1.5gpa grade al-si coated hot forming steel using metal powder type flux-cored wire and method for manufacturing the same

Abstract

The application discloses a metal powder type flux-cored wire suitable for 1.5GPa-grade aluminum-silicon plated layer hot forming steel and a preparation method thereof. The component design of the application is reasonable, the process compatibility is good, the welding penetration is large, the workpiece deformation is small, and the welding efficiency is high, so that the high reliable connection requirement of 1.5GPa-grade aluminum-silicon plated layer hot forming super-high-strength structural parts can be met. Meanwhile, the preparation process is mature, and the application can be produced on a large scale. The technical problems of insufficient joint strength, serious softening of heat affected zone, poor crack resistance and weak laser welding adaptability of the existing similar welding wires are solved.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, specifically to a metal powder-cored welding wire suitable for 1.5GPa grade aluminum-silicon coated hot-formed steel and its preparation method. Background Technology

[0002] With the continuous improvement of lightweighting and overall safety levels in new energy vehicles, 1.5GPa grade aluminum-silicon coated hot-formed steel is widely used in core safety structural components of vehicle bodies. This type of steel is formed by high-temperature austenitization and rapid quenching, possessing ultra-high strength and high hardness, but it has a high tendency to harden during welding, high sensitivity to cold cracking, and a narrow range of applicable welding processes.

[0003] Hot-formed steel is usually coated with an aluminum-silicon protective layer to inhibit high-temperature oxidation and surface decarburization. However, the aluminum-silicon coating can cause defects such as porosity, inclusions, and uneven composition during the welding process. At the same time, existing welding wires are prone to softening of the heat-affected zone and large hardness gradient after welding, which ultimately leads to a significant decrease in the strength of the welded joint and seriously affects the mechanical properties and service reliability of the components.

[0004] Laser-arc hybrid welding combines the advantages of laser welding (large penetration and high precision) with arc welding (good filling properties and high tolerance for errors), making it the mainstream welding process for ultra-high strength hot-formed steel body components. Existing conventional flux-cored welding wires are unsuitable for the application requirements of 1.5GPa grade aluminum-silicon coated hot-formed steel, generally exhibiting problems such as high diffusible hydrogen content in the deposited metal, severe softening of the heat-affected zone, insufficient tensile strength of the joint, and poor microstructure uniformity, making it difficult to meet the stringent requirements of industrial mass production and long-term service. Therefore, the industry urgently needs to develop a dedicated metal powder flux-cored welding wire. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the purpose of this invention is to provide a metal powder-type flux-cored wire suitable for 1.5GPa grade aluminum-silicon coated hot-formed steel and its preparation method.

[0006] This invention addresses the technical challenges of low joint strength, severe softening of the heat-affected zone, numerous weld defects, and high diffusible hydrogen content when welding ultra-high strength hot-formed steel with existing welding wires, aiming to achieve a high-strength, highly stable, and low-defect welding joint.

[0007] A metal powder-cored welding wire suitable for 1.5GPa grade aluminum-silicon coated hot-formed steel, comprising a carbon steel outer sheath and a welding wire core, wherein the welding wire core comprises, by weight percentage, the following components:

[0008] Graphite 0.27%–0.32%;

[0009] Nickel powder 3.25%–3.75%;

[0010] Rare earth silicon ferrosilicon: 0.58%–0.67%;

[0011] Mn-Si composite deoxidizer 0.54%~0.63%;

[0012] High-purity metallic manganese: 1.82%–2.10%;

[0013] Ferromanganese master alloy: 0.32%–0.37%;

[0014] Metallic chromium: 1.76%–2.10%;

[0015] Titanium iron 0.10%~0.20%;

[0016] Nb-Fe microalloying agent 0.03%~0.045%;

[0017] Fe-B boride alloy 0.10%~0.30%,

[0018] The remainder consists of iron powder and unavoidable trace impurities;

[0019] The outer sheath of the steel strip is a carbon steel strip, and the chemical element conditions of the carbon steel strip are as follows:

[0020] C: 0.025%~0.035%, Mn: 0.20%~0.30%, Si: ≤0.03%, P: ≤0.004%, S: ≤0.004%, Al: ≤0.02%, N: ≤0.002%;

[0021] The filler content of the flux-cored portion in the metal powder-based flux-cored wire is 12% to 15%.

