Iron-based welding wire for tailored blank laser welding of aluminum-silicon coating hot-formed steel and tailored blank welding method

Abstract

The invention discloses an iron-based welding wire for tailored blank laser welding of aluminum-silicon coating hot-formed steel and a tailored blank welding method, and the iron-based welding wire comprises the following components in percentage by mass: 3.5%-10% of Mn, 0.1%-0.3% of C, 0.1%-1.0% of Cr, 0.1%-0.3% of Si, 0.04%-0.2% of Nb, 0.1%-1.0% of V, 0-2% of Ni and the balance of Fe and inevitable impurities. According to the welding wire, the elements such as manganese, niobium and vanadium are optimally proportioned and cooperate with one another, so that the welding wire has excellent anti-cracking performance and metallurgical bonding performance; the tensile strength, toughness and other mechanical properties of the welded joint are remarkably improved, and the performance requirements of the high-strength steel plate spliced and welded joint are met; the welding wire can effectively solve the embrittlement problem of the aluminum-silicon coating in the welding process, and the influence of the coating on the welding quality is reduced. In addition, the iron-based welding wire has good compatibility with a steel plate material.

Description

Technical Field

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

[0002] As the automotive industry pursues lightweight, safety, energy conservation and environmental protection, hot stamping technology has been widely used in automobile manufacturing. After hot stamping, high-strength steel plates such as 22MnB5 have high strength and excellent impact resistance, which can meet the high requirements of body structural parts to resist deformation. In order to improve the oxidation resistance and corrosion resistance, this type of hot stamping steel plate is usually coated with an aluminum silicon (Al-Si) coating.

[0003] Laser welding technology can precisely join steel plates of different thicknesses or materials to produce a variety of complex body parts. Laser welding has the advantages of narrow welds, fast welding speeds, and small heat-affected zones, making it particularly suitable for the manufacture of body structural parts. However, for hot stamped steel with aluminum silicon coatings, the aluminum silicon coating will enter the molten pool during the laser welding process, and the aluminum element is prone to segregation near the fusion line to form a banded δ-ferrite phase, which can easily cause cracks and reduce the strength and toughness of the joint.

[0004] At present, the methods to solve the laser welding problem of hot stamping plates with aluminum silicon coating are as follows: (1) pre-welding coating removal technology, that is, before laser welding, the coating is removed by using carbide tools and laser ablation technology. This technology increases the complexity of the process, reduces production efficiency, and may damage the surface of the substrate; (2) oscillating laser beam welding technology, that is, using oscillating laser welding with an "∞"-shaped path to increase the diversity of the flow direction of the molten pool, stir the molten pool, accelerate the diffusion of aluminum elements, and achieve the purpose of reducing aluminum segregation. However, the oscillating laser beam has high requirements for equipment, increases costs, and is difficult to control the uniformity of the weld; (3) laser wire filling welding technology, that is, filling carbon steel welding wire during laser welding to dilute the aluminum element in the weld to reduce aluminum segregation. At present, high nickel content welding wire is mainly used. Although this type of welding wire has excellent crack resistance and weldability, nickel is a rare metal and its price is relatively high, resulting in a significant increase in welding costs, which limits the economy and popularity of this technology in large-scale industrial applications.

[0005] Therefore, the optimization of laser welding process for hot stamping plates with Al-Si coating, especially the development of suitable welding wire materials, has become a key research topic. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides an iron-based welding wire and a welding method for laser welding of aluminum-silicon coated hot-formed steel. The components in the welding wire are adjusted, and the combined effect of multiple alloy elements significantly improves the strength, plasticity and toughness of the weld, which can meet the strict performance requirements of high-strength steel plates in automobile manufacturing. High-quality welding can be achieved without removing the surface coating, which simplifies the welding process and improves production efficiency. At the same time, the welding wire does not require a high content of manganese components and has low cost.

[0007] In order to solve the above technical problems, the present invention provides, on one hand, an iron-based welding wire for laser welding of hot-formed steel with aluminum-silicon coating, which comprises the following components by mass percentage:

[0008] Mn: 3.5-10%,

[0009] C: 0.1~0.3%,

[0010] Cr: 0.1~1.0%,

[0011] Si: 0.1-0.3%,

[0012] Nb: 0.04~0.2%,

[0013] V: 0.1~1.0%,

[0014] Ni: 0-2%,

[0015] The balance is Fe and inevitable impurities.

