Tailor welding method for 1500 Mpa grade aluminum-silicon coating hot forming steel

Abstract

The invention discloses a tailor-welding method for 1500Mpa grade aluminum-silicon coating hot forming steel, which comprises the following steps of: splicing plate materials to be welded together, and fixing through a tool clamp; under the protective atmosphere, welding wires are fed into the splicing gaps of the to-be-welded plate materials in a front wire feeding mode, and laser tailored blank welding is conducted through a laser; in the laser tailored blank laser welding process of the laser device, a laser beam advances along a welding seam in a swinging mode, and the swinging mode is circular, infinite, linear, sinusoidal, equilateral triangle, oval or rhombic circulating swinging. And carrying out heat treatment on the welded plate and then quenching. In the laser filler wire tailor-welding process, different forms of laser stirring paths and different welding process parameters are set, the liquidity of a molten pool is effectively improved, the mixing effect of metal liquid is enhanced, and components and organizations of a welding seam are distributed more evenly; meanwhile, formation of welding air holes is reduced, crack sensitivity is reduced, and the quality and performance of a welded joint are improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser welding, and in particular to a method for welding 1500Mpa-grade aluminum-silicon coated hot-formed steel. Background Art

[0002] With the development of the automobile industry, lightweight and safety performance have become the core directions of design and manufacturing. By reducing the weight of the car body, the car can not only significantly improve fuel economy and reduce carbon emissions, but also improve power performance and handling. High-strength hot-formed steel has become one of the preferred materials for body structural parts and collision safety parts due to its excellent strength and ductility. This type of steel is formed at high temperature and quickly cooled to obtain a high-strength structure with a martensitic structure, which can not only meet the needs of lightweight automobiles, but also ensure the safety of structural parts under extreme conditions. However, hot-formed steel is easily oxidized during high-temperature heating. This oxidation phenomenon will lead to a decrease in welding quality and degradation of part surface performance, which in turn affects the overall processing effect.

[0003] In order to overcome the problem of high-temperature oxidation, hot-formed steel usually uses aluminum-silicon coating for surface protection. With its excellent anti-oxidation performance and high-temperature stability, aluminum-silicon coating can not only protect the integrity of the substrate during high-temperature processing, but also maintain good mechanical properties during subsequent welding and forming processes. Therefore, aluminum-silicon coated steel has become one of the important materials in the field of automobile manufacturing and is widely used in the manufacture of complex structural parts. However, due to the special metallurgical properties of aluminum-silicon coating, welding defects such as pores and cracks are prone to occur during laser welding. At the same time, a large amount of Al in the coating enters the molten pool, the fluidity and dynamic behavior of the molten pool are difficult to control, and the heat input distribution is uneven. It is easy to form a brittle phase, which seriously affects the performance of the welded joint. For the laser welding of aluminum-silicon coated steel, the main difficulty of the existing process is how to optimize the welding heat input, reduce the heat-affected zone, and improve the strength and toughness of the weld.

[0004] The current methods for welding aluminum-silicon coated hot-formed steel include laser ablation welding technology and laser wire welding technology. Laser ablation welding technology uses a high-energy pulsed laser beam to ablate the upper surface coating of the joint area before welding, and then performs laser welding to prevent the aluminum-silicon coating from entering the molten pool. However, this process increases the production process, resulting in a significant increase in production costs and reduced efficiency. Laser wire welding technology improves weld performance by filling welding wires with different compositions, but the matching of welding wires and parent materials is limited, which restricts the performance improvement of welded joints. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a welding method for 1500Mpa grade aluminum-silicon coated hot-formed steel. During the laser wire-filling welding process, different forms of laser stirring paths and different welding process parameters are set according to needs, which can effectively improve the fluidity of the molten pool, enhance the mixing effect of the metal liquid, and make the composition and organizational distribution of the weld more uniform; at the same time, the optimized laser stirring form can also reduce the formation of welding pores, reduce crack sensitivity, and further improve the quality and performance of the welded joint.

[0006] In order to solve the above technical problems, the present invention provides a method for welding 1500Mpa grade aluminum-silicon coated hot-formed steel, comprising the following steps:

[0007] S1. Splice the sheets to be welded together and fix them with fixtures;

[0008] S2. Under a protective atmosphere, the welding wire is fed into the joint gap of the sheets to be welded by means of front wire feeding, and laser welding is performed by means of a laser;

[0009] Wherein, during the laser welding process, the laser beam moves forward along the joint gap in a swinging manner, and the swinging form is circular, infinite, straight, sinusoidal, equilateral triangle, elliptical or diamond cyclic swing;

[0010] S3, quenching the welded sheets after heat treatment.