[0022] The high-purity metallic manganese of this invention is high-purity metallic manganese with Mn ≥ 99.7%.

[0023] The ferromanganese master alloy of the present invention is a high-carbon ferromanganese, wherein the high-carbon ferromanganese has a Mn content of 70-75% and a carbon content of 5-7%.

[0024] The Mn-Si composite deoxidizer of the present invention is specifically a silicon-manganese alloy, wherein the Mn content of the silicon-manganese alloy is 62.0-66.0% and the silicon content is 19-23%.

[0025] The boron content of the Fe-B boride alloy of the present invention is 0.9-1.1%.

[0026] The Nb content in the Nb-Fe microalloying agent of this invention is ≥65%.

[0027] A metal powder-based flux-cored welding wire suitable for 1.5 GPa grade aluminum-silicon coated hot-formed steel, wherein the weld metal formed by welding the wire comprises the following chemical components:

[0028] C: 0.2%–0.4%, Si: 0.15%–0.55%, Mn: 2.0%–3.0%, Ni: 3.0%–5.0%, Cr: 1.5%–2.5%, B: 0.002%–0.004%, Nb: 0.02%–0.05%, S≤0.015%, P≤0.015%, with the balance being Fe and unavoidable impurities.

[0029] A metal powder-type flux-cored welding wire suitable for 1.5GPa grade aluminum-silicon coated hot-formed steel, wherein the diffusible hydrogen content of the weld metal formed by the welding wire is ≤4mL / 100g, which can effectively avoid hydrogen-induced cracking defects.

[0030] The joints welded using the welding wire of this invention, after hot stamping and pressure holding quenching in the mold, both the weld zone and the heat-affected zone form a uniform and dense martensitic structure; the hardness difference of the heat-affected zone of the welded joint is ≤100HV, with no obvious softening area, thus completely solving the problem of softening in ultra-high strength steel welding.

[0031] The joints welded using the welding wire of this invention exhibit a room temperature tensile strength ≥1500MPa after heat treatment, with the fracture location situated in the base metal region. This demonstrates excellent strength matching with the base metal, meeting the load-bearing requirements of ultra-high strength components. Key points include... Figure 1-3 As shown.

[0032] A method for preparing a metal powder-based flux-cored welding wire suitable for 1.5 GPa grade aluminum-silicon coated hot-formed steel includes the following steps:

[0033] S1. Raw material pretreatment: Grind the graphite, nickel powder, rare earth ferrosilicon, Mn-Si composite deoxidizer, high-purity metallic manganese, manganese-iron master alloy, metallic chromium, titanium-iron, Nb-Fe microalloying agent, Fe-B boron alloy, and the balance iron powder to 100 to 325 mesh, mix and stir evenly, bake at 180 to 220°C for 1 to 2 hours to remove impurities, and cool to room temperature;

[0034] S2. Forming and filling: Low carbon steel strip is used as the outer skin, and the pretreated mixed powder is filled and formed, controlling the flux core to account for 12% to 15% of the total mass of the welding wire;

[0035] S3. Rolling and drawing finishing: Through multi-pass rolling shaping and diameter reduction, and then through multi-stage drawing process, finished welding wire with a diameter of 0.8mm to 1.2mm is prepared;

[0036] S4. Post-processing inspection: The finished welding wire is cleaned and rust-proofed. After passing the inspection of the linearity (relaxation direct length ≥ 800mm, warp ≤ 5mm) and appearance (must be free of defects such as pitting, breakage, black streaks, mottled streaks, bamboo joints, transverse tearing, excessive shine, etc., and the color must be uniform), it is rolled and packaged to complete the preparation.

[0037] The beneficial effects of this invention are as follows:

[0038] 1. This invention adopts a C-Mn-Ni-Cr-Nb-Ti-B multi-element microalloying system, combined with Mn-Si composite deoxidizer and rare earth ferrosilicon to synergistically purify the molten pool, which can effectively refine grains, remove oxygen and sulfur impurities, avoid porosity and inclusion defects caused by aluminum-silicon coating, and ensure stable weld formation quality.

