WO2022016594A1

WO2022016594A1 - Method for manufacturing parts made of aluminium-silicon plated steel/high-strength press-harden steel composite steel

Info

Publication number: WO2022016594A1
Application number: PCT/CN2020/105539
Authority: WO
Inventors: 孙茜; 朱天才; 王晓南; 胡增荣; 孙立宁
Original assignee: 苏州大学
Priority date: 2020-07-22
Filing date: 2020-07-29
Publication date: 2022-01-27
Also published as: CN111843214A

Abstract

Disclosed in the present invention is a method for manufacturing parts made of aluminium-silicon plated steel/high-strength press-harden steel composite steel, comprising: fixing an aluminium-silicon plated steel plate and a high-strength press-harden steel plate on a working table in a splicing manner, so that the two steel plates are in close contact; under a protective atmosphere, performing laser galvanometer welding at a joint of the two steel plates, so that the joint is melted and solidified to form a high-quality welding seam; and performing hot stamping on the welded steel plate to obtain a part made of aluminium-silicon plated steel/high-strength press-harden steel composite steel, wherein the protective atmosphere contains 5-100 vol. % of an oxidizing gas, and a movement path of a light spot is controlled to be shifted by 0-3 mm towards the side of the high-strength press-harden steel plate during galvanometer welding. The laser welding method of aluminium-silicon plated steel/high-strength press-harden steel of the present invention can achieve a good connection between an AI-Si plated steel and other high-strength press-harden steel without removing an Al-Si plating layer, improve the mechanical properties of a welding joint, and reduce the formation of δ ferrite in a welding seam.

Description

A kind of manufacturing method of aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts

technical field

The invention relates to the technical field of automobile parts manufacturing, in particular to a laser welding method for steel and high-strength hot forming steel without removing aluminum-silicon coating.

Background technique

Automobile lightweight is an important development direction of modern automobiles, and reducing body weight is an important way to achieve automobile lightweight. Using advanced high-strength steel or ultra-high-strength steel instead of ordinary steel in the body can reduce the weight of the car on the premise of ensuring the safety of the car. Hot-formed steel (Press-harden steel, PHS) is currently one of the highest strength steels for automobile body-in-white, and its tensile strength can reach more than 1500MPa. Hot-formed steel has ultra-high strength, which can well maintain the internal structure of the car body in the process of car collision, so as to avoid serious injury to passengers, and effectively improve the safety performance of the car. In the production process of hot stamped steel, in order to prevent surface oxidation and decarburization during the stamping process, the surface of the steel plate is usually pre-applied with an aluminum-silicon coating. The existence of aluminum-silicon coating can provide good corrosion resistance and high-temperature oxidation resistance for steel plates, but it will bring new problems to the welding of steel plates.

Scholars at home and abroad have done a lot of research on the welding performance of aluminum-silicon-coated steel, and obtained a lot of valuable research results. The precipitation of soft ferrite will seriously deteriorate the mechanical properties of welded joints.

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

For the removal of Al-Si coating, the existing main technical routes include mechanical stripping, laser ablation and chemical removal. Comparatively speaking, laser ablation is the most effective technology, and it is also the only technology for industrialized production of aluminum-silicon-coated laser-tailored welded blanks. Although laser ablation and electron beam ablation can be used to achieve laser welding of tailor-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 filler welding, the formation of delta ferrite in the weld is suppressed by adding a wire containing austenite-forming elements (C, Mn, Ni, N). Although laser ablation before welding is avoided, laser welding filler wire undoubtedly increases the investment 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, 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.

The Chinese patent with publication number CN106392328B (published on February 15, 2017) discloses a method for tailor welding a thermoformed steel sheet with Al-Si coating under the condition of protective gas using laser welding equipment, wherein the protection The gas includes a mixture of one or both of oxygen and carbon dioxide and an inert gas. The oxidizing gas used in this patent increases the oxygen partial pressure in the welding pool, so that the Al element entering the welding pool combines with the O element to form Al ₂ O ₃ that does not affect the strength and toughness of the weld, inhibiting Al and Fe The elements form intermetallic compounds and affect the austenite transformation, and finally a weld zone with a full lath martensitic structure is obtained, and the strength of the weld reaches the level of the base metal. The method does not need to add welding wire and does not need to remove the coating layer before welding, the method is simple, the production efficiency is improved, and the production cost is reduced. However, this solution still has the following shortcomings: First, the group of tailor-welded blanks has high requirements on the gap, and the gap is generally required to be no more than 0.1t, which is virtually equivalent to increasing the difficulty of welding; second, during the welding process , if the aluminum in the coating enters the welding pool, there will still be a risk of segregation, resulting in instability in the production process; third, the welding pool stays for a very short time, and the oxidation reaction of aluminum is limited, resulting in poor results.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts, which can realize Al-Si coated steel and Al-Si coated steel without removing the Al-Si coating. The good connection of other high-strength hot-formed steels improves the mechanical properties of welded joints and reduces the formation of delta ferrite in the weld, providing favorable conditions for the next step of hot stamping.