[0011] By setting different forms of laser stirring paths, the present invention can effectively improve the fluidity of the molten pool, enhance the mixing effect of the metal liquid, and make the composition and organizational distribution of the weld more uniform; at the same time, the optimized laser stirring form can also reduce the formation of welding pores, reduce crack sensitivity, and further improve the quality and performance of the weld joint.

[0012] At the same time, the present invention comprehensively optimizes the welding process parameters, including key factors such as laser power, welding speed, defocusing amount, and shielding gas flow rate, which can significantly improve the dynamic characteristics of the welding pool, reduce the residual stress in the weld, and minimize the heat-affected zone, thereby achieving high-strength and high-toughness welds. In addition, in view of the special needs of aluminum-silicon coated steel welding, the selection of suitable welding wire materials further improves the welding effect.

[0013] The welding method of the present invention can not only significantly improve the quality of welds, but also improve production efficiency, meeting the stringent requirements of the automotive manufacturing field for high-strength and lightweight components; the optimized process provides strong technical support for the application of aluminum-silicon coated steel in lightweight and high-performance automotive structural parts, and has broad market prospects and application value.

[0014] Among the different types of swing forms, circular, infinite, straight, and sinusoidal swings are swung perpendicular to the direction of the weld. By controlling the radius of the swing shape, the molten pool width is increased, thereby effectively increasing the base material fusion ratio in the weld and improving weldability. In addition, the laser stirring path is used to interfere with the flow form of the molten pool to achieve the effect of uniform composition in the weld area, and the internal bubbles can be fully escaped to reduce the possibility of porosity defects. In contrast, the energy distribution of circular swing is more uniform; in the infinite swing mode, the weld energy is concentrated in the middle, and it is more likely to be welded through during the welding process. Therefore, the laser power used is appropriately reduced, and this method omits the preheating effect on the welding path; the characteristic of sinusoidal swing is that the energy near the fusion line of the weld edge is more uniform, and compared with the straight shape, the weld edge is smoother and less likely to form a serrated shape. In addition, in order to ensure that the welding wire completely enters the molten pool, the radius of the swing shape is controlled so that the molten pool width ≥ the wire diameter.

[0015] The use of an equilateral triangle laser oscillation form can optimize the welding performance between plates with different thicknesses. During the laser welding process, it is necessary to adapt to the thickness requirements of different parts in order to achieve the purpose of lightweighting. Therefore, it is often necessary to use plates with different thicknesses for welding. When the thickness of the plates on both sides is large, the weld obtained by using conventional welding methods is easy to cause the thin plate side to be welded through while the thick plate side is not welded through because the laser heat distribution on both sides is the same but the plate thickness is different, resulting in poor welding quality. When using an equilateral triangle laser oscillation form, the base of the triangle needs to overlap with the thick plate side so that more laser beam energy acts on the thick plate side, while the thin plate side obtains less energy. This laser head oscillation method can effectively control the energy distribution and improve the quality of welding plates with different thicknesses. In addition, in order to ensure that the welding wire completely enters the molten pool, the height of the triangle ≥ the wire diameter.

[0016] When using the diamond and elliptical swing mode, the long axis of the diamond and ellipse is parallel to the weld direction, the short axis is perpendicular to the weld and the short axis length is ≥ the wire diameter, and the aspect ratio is ≤ 2:1. The diamond and elliptical swing modes distribute most of the energy on the welding path, so that the unmelted area on the welding path is preheated in advance, and a certain amount of heat is input to the welded area, which can slow down the sudden change of heat at the front and rear ends of the molten pool, reduce welding thermal stress, and effectively avoid cracks caused by excessive instantaneous thermal changes. In addition, the elliptical swing can better adjust the edge position of the weld, making its transition smoother and less likely to form jagged edges.

[0017] Furthermore, in S1, the gap between the sheets to be welded is ≤0.2 mm.

[0018] Furthermore, in S2, when the thickness difference of the sheets to be welded is greater than 0.6 mm, an equilateral triangle swinging form is adopted.

[0019] Furthermore, in S2, the distance between the laser head of the laser and the upper surface of the sheet to be welded with a greater thickness is equal to the focal length of the laser.

