting time is any value between 40 minutes and 90 minutes. That is, the smelting temperature of the smelting process can be 1600°C, 1620°C, 1640°C, 1650°C, 1660°C, 1680°C, or 1700°C, or any other value between 1600°C and 1700°C, and the smelting time can be 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, or 90 minutes, or any other value between 40 minutes and 90 minutes. In this embodiment, by setting the smelting temperature and smelting time within the above ranges, the carbon element is ensured to be fully dissolved in the molten steel, while excessive burning of other alloying elements is avoided, thereby ensuring the accuracy of the molten steel composition.

[0044] The present invention also provides a welding wire for laser tailor welding with filler wire, which is prepared according to the above preparation method. The preparation method of the welding wire will not be described in detail here.

[0045] The technical solution of this application is described in detail below based on specific embodiments.

[0046] In some embodiments, in a method for preparing a welding wire for laser tailor welding with filler wire, a steel billet of a preset density is first prepared, and then the steel billet is subjected to a calibrating treatment to obtain a calibrated steel billet having a first density. The calibrated steel billet is then subjected to a heat treatment at a first preset temperature, and the first preset temperature is any value between 700°C and 800°C, so that the tensile strength of the calibrated steel billet is any value between 800MPa and 1000MPa, and the wire winding diameter of the calibrated steel billet is any value between 400mm and 600mm. The calibrated steel billet that has undergone the first heat treatment is then subjected to a peeling treatment and a second heat treatment. A drawing treatment is performed, wherein the drawing speed of the first drawing treatment is any value between 25m / min-30m / min, and the initially drawn steel wire is obtained. Thereafter, the initially drawn steel wire is subjected to a secondary heat treatment under a first preset temperature condition, and the temperature of the secondary heat treatment is any value between 700℃-800℃, so that the wire winding diameter of the initially drawn steel wire is any value between 400mm-600mm. Finally, the initially drawn steel wire that has undergone the secondary heat treatment is subjected to a second drawing treatment and a layer winding treatment in sequence, and the drawing speed of the second drawing treatment is any value between 15m / min-20m / min, to prepare the welding wire.

[0047] Example 1 First, a steel billet of a preset density is prepared, and then the steel billet is subjected to a sizing treatment. No coolant is added during the sizing treatment process to obtain a sizing billet with a first density. The sizing billet is then subjected to a heat treatment at a first preset temperature, which is 800°C, so that the tensile strength of the sizing billet is 900MPa and the wire winding diameter of the sizing billet is 400mm. The sizing billet that has undergone the primary heat treatment is then subjected to a peeling treatment and a first drawing treatment in sequence, with a drawing speed of the first drawing treatment being 25m / min, to obtain an initially drawn steel wire. The initially drawn steel wire is then subjected to a secondary heat treatment under the first preset temperature conditions, with a temperature of 800°C, so that the wire winding diameter of the initially drawn steel wire is 400mm. Finally, the initially drawn steel wire that has undergone the secondary heat treatment is subjected to a second drawing treatment and a layer winding treatment in sequence, with a drawing speed of 15m / min, to prepare a welding wire.

[0048] The tensile strength of the prepared welding wire is 2000 MPa, and the preparation cost is reduced by 37%.

[0049] According to the tensile strength and preparation cost of the welding wire prepared in Example 1, the caliper treatment in Example 1, in conjunction with two heat treatments and two drawing treatments, can significantly reduce the preparation cost while improving the tensile strength of the prepared welding wire.

[0050] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing welding wire for laser tailor welding with filler wire, characterized in that: include: preparing a steel billet having a preset density; Performing a caliper treatment on the steel billet to obtain a caliper steel billet having a first density; The sizing steel billet is subjected to a heat treatment at a first preset temperature, so that the tensile strength of the sizing steel billet is any value between 800 MPa and 1000 MPa, and the wire winding diameter of the sizing steel billet is any value between 400 mm and 600 mm; performing a peeling process and a first drawing process on the steel billet after the primary heat treatment to obtain a pre-drawn steel wire; Performing a secondary heat treatment on the initially drawn steel wire under the first preset temperature condition, so that the diameter of the initially drawn steel wire is any value between 1.8 mm and 2.5 mm, and the diameter of the wire winding is any value between 400 mm and 600 mm; performing a second drawing process and a layer winding process on the initially drawn steel wire that has undergone the secondary heat treatment in sequence to prepare the welding wire; Wherein, no coolant is added in the sizing treatment, the first density is greater than the preset density, the first preset temperature is any value between 700°C and 800°C, and the drawing speed of the first drawing treatment is greater than the drawing speed of the second drawing treatment.

2. The method for preparing welding wire according to claim 1, wherein: The drawing speed of the first drawing process is any value between 25 m / min and 30 m / min, and the drawing speed of the second drawing process is any value between 15 m / min and 20 m / min.

3. The method for preparing welding wire according to claim 2, wherein: The number of drawing times in the first drawing process is any value between 6 and 12.

4. The method for preparing welding wire according to claim 3, wherein: The number of drawing times in the second drawing process is any value from 3 to 9.

5. The method for preparing welding wire according to claim 4, wherein: The drawing tolerance of the first drawing process is less than ±0.08 mm, and the drawing tolerance of the second drawing process is less than ±0.06 mm.

6. The method for preparing welding wire according to claim 5, characterized in that: The steel billet includes the following elements in weight percentages: Carbon: 0.15%-0.6%, Silicon: 0.2%-0.5%, Manganese: 0.3%-2.0%, Phosphorus: ≤0.025%, Sulfur: ≤0.025%, Nickel: 0.1%-0.4%, Chromium: 0.01%-0.2%, Niobium: 0.01%-0.1%, Titanium: 0.01%-0.1%, Molybdenum: 0.01%-0.3%, Boron: 0.0005%-0.005%.

7. The method for preparing welding wire according to claim 6, wherein: The step of preparing a steel billet having a preset density comprises: Adding the plurality of elements into a smelting furnace for smelting to prepare molten steel; The molten steel is cast into a steel billet body, and the steel billet body is cooled to a second preset temperature to obtain the steel billet.

8. The method for preparing welding wire according to claim 7, wherein: The second preset temperature is any value between 20°C and 30°C.

9. The method for preparing welding wire according to claim 8, wherein: The smelting temperature of the smelting treatment is any value between 1600° C. and 1700° C., and the smelting time is any value between 40 min and 90 min.

10. A welding wire for laser tailor welding with filler wire, characterized in that: The welding wire is prepared according to the preparation method described in any one of claims 1-9.

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