In order to solve the above-mentioned technical problems, the present invention provides the following technical solutions:

A method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts, comprising:

Step 1: Fix an aluminum-silicon-coated steel plate and a high-strength hot-formed steel plate on the workbench in the form of splicing, so that the two steel plates are in close contact;

Step 2: under a protective atmosphere, laser galvanometer welding is performed on the butt joints of the two steel plates, so that the joints are melted and solidified to form a high-quality weld;

Step 3: hot stamping the welded steel plate to obtain aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts;

Wherein, the protective atmosphere contains 5-100 vol.% oxidizing gas, and the moving path of the light spot is controlled to be offset by 0-3 mm to the side of the high-strength hot-formed steel sheet during the galvanometer welding.

Further, in step 1, the thickness of the aluminum-silicon coating of the aluminum-silicon coated steel sheet is 5-50 μm, and the aluminum content in the aluminum-silicon coating is more than 70%.

Further, in step 1, the thickness of the two steel plates is 0.8-3.0 mm, and the gap between the two steel plates is controlled to be less than 0.3t during fixing.

Further, in step 1, the composition of the steel plate in the aluminum-silicon coated steel plate is: 0.10%≤C≤0.5%; 0.5%≤Mn≤3%; 0.1%≤Si≤1%; 0.01%≤Cr≤1% ; Ti≤0.2%; Al≤0.1%; S≤0.05%; P≤0.1%; 0.0002%≤B≤0.010%, and the rest is iron.

Further, in step 1, the composition of the high-strength hot-formed steel sheet is: 0.10%≤C≤0.5%; 0.5%≤Mn≤3%; 0.1%≤Si≤1%; 0.01%≤Cr≤1%; Ti ≤ 0.2%; Al≤0.1%; S≤0.05%; P≤0.1%; 0.0002%≤B≤0.010%, V≤0.2%, and the rest is iron.

Further, in step 2, the protective atmosphere is an oxidizing gas or is composed of an oxidizing gas and an inert gas, and the inert gas is selected from one or more of helium, argon, and nitrogen, and the oxidizing gas is The gas is CO ₂ .

Further, in step 2, the protective atmosphere is the protective atmosphere in which the content of oxygen is less than or equal to 15 vol.%, and _{the content of CO 2 is} less than or equal to 100 vol.%.

Further, in step 2, the flow rate of the protective atmosphere is 5-35 L/min, the upper and lower surfaces of the steel plate need to be protected by shielding gas during the welding process, and the angle between the upper surface shielding gas nozzle and the surface of the steel plate is less than 90°.

Further, in step 2, the parameters of the laser galvanometer welding are: laser power 1000-10000W, welding speed 1-20m/min, scanning trajectory is "○", "∞", "←→" or

, the scanning radius is 0.3~3.0mm, and the scanning speed is 200~2000mm/s.

Further, in step 3, the heating temperature during hot stamping is between 900-1000°C, the heating time is controlled at 3-8 min, and the cooling rate after hot stamping is controlled at more than 30°C/s.

Beneficial effects of the present invention:

1. The laser welding method of the aluminum-silicon coated steel/high-strength hot-formed steel of the present invention can realize the good connection between the Al-Si coated steel and other high-strength hot-formed steel without removing the Al-Si coating, and improve the welding joint. The laser welding method of reducing the formation of delta ferrite in the weld provides favorable conditions for the next step of hot stamping.