[0016] The increase of manganese (Mn) content in the present invention can effectively improve the phase transformation behavior of the weld zone, enhance the stability of austenite, promote the transformation of delta ferrite to austenite, and improve the toughness of the weld. At the same time, a relatively high manganese element is enriched in the austenite. When cooled to room temperature, part of the residual austenite does not undergo martensitic transformation. This part of the austenite undergoes martensitic transformation during the room temperature stretching process, resulting in a phase transformation induced plasticity (TRIP) effect, thereby improving the plasticity of the material. The addition of niobium (Nb) and vanadium (V) further improves the strength and plasticity of the weld joint through grain refinement and precipitation strengthening mechanism. The addition of a small amount of nickel (Ni) can reduce the formation of delta ferrite by reducing the temperature range of the peritectic reaction, and can further improve the crack resistance of the welded joint and the toughness of the weld without significantly increasing the cost; the introduction of an appropriate amount of silicon (Si) helps to improve the oxidation resistance during the welding process and reduce the problem of oxide inclusions; the addition of an appropriate amount of chromium (Cr) further improves the oxidation resistance of the weld. Chromium has strong corrosion resistance and can effectively prevent high-temperature oxidation problems generated during welding, improving the corrosion resistance of the welded joint. At the same time, chromium can also refine the grains and improve the strength and toughness of the weld.

[0017] The welding wire in the present invention not only plays the role of filling the weld, but also can improve the performance of the welded components by adjusting the chemical composition of the weld: through the optimized ratio of elements such as manganese, niobium, and vanadium, the elements cooperate with each other, and the welding wire has excellent crack resistance and metallurgical bonding performance; the tensile strength, toughness and other mechanical properties of the welded joint are significantly improved, meeting the performance requirements of the high-strength steel plate welded joint; the welding wire can effectively deal with the embrittlement problem of the aluminum silicon coating during the welding process, and reduce the influence of the coating on the welding quality. In addition, the iron-based welding wire has good compatibility with the steel plate material.

[0018] The present invention can achieve high-quality welding without removing the surface coating, simplifies the welding process and improves production efficiency; compared with traditional high-nickel welding wire, the present invention uses manganese component welding wire, which has higher economic benefits and can effectively improve the plasticity of the weld through the TRIP effect.

[0019] Furthermore, the diameter of the welding wire is 1.0-1.4 mm.

[0020] A second aspect of the present invention provides a laser welding method for hot-formed steel with an aluminum-silicon coating, using the iron-based welding wire described in the first aspect, comprising the following steps:

[0021] S1, providing a first substrate and a second substrate;

[0022] Wherein, the first substrate and the second substrate both include a steel plate and an aluminum-silicon coating disposed on both sides of the steel plate;

[0023] S2, welding the first substrate and the second substrate by laser welding using a fiber laser under a protective atmosphere;

[0024] The welding parameters are: welding power 4-6kW, welding rate 3-7m / min, wire feeding speed 2-5m / min;

[0025] S3. After the welding is completed, heat treatment and hot stamping are performed to obtain the welded components.

[0026] The laser wire-filling welding technology of the present invention has reduced assembly requirements, strong welding adaptability, high efficiency and more stable welding quality.

[0027] Furthermore, the thickness of the first substrate and the second substrate are independently selected from 0.6-3 mm.

[0028] Furthermore, the thickness of the aluminum silicon coating of the first substrate and the second substrate is independently selected from 15-40 μm.

[0029] Furthermore, in S3, the heat treatment temperature is 900-950° C., and the insulation time is 3-8 min.

[0030] Furthermore, in S2, the welded joint is an I-type butt joint, and a preset gap between the first substrate and the second substrate is 0-0.5 mm.

[0031] Furthermore, in S2, the protective atmosphere is pure argon gas with a flow rate of 15-20 L / min.

[0032] Furthermore, in S2, the laser spot diameter is 0.2-0.6 mm, and the defocus is -5 to 5 mm.

[0033] Furthermore, in S1, the material of the steel plate is 22MnB5 steel.

[0034] Furthermore, the weld of the tailor-welded component contains martensite and austenite structures, wherein the volume percentage of the martensite is greater than 95%, and the volume percentage of the austenite is less than 5%.

[0035] Beneficial effects of the present invention:

[0036] The invention optimizes the ratio of elements such as manganese, niobium, and vanadium, and the elements cooperate with each other, so that the welding wire has excellent crack resistance and metallurgical bonding performance; the tensile strength, toughness and other mechanical properties of the welded joint are significantly improved, meeting the performance requirements of high-strength steel plate butt welded joints; the welding wire can effectively deal with the embrittlement problem of aluminum silicon coating during welding, and reduce the influence of coating on welding quality. In addition, the iron-based welding wire has good compatibility with steel plate materials.

