CN110293312A - A kind of preparation method of the drop stamping material of aluminium silicon cladding steel - Google Patents

Abstract

The invention provides a method for preparing a hot stamping material of aluminum-silicon-coated steel, comprising the following steps: A) performing laser ablation on the aluminum-silicon coatings on the surface of two or more pieces of hot-formed steel; Laser welding the hot-formed steel sheets under an alternating magnetic field to obtain a laser tailor-welded blank; C) performing hot stamping and cooling on the laser tailor-welded blank in sequence to obtain a hot stamping material of aluminum-silicon-coated steel. In this application, laser ablation is first used to reduce the amount of aluminum entering, and then the alternating magnetic field is used to assist the laser welding process to promote the uniform distribution of aluminum in the weld and avoid the occurrence of aluminum segregation areas; the final hot stamping ensures the laser welded blank The weld zone is a lath martensitic structure. The above preparation method provided by the present invention improves the service life and service safety of welded joints and hot stamping materials, and improves production efficiency.

Description

A kind of preparation method of hot stamping material of aluminum-silicon coated steel

technical field

The invention relates to the field of welding and the field of manufacturing hot stamping parts, in particular to a method for preparing a hot stamping material of aluminum-silicon coated steel.

Background technique

Tailored welded blank technology can weld steel plates of different thickness specifications and strength levels together to achieve structural weight reduction, reduce mold usage, and improve production efficiency. Compared with other welding methods, laser welding to manufacture tailor-welded blanks has higher production efficiency and a higher degree of automation. Aluminum-silicon-coated hot-formed steel is one of the highest-strength steels in the field of automobile bodies, with a tensile strength of up to 1500 MPa. It is mainly used in the manufacture of safety structural parts such as A-pillars, B-pillars, anti-collision beams, and intermediate passages.

In recent years, laser welded blanks obtained from aluminum-silicon-coated hot-formed steel have been widely used in the manufacture of door knockers and other auto parts. However, the aluminum-silicon coating on the surface of the hot-formed steel enters the welding pool during the welding process, and the aluminum will increase the content of the primary phase delta ferrite in the solidification of the laser welding pool, so that the delta ferrite remains at room temperature, and the hot-stamped austenite The delta ferrite cannot be eliminated during the stamping process, resulting in that the weld strength after hot stamping cannot reach the level of the base metal.

In order to solve this problem, a large number of solutions have been proposed at home and abroad; they can be summarized into the following three aspects: first, remove the aluminum-silicon coating; second, laser wire-filled welding; third, optimize the welding process.

For the removal of aluminum-silicon coating, the existing main technical routes include mechanical stripping, laser ablation and chemical removal. In contrast, laser ablation is the most effective technology, and it is also the only technology for the industrial production of aluminum-silicon-coated laser tailor-welded blanks. In the patent 200780013854.1, ArcelorMittal of France disclosed a method of using laser ablation technology to remove the aluminum-silicon coating, followed by laser welding. Kunshan Baojin Tailored Welded Blank Co., Ltd.’s patent 201610166320.3 discloses a laser processing method that integrates coating removal and welding of hot-rolled steel sheets. In essence, this method still requires the use of nanosecond lasers or picosecond lasers to remove the aluminum-silicon coating in advance. , and then use one of CO ₂ gas laser, YAG solid-state laser, fiber laser and semiconductor laser for laser welding; at the same time, the patent 201610167791.6 applied by the company discloses an ultrashort pulse laser galvanometer scanning to remove hot-rolled steel plates Coating method. Patent CN106232285A discloses a steel welded part with aluminum or aluminum alloy coating and its manufacturing method. This method peels off 100% of the aluminum layer on the surface and retains 100% of the intermetallic compound layer; the Chinese patent with publication number 106334875A A method is disclosed for producing welded parts with good mechanical properties from rolled coated sheet which strips off all coating substances including 100% of the aluminum layer and 100% of the intermetallic compound layer. Patent 201810581119.0 discloses a method for removing the surface coating of steel plates and a welding stamping method, which mainly removes the aluminum coating in the area to be welded by high-energy electron beam ablation in an atmospheric environment; patent 201810223902.X uses plasma ablation, etc. Remove the Al-Si coating.