2. The present invention utilizes laser galvanometer welding to replace existing laser linear welding, and the whirling vibration of laser galvanometer welding helps to stir the laser molten pool, so that the Al elements on the surface of the aluminum-silicon coated steel are uniformly dispersed in the molten pool, It helps to homogenize the elements in the molten pool, thereby enhancing the strength and toughness of the weld and improving the performance of the welded joint.

3. In the laser galvanometer welding of the present invention, the moving path of the laser beam spot during welding is shifted by a certain distance to the side of the high-strength thermoforming steel. When the moving path of the light spot has no deviation, the chemical composition content in the welding pool is a mixture of 50% Al-Si coated steel and 50% high-strength hot-forming steel; The content of molten high-strength hot-formed steel in the molten pool is higher than 50%, while the content of molten aluminum-silicon coated steel is less than 50%, thereby reducing the content of Al in the molten pool, so that no delta ferrite is formed in the weld, all of which are Lath martensite, which significantly increases the strength and toughness of the weld.

4. The present invention utilizes laser galvanometer to weld aluminum-silicon-coated steel and high-strength thermoforming steel to obtain a beautifully formed weld surface, no segregation of aluminum elements in the weld, no welding defects such as cracks, pores and inclusions, and no obvious weld surface. Oxidation phenomenon. Compared with traditional laser linear welding, laser beam swing welding has a wider seam width, and laser beam swing welding has a greater tolerance to the weld gap, which can reach 0.3t and below, so it can reduce the difficulty of welding, thereby reducing Welding costs.

Description of drawings

Fig. 1 is the schematic diagram of the laser welding method of the present invention;

Fig. 2 is the macroscopic topography of the upper surface of the weld seam welded by laser galvanometer in Example 1 (the upper side plate is aluminum-silicon coated steel, and the lower side plate is 2GPa hot-formed steel);

Figure 3 is the microstructure of the weld after linear laser welding and hot forming in Comparative Example 1 (LM refers to lath martensite, δ-F refers to δ ferrite);

Fig. 4 is the microstructure of the welded seam after laser galvanometer welding and thermoforming in Comparative Example 2;

5 is the microstructure of the welded seam after laser galvanometer welding and thermoforming in Example 1.

detailed description

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As mentioned in the background art, in the prior art, the welding of aluminum-silicon coated plates is mainly realized by three means: removing the aluminum-silicon coating, laser wire filling welding and optimizing the welding process. However, these three methods increase equipment investment and change the Various problems such as alloy composition and increased production cost.

In order to solve the above-mentioned various technical problems, the present invention provides a manufacturing method of aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts, including:

Fix an aluminum-silicon-coated steel plate and a high-strength hot-formed steel plate on the workbench in the form of splicing, so that the two steel plates are in close contact;

Under a protective atmosphere, laser galvanometer welding is performed on the butt joints of the two steel plates, so that the joints are melted and solidified to form high-quality welds;

Hot stamping the welded steel plate to obtain aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts;

In the present invention, the steel plate is preferably pretreated before welding to remove oil stains on the surface of the steel plate. The pretreatment is specifically cleaning the hot-formed steel sheet with a solvent, and then air-drying. As the solvent, ethanol, acetone and other commonly used cleaning solvents in the art can be used.

In the present invention, the steel plate can be directly fixed for welding after cleaning, and there is no need to remove the aluminum-silicon coating on the surface of the hot-formed steel plate by means of laser ablation, mechanical peeling, etc., which not only simplifies the welding process, but also reduces equipment investment and production costs. .

In the present invention, fixing the steel plates on the workbench in the form of splicing is specifically: placing two steel plates on the workbench, and using welding fixtures to fix them, so that the two steel plates are butted together. Wherein, the workbench and the welding fixture are not limited, and may be workbenches and welding fixtures well known to those skilled in the art.

In the present invention, the thickness of the two steel plates may be equal or unequal, and the thickness of the two steel plates is preferably between 0.8 and 3.0 mm.

In the present invention, when two steel plates are butted together, the gap between the steel plates can be controlled to be less than 0.3t, while the gap requirement of ordinary laser linear welding is not more than 0.1t. This shows that the welding method of the present invention has a higher tolerance of the gap of the welding seam, and can be used on components with lower requirements on the gap.

In the present invention, the source of the aluminum-silicon-coated steel sheet used is not particularly limited, and it can be the aluminum-silicon-coated steel sheet commonly used in the field. Wherein, the thickness of the aluminum-silicon coating is preferably between 5 and 50 μm, and the aluminum content in the aluminum-silicon coating is preferably more than 70%.