[0037] The present invention can achieve high-quality welding without removing the surface coating, simplifies the welding process and improves production efficiency; compared with traditional high-nickel welding wire, the present invention uses manganese component welding wire, which has higher economic benefits and can effectively improve the plasticity of the weld through the TRIP effect.

[0038] The present invention adopts laser wire-filling welding technology, which reduces assembly requirements, has strong welding adaptability, high efficiency, and more stable welding quality; the martensite content in the weld is above 95%, and contains less than 5% of residual austenite to improve toughness. The strength of the welded joint can reach above 1500MPa, and the elongation can reach above 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is a metallographic structure diagram of the weld position of the tailor-welded blank after heat treatment in Example 1 of the present invention;

[0041] Figure 2 is a metallographic structure diagram of the weld position of the tailor-welded blank after heat treatment in Example 2 of the present invention;

[0042] Figure 3 is a metallographic structure diagram of the weld position of the tailor-welded blank after heat treatment in Example 3 of the present invention;

[0043] Figure 4 is a metallographic structure diagram of the weld position of the tailor-welded blank after heat treatment in Example 4 of the present invention;

[0044] Figure 5 This is a metallographic structure diagram of the weld position of the tailor-welded blank after heat treatment in Example 5 of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] This embodiment provides an iron-based welding wire for laser welding of hot-formed steel with aluminum-silicon coating, which includes the following components by mass percentage: Mn: 3.5-10%, C: 0.1-0.3%, Cr: 0.1-1.0%, Si: 0.1-0.3%, Nb: 0.04-0.2%, V: 0.1-1.0%, Ni: 0-2%, and the balance is Fe and unavoidable impurities. Preferably, the diameter of the welding wire is 1.0-1.4 mm

[0047] In this embodiment, the increase in manganese (Mn) content can effectively improve the phase transformation behavior of the weld zone, enhance the stability of austenite, promote the transformation of delta ferrite to austenite, and improve the toughness of the weld. At the same time, a relatively high manganese element is enriched in the austenite. When cooled to room temperature, part of the residual austenite does not undergo martensitic transformation. This part of the austenite undergoes martensitic transformation during the room temperature stretching process, resulting in a phase transformation induced plasticity (TRIP) effect, thereby improving the plasticity of the material. The addition of niobium (Nb) and vanadium (V) further improves the strength and plasticity of the weld joint through grain refinement and precipitation strengthening mechanism. Adding a small amount of Nickel (Ni) can reduce the formation of delta ferrite by reducing the temperature range of peritectic reaction, and can further improve the crack resistance of welded joints and the toughness of welds without significantly increasing costs; the introduction of an appropriate amount of silicon (Si) helps to improve the oxidation resistance during welding and reduce the problem of oxide inclusions; the addition of an appropriate amount of chromium (Cr) further improves the oxidation resistance of welds. Chromium has strong corrosion resistance and can effectively prevent high-temperature oxidation problems during welding, improving the corrosion resistance of welded joints. At the same time, chromium can also refine grains and improve the strength and toughness of welds.

[0048] This embodiment optimizes the ratio of elements such as manganese, niobium, and vanadium, and the elements cooperate with each other, so that the welding wire has excellent crack resistance and metallurgical bonding performance; the tensile strength, toughness and other mechanical properties of the welded joint are significantly improved, meeting the performance requirements of the high-strength steel plate butt welded joint; the welding wire can effectively deal with the embrittlement problem of the aluminum silicon coating during the welding process, and reduce the influence of the coating on the welding quality. In addition, the iron-based welding wire has good compatibility with the steel plate material; high-quality welding can be achieved without removing the surface coating, which simplifies the welding process and improves production efficiency; compared with the traditional high-nickel welding wire, the present invention uses manganese component welding wire, which has higher economic benefits, and can effectively improve the plasticity of the weld through the TRIP effect.