It can be seen that although laser ablation and electron beam ablation can be used to realize laser welding of laser welded blanks containing aluminum-silicon coated steel, the laser ablation process undoubtedly increases equipment investment, reduces production efficiency, and increases production costs. .

For laser wire welding, the formation of delta ferrite in the weld is suppressed by adding a wire containing austenite formers (C, Mn, Ni, N). Patent 201380001259.1 discloses a filler wire (the content of C is 0.1%-0.8%wt higher than that of the base material, and the content of Mn is 1.5%-7.0%wt higher than that of the base material) to suppress the occurrence of ferrite transformation in the weld zone. It realizes direct laser tailor welding without removing the Al-Si coating, and can obtain high-quality tailor welded blanks of different materials or thicknesses. Patent 201510165732.0 discloses a method for manufacturing tailor-welded blanks, which involves welding one or more pairs of different coated steel sheets with different thicknesses or strengths by laser using a filler wire. Patent 201180034151.3 discloses a method of arc/laser hybrid welding of aluminum-coated steel parts with gamma elements and gas containing less than 10% nitrogen or oxygen, and the welding pool is formed on at least one steel part including aluminum surface coating Above, the consumable welding wire contains at least 3% by weight of one or more gamma elements (especially gamma elements selected from C, Mn, Ni and N), and the shielding gas consists of helium and/or argon and additionally nitrogen or oxygen with a volume content of at least 10%. Patent 201810032131.6 discloses a method of manufacturing aluminum-silicon-coated thermoformed steel tailor-welded blanks by laser wire-filling welding. The welding wire used is added with rich austenite-poor ferrite elements, and suppresses aluminum through a comprehensive method of dilution and element transition. Effect of silicon coating.

Although laser ablation before welding is avoided, laser welding wire filler undoubtedly increases the input of welding wire and changes the alloying composition of the laser weld, which may bring new problems to the subsequent hot stamping forming process. For optimizing the laser welding process, it is mainly by adjusting the laser welding power, changing the shape of the weld, or using laser swing welding. Although the strength of the laser weld can be slightly improved, it cannot fundamentally solve this problem.

In view of the problems existing in the above-mentioned existing technologies, it is urgent to propose a new manufacturing method for tailor-welded blanks for aluminum-silicon coated steel, which can not only improve the mechanical properties of welded joints, but also reduce the degree of weld alloying and production costs.

Contents of the invention

The technical problem solved by the present invention is to provide a method for preparing a hot stamping material of aluminum-silicon coated steel. The hot stamping material of aluminum-silicon coated steel prepared by the method can reduce the alloying degree of the weld seam and improve the mechanical properties of the welded joint.

In view of this, the present application provides a method for preparing a hot stamping material of aluminum-silicon coated steel, comprising the following steps:

A) performing laser ablation on the aluminum-silicon coatings on the surfaces of more than two pieces of thermoformed steel respectively, the removal thickness of the aluminum-silicon coatings being 45% to 65% of the original thickness of the aluminum-silicon coatings;

B) performing laser welding on the thermoformed steel sheet obtained in step A) under an alternating magnetic field to obtain a tailor-welded blank;

C) Hot stamping and cooling the tailor-welded blank in sequence to obtain a hot stamping material of aluminum-silicon-coated steel.

Preferably, the thickness of the aluminum-silicon-coated steel is 0.8 mm to 2.0 mm, and the removed thickness of the aluminum-silicon coating is 45% to 65% of the original thickness of the aluminum-silicon coating.

Preferably, in step B), the laser for laser welding is selected from one of fiber laser, _CO2 laser, Nd:YAG laser and semiconductor laser; the laser power of the laser is 1000-6000W, and the welding speed is 5 ~15m/min.

Preferably, the laser power of the laser is 2000-4000W, and the welding speed is 10-15m/min.

Preferably, the alternating magnetic field is emitted by a laser generator, the frequency of the laser generator is 0-50 Hz, and the current is 0-60A.

Preferably, the frequency of the laser generator is 20-50 Hz, and the current is 20-40A.

Preferably, the laser welding is carried out in carbon dioxide, oxygen or a mixed gas of carbon dioxide, oxygen and inert gas.

Preferably, the laser welding is carried out in a mixed gas of carbon dioxide, oxygen and inert gas, and the specific ratio is x%CO ₂ +y%O ₂ +(100-xy)%Ar, wherein x is 10-40, y 11-20.

