A splicing method of 1500mpa grade al-si plated hot forming steel

Abstract

The application discloses a kind of 1500Mpa grade aluminium silicon coating hot forming steel's splicing welding method, comprising the following steps: to be welded plate material splicing together, and fixed by tool fixture;In protective atmosphere, by the way of pre-wire feeding, welding wire is sent into the splicing gap of to-be-welded plate material, and laser splicing welding is carried out by laser;During the process that laser splicing welding is carried out by the laser, laser beam is swung along weld and advances, and the form of swing is circular, infinite, one-word, sinusoidal, equilateral triangle, elliptical or diamond cyclic swing;After heat treatment, the plate material of splicing welding is quenched.The application sets different forms of laser stirring path and different welding process parameters in the process of laser filling wire splicing welding, effectively improves the fluidity of molten pool, enhances the mixing effect of metal liquid, makes the composition and organization distribution of weld more uniform;Meanwhile, the formation of welding pores is reduced, the crack sensitivity is reduced, and the quality and performance of welded joint are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser welding, and particularly relates to a butt welding method of 1500Mpa grade aluminum-silicon plated hot forming steel. BACKGROUND

[0002] With the development of the automobile industry, lightweight and safety performance have become the core direction of design and manufacturing. By reducing the weight of the vehicle body, the automobile can not only significantly improve fuel economy and reduce carbon emissions, but also improve power performance and handling. High-strength hot forming steel has become one of the preferred materials for vehicle body structural parts and safety parts in collision due to its excellent strength and ductility. This kind of steel is formed at high temperature and rapidly cooled to obtain high-strength structure with martensitic structure, which can not only meet the demand of automobile lightweight, but also ensure the safety of structural parts under extreme conditions. However, the hot forming steel is easy to oxidize during high-temperature heating, and this oxidation phenomenon will lead to the decline of welding quality and the degradation of the surface performance of the part, thereby affecting the overall processing effect.

[0003] To overcome the problem of high-temperature oxidation, hot forming steel usually adopts aluminum-silicon plating layer for surface protection. The aluminum-silicon plating layer, with its excellent oxidation resistance and high-temperature stability, not only can protect the integrity of the base material during high-temperature processing, but also can maintain good mechanical properties during subsequent welding and forming. Therefore, aluminum-silicon plated steel has become one of the important materials in the field of automobile manufacturing, and is widely used in the manufacturing of complex structural parts. However, due to the special metallurgical characteristics of the aluminum-silicon plating layer, welding defects such as pores and cracks are easily produced during laser butt welding, and at the same time, a large amount of Al in the plating layer enters the molten pool, the flowability and dynamic behavior of the molten pool are difficult to control, the heat input is unevenly distributed, and other factors, which easily form brittle phases, seriously affect the performance of the welded joint. For laser butt welding of aluminum-silicon plated 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 butt welding of aluminum-silicon plated hot forming steel include laser ablation butt welding technology and laser wire filling welding technology. Laser ablation butt welding technology first uses a high-energy pulsed laser beam to ablate the surface plating layer in the butt joint area before welding, and then performs laser welding to avoid the entry of aluminum-silicon plating layer into the molten pool. However, this process increases the production process, resulting in a significant increase in production cost and a decrease in efficiency. Laser wire filling welding technology improves the performance of the weld by filling different composition welding wires, but the matching of the welding wire with the base material is limited, which restricts the improvement of the performance of the welded joint. SUMMARY

[0005] The present application aims at the deficiencies in the prior art, and provides a 1500Mpa grade aluminum-silicon plated hot forming steel splicing welding method, in the process of laser wire filling splicing welding, different forms of laser stirring paths and different welding process parameters are set according to requirements, the fluidity of the molten pool can be effectively improved, the mixing effect of the metal liquid is enhanced, the composition and organization distribution of the weld are more uniform, the formation of welding pores is reduced by the optimized laser stirring form, the crack sensitivity is reduced, and the quality and performance of the welded joint are further improved.

[0006] In order to solve the above technical problems, the present application provides a 1500Mpa grade aluminum-silicon plated hot forming steel splicing welding method, comprising the following steps:

[0007] S1, splice the to-be-welded sheet together and fix through a fixture;

[0008] S2, in a protective atmosphere, the welding wire is sent into the splicing gap of the to-be-welded sheet through a pre-wire feeding mode, and laser splicing welding is carried out through a laser;

[0009] In the process of laser splicing welding of the laser, the laser beam swings along the splicing gap and advances in a circular, infinite, one-word, sinusoidal, equilateral triangular, elliptical or rhombic circular swing form;

[0010] S3, after the splicing welding of the sheet is completed, the sheet is quenched after heat treatment.