[0049] Another embodiment provides a laser welding method for hot-formed steel with an aluminum-silicon coating, using the iron-based welding wire described in the above embodiment, including the following steps:

[0050] S1, providing a first substrate and a second substrate;

[0051] Wherein, the first substrate and the second substrate both include a steel plate and an aluminum-silicon coating disposed on both sides of the steel plate; the thickness of the first substrate and the second substrate is independently selected from 0.6-3 mm; the thickness of the aluminum-silicon coating of the first substrate and the second substrate is independently selected from 15-40 μm

[0052] S2, welding the first substrate and the second substrate by laser welding using a fiber laser under a protective atmosphere;

[0053] The welding parameters are as follows: welding power 4-6kW, welding rate 3-7m / min, wire feeding speed 2-5m / min, laser spot diameter 0.2-0.6mm, defocusing amount -5-5mm; the protective atmosphere is pure argon gas with a flow rate of 15-20L / min;

[0054] S3, after the welding is completed, heat treatment and hot stamping are performed to obtain the welded component;

[0055] Wherein, the heat treatment temperature is 900-950°C, and the insulation time is 3-8 minutes.

[0056] As a specific example, in S2, the welded joint is an I-type butt joint, and the preset gap between the first substrate and the second substrate is 0-0.5 mm.

[0057] As a specific example, in S1, the material of the steel plate is 22MnB5 steel.

[0058] The weld of the tailor-welded component contains martensite and austenite structures, wherein the martensite content in the weld is above 95%, and contains less than 5% of residual austenite to improve toughness. The strength of the welded joint can reach above 1500MPa, and the elongation can reach above 5%.

[0059] This embodiment adopts laser wire-filling welding technology, which reduces assembly requirements, has strong welding adaptability, high efficiency, and more stable welding quality.

[0060] The following are specific embodiments.

[0061] Example 1

[0062] The present embodiment relates to a laser welding method for hot-formed steel with aluminum silicon coating. The mass percentages of the elements except iron and impurities in the welding wire used are shown in Table 1. The diameter of the welding wire is 1.2 mm. The welded plate is 22MnB5 steel, and both sides are coated with aluminum silicon. The average thickness of the coating is 30 um. The thicknesses of the two welded plates are 1.4 mm and 1.6 mm, respectively. To facilitate welding installation, the length and width of the welded plates are uniformly cut to 100 mm*50 mm. The welding is carried out in a butt-jointed manner, with an I-type joint and a preset gap of 0.2 mm. The surface of the welded plate is cleaned with acetone and alcohol before welding.

[0063] The specific welding process is: using the front wire feeding method, the laser defocus is 0mm, the laser spot size is 0.6mm, the angle between the welding gun and the laser beam is 40°, the shielding gas is pure argon, and the flow rate is 20L / min. The specific welding process parameters are: laser power is 5-6kW, welding speed is 4.0-5.0m / min, and wire feeding speed is 2.0-3.0m / min.

[0064] The welding process maintains the liquid bridge transition mode, and the welding process is stable without spatter and obvious welding defects. After welding, it is placed in a 930℃ heating furnace for 5 minutes, and then hot stamped. The obtained welded joint has more than 95% martensite structure. Among them, the metallographic structure of the weld position of the heat-treated tailor-welded plate is as follows Figure 1 shown.

[0065] Example 2

[0066] The present embodiment relates to a laser welding method for hot-formed steel with aluminum silicon coating. The mass percentages of the elements except iron and impurities in the welding wire used are shown in Table 1. The diameter of the welding wire is 1.2 mm. The welded plate is 22MnB5 steel, and both sides have aluminum silicon coatings with an average coating thickness of 30 um. The thicknesses of the two welded plates are 1.2 mm and 2.0 mm, respectively. To facilitate welding installation, the length and width of the welded plates are uniformly cut to 100 mm*50 mm. The welding is carried out in a butt-jointed manner, with an I-type joint and a preset gap of 0.2 mm. The surface of the welded plate is cleaned with acetone and alcohol before welding.

[0067] The specific welding process is: using the front wire feeding method, the laser defocus is 0mm, the laser spot size is 0.4mm, the angle between the welding gun and the laser beam is 40°, the shielding gas is pure argon, and the flow rate is 15L / min. The specific welding process parameters are: laser power is 4-5kW, welding speed is 3.5-5.0m / min, and wire feeding speed is 3.0-4.5m / min.

[0068] The welding process maintains the liquid bridge transition mode, and the welding process is stable without spatter and obvious welding defects. After welding, it is placed in a 930℃ heating furnace for 5 minutes, and then hot stamped. The obtained welded joint has more than 95% martensite structure. Among them, the metallographic structure of the weld position of the heat-treated tailor-welded plate is as follows Figure 2 shown.