[0039] 2. After hot stamping and quenching, the weld joint of the welding wire of the present invention has a martensitic structure in both the weld and the heat-affected zone, with no obvious softening zone. The hardness difference in the heat-affected zone is ≤100HV, and the tensile strength of the joint is ≥1500MPa. This is highly matched with the strength of the 1.5GPa grade aluminum-silicon coated hot-formed steel base material, thus solving the problem of sudden drop in joint strength and uneven performance after welding with traditional welding wire.

[0040] 3. The diffusible hydrogen content of the welding wire of this invention is ≤4mL / 100g. The extremely low diffusible hydrogen content can effectively inhibit the generation of hydrogen-induced cooling cracks, greatly improve the service stability and fatigue performance of the welded joint, and is suitable for the harsh operating conditions of ultra-high strength hot-formed steel components for automobiles.

[0041] 4. The preparation process of this invention is simple and highly controllable, with precise raw material ratios, good product consistency, and can achieve large-scale mass production. The specifications of the finished welding wire are compatible with conventional welding equipment, making it highly versatile. Attached Figure Description

[0042] Figure 1 This is a diagram showing the weld effect of laser-assisted composite welding in Embodiment 1 of the present invention.

[0043] Figure 2 This is a diagram showing the weld effect of laser-assisted composite welding in Embodiment 2 of the present invention.

[0044] Figure 3 This is a diagram showing the weld effect of laser-assisted composite welding in Embodiment 3 of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention. Furthermore, in the following descriptions, well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of the invention.

[0046] The carbon steel outer sheath and flux core of the welding wire of the present invention have a steel strip specification of 1.0mm×14mm. The main chemical elements of the steel strip meet the following requirements: C: 0.025%~0.035%, Mn: 0.20%~0.30%, Si: ≤0.03%, P: ≤0.004%, S: ≤0.004%, Al: ≤0.02%, N: ≤0.002%, and are filled with flux core at a filling rate of 12%~15%.

[0047] This invention relates to an alloy formulation system adapted for laser-arc hybrid welding and subsequent hot stamping and quenching processes of ultra-high strength hot-formed steel. It specifically addresses problems encountered in welding aluminum-silicon coated steel plates, such as low molten pool purity, frequent porosity and inclusions, uneven composition, coarsening of grains in the heat-affected zone, large hardness gradient, localized softening, and high crack sensitivity. Through precise proportioning and functional coupling of graphite, nickel powder, and multiple alloy components, and relying on synergistic mechanisms such as multi-stage deoxidation and desulfurization, hardenability control, grain refinement, and precipitation strengthening, this invention achieves comprehensive performance of high strength, high toughness, crack resistance, and stable microstructure in the welded joint, meeting the service requirements for welding 1.5 GPa-level ultra-high strength hot-formed steel. The mechanisms of action and synergistic principles of each component are as follows:

[0048] Graphite serves as a precisely controllable carbon source for the system, allowing for quantitative regulation of the carbon content in the deposited metal. This ensures the formation of a uniform and dense martensitic structure after hot stamping and quenching, resulting in a stable joint strength exceeding 1500 MPa. Carbon can combine with chromium, niobium, and titanium to form dispersed fine carbides, which, through precipitation strengthening and grain refinement, inhibit grain coarsening, reduce hardness deviations, and eliminate softening in the heat-affected zone. Simultaneously, graphite assists in deoxidation and stabilizes the arc, effectively improving porosity and inclusion defects in aluminum-silicon coating welding, making it suitable for laser-arc hybrid welding processes.

[0049] After extensive experimentation, the inventors of this invention limited the amount of graphite added to 0.27% to 0.32%. This ensures the hardenability and strength of the weld while avoiding matrix embrittlement and hydrogen-induced cracking caused by excessive carbon content, and achieves a balance of strength and toughness in conjunction with nickel.