[0011] The present application can effectively improve the fluidity of the molten pool, enhance the mixing effect of the metal liquid, make the composition and organization distribution of the weld more uniform, reduce the formation of welding pores by the optimized laser stirring form, reduce the crack sensitivity, and further improve the quality and performance of the welded joint.

[0012] Meanwhile, the present application comprehensively optimizes the welding process parameters, including laser power, welding speed, defocusing amount and protective gas flow rate and other key factors, which can significantly improve the dynamic characteristics of the welding molten pool, reduce the residual stress in the weld, and at the same time ensure that the heat affected zone range is minimized, so as to realize the high-strength and high-toughness weld.

[0013] The welding method of the present application not only can significantly improve the weld quality, but also can improve the production efficiency, meet the strict requirements of the automobile manufacturing field for high-strength and lightweight parts, and provide strong technical support for the application of aluminum-silicon plated steel in automobile lightweight and high-performance structural parts, which has broad market prospect and application value.

[0014] Among different types of oscillation forms, circular, infinite, linear, and sinusoidal oscillation are performed in the direction perpendicular to the weld, and the radius of the oscillation shape is controlled to increase the width of the molten pool, thereby effectively increasing the base metal fusion ratio in the weld and improving the weldability. In addition, by interfering with the stirring path of the laser, the flow form of the molten pool is disturbed, the composition homogenization effect of the weld area is realized, and the internal bubbles can also fully escape, reducing the possibility of pore defects. In contrast, the energy distribution of circular oscillation is more uniform; the weld energy of infinite oscillation is concentrated in the middle, and it is more prone to weld-through during welding, so the laser power used is appropriately reduced, and this method omits the preheating effect on the welding path; the characteristic of sinusoidal oscillation is that the energy near the weld edge fusion line is more uniform, and compared with linear, the weld edge is smoother and less likely to form a jagged shape. In addition, in order to ensure that the welding wire completely enters the molten pool, the radius of the oscillation shape is controlled so that the width of the molten pool is ≥ the diameter of the welding wire.

[0015] The use of equilateral triangle laser oscillation form can optimize the performance of differential thickness plate welding. In the process of laser welding, it is necessary to adapt to the thickness requirements of different positions of the part to achieve the purpose of lightweight, so it is often necessary to use differential thickness plates for welding. When the thickness of the two side plates is large, the weld obtained by using the conventional welding method is prone to weld-through on the thin plate side and incomplete penetration on the thick plate side due to the same heat distribution of the two sides but different thicknesses of the plates, resulting in poor welding quality. When using equilateral triangle laser oscillation form, the base of the triangle is coincided with the thick plate side, so that more laser beam energy acts on the thick plate side, and less energy is obtained on the thin plate side. Through this laser head oscillation form, the energy distribution can be effectively controlled, and the welding quality of differential thickness plates can be improved. In addition, in order to ensure that the welding wire completely enters the molten pool, the height of the triangle is ≥ the diameter of the welding wire.

[0016] When using diamond and elliptical oscillation forms, 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 diameter of the welding wire, and the length-width ratio is ≤ 2:1. Diamond and elliptical oscillation forms distribute most of the energy on the welding path, preheat the non-melted area on the welding path, and also have a certain heat input to the welded area, so as to slow down the sudden change of heat at the front and tail of the molten pool, reduce the welding thermal stress, and effectively avoid cracks caused by excessive instantaneous heat change. In addition, elliptical oscillation can better adjust the position of the weld edge, making the transition smoother and less likely to form a jagged edge.

[0017] Further, in S1, the gap between the to-be-welded plates is ≤ 0.2mm.

[0018] Further, in S2, when the thickness difference of the to-be-welded plates is > 0.6mm, an equilateral triangle oscillation form is used.

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

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

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

[0022] Further, in S2, the protective atmosphere is argon, and the flow rate is 10-25 L / min.

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

[0024] Further, in S1, the to-be-welded sheet is an aluminum-silicon plated sheet with a thickness of 1.0-2.0 mm, wherein the thickness of the aluminum-silicon plating layer is 25-30 μm.

[0025] Further, in S1, the to-be-welded sheet is an aluminum-silicon plated sheet with a thickness of 1.0-2.0 mm, wherein the thickness of the aluminum-silicon plating layer is 25-30 μm.