As the above-mentioned Al-Si coated steel sheet, the composition of the steel sheet may be (in mass percentage): 0.10%≤C≤0.5%; 0.5%≤Mn≤3%; 0.1%≤Si≤1%; 0.01%≤Cr≤1 %; Ti≤0.2%; Al≤0.1%; S≤0.05%; P≤0.1%; 0.0002%≤B≤0.010%, the rest are iron and inevitable impurities in the production process.

As the above-mentioned high-strength hot-formed steel sheet, its composition may be (in mass percentage): 0.10%≤C≤0.5%; 0.5%≤Mn≤3%; 0.1%≤Si≤1%; 0.01%≤Cr≤1%; Ti≤0.2%; Al≤0.1%; S≤0.05%; P≤0.1%; 0.0002%≤B≤0.010%, V≤0.2%, and the rest is iron.

In the present invention, the protective atmosphere is an oxidizing gas; or a mixed gas composed of an oxidizing gas and an inert gas. The oxidizing gas can be CO ₂ ; the inert gas can be one or more of helium, argon, and nitrogen. Preferably, in the protective atmosphere, the content of oxygen is less than or equal to 15 vol.%, and _{the content of CO 2 is} less than or equal to 100 vol.%. Further preferably, the protective atmosphere is: 80% Ar+20% CO ₂ or 100% CO ₂ .

In the present invention, the flow rate of the protective atmosphere is preferably 5-35 L/min, preferably 10-20 L/min.

In the present invention, the upper and lower surfaces of the steel plate must be fed with protective gas at the same time, and the angle between the upper surface gas nozzle and the surface of the steel plate is less than 90°.

In the present invention, the used laser welding equipment can be a fiber laser, a semiconductor laser or a carbon dioxide laser.

In the present invention, the parameters of laser galvanometer welding are: the laser power is preferably 1000-10000W, the welding speed is preferably 1-20m/min, and the scanning trajectory can be "○" or "∞" or

Or "←→" or the like can achieve similar trajectory changes, the scanning radius is preferably 0.3-3.0 mm, and the scanning speed is preferably 200-2000 mm/s.

In the present invention, the moving path of the light spot is shifted to the side of the high-strength thermoforming steel sheet by 0-3 mm, which means that the center of the laser scanning track is located on the side of the high-strength thermoforming steel sheet, and the distance between the butt joints with the two steel sheets is 0 to 3 mm, for example, may be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.5 mm, 2.5 mm, or the like. Its function is to not only realize the fusion welding of two steel plates, but also realize that the mass fraction of Al element in the molten pool is lower than the minimum mass fraction for forming delta ferrite.

In the present invention, the heating temperature during hot stamping of the tailor welded blank is preferably between 900 and 1000°C, the heating time is preferably controlled at 3 to 8 minutes, and the cooling rate after hot stamping is preferably controlled at more than 30°C/s. Through the above hot stamping treatment, it is ensured that the microstructure of the substrate and the weld is mainly lath martensite.

In the present invention, the welding seam strength of the laser welded joint formed after welding is 1000-1500 MPa, the strength of the aluminum-silicon coating side of the steel parts after hot stamping can reach 1500 MPa, and the strength of the high-strength hot-formed steel side can reach 2000 MPa.

The steel parts prepared by the invention can be used for possible future application positions such as A-pillars, B-pillars, intermediate passages, door knockers, etc. of the body-in-white of automobiles.

The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial sources unless otherwise specified.

Example 1

The welding method of oscillating galvanometer of aluminum-silicon-coated steel/high-strength hot-formed steel includes the following steps:

Step (1): select 1.5mm thick aluminum-silicon-coated 22MnB5 steel and 1.5mm-thick 2GPa hot-formed steel, remove oil stains with alcohol; the coating thickness of aluminum-silicon coated 22MnB5 steel is 20 μm to 40 μm.

Step (2): Place the two steel plates on the workbench in the form of splicing, and use a special welding fixture to make the two steel plates in close contact.