[0050] Nickel powder is a core component for regulating martensitic microstructure and balancing weld strength and toughness. Nickel can lower the martensitic transformation temperature, refine the martensitic grains in the weld and heat-affected zone, inhibit grain coarsening, reduce hardness gradient, and eliminate local softening. It can significantly improve the plasticity and toughness of the martensitic matrix, effectively eliminating the problem of high strength but low toughness in ultra-high strength welds, while also inhibiting sulfur and phosphorus grain boundary segregation and improving the weld's resistance to hot cracking and hydrogen-induced delayed cracking. In addition, nickel can promote uniform diffusion of alloys in the molten pool, improve compositional segregation caused by aluminum-silicon coatings, and stabilize the weld microstructure and properties.

[0051] After extensive testing, the inventors of this invention limited the amount of nickel powder added to 3.25% to 3.75%, which can fully exert the toughening and crack-resistant effect, while avoiding the risk of hot cracking caused by excessive nickel content, ensuring the formation of a complete martensitic structure after quenching, and matching the usage requirements of 1.5GPa grade aluminum-silicon coated hot-formed steel.

[0052] Rare earth ferrosilicon achieves multiple strengthening effects through the synergistic metallurgical effect of rare earth elements and silicon. Rare earth elements can efficiently deoxidize and desulfurize, deeply purify the molten pool, and fundamentally suppress porosity and inclusion defects in aluminum-silicon coating welding; at the same time, they refine the microstructure of the weld and heat-affected zone, weaken grain boundary brittleness, and reduce hardness gradient. Silicon can improve the fluidity of the molten pool, optimize weld formation, and enhance joint toughness and crack resistance.

[0053] After extensive testing, the inventors of this invention determined that the formulation of this invention can achieve excellent metallurgical stability and is suitable for laser-arc composite welding and hot stamping quenching processes.

[0054] Mn-Si composite deoxidizers, through the synergistic effect of manganese and silicon, efficiently remove free oxygen from the molten pool, significantly reducing oxide inclusions and porosity defects, and improving the purity of the molten pool. Simultaneously, they stabilize the molten pool state, optimize weld formation, and synergistically enhance weld density and crack resistance with other components.

[0055] The Mn-Si composite deoxidizer of the present invention is specifically a silicon-manganese alloy, wherein the Mn content of the silicon-manganese alloy is 62.0-66.0% and the silicon content is 19-23%.

[0056] High-purity metallic manganese, as the core manganese source, has the functions of deoxidation, solid solution strengthening, and grain refinement, and can remove residual oxygen in the molten pool and reduce inclusion defects. The high-purity metallic manganese in this invention is high-purity metallic manganese with Mn ≥ 99.7%.

[0057] Manganese can simultaneously improve the strength and toughness of welds, suppress the segregation of harmful impurities, optimize grain boundary conditions, and enhance the crack resistance and microstructure uniformity of joints after solid solution treatment.

[0058] Ferromanganese master alloys (specifically high-carbon ferromanganese, with a Mn content of 70-75% and a carbon content of 5-7%) can continuously and steadily replenish manganese, forming a multi-stage deoxidation system with high-purity metallic manganese to efficiently remove impurities and reduce oxide inclusions. At the same time, solid solution strengthening refines the grains and homogenizes the microstructure, improving the strength, toughness, and crack resistance of the weld, and ensuring the stability of the joint performance after welding and heat treatment.

[0059] Metallic chromium can achieve solid solution strengthening and improve hardenability, effectively enhancing the hardenability of welds and heat-affected zones, ensuring the formation of a stable and uniform martensitic structure after quenching, and improving joint strength and hardness. Simultaneously, chromium can improve the high-temperature stability of welds, inhibit grain coarsening, reduce hardness unevenness, and improve joint crack resistance and corrosion resistance.

[0060] Titanium in ferrotitanium possesses strong deoxidizing and nitrogen-fixing capabilities, effectively removing oxygen and nitrogen from the molten pool and eliminating porosity and inclusion defects in aluminum-silicon coating welding. Titanium can generate dispersed carbonitrides, which refine grains and inhibit grain growth through grain boundary pinning, reducing hardness gradient, improving microstructure stability and cold crack resistance, and working synergistically with other components to ensure excellent mechanical properties of the joint.