[0069] Example 3

[0070] The present embodiment relates to a laser welding method for hot-formed steel with aluminum silicon coating. The mass percentages of the elements except iron and impurities in the welding wire used are shown in Table 1. The diameter of the welding wire is 1.2 mm. The welded plate is 22MnB5 steel, and both sides are coated with aluminum silicon. The average thickness of the coating is 30 um. The thicknesses of the two welded plates are 1.4 mm and 1.6 mm, respectively. To facilitate welding installation, the length and width of the welded plates are uniformly cut to 100 mm*50 mm. The welding is carried out in a butt-jointed manner, with an I-type joint and a preset gap of 0.2 mm. The surface of the welded plate is cleaned with acetone and alcohol before welding.

[0071] The specific welding process is: using the front wire feeding method, the laser defocus is -2mm, the laser spot size is 0.6mm, the angle between the welding gun and the laser beam is 40°, the shielding gas is pure argon, and the flow rate is 20L / min. The specific welding process parameters are: laser power is 5~6kW, welding speed is 4.0~5.0m / min, and wire feeding speed is 2.5~3.0m / min.

[0072] The welding process maintains the liquid bridge transition mode, and the welding process is stable without spatter and obvious welding defects. After welding, it is placed in a 930℃ heating furnace for 5 minutes, and then hot stamped. The obtained welded joint has more than 95% martensite structure. Among them, the metallographic structure of the weld position of the heat-treated tailor-welded plate is as follows Figure 3 shown.

[0073] Example 4

[0074] The present embodiment relates to a laser welding method for hot-formed steel with aluminum silicon coating. The mass percentages of the elements except iron and impurities in the welding wire used are shown in Table 1. The diameter of the welding wire is 1.2 mm. The welded plate is 22MnB5 steel, and both sides are coated with aluminum silicon. The average thickness of the coating is 30 um. The thicknesses of the two welded plates are 1.4 mm and 1.6 mm respectively. To facilitate welding installation, the length and width of the welded plates are uniformly cut to 100 mm*50 mm. The welding is carried out in a butt-jointed manner, with an I-type joint and a preset gap of 0.4 mm. The surface of the welded plate is cleaned with acetone and alcohol before welding.

[0075] The specific welding process is: using the front wire feeding method, the laser defocus is 0mm, the laser spot size is 0.4mm, the angle between the welding gun and the laser beam is 40°, the shielding gas is pure argon, and the flow rate is 20L / min. The specific welding process parameters are: laser power is 3~4kW, welding speed is 2.0~3.5m / min, and wire feeding speed is 2.5~3.0m / min.

[0076] The welding process maintains the liquid bridge transition mode, and the welding process is stable without spatter and obvious welding defects. After welding, it is placed in a 930℃ heating furnace for 5 minutes, and then hot stamped. The obtained welded joint has more than 95% martensite structure. Among them, the metallographic structure of the weld position of the heat-treated tailor-welded plate is as follows Figure 4 shown.

[0077] Example 5

[0078] The present embodiment relates to a laser welding method for hot-formed steel with aluminum silicon coating. The mass percentages of the elements except iron and impurities in the welding wire used are shown in Table 1. The diameter of the welding wire is 1.2 mm. The welded plate is 22MnB5 steel, and both sides are coated with aluminum silicon. The average thickness of the coating is 30 um. The thicknesses of the two welded plates are 1.4 mm and 1.6 mm, respectively. To facilitate welding installation, the length and width of the welded plates are uniformly cut to 100 mm*50 mm. The welding is carried out in a butt-jointed manner, with an I-type joint and a preset gap of 0.2 mm. The surface of the welded plate is cleaned with acetone and alcohol before welding.

[0079] The specific welding process is: using the front wire feeding method, the laser defocus is 0mm, the laser spot size is 0.4mm, the angle between the welding gun and the laser beam is 40°, the shielding gas is pure argon, and the flow rate is 20L / min. The specific welding process parameters are: laser power is 3~4kW, welding speed is 3.0~4.0m / min, and wire feeding speed is 2.5~3.0m / min.

[0080] The welding process maintains the liquid bridge transition mode, and the welding process is stable without spatter and obvious welding defects. After welding, it is placed in a 930℃ heating furnace for 5 minutes, and then hot stamped. The obtained welded joint has more than 95% martensite structure. Among them, the metallographic structure of the weld position of the heat-treated tailor-welded plate is as follows Figure 5 shown.

[0081] Comparative Example 1

[0082] This comparative example relates to a laser welding method for aluminum-silicon coated hot-formed steel. The mass percentage of each element in the welding wire used is shown in Table 1, and other parameters are the same as those in Example 1.