[0020] Furthermore, in S2, the wire feeding angle of the pre-wire feeding is 30-60°, and the wire feeding rate is 1.2-3.0 m / min.

[0021] Furthermore, in S2, the parameters of the laser welding are: laser power 4-6kW, welding rate 30-60mm / s.

[0022] Furthermore, in S2, the protective atmosphere is argon gas with a flow rate of 10-25 L / min.

[0023] Furthermore, in S3, the temperature of the heat treatment is 930±10°C, the quenching is performed using quenching oil, and the cooling rate is >50°C / s.

[0024] Further, in S1, the sheet material to be welded is an aluminum-silicon coated sheet with a thickness of 1.0-2.0 mm, wherein the thickness of the aluminum-silicon coating is 25-30 μm;

[0025] And / or, the yield strength of the sheet material to be welded is 900-1200 MPa, the tensile strength is 1300-1600 MPa, and the elongation is greater than 4%.

[0026] Further, in S2, the diameter of the welding wire is 0.8-1.6 mm, and the components of the welding wire are, by mass percentage, 3-10 wt% Mn, 0.1-0.3% C, 0.1-1.0% Cr, 0.1-0.5% Si, 0.04-0.2% Nb, 0.1-1.0% V, 0-2% Ni, and the balance is Fe and unavoidable impurities. The high Mn content improves the stability of austenite in the weld and reduces the ferrite content, while the austenite can improve the plasticity of the weld through the TRIP effect; in addition, a small amount of V and Nb is added to the welding wire to refine the grain size in the weld, thereby improving the strength and plasticity of the weld.

[0027] Furthermore, in S2, the swing distance d of the laser beam on both sides of the center line of the splicing gap is the same, and d≥the radius of the welding wire.

[0028] Furthermore, in S1, the surfaces to be welded are polished before the sheets to be welded are spliced.

[0029] Furthermore, after S3, the martensite content in the weld area is ≥95%, the strength is 1400-1600 MPa, the hardness is 450-500 Hv, and the elongation is ≥5%.

[0030] Beneficial effects of the present invention:

[0031] The present invention sets different forms of laser stirring paths and cooperates with different welding process parameters during the laser wire filling welding process, which effectively improves the fluidity of the molten pool, enhances the mixing effect of the metal liquid, and makes the composition and tissue distribution of the weld more uniform; at the same time, the swinging mode makes the laser energy distribution more reasonable, plays a role of preheating before welding, and reduces the formation of welding pores, thereby reducing crack sensitivity.

[0032] The strength of the weld area formed by the tailor-welding method of the present invention is close to that of the parent material, and the plasticity is greatly improved, thereby improving the quality and performance of the welded structure.

[0033] The welding process of the present invention can adjust the swing form according to the needs, and can be adapted to the laser welding of aluminum-silicon coated hot-formed steel plates of various thicknesses, and has strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 The circular oscillating welding path of embodiment 1 of the present invention;

[0036] Figure 2 The infinite swing welding path of the second embodiment of the present invention;

[0037] Figure 3 The straight-line swing welding path of embodiment 3 of the present invention;

[0038] Figure 4 is the sinusoidal oscillating welding path of embodiment 4 of the present invention;

[0039] Figure 5 It is the triangular swing welding path of embodiment 5 of the present invention;

[0040] Figure 6 The diamond-shaped swing welding path of Example 6 of the present invention;

[0041] Figure 7 This is an elliptical oscillating welding path according to Example 7 of the present invention. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0043] This embodiment provides a method for welding 1500Mpa grade aluminum-silicon coated hot-formed steel, comprising the following steps:

[0044] S1. Grind the surfaces of the sheets to be welded, splice them together, and fix them with fixtures;

[0045] Among them, the gap of splicing is ≤0.2mm

[0046] S2. In a protective atmosphere, feed the welding wire into the joint gap of the sheets to be welded by front wire feeding at a wire feeding angle of 30-60° and a wire feeding rate of 1.2-3.0 m / min, and perform laser welding by using a laser with a laser power of 4-6 kW and a welding rate of 30-60 mm / s;

[0047] Wherein, during the laser welding process, the laser beam moves forward along the weld in a swinging manner, and the swinging form is circular, infinite, straight, sinusoidal, equilateral triangle, elliptical or diamond cyclic swing;

[0048] S3, quenching the welded sheets after heat treatment.