[0061] Niobium in Nb-Fe microalloying agents can precipitate dispersed carbonitrides, which inhibit grain coarsening through grain boundary pinning, reduce hardness differences in the heat-affected zone, and eliminate softening. Simultaneously, niobium can improve weld hardenability, stabilize martensitic structure, strengthen matrix strength, improve joint resistance to cold cracking, and ensure stable and balanced joint microstructure and mechanical properties.

[0062] In Fe-B boron alloys (with a boron content of 0.9-1.1%), boron significantly improves the hardenability of the weld metal, inhibits the formation of soft structures such as pearlite and ferrite, ensures the formation of a uniform martensitic structure after quenching, and prevents softening of the heat-affected zone. Trace amounts of boron can strengthen grain boundary strength, reduce susceptibility to hydrogen-induced cracking, refine the microstructure, and synergistically stabilize the mechanical properties of the joint.

[0063] This invention constructs a comprehensive weld performance regulation system through multi-element coupling and synergy: carbon-chromium-niobium-boron synergistically enhance hardenability, ensuring the formation of a complete and uniform martensitic structure after heat treatment, and solving the problems of softening and uneven hardness in the heat-affected zone; manganese-silicon-rare earth-titanium form a multi-level deoxidation and desulfurization system, deeply purifying the molten pool and completely solving the welding porosity and inclusion defects of aluminum-silicon coatings; nickel-niobium synergistically refine grains and regulate martensitic structure, effectively balancing the high strength and high toughness of the weld.

[0064] This invention avoids defects such as embrittlement and cracking caused by excessive elements by limiting the optimal ratio range of graphite and nickel powder. The components complement each other and work synergistically to give the welded joint the advantages of low hydrogen, resistance to softening, high crack resistance and stable structure. It is compatible with laser-arc hybrid welding and hot stamping quenching complete process and meets the industrial welding needs of 1.5GPa grade ultra-high strength hot-formed steel.

[0065] The present invention will be further described below with reference to specific embodiments.

[0066] Examples 1-3:

[0067] A 1.5GPa grade aluminum-silicon coated hot-formed steel metal powder-cored welding wire and its preparation method.

[0068] 1. The methods in Examples 1-3 and Comparative Example 1 are as follows:

[0069] The raw materials used in this invention are pre-screened for particle size. The added graphite, nickel powder, rare earth ferrosilicon, Mn-Si composite deoxidizer, high-purity metallic manganese, ferromanganese master alloy, metallic chromium, ferrotitanium, Nb-Fe microalloying agent, Fe-B boron alloy, and the balance iron powder are all powder particles with a particle size range of 100 to 325 mesh, and are configured according to the proportions in the table below.

[0070] Table 1 shows the percentage of flux-cored wire in Examples 1-3 and Comparative Example 1 (%):

[0071]

[0072] This invention also provides a method for preparing the 1.5GPa grade aluminum-silicon coated hot-formed steel metal powder-cored welding wire as described in any one of the above claims, comprising the following steps:

[0073] S1. Raw material pretreatment: Grind graphite, nickel powder, rare earth ferrosilicon, Mn-Si composite deoxidizer, high-purity metallic manganese, ferromanganese master alloy, metallic chromium, ferrotitanium, Nb-Fe microalloying agent, Fe-B boron alloy, and the remaining iron powder to 100-325 mesh. Put all raw materials into a mixing device and stir thoroughly for 45 minutes to ensure uniform mixing. Then, place the mixed powder in a constant temperature baking device for baking treatment to remove moisture and volatile impurities from the powder and reduce the source of hydrogen diffusion in the weld. The baking temperature is 200℃ and the baking time is 1.5 hours. After baking, cool to room temperature for later use.

[0074] S2. Welding wire forming: Low-carbon steel strip is selected as the outer sheath of the welding wire. The chemical composition and mechanical properties of the low-carbon steel strip are shown in Tables 2 and 3. The pre-treated mixed powder is evenly filled into the U-shaped groove of the low-carbon steel strip. The steel strip is closed and sealed by the forming unit to form a continuous flux-cored welding wire blank. The flux filling amount is strictly controlled. Five 20-30cm welding wires are cut off at the forming line to test the filling rate (three repeated tests) so that the flux accounting for 12% to 15% of the total mass of the welding wire is stable.