Step (3): use the IPG-6kW fiber laser to weld the test board, the laser power used is 3.0kW, the welding speed is 5.0m/min, the swing diameter is 0.5mm, the swing frequency is 50Hz, and the defocus amount is +5.0mm, the shielding gas used is 80% Ar+20% CO ₂ , and the path of the light spot during welding is shifted by 0.5mm from the splicing path of the two plates to the 2GPa hot-formed steel side.

Step (4): After obtaining the tailored laser welded blank, post-weld heat treatment is performed on it, and the heat treatment process is 930° C. for 5 minutes, followed by quenching treatment (water quenching), and finally a quenched laser tailored blank is obtained.

Referring to Figure 5, after welding, the macroscopic appearance of the weld was observed to be excellent, and there was no obvious splash. The structure of the weld was all lath martensite and no delta ferrite. The strength of welded joints reaches 1500MPa and above. After hot forming, the strength of the aluminum-silicon coating 22MnB5 steel side reaches 1500MPa and above, and the strength of the high-strength steel side reaches 2000MPa. The structure of the entire tailor welded blank parts is martensite.

Example 2

Oscillating laser welding of Al-Si-coated steel/high-strength hot-formed steel includes the following steps:

Step (1): Select 2.0mm thick aluminum-silicon-coated 22MnB5 steel and 1.5mm-thick 1800MPa hot-formed steel, and remove oil stains with alcohol; the coating thickness of aluminum-silicon coated 22MnB5 steel is 20 μm to 40 μm.

Step (3): Use the IPG-10kW fiber laser to splicing and welding the test board. The laser power used is 10.0kW, the welding speed is 6.0m/min, the defocusing amount is 0mm, the swing diameter is 6.0mm, and the spot direction is 1800MPa. The steel side is offset by 2.5mm and the swing frequency is 50Hz. The protective gas used is 100% CO ₂ , and the moving path of the spot during welding is the splicing path of two steel plates.

Step (4): After obtaining the tailored laser welded blank, heat treatment is performed on it. The heat treatment process is 950° C. for 5 minutes, and then quenched (water quenching) to finally obtain a quenched tailored laser welded blank.

The strength of the welded joint can reach more than 1500MPa, and the tensile fracture position appears on the aluminum-silicon-coated steel side. After hot forming, the strength of the aluminum-silicon coating 22MnB5 steel side reaches 1500MPa, and the strength of the high-strength steel side can reach 1800MPa. The microstructure of the entire composite part is lath martensite without other structures.

Comparative Example 1

Linear laser welding of Al-Si-coated steel/high-strength hot-formed steel includes the following steps:

Step (3): Use the IPG-6kW fiber laser to weld the test board, the laser power used is 3.0kW, the welding speed is 5.0m/min, the defocusing amount is +5.0mm, and the shielding gas used is 80% Ar +20% CO ₂ , the moving path of the spot during welding is the splicing path of two steel plates.

Step (4): After obtaining the tailored laser welded blank, heat treatment is performed on it. The heat treatment process is 930° C. for 5 minutes, and then quenched (water quenching) to finally obtain a quenched tailored laser welded blank.

It can be seen from Figure 3 that the macroscopic appearance of the weld is excellent, and there is more delta ferrite on the side of the welded joint near the 22MnB5 steel of the Al-Si coating. The strength of welded joints can reach 1400MPa and above. After hot forming, the strength of the aluminum-silicon coating 22MnB5 steel side reaches 1500MPa, and the strength of the high-strength steel side can reach 2000MPa.

Comparative Example 2

Step (1): select 1.5mm thick aluminum-silicon-coated 22MnB5 steel and 1.5mm-thick 2GPa hot-forming steel, remove oil stains with alcohol; the coating thickness of aluminum-silicon coated 22MnB5 steel is 20 μm to 30 μm.

Step (3): Use the IPG-6kW fiber laser to weld the test board. The laser power used is 3.0kW, the welding speed is 5.0m/min, the defocusing amount is +5.0mm, and the swing diameter is 0.5mm and 0.8 mm, the swing frequency is 50Hz. The protective gas used is 80% Ar+20% CO ₂ , and the moving path of the spot during welding is the splicing path of two steel plates.

When the swing diameter is 0.5 mm, there is no obvious splash, and it is observed that the macroscopic appearance of the weld is excellent. When the swing diameter is 0.8 mm, the spatter is obvious, and the macroscopic appearance of the weld is observed to be poor. There is a small amount of delta ferrite near the Al-Si coating 22MnB5 steel side of the welded joints under the two swing diameters. The strength of welded joints can reach 1400MPa and above. After hot forming, the strength of the aluminum-silicon coating 22MnB5 steel side reaches 1500MPa, and the strength of the high-strength steel side can reach 2000MPa.