Preferably, the temperature of the hot stamping is 980-1050° C., and the time is 5-10 minutes.

Preferably, the microstructure of the welded joint of the aluminum-silicon-coated steel hot stamping material is lath martensite.

The present application provides a method for preparing a hot stamping material of aluminum-silicon-coated steel. First, the aluminum-silicon coating on the surface of the hot-formed steel is ablated respectively to remove 45% to 65% of the aluminum-silicon coating, and then the obtained The hot-formed steel plate is laser-welded under an alternating magnetic field, and finally hot-stamped and cooled to obtain a hot-stamped material; this application first removes 45% to 65% of the aluminum-silicon coating to greatly reduce the aluminum-silicon coating during the laser welding process. The amount of entering the weld pool avoids deterioration of the weld performance; on this basis, laser welding is carried out under an alternating magnetic field to ensure that the aluminum in the weld pool can be evenly distributed, and no deviation occurs in the upper part of the weld or near the fusion line. Polymerization helps to improve problems such as weld sag and pore defects; the final hot stamping further ensures that the weld structure of the hot stamping material is lath martensite, which further ensures the mechanical properties of the welded joint of the hot stamping material. Furthermore, laser welding is carried out in an oxidizing atmosphere, which converts solid solution aluminum into alumina inclusions, reduces the amount of aluminum entering the molten pool, and further ensures the mechanical properties of the welded joint.

Description of drawings

Fig. 1 is the schematic diagram that the hot stamping material preparation of aluminum-silicon coated steel provided by the present invention;

Fig. 2 is the scanning electron micrograph of the welded joint of the hot stamping material of the aluminum-silicon coated steel prepared in comparative example 1 of the present invention;

Fig. 3 is a scanning electron microscope image of the welded joint of the hot stamping material of aluminum-silicon-coated steel prepared in Example 1 of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

The main reason why aluminum-silicon-coated thermoformed steel laser tailor-welded blanks cannot be welded with coating is that aluminum entering the welding pool will increase the content of delta ferrite in the solidified primary phase of the molten pool, resulting in incomplete delta ferrite. It turns into austenite and finally stays at room temperature, and, in the subsequent hot stamping process, delta ferrite cannot disappear, so it remains in the weld after hot stamping. Ultimately, the presence of ferrite causes the quality of welded joints to fail to meet service requirements. To solve this problem, the key is to control the content and distribution of aluminum in the weld. This application takes this as a starting point, firstly through laser ablation to appropriately reduce the amount of aluminum entering, and then preferably through oxidizing atmosphere welding in the laser welding process to further transform solid solution aluminum into alumina inclusions, and use alternating magnetic field to assist laser welding The process promotes the uniform distribution of aluminum in the weld and avoids the occurrence of aluminum segregation zones; in order to ensure that the weld zone is still lath martensite after hot stamping, this application further limits the temperature of hot stamping. Specifically, the embodiment of the present invention discloses a method for preparing a hot stamping material of aluminum-silicon coated steel, which includes the following steps:

A) performing laser ablation on the aluminum-silicon coatings on the surfaces of more than two pieces of thermoformed steel respectively, the removal thickness of the aluminum-silicon coatings being 45% to 65% of the original thickness of the aluminum-silicon coatings;

B) performing laser welding on the thermoformed steel sheet obtained in step A) under an alternating magnetic field to obtain a tailor-welded blank;

C) Hot stamping and cooling the tailor-welded blank in sequence to obtain a hot stamping material of aluminum-silicon-coated steel.

In the preparation process of the hot stamping material of aluminum-silicon coated steel, the application firstly performs laser ablation of the aluminum-silicon coating on the surface of the hot-formed steel; Yes, the thermoformed steel plates are welded together according to the requirements of the product, and the welded joints are formed between the steel plates. Both the upper and lower surfaces of the hot-formed steel sheet have aluminum-silicon coatings, so the aluminum-silicon coatings on the upper and lower surfaces need to be removed. In the above process, the removed thickness of the aluminum-silicon coating is 45% to 65% of the original thickness of the aluminum-silicon coating. In a specific embodiment, the removed thickness of the aluminum-silicon coating is the original thickness of the aluminum-silicon coating 48-55% of the thickness; if the removal thickness is less than 45%, the aluminum content in the weld after welding will be too high, and a coarse aluminum-rich delta ferrite structure will still appear, and the performance cannot meet the requirements. If it is higher than 65%, the The cost will be increased, and the performance will not be significantly improved; further, the removal thickness of the aluminum-silicon coating described in this application is related to the subsequent operation and cannot be viewed separately. The thickness of the hot-formed steel is 0.8-2.0 mm, and in a specific embodiment, the thickness of the hot-formed steel is 1.0-1.8 mm. The technical method of the laser ablation is well known to those skilled in the art, and there is no particular limitation in this application. In a specific embodiment, the laser ablation uses a nanosecond laser or a picosecond laser. More specifically, the The laser ablation described above uses a picosecond laser.