[0026] Further, in S2, the diameter of the welding wire is 0.8-1.6 mm, and the components of the welding wire are as follows in terms of mass percentage: Mn 3-10 wt%, C 0.1-0.3%, Cr 0.1-1.0%, Si 0.1-0.5%, Nb 0.04-0.2%, V 0.1-1.0%, Ni 0-2%, and the balance is Fe and inevitable impurities. The higher Mn content can increase the stability of austenite in the weld and reduce the content of ferrite, and the austenite can increase the plasticity of the weld through the TRIP effect. In addition, a small amount of V and Nb is added to the welding wire, which can refine the grain size in the weld and improve the strength and plasticity of the weld.

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

[0028] Further, in S1, the to-be-welded surface is polished before the to-be-welded sheet is spliced.

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

[0030] The beneficial effects of the present application are as follows:

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

[0032] The welding seam area formed by the welding method of the present application has a strength close to the base material and a greatly improved plasticity, thereby improving the quality and performance of the welded structure.

[0033] The welding process of the present application can adjust the swing form as needed, and can be adapted to laser welding of aluminum-silicon plated hot-formed steel sheets of various thicknesses, and has strong adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0035] Figure 1 is a circular swing type welding path of embodiment 1 of the present application;

[0036] Figure 2 is an infinite swing type welding path of embodiment 2 of the present application;

[0037] Figure 3 is a linear swing type welding path of embodiment 3 of the present application;

[0038] Figure 4 is a sine swing type welding path of embodiment 4 of the present application;

[0039] Figure 5 is a triangular swing type welding path of embodiment 5 of the present application;

[0040] Figure 6 is a rhombus swing type welding path of embodiment 6 of the present application;

[0041] Figure 7 is an elliptical swing type welding path of embodiment 7 of the present application. DETAILED DESCRIPTION

[0042] The technical solutions of the present application will be clearly and completely described below in combination with specific embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present application.

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

[0044] S1, the welding surfaces of the to-be-welded plates are polished and then spliced together, and fixed by a fixture;

[0045] The gap of the splicing is ≤0.2mm.

[0046] S2, under a protective atmosphere, the welding wire is sent into the splicing gap of the to-be-welded plates by a pre-wire feeding mode at a wire feeding angle of 30-60° and a wire feeding rate of 1.2-3.0m / min, and laser tailor-welding is performed by a laser at a laser power of 4-6kW and a welding rate of 30-60mm / s.

[0047] During the laser tailor-welding process of the laser, the laser beam advances in a swing mode along the weld, and the swing mode is circular, infinite, one-dimensional, sinusoidal, equilateral triangular, elliptical or rhombic circular swing.

[0048] S3, the spliced plates are heat treated and then quenched.

[0049] The present embodiment can effectively improve the fluidity of the molten pool, enhance the mixing effect of the metal liquid, and make the composition and structure 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 the crack sensitivity, and further improve the quality and performance of the welded joint. The welding process parameters are comprehensively optimized, including the key factors such as laser power, welding speed, defocusing amount and protective gas flow rate, which can significantly improve the dynamic characteristics of the welding pool, reduce the residual stress in the weld, and at the same time ensure that the heat-affected zone range is minimized, so as to realize a high-strength and high-toughness weld. In addition, the selection of suitable welding wire material further improves the welding effect according to the special requirements of aluminum-silicon coated steel welding.

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

[0051] As a preferred embodiment, in S2, the protective atmosphere is argon, and the flow rate is 10-25 L / min; the diameter of the welding wire is 0.8-1.6 mm, and the components of the welding wire, by mass percentage, are: Mn 3-10 wt%, C 0.1-0.3%, Cr 0.1-1.0%, Si 0.1-0.5%, Nb 0.04-0.2%, V 0.1-1.0%, Ni 0-2%, and the balance of Fe and inevitable impurities; the distance between the laser head of the laser and the upper surface of the thicker one of the plates 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 center line of the weld is the same, and d≥the radius of the welding wire.

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

[0054] In the following examples and comparative examples, the plates to be welded are 1.0-2.0 mm thick, the base material is 22MnB5 steel, and both sides are plated with an aluminum-silicon coating layer of 25-30 um, and the joint gap is 0.15 mm; except for Comparative Example 2, the components of the welding wire, by mass percentage, are: Mn 5 wt%, C 0.2 wt%, Cr 0.45 wt%, Si 0.17 wt%, Nb 0.08 wt%, V 0.2 wt%, Ni 1.0 wt%, and the balance of Fe and inevitable impurities (wherein P <0.004 wt%, S <0.005 wt%, N 0.003 wt%).