[0075] S3. Drawing and finishing: The formed welding wire blank is shaped and reduced in diameter through multiple rolling processes to eliminate defects in the blank forming and ensure that the outer diameter of the welding wire is uniform and the structure is dense. Then, the welding wire specifications are gradually refined through a multi-stage drawing process, and finally finished flux-cored welding wire with a diameter of 0.8mm to 1.2mm is obtained.

[0076] S4. Finished product processing: The finished welding wire is cleaned and rust-proofed after precision machining. The outer diameter and surface quality of the welding wire are tested. After passing the inspection, the wire is rolled and packaged to obtain the finished welding wire.

[0077] Table 2 shows the content of various chemical components in low-sulfur, low-phosphorus carbon steel strip:

[0078]

[0079] Table 3 shows the main mechanical properties of low-sulfur, low-phosphorus carbon steel strips:

[0080]

[0081] 2. The metal powder-cored flux-cored welding wires obtained in Examples 1 to 3 and Comparative Example 1 were tested. They were welded using 75% to 85% Ar + 15 to 25% CO2 gas shielding. The chemical composition (mass fraction %) of the deposited metal was tested and the results are shown in Table 4.

[0082] Table 4 shows the chemical composition of Examples 1-3 and Comparative Example 1:

[0083] Chemical composition of deposited metal (%)

[0084]

[0085] Table 5 Joint strength of spliced ​​panels after heat treatment

[0086]

[0087] Table 6 Maximum Hardness Difference in the Heat-Affected Zone

[0088]

[0089] In this embodiment, the tensile mechanical properties of the three metal powder-cored welding wire joints described in this invention were tested according to GB / T 2651-2021 after heat treatment. As can be seen from Table 5, the tensile strength of the joints is ≥1500MPa.

[0090] In this embodiment, the hardness test of the heat-affected zone of the joint obtained by welding with the three metal powder-cored welding wires of the present invention was performed according to GB / T 4340.1-2009. As can be seen from Table 6, the maximum hardness difference of the heat-affected zone is 82HV≤100HV.

[0091] Diffusible hydrogen tests were conducted on the three types of metal powder-cored welding wires described in this invention and Comparative Example 1. The diffusible hydrogen content of the deposited metal was tested according to GB / T 3965-2012. As can be seen from Table 7, the diffusible hydrogen content of the deposited metal was less than 4 mL / 100g.

[0092] Table 7 Diffused hydrogen content in examples

[0093]

[0094] In addition, radiographic testing was performed on the welded joints of Examples 1 to 3 above. The radiographic testing was carried out in accordance with the GB / T3323-2019 test. The test results were Grade I, which means there are no excessive pores, inclusions, or cracks. This corresponds to the effect of solving the welding defects of aluminum-silicon coating.

[0095] This welding wire is suitable for laser-arc hybrid welding processes. The deposited metal adopts a C-Mn-Ni-Cr-Nb-Ti-B multi-element microalloying design, strictly limiting the content of harmful impurities such as sulfur and phosphorus. This welding wire features low diffusible hydrogen, low heat input sensitivity, resistance to heat-affected zone softening, and resistance to delayed cracking, effectively solving the problems of porosity and inclusions that easily occur in aluminum-silicon coated welding. After laser-arc hybrid welding, combined with hot stamping and in-mold pressure quenching, both the weld zone and heat-affected zone of the weld joint exhibit martensitic structure; the room temperature tensile strength of the joint is ≥1500MPa, the hardness difference in the heat-affected zone is ≤100HV, and there is no obvious softening area.

[0096] This invention features a rationally designed composition, good process compatibility, deep welding penetration, minimal workpiece deformation, and high welding efficiency. It can meet the high reliability connection requirements of 1.5GPa-level aluminum-silicon coated thermoformed ultra-high strength structural parts. At the same time, the preparation process is mature and can be mass-produced. It overcomes the technical problems of insufficient strength, severe softening of the heat-affected zone, poor crack resistance, and weak adaptability to laser welding of existing similar welding wire joints.