After laser ablation, prepare for laser welding according to the routine operations of those skilled in the art, that is, place the hot-formed steel obtained above on the workbench in a spliced manner and fix it with a welding fixture to prepare for laser welding (as shown in Figure 1 shown); after the preparatory work, the above-mentioned hot-formed steel is laser welded under an alternating magnetic field to obtain a tailor-welded blank; in the above-mentioned process, the alternating magnetic field is provided by a magnetic field generator, and its frequency is 0-50HZ, the current is 0-60A; in a specific embodiment, the frequency of the magnetic field generator is 20-50HZ, and the current is 20-40A. In order to ensure that the aluminum in the welding pool can be evenly distributed, and no segregation occurs in the middle and upper parts of the weld and near the fusion line, the welding pool is electromagnetically stirred by the magnetic field generator under the welding fixture during the welding process, thus ensuring that the aluminum in the welding Evenly distributed in the seam, and at the same time help to improve the problems of weld sags, pores and other defects.

Further, the laser welding is carried out in carbon dioxide, oxygen or a mixed gas of carbon dioxide, oxygen and inert gas; more specifically, the laser welding is carried out in a mixed gas of carbon dioxide, oxygen and inert gas, and the specific ratio is x %CO ₂ +y%O ₂ +(100-xy)%Ar, wherein x is 10-40 and y is 11-20. The laser welding is carried out under the above-mentioned atmosphere, and the oxygen element in it can promote the reaction between aluminum and oxygen in the welding pool to form alumina inclusions, further reducing the content of solid-solution aluminum in the weld.

The specific technical mode of the laser welding described in the application is carried out according to the manner well known to those skilled in the art, and the laser of the laser welding described in the application is selected from a fiber laser, CO ₂ lasers, Nd: a kind of in YAG lasers and semiconductor lasers; The laser power of the laser is 1000-6000W, and the welding speed is 5-15m/min. In a specific embodiment, the laser power of the laser is 2000-4000W, and the welding speed is 10-15m/min.

At the end of the present application, the laser welded tailor welded blank is hot stamped and cooled to obtain the hot stamping material of aluminum-silicon coated steel. The specific technical means of the hot stamping and the cooling are well known to those skilled in the art, and there is no particular limitation in this application; in a specific embodiment, the temperature of the hot stamping is 980-1100°C.

In the process of preparing the hot stamping material of aluminum-silicon-coated steel, this application finally guarantees laser tailor welding through the lower removal amount of aluminum-silicon coating combined with the limitations of the subsequent alternating magnetic field, laser welding and hot stamping. The microstructure of the welded joint of the plate is full lath martensite, which improves the mechanical properties of the welded joint.

In order to further understand the present invention, the preparation method of the aluminum-silicon-coated steel hot stamping material provided by the present invention will be described in detail below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.

Example 1

S1) Take two aluminum-silicon-coated steel sheets with a thickness of 1.5 mm. The base metal structure is pearlite and ferrite. Use a nanosecond laser to perform laser ablation to remove the coating. The removal amount of the coating is 18 μm (60%). 12 μm (40%) (the total thickness of the coating is calculated as 30 μm), and the upper and lower surfaces of the two steel plates are removed respectively;

S2) placing the two steel plates obtained in step S1) on the workbench in a spliced manner and fixing them with a welding fixture;

S3) Turn on the magnetic field generator, and after the magnetic field is stable, use the IPG-6kW fiber laser to irradiate the steel plate with 80% Ar+20% _CO in an oxidizing atmosphere to weld the joint of the two steel plates. During the welding process, the joint is melted, Solidification and cooling form a high-quality weld, and complete the welding of two steel plates; in the above process, the welding power is 2000W, the welding speed is 5m/min, the defocus is +5mm, and the spot diameter is 0.40mm; the magnetic field generator The parameters are designed to have a frequency of 20HZ and a current of 20A;

S4) Put the tailor-welded blank obtained in step S3) into the heating furnace through the roller table, and carry out the austenitization process at 980°C for 5 minutes, then use the robot arm to move the tailor-welded blank to the hot stamping die, and Hot stamping and quenching are done in the mold.