[0049] This embodiment can effectively improve the fluidity of the molten pool, enhance the mixing effect of the metal liquid, and make the composition and organization distribution of the weld more uniform by setting different forms of laser stirring paths; at the same time, the optimized laser stirring form can also reduce the formation of welding pores, reduce crack sensitivity, and further improve the quality and performance of the welded joint. The welding process parameters are fully optimized, including key factors such as laser power, welding speed, defocusing amount, and shielding gas flow rate, which can significantly improve the dynamic characteristics of the welding molten pool, reduce the residual stress in the weld, and minimize the heat-affected zone, thereby achieving high-strength and high-toughness welds. In addition, in view of the special needs of aluminum-silicon coated steel welding, the selection of suitable welding wire materials further improves the welding effect.

[0050] As a preferred embodiment, in S1, the sheet to be welded is an aluminum-silicon coated sheet with a thickness of 1.0-2.0 mm, wherein the thickness of the aluminum-silicon coating is 25-30 μm; the yield strength of the sheet to be welded is 900-1200 MPa, the tensile strength is 1300-1600 MPa, and the elongation is greater than 4%.

[0051] As a preferred embodiment, in S2, the protective atmosphere is argon gas with a flow rate of 10-25 L / min; the diameter of the welding wire is 0.8-1.6 mm, and the components of the welding wire are, by mass percentage, Mn 3-10wt%, C 0.1-0.3%, Cr0.1-1.0%, Si 0.1-0.5%, Nb 0.04-0.2%, V 0.1-1.0%, Ni 0-2%, and the balance is Fe and unavoidable impurities; the distance between the laser head of the laser and the upper surface of the thicker sheet to be welded is equal to the focal length of the laser.

[0052] As a preferred embodiment, in S2, the swing distance d of the laser beam on both sides of the weld center line is the same, and d≥welding wire radius.

[0053] As a preferred embodiment, in S3, the heat treatment temperature is 930±10°C, the quenching is carried out using quenching oil, and the cooling rate is >50°C / s; after S3, the martensite content in the weld area is ≥95%, the strength is 1400-1600MPa, the hardness is 450-500Hv, and the elongation is ≥5%.

[0054] The following embodiments and comparative examples adopt a 1.0-2.0 mm thick sheet to be welded, the substrate is 22MnB5 steel, and both sides are plated with 25-30 um aluminum-silicon coating, and the splicing gap is 0.15 mm; except for comparative example 2, the components of the welding wire are, by mass percentage: Mn 5wt%, C 0.2wt%, Cr 0.45wt%, Si 0.17wt%, Nb 0.08wt%, V 0.2wt%, Ni1.0wt%, and the balance is Fe and unavoidable impurities (wherein P<0.004wt%, S<0.005wt%, N 0.003wt%).

[0055] Example 1

[0056] This embodiment relates to a method for welding aluminum-silicon coated hot-formed steel, comprising the following steps:

[0057] (1) Splice the sheets to be welded together and fix them with fixtures;

[0058] (2) Under a protective atmosphere, the welding wire is fed into the joint gap of the sheets to be welded by front wire feeding, and the laser is used for swing laser welding.

[0059] (2) The welded sheets are heat treated and then quenched.

[0060] The laser swing is circular, and the welding route is based on Figure 1, frequency is 65Hz, swing radius (distance d from weld center to swing end) is 0.6mm, wire diameter is 1.2mm, wire feed head is at 40° angle to the plane to be welded, thickness combination of tailored welded sheet is 2.0+2.0mm, laser power is 4.4kW, welding speed is 50mm / s, wire feed speed is 1.5m / min, shielding gas flow rate is 15L / min. After welding, the sheet is heated at 930℃ for 5min, then put into quenching oil for quenching, cooling rate>50℃ / s.

[0061] Example 2

[0062] The difference between this embodiment and embodiment 1 is that the swing form of the laser head is infinite. Figure 2 As shown, the laser power is 4.2 kW, and the other parameters and steps remain unchanged.

[0063] Example 3

[0064] The difference between this embodiment and embodiment 1 is that the swinging form of the laser head is a straight line, such as Figure 3 As shown, the frequency is 70 Hz, the thickness combination of the tailored welded sheets is 1.4+1.4 mm, the laser power is 3.8 kW, the wire feeding speed is 1.7 m / min, and the other parameters and steps remain unchanged.