[0055] Example 1

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

[0057] (1) splice the plates to be welded together and fix them by a fixture;

[0058] (2) under a protective atmosphere, feed the welding wire into the joint gap of the plates to be welded by a pre-wire feeding method, and perform a swing type laser splicing by a laser

[0059] (2) perform heat treatment and quenching on the spliced plates.

[0060] Among them, the swing form of the laser is circular, and the welding route is as shown in Figure 1, the frequency is 65 Hz, the swing radius (the distance d from the weld center to the swing end) is 0.6 mm, the wire diameter is 1.2 mm, the wire feeding head and the welding plane forms an angle of 40°, the thickness combination of the tailor-welded blank is 2.0+2.0 mm, the laser power is 4.4 kW, the welding speed is 50 mm / s, the wire feeding speed is 1.5 m / min, and the protective gas flow rate is 15 L / min. The welded plate is heated at 930 ℃ for 5 min, and then quenched in quenching oil, with a cooling rate > 50 ℃ / s.

[0061] Example 2

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

[0063] Example 3

[0064] The difference between this example and Example 1 is that the swing form of the laser head is a straight line, as shown in Figure 3 , the frequency is 70 Hz, the thickness combination of the tailor-welded blank 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 example and Example 3 is that the swing form of the laser head is sinusoidal, as shown in Figure 4 , and the other parameters and steps remain unchanged.

[0067] Example 5

[0068] The difference between this example and Example 1 is that the swing form of the laser head is an equilateral triangle, as shown in Figure 5 , the frequency is 80 Hz, the thickness combination of the tailor-welded blank 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 example and Example 1 is that the swing form of the laser head is a rhombus, as shown in Figure 6 , the frequency is 70 Hz, the laser power is 4.8 kW, the wire feeding speed is 1.7 m / min, and the other parameters and steps remain unchanged.

[0071] Example 7

[0072] The difference between this example and Example 6 is that the swing form of the laser head is an ellipse, as shown in Figure 7 , and the other parameters and steps remain unchanged.

[0073] Comparative Example 1

[0074] The difference between the present comparative example and Example 3 is that the weaving mode is not used in the process of tailor welding, and other parameters and steps are unchanged.

[0075] Comparative Example 2

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

[0077] Comparative Example 3

[0078] The difference between the present comparative example and Comparative Example 1 is that the weaving mode is not used, and the welding wire is not welded by laser self-melting, and other parameters and steps are unchanged.

[0079] Comparative Example 4

[0080] The difference between the present comparative example and Example 5 is that the weaving mode is circular, and other parameters and steps are unchanged.

[0081] Comparative Example 5

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

[0083] Comparative Example 6

[0084] The difference between the present comparative example and Example 5 is that the weaving mode is not used, and other parameters and steps are unchanged.

[0085] Comparative Example 7

[0086] The difference between the present comparative example and Example 6 and Example 7 is that the weaving mode is circular, and other parameters and steps are unchanged.

[0087] The mechanical properties of the welding seams of the tailor-welded products obtained in Examples 1-7 and Comparative Examples 1-7 are detected, 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 application can effectively improve the mechanical properties of the welding seam, and the reason is that the higher Mn content increases the stability of the austenite in the welding seam, reduces the content of ferrite, and the austenite can improve the plasticity of the welding seam through the TRIP effect; in addition, a small amount of V and Nb is added in the welding wire of the present application, which refines the grain size in the welding seam, and improves the strength and plasticity of the welding seam.

[0091] From the comparison of Example 3 and Comparative Example 1, it can be seen that by adjusting the laser head swinging form, the flow form of the molten pool can be effectively improved, the welding stability is improved, and the weld performance is improved. From the comparison of Comparative Example 1 and Comparative Example 3, it can be seen that compared with self-melting welding, the use of filler wire welding can avoid the appearance of brittle welds, and the welding wire can add alloying elements to the weld, which has a regulating effect on the weld structure, effectively improves the performance of the weld, and compared with self-melting welding, the filler wire welding has lower assembly precision and stronger applicability. Therefore, the laser filler wire welding method has better application prospect than self-melting welding.