Comparative Example 3

Step (3): Use the IPG-6kW fiber laser to weld the test board, the laser power used is 3.0kW, the welding speed is 5.0m/min, the defocusing amount is +5.0mm, and the shielding gas used is 80% Ar +20% CO ₂ , the light spot path during welding is offset by 0.5mm from the splicing path of the two plates to the 2GPa hot-formed steel side.

After welding, it was observed that there were some incomplete penetration defects on the 22MnB5 steel side of the aluminum-silicon coating of the weld, and the strength of the welded joint was poor, which could not meet the requirements of actual production.

Table 1 Tensile strength of joints under different welding methods

From the results in Table 1, it can be seen that compared with simple linear welding and swing welding, the use of swing welding + offset of 0.5 mm can improve the tensile strength of the welded joint.

The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

A method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts, comprising:

Step 1: Fix an aluminum-silicon-coated steel plate and a high-strength hot-formed steel plate on the workbench in the form of splicing, so that the two steel plates are in close contact;

Step 2: under a protective atmosphere, laser galvanometer welding is performed on the butt joints of the two steel plates, so that the joints are melted and solidified to form a high-quality weld;

Step 3: hot stamping the welded steel plate to obtain aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts;

Wherein, the protective atmosphere contains 5-100 vol.% oxidizing gas, and the moving path of the light spot is controlled to be offset by 0-3 mm to the side of the high-strength hot-formed steel sheet during the galvanometer welding.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 1, wherein in step 1, the thickness of the aluminum-silicon coating of the aluminum-silicon coated steel plate is 5-50 μm , the aluminum content in the aluminum-silicon coating is more than 70%.
The method for manufacturing an aluminum-silicon-coated steel/high-strength hot-formed steel composite steel part according to claim 1, wherein in step 1, the thickness of the two steel plates is 0.8-3.0 mm, and when fixing Control the gap between the two steel plates below 0.3t.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 1, wherein in step 1, the composition of the steel plate in the aluminum-silicon coated steel plate is: 0.10%≤ C≤0.5%; 0.5%≤Mn≤3%; 0.1%≤Si≤1%; 0.01%≤Cr≤1%; Ti≤0.2%; Al≤0.1%; S≤0.05%; P≤0.1%; 0.0002 %≤B≤0.010%, the rest is iron.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 1, wherein in step 1, the composition of the high-strength hot-formed steel plate is: 0.10%≤C≤ 0.5%; 0.5%≤Mn≤3%; 0.1%≤Si≤1%; 0.01%≤Cr≤1%; Ti≤0.2%; Al≤0.1%; S≤0.05%; P≤0.1%; 0.0002%≤ B≤0.010%, V≤0.2%, the rest is iron.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 1, wherein in step 2, the protective atmosphere is an oxidizing gas or a combination of oxidizing gas and inert gas Gas composition, the inert gas is selected from one or more of helium, argon, and nitrogen, and the oxidizing gas is CO 2 .
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 6, wherein in step 2, the protective atmosphere is the protective atmosphere with an oxygen content ≤ 15vol.%, CO 2 content≤100vol.%.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 1, wherein in step 2, the flow rate of the protective atmosphere is 5-35L/min, and the welding process The upper and lower surfaces of the middle steel plate need to be protected by protective gas, and the angle between the protective gas nozzle on the upper surface and the surface of the steel plate is less than 90°.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-forming steel composite steel parts according to claim 1, wherein in step 2, the parameters of the laser galvanometer welding are: laser power 1000-10000W , the welding speed is 1~20m/min, the scanning trajectory is "○", "∞", "←→" or "/\/\/\/\/\/", the scanning radius is 0.3~3.0mm, and the scanning speed is 200～2000mm/s.
The method for manufacturing aluminum-silicon-coated steel/high-strength hot-formed steel composite steel parts according to claim 1, wherein in step 3, the heating temperature during hot stamping is between 900 and 1000 °C, and the heating time is It is controlled at 3-8min, and the cooling rate after hot stamping is controlled at more than 30°C/s.