[0065] Example 4

[0066] The difference between this embodiment and embodiment 3 is that the swing form of the laser head is sinusoidal. Figure 4 As shown, other parameters and steps remain unchanged.

[0067] Example 5

[0068] The difference between this embodiment and embodiment 1 is that the swing form of the laser head is an equilateral triangle, such as Figure 5 As shown, the frequency is 80 Hz, the thickness combination of the welded blanks is 1.0+2.0 mm, the laser power is 4.0 kW, and the other parameters and steps remain unchanged.

[0069] Example 6

[0070] The difference between this embodiment and embodiment 1 is that the swing form of the laser head is a diamond shape, such as Figure 6 As shown, the frequency is 70 Hz, the laser power is 4.8 kW, the wire feeding rate is 1.7 m / min, and the other parameters and steps remain unchanged.

[0071] Example 7

[0072] The difference between this embodiment and embodiment 6 is that the swing form of the laser head is elliptical, such as Figure 7 As shown, other parameters and steps remain unchanged.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 3 is that the welding process does not adopt the swinging method, and the other parameters and steps remain unchanged.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that a welding wire with a brand of ER70S-6 is used, and other parameters and steps remain unchanged.

[0077] Comparative Example 3

[0078] The difference between this comparative example and comparative example 1 is that the swinging form is not adopted, and the laser self-melting welding with welding wire is not used, and other parameters and steps remain unchanged.

[0079] Comparative Example 4

[0080] The difference between this comparative example and Example 5 is that the swinging form is circular, and other parameters and steps remain unchanged.

[0081] Comparative Example 5

[0082] The difference between this comparative example and Example 1 is that the swing radius is 0.3 mm, the laser power is 4.2 kW, and the other parameters and steps remain unchanged.

[0083] Comparative Example 6

[0084] The difference between this comparative example and Example 5 is that the swinging form is not adopted, and other parameters and steps remain unchanged.

[0085] Comparative Example 7

[0086] The difference between this comparative example and Example 6 and Example 7 is that the swinging form is circular, and other parameters and steps remain unchanged.

[0087] The weld mechanical properties of the tailor-welded products obtained in Examples 1-7 and Comparative Examples 1-7 were tested, and the results are shown in Table 1.

[0088] Table 1

[0089] Group Yield Strength(Mpa) Tensile strength(Mpa) Elongation(%) Hardness(Hv) Example 1 1105.39 1499.29 8.29 457.8 Example 2 1096.95 1505.91 5.92 462.1 Example 3 1039.20 1484.17 5.26 452.9 Example 4 1022.74 1454.33 5.11 447.4 Example 5 1148.18 1451.36 6.52 446.3 Example 6 1088.61 1477.93 6.48 458.5 Example 7 1073.25 1467.22 7.21 453.9 Comparative Example 1 1016.37 1474.16 3.59 447.6 Comparative Example 2 1003.42 1421.16 2.74 473.2 Comparative Example 3 988.91 1321.33 1.97 440.6 Comparative Example 4 1081.59 1496.26 3.93 455.1 Comparative Example 5 1104.55 1409.07 3.07 412.1 Comparative Example 6 1001.70 1313.45 1.96 427.4 Comparative Example 7 1091.25 1481.33 3.41 455.3

[0090] From the comparison between Example 1 and Comparative Example 2, it can be seen that the welding wire with the specific components of the present invention can effectively improve the mechanical properties of the weld. The reason is that the higher Mn content improves the stability of austenite in the weld and reduces the ferrite content. At the same time, austenite can improve the plasticity of the weld through the TRIP effect. In addition, a small amount of V and Nb is added to the welding wire of the present invention, which refines the grain size in the weld and improves the strength and plasticity of the weld.

[0091] From the comparison between Example 3 and Comparative Example 1, it can be seen that by adjusting the swing form of the laser head, the flow form of the molten pool can be effectively improved, the welding stability can be improved, and the weld performance can be improved. From the comparison between Comparative Example 1 and Comparative Example 3, it can be seen that compared with autogenous welding, the use of filler wire welding can avoid the brittleness of the weld, and the welding wire can add alloying elements to the weld, which has a regulating effect on the weld structure and effectively improves the weld performance. Compared with autogenous welding, filler wire welding has lower assembly precision and stronger applicability. Therefore, laser filler wire welding has better application prospects than autogenous welding.