The macroscopic appearance of the weld after laser welding and hot stamping is excellent, without obvious spatter; there is no high-temperature δ ferrite in the weld microstructure, and the weld microstructure is a full lath martensite structure (as shown in Figure 3 shown); the strength of the welded joint reaches the level of the base metal, the tensile fracture position is at the base metal, and the tensile strength is 1640MPa.

Comparative example 1

The preparation method of the hot stamping material of aluminum-silicon coated steel is the same as that of Example 1, the difference being that the removal amount of the coating is adjusted to be 9 μm (30%) in the S1 process, and the retention amount is 21 μm (70%) (the coating The total thickness is calculated as 30μm); the temperature of hot stamping is 950°C.

The scanning electron micrograph of the welded joint of the hot stamping material of the aluminum-silicon coated steel prepared in this comparative example is shown in Figure 2; after quenching, it was found that there was a certain amount of δ ferrite and α ferrite in the weld, The middle fracture position appears in the weld zone, and the tensile strength is only 1380MPa.

Example 2

S1) Take aluminum-silicon-coated steel sheets with thicknesses of 1.2mm and 1.8mm respectively, the base metal structure is pearlite and ferrite, and use a picosecond laser to perform laser ablation to remove the coating, and the removal amount of the coating is 13.5 μm (45%) , the retention amount is 16.5 μm (65%) (the total thickness of the coating is calculated as 30 μm), and the upper and lower surfaces of the two steel plates are removed respectively;

S2) Place the two steel plates that have been decontaminated in step S1 on the workbench in a spliced manner and fix them with a welding fixture;

S3) Turn on the magnetic field generator, and after the magnetic field is stable, use a semiconductor laser to irradiate the joint of the two steel plates in an oxidizing atmosphere of 55% Ar+30% CO ₂ +15% O ₂ for laser welding. Melting, solidification and cooling to form a high-quality weld seam to complete the welding of two steel plates; in the above process, the welding power is 4000W, the welding speed is 10m/min, the defocus is -5mm, and the spot size is 0.8mm×0.8 mm; The parameters of the magnetic field generator are designed to have a frequency of 30HZ and a current of 40A;

S4) Put the tailor-welded blank obtained in step S3) into the heating furnace through the roller table, and carry out the austenitization process at 1100°C for 5 minutes, then use the robot arm to move the tailor-welded blank to the hot stamping die, and Hot stamping and quenching are done in the mold.

The macroscopic appearance of the weld after laser welding and hot stamping is excellent, without obvious spatter; there is no high-temperature δ ferrite in the microstructure of the weld, and the weld structure is a full lath martensite structure, and the strength of the welded joint is Reaching the level of the base material, the tensile strength is 1650MPa, and the tensile fracture position appears in the base material.

Comparative example 2

The preparation method of the hot stamping material of aluminum-silicon coated steel is the same as that of Example 2, the difference is that the current design value of the magnetic field generator in the S3 process is 15A, and a small amount of δ ferrite can be observed in the weld near the fusion line after heat treatment EDS energy spectrum analysis shows that there is obvious segregation of aluminum elements here, and the weld structure cannot achieve full lath martensitization; the tensile fracture position appears in the weld zone, and the tensile strength is 1480MPa.

Comparative example 3

The preparation method of the hot stamping material of aluminum-silicon coated steel is the same as that of Example 2, except that the heat treatment temperature in the S5 process is adjusted to 920°C, and the temperature is kept for 5 minutes for austenitization, followed by hot stamping and quenching. After heat treatment, α-ferrite, which softens the structure, will appear in the weld structure, resulting in that the weld structure is not full lath martensite; the fracture position appears in the weld zone during the stretching process, and the tensile strength is only 1400MPa.