[0083] Comparative Example 2

[0084] This comparative example relates to a laser welding method for aluminum-silicon coated hot-formed steel. The mass percentage of each element in the welding wire used is shown in Table 1, and other parameters are the same as those in Example 1.

[0085] Table 1

[0086] category C％ Mn% Ni% Cr％ V％ Nb% Si% Example 1 0.210 3.99 1.03 0.45 0.21 0.08 0.15 Example 2 0.189 3.55 0.96 0.44 0.17 0.08 0.15 Example 3 0.196 5.04 1.07 0.48 0.23 0.09 0.17 Example 4 0.207 4.01 0.11 0.42 0.21 0.12 0.15 Example 5 0.198 4.03 1.03 0.44 0.16 0.08 0.28 Comparative Example 1 0.187 1.78 2.08 0.35 0 0 0.63 Comparative Example 2 0.202 4.01 1.01 3.02 0.20 0.08 0.7

[0087] Test Case

[0088] The performance of the welded joints in the aluminum-silicon coated hot-formed steels of Examples 1-5 and Comparative Examples 1-2 was tested, and the results are shown in Table 2.

[0089] Table 2

[0090] Group Yield strength / MPa Tensile strength / MPa Elongation after break / % Example 1 1269 1546 4.55 Example 2 1294 1579 4.83 Example 3 1196 1484 6.32 Example 4 1208 1492 4.31 Example 5 1174 1426 4.33 Comparative Example 1 1106 1340 3.23 Comparative Example 2 1342 1566 1.09

[0091] It can be seen from Table 2 that the performance of the welded joints in the aluminum-silicon coated hot-formed steels in Examples 1-5 of the present invention is excellent, especially in Example 2, where the yield strength is as high as 1294 MPa and the tensile strength is as high as 1579 MPa, and the elongation after fracture is excellent.

[0092] From the comparison between Example 1 and Comparative Example 1, it can be seen that the lower Mn content cannot stabilize the austenite structure in the weld, and the presence of high Si content promotes the formation of delta ferrite. In addition, elements such as Nb and V are not added to form fine dispersed carbonitrides to produce a strengthening effect, thereby causing the weld strength to decrease.

[0093] From the comparison between Example 1 and Comparative Example 2, it can be seen that high contents of Cr and Si tend to form hard and brittle compounds during welding, which improves the strength of the weld but reduces the ductility.

[0094] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. An iron-based welding wire for laser welding of aluminum-silicon coated hot-formed steel, characterized in that: Calculated by mass percentage, it includes the following components: Mn: 3.5-10%, C：0.1～0.3％， Cr：0.1～1.0％， Si: 0.1-0.3%, Nb: 0.04~0.2%, V：0.1～1.0％， Ni: 0-2%, The balance is Fe and inevitable impurities.

2. The iron-based welding wire for laser tailor welding of aluminum-silicon coated hot-formed steel according to claim 1, characterized in that: The diameter of the welding wire is 1.0-1.4 mm.

3. A laser welding method for hot-formed steel with aluminum silicon coating, characterized in that: The iron-based welding wire according to any one of claims 1 to 2 is used, comprising the following steps: S1, providing a first substrate and a second substrate; Wherein, the first substrate and the second substrate both include a steel plate and an aluminum-silicon coating disposed on both sides of the steel plate; S2, welding the first substrate and the second substrate by laser welding using a fiber laser under a protective atmosphere; The welding parameters are: welding power 4-6kW, welding rate 3-7m / min, wire feeding speed 2-5m / min; S3. After the welding is completed, heat treatment and hot stamping are performed to obtain the welded components.

4. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: The thickness of the first substrate and the second substrate are independently selected from 0.6-3 mm.

5. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: The thickness of the aluminum silicon coating of the first substrate and the second substrate is independently selected from 15-40 μm.

6. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: In S3, the heat treatment temperature is 900-950°C, and the insulation time is 3-8 minutes.

7. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: In S2, the welded joint is an I-type butt joint, and the preset gap between the first substrate and the second substrate is 0-0.5 mm.

8. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: In S2, the protective atmosphere is pure argon gas with a flow rate of 15-20 L / min.

9. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: In S1, the material of the steel plate is 22MnB5 steel.

10. The laser welding method for hot-formed steel with aluminum silicon coating as claimed in claim 3, characterized in that: The weld of the tailor-welded component contains martensite and austenite structures, wherein the volume percentage of the martensite is greater than 95%, and the volume percentage of the austenite is less than 5%.

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