[0097] The foregoing has shown and described the basic principles and main features of the invention and the advantages of the invention.

[0098] Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A metal powder-cored welding wire suitable for 1.5GPa grade aluminum-silicon coated hot-formed steel, comprising a carbon steel outer sheath and a welding wire core, characterized in that, The flux-cored portion of the welding wire comprises, by weight percentage, the following components: Graphite 0.27%–0.32%; Nickel powder 3.25%–3.75%; Rare earth silicon ferrosilicon: 0.58%–0.67%; Mn-Si composite deoxidizer 0.54%~0.63%; High-purity metallic manganese: 1.82%–2.10%; Ferromanganese master alloy: 0.32%–0.37%; Metallic chromium: 1.76%–2.10%; Titanium iron 0.10%~0.20%; Nb-Fe microalloying agent 0.03%~0.045%; Fe-B boride alloy 0.10%~0.30%, The remainder consists of iron powder and unavoidable trace impurities; The outer sheath of the steel strip is a carbon steel strip, and the chemical element conditions of the carbon steel strip are as follows: C: 0.025%~0.035%, Mn: 0.20%~0.30%, Si: ≤0.03%, P: ≤0.004%, S: ≤0.004%, Al: ≤0.02%, N: ≤0.002%; The filler content of the flux-cored portion in the metal powder-based flux-cored wire is 12% to 15%.

2. The metal powder-cored welding wire for hot-formed steel with aluminum-silicon coating at 1.5 GPa level as described in claim 1, characterized in that, The high-purity metallic manganese is high-purity metallic manganese with Mn ≥ 99.7%; The ferromanganese master alloy is a high-carbon ferromanganese alloy, wherein the Mn content of the high-carbon ferromanganese alloy is 70-75%, and the carbon content is 5-7%. The Mn-Si composite deoxidizer is specifically a silicon-manganese alloy, wherein the Mn content of the silicon-manganese alloy is 62.0-66.0% and the silicon content is 19-23%. The boron content of the Fe-B boride alloy is between 0.9% and 1.1%. The Nb content in the Nb-Fe microalloying agent is ≥65%.

3. The metal powder-cored welding wire for hot-formed steel with aluminum-silicon coating at 1.5 GPa level as described in claim 1, characterized in that, The weld metal formed by welding the welding wire includes the following chemical components: C: 0.2%–0.4%, Si: 0.15%–0.55%, Mn: 2.0%–3.0%, Ni: 3.0%–5.0%, Cr: 1.5%–2.5%, B: 0.002%–0.004%, Nb: 0.02%–0.05%, S≤0.015%, P≤0.015%, with the balance being Fe and unavoidable impurities.

4. The metal powder-cored welding wire for hot-formed steel with aluminum-silicon coating at 1.5 GPa level as described in claim 1, characterized in that, The diffusible hydrogen content of the weld metal formed by welding with the welding wire is ≤4mL / 100g.

5. A method for preparing a metal powder-type flux-cored welding wire suitable for 1.5 GPa grade aluminum-silicon coated hot-formed steel according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Raw material pretreatment: Grind the graphite, nickel powder, rare earth ferrosilicon, Mn-Si composite deoxidizer, high-purity metallic manganese, manganese-iron master alloy, metallic chromium, titanium-iron, Nb-Fe microalloying agent, Fe-B boron alloy, and the balance iron powder to 100 to 325 mesh, mix and stir evenly, bake at 180 to 220°C for 1 to 2 hours to remove impurities, and cool to room temperature; S2. Forming and filling: Low carbon steel strip is used as the outer skin, and the pretreated mixed powder is filled and formed, controlling the flux core to account for 12% to 15% of the total mass of the welding wire; S3. Rolling and drawing finishing: Through multi-pass rolling shaping and diameter reduction, and then through multi-stage drawing process, finished welding wire with a diameter of 0.8mm to 1.2mm is prepared; S4. Post-processing and inspection: The finished welding wire is cleaned and rust-proofed. After passing the linearity and appearance inspection, it is rolled and packaged to complete the preparation.

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