[0092] From the comparison between Example 5 and Comparative Examples 4 and 6, it can be seen that when the difference in sheet thickness is large, a good weld cannot be obtained by using a non-oscillating or other form of oscillating welding method, but the use of a triangular laser oscillation form can achieve effective distribution of laser energy, so that the thick plate side obtains more energy and the thin plate side is allocated less energy. This makes the melting effect of the thick and thin plates more uniform, and also enables the base material and the welding wire to obtain a good combination at the weld, thereby improving the weld strength and plasticity.

[0093] From the comparison between Example 1 and Comparative Example 5, it can be seen that the radius of the laser head swing affects the effect of the welding wire entering the molten pool. The smaller laser swing radius in the comparative example makes it impossible for the welding wire to be completely integrated into the molten pool, and surface defects such as flying wires are more likely to occur. Therefore, the control of the laser head swing radius during welding also has a great influence on the strength and toughness of the weld.

[0094] From the comparison between Examples 6 and 7 and Comparative Example 7, it can be seen that under the condition of high output power, the use of diamond-shaped and elliptical laser head swing forms can make the laser energy act on the front and rear ends of the molten pool, which not only achieves the preheating effect on the unmelted area in the welding direction, but also slows down the solidification rate of the molten pool, avoids the formation of cracks in the weld area due to extremely rapid heat changes, and improves the plasticity of the weld.

[0095] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for welding 1500Mpa grade aluminum silicon coated hot-formed steel, characterized in that: The steps include: S1. Splice the sheets to be welded together and fix them with fixtures; S2. Under a protective atmosphere, the welding wire is fed into the joint gap of the sheets to be welded by means of front wire feeding, and laser welding is performed by means of a laser; Wherein, during the laser welding process, the laser beam moves forward along the joint gap in a swinging manner, and the swinging form is circular, infinite, straight, sinusoidal, equilateral triangle, elliptical or diamond cyclic swing; S3, quenching the welded sheets after heat treatment.

2. The method for welding 1500Mpa grade aluminum-silicon coated hot-formed steel according to claim 1, characterized in that: In S1, the gap between the sheets to be welded is ≤0.2 mm.

3. The method for welding 1500Mpa grade aluminum-silicon coated hot-formed steel according to claim 1, characterized in that: In S2, the wire feeding angle of the pre-wire feeding is 30-60°, and the wire feeding rate is 1.2-3.0 m / min.

4. The method for welding 1500Mpa grade aluminum-silicon coated hot-formed steel according to claim 1, characterized in that: In S2, the parameters of the laser welding are: laser power 4-6kW, welding rate 30-60mm / s.

5. The method for welding 1500Mpa grade aluminum silicon coated hot-formed steel according to claim 1, characterized in that: In S2, the protective atmosphere is argon gas with a flow rate of 10-25 L / min.

6. The method for welding 1500Mpa grade aluminum silicon coated hot-formed steel according to claim 1, characterized in that: In S3, the temperature of the heat treatment is 930±10°C, the quenching is performed using quenching oil, and the cooling rate is >50°C / s.

7. The method for welding 1500Mpa grade aluminum silicon coated hot-formed steel according to claim 1, characterized in that: In S1, the sheet to be welded is an aluminum-silicon coated sheet with a thickness of 1.0-2.0 mm, wherein the thickness of the aluminum-silicon coating is 25-30 μm; And / or, the yield strength of the sheet material to be welded is 900-1200 MPa, the tensile strength is 1300-1600 MPa, and the elongation is greater than 4%.

8. The method for welding 1500Mpa grade aluminum silicon coated hot-formed steel according to claim 1, characterized in that: In S2, the diameter of the welding wire is 0.8-1.6 mm, and the components of the welding wire are, by mass percentage, 3-10wt% Mn, 0.1-0.3% C, 0.1-1.0% Cr, 0.1-0.5% Si, 0.04-0.2% Nb, 0.1-1.0% V, 0-2% Ni, and the balance is Fe and unavoidable impurities.

9. The method for welding 1500Mpa grade aluminum silicon coated hot-formed steel according to claim 1, characterized in that: In S2, the swing distance d of the laser beam on both sides of the center line of the splicing gap is the same, and d≥the radius of the welding wire.

10. The method for welding 1500Mpa grade aluminum silicon coated hot-formed steel according to claim 1, characterized in that: In S1, the surfaces to be welded are polished before the sheets to be welded are spliced.

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