[0092] From the comparison of Example 5 and Comparative Examples 4 and 6, it can be seen that when the thickness difference of the plates is large, the use of non-swinging or other forms of swinging splicing method cannot obtain a good weld, but the use of triangular laser swinging form can realize effective distribution of laser energy, so that the thick plate side obtains more energy and the thin plate side distributes less energy, which makes the melting effect of the thick and thin plate sides more uniform, and also makes the base material and the welding wire obtain good combination at the weld, thereby improving the weld strength and plasticity.

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

[0094] From the comparison of Examples 6 and 7 and Comparative Example 7, it can be seen that under the condition of high output power, the use of rhombus and ellipse laser head swinging forms can make the laser energy act on the front and rear of the molten pool, which not only realizes the preheating effect on the un-melted area in the welding direction, but also delays the solidification speed of the molten pool, avoids the formation of cracks in the weld area due to the rapid change of heat, and improves the plasticity of the weld.

[0095] The above detailed description of the present application is made in combination with specific embodiments and exemplary examples, but these descriptions cannot be understood as limitations of the present application. Those skilled in the art understand that the technical solutions and embodiments of the present application can be variously replaced, modified or improved without deviating from the spirit and scope of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A method of tailor-welding a 1500 MPa grade aluminium-silicon coated hot-formed steel, characterized in that, It comprises the following steps: S1, splice the to-be-welded sheet together and fix it through a fixture; S2, under a protective atmosphere, send the welding wire into the splicing gap of the to-be-welded sheet through a pre-wire feeding mode, and perform laser welding through a laser; During the laser welding performed by the laser, the laser beam swings along the splicing gap and the swinging form is circular, infinite, linear, sinusoidal, equilateral triangular, elliptical or rhombic circular swinging; the swinging distance d of the laser beam on both sides of the center line of the splicing gap is the same, and d≥welding wire radius; The circular, infinite, linear, sinusoidal swinging is swinging in the direction perpendicular to the weld, the radius of the swinging shape is controlled to increase the width of the molten pool, and the base metal fusion ratio in the weld is increased; the stirring path of the laser interferes with the flow form of the molten pool, realizes the composition homogenization of the weld area, and makes the internal bubbles escape; When the equilateral triangular laser swinging form is adopted, the base of the triangle is coincided with the thick plate side, so that more laser beam energy acts on the thick plate side and less energy is obtained on the thin plate side, thereby effectively controlling the energy distribution; the height of the triangle is≥welding wire diameter; When the rhombic and elliptical swinging forms are adopted, the long axis of the rhombic and elliptical is parallel to the weld direction, the short axis is perpendicular to the weld and the short axis length is≥welding wire diameter, and the length-width ratio is≤2:1; the rhombic and elliptical swinging forms distribute most of the energy on the welding path, so that the non-melted area on the welding path is preheated in advance, and there is a certain heat input to the welded area, so as to slow down the heat sudden change at the front and tail of the molten pool; S3, quenching after heat treatment of the completed spliced sheet; The to-be-welded sheet is an aluminum-silicon plated sheet with a thickness of 1.0-2.0mm, wherein the thickness of the aluminum-silicon plating layer is 25-30μm; The diameter of the welding wire is 0.8-1.6mm, and the components of the welding wire are, by mass percentage: Mn 3~10wt%, C 0.1~0.3%, Cr 0.1~1.0%, 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 temperature of the heat treatment is 930-940℃, and the quenching is performed by quenching oil, and the cooling rate is >50℃ / s.

2. The method of tailor welding a 1500 MPa grade Al-Si coated hot stamped steel according to claim 1, characterized in that, In S1, the gap of the spliced to-be-welded sheet is≤0.2mm.

3. The method of tailor welding a 1500 MPa grade Al-Si clad hot stamped 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 1.2-3.0m / min.

4. The method of tailor welding a 1500 MPa grade Al-Si clad hot stamped 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 of tailor welding a 1500 MPa grade Al-Si clad hot stamped steel according to claim 1, characterized in that, In S2, the protective atmosphere is argon, and the flow rate is 10-25L / min.

6. The method of tailor welding a 1500 MPa grade Al-Si clad hot stamped steel according to claim 1, characterized in that, In S1, the yield strength of the to-be-welded sheet is 900-1200Mpa, the tensile strength is 1300-1600Mpa, and the elongation is >4%.

7. The method of tailor welding a 1500 MPa grade Al-Si clad hot stamped steel according to claim 1, characterized in that, In S1, the to-be-welded surface is polished before splicing the to-be-welded sheet.

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