Comparative example 4

The preparation method of the hot stamping material of aluminum-silicon coated steel is the same as that of Example 2, except that the shielding gas used during laser welding in the S3 process is adjusted to 85% Ar+10% CO2+5% O2. After quenching, a certain amount of δ ferrite and α ferrite appeared in the final weld, resulting in the strength of the joint being lower than that of the base metal, and the fracture position appeared in the weld, with a tensile strength of 1500MPa.

Example 3

S1) Take aluminum-silicon-coated steel plates with thicknesses of 1.2mm and 1.8mm respectively. The base metal structure is pearlite and ferrite. Use a picosecond laser to perform laser ablation to remove the coating. The removal amount of the coating is 16 μm (the total thickness of the coating is 30 μm), remove the upper and lower surfaces of the two steel plates respectively;

S2) Place the two steel plates that have been decontaminated in step S1) on the workbench in a spliced manner and fix them with a welding fixture;

S3) Turn on the magnetic field generator, and after the magnetic field is stable, use a semiconductor laser to irradiate the joint of the two steel plates in an oxidizing atmosphere of 55% Ar+30% CO ₂ +15% O ₂ for laser welding. Melting, solidification and cooling to form a high-quality weld seam to complete the welding of two steel plates; in the above process, the welding power is 4000W, the welding speed is 10m/min, the defocus is -5mm, and the spot size is 0.8mm×0.8 mm; The parameters of the magnetic field generator are designed to have a frequency of 30HZ and a current of 40A;

S4) Put the tailor-welded blank obtained in step S3) into the heating furnace through the roller table, and carry out the austenitization process at 1100°C for 5 minutes, then use the robot arm to move the tailor-welded blank to the hot stamping die, and Hot stamping and quenching are done in the mold.

The macroscopic appearance of the weld after laser welding and hot stamping is excellent, without obvious spatter, and there is no high-temperature δ ferrite in the microstructure of the weld. Reaching the level of the base material, the tensile strength is 1650MPa, and the tensile fracture position appears in the base material.

The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A preparation method of a hot stamping material of aluminum-silicon coated steel, comprising the following steps: A) performing laser ablation on the aluminum-silicon coatings on the surfaces of more than two pieces of thermoformed steel respectively, the removal thickness of the aluminum-silicon coatings being 45% to 65% of the original thickness of the aluminum-silicon coatings; B) performing laser welding on the thermoformed steel sheet obtained in step A) under an alternating magnetic field to obtain a tailor-welded blank; C) Hot stamping and cooling the tailor-welded blank in sequence to obtain a hot stamping material of aluminum-silicon-coated steel. 2. The preparation method according to claim 1, characterized in that the thickness of the aluminum-silicon coating steel is 0.8 mm to 2.0 mm, and the removal thickness of the aluminum-silicon coating is 45% to 65% of the original thickness of the aluminum-silicon coating. %. 3. preparation method according to claim 1, is characterized in that, step B) in, the laser of described laser welding is selected from fiber laser, CO ₂ lasers, Nd: a kind of in YAG laser and semiconductor laser; The laser power of the laser is 1000-6000W, and the welding speed is 5-15m/min. 4. The preparation method according to claim 3, characterized in that the laser power of the laser is 2000-4000W, and the welding speed is 10-15m/min. 5. The preparation method according to claim 1, wherein the alternating magnetic field is emitted by a laser generator, the frequency of the laser generator is 0-50 Hz, and the current is 0-60A. 6. The preparation method according to claim 5, characterized in that, the frequency of the laser generator is 20-50 Hz, and the current is 20-40A. 7. The preparation method according to claim 1, characterized in that the laser welding is carried out in carbon dioxide, oxygen or a mixed gas of carbon dioxide, oxygen and inert gas. 8. The preparation method according to claim 7, wherein the laser welding is carried out in a mixed gas of carbon dioxide, oxygen and inert gas, and the specific proportion is x%CO ₂ +y%O ₂ +(100- xy)% Ar, wherein x is 10-40, and y is 11-20. 9. The preparation method according to claim 1, characterized in that the temperature of the hot stamping is 980-1050° C., and the time is 5-10 minutes. 10. The preparation method according to claim 1, characterized in that, the microstructure of the welded joint of the hot stamping material of the aluminum-silicon coated steel is lath martensite.