Metal powder core welding wire for laser tailored blank welding of thermal forming aluminum-silicon coating steel plate and welding process

Abstract

The invention discloses a metal powder core welding wire for tailored blank laser welding of a thermal forming aluminum-silicon coating steel plate and a welding process, and belongs to welding wires for tailored blank laser welding, the metal powder core welding wire is composed of an external metal sheath skin and an internal powder core filler, and the welding wire comprises the following chemical components in percentage by weight: 0.05%-0.10% of C, 0.20%-0.40% of Si, 1.50%-1.75% of Mn, 23.0%-25.5% of Cr, 1.00%-3.50% of Ni, 0.10%-0.50% of Mo, 0.01%-0.03% of Al, 0.001%-0.005% of B, 0-0.20% of Cu, less than or equal to 0.05% of Ti, less than or equal to 0.012% of P, less than or equal to 0.008% of S and the balance of Fe and In this way, the overall quality of a welding seam is improved.

Description

Technical Field

[0001] This invention relates to the field of welding wire technology for laser welding, specifically to metal powder core welding wire and welding process for laser welding of hot-formed aluminum-silicon coated steel plates. Background Technology

[0002] Hot-formed aluminum-silicon coated steel sheets are widely used in automotive body structural components, safety components, and high-temperature service parts due to their excellent high-temperature oxidation resistance, corrosion resistance, and high strength. Laser welding, as a highly efficient and precise joining technology, can achieve high-quality welding of hot-formed steel sheets.

[0003] Existing technologies have made many improvements to welding wires. For example, Chinese patent CN120715486A discloses a welding wire for laser filler wire welding and its preparation method. The method involves: 1) pressing a steel billet to obtain a pressed steel billet with a first density; 2) subjecting the pressed steel billet to a first preset temperature heat treatment to achieve a tensile strength of 800MPa-1000MPa and a winding diameter of 400mm-600mm; 3) subjecting the first heat-treated pressed steel billet to a peeling process and a first drawing process; 4) subjecting the initially drawn steel wire to a second heat treatment at the first preset temperature to achieve a winding diameter of any value between 400mm and 600mm; and 5) subjecting the second heat-treated initially drawn steel wire to a second drawing process and a layer winding process to obtain the welding wire.

[0004] However, the aforementioned patents and existing technologies still have the following shortcomings in practical applications: 1. The above-mentioned patent uses solid welding wire with a composition system of high-strength structural steel. It is not designed for the welding characteristics of coated steel plates. Due to the interference of coating elements, it is easy to cause problems such as weld porosity and cracks. 2. The drawing speed is controlled in stages (faster first drawing, slower second drawing), and the wire feeding characteristics are not optimized for high-speed laser welding, resulting in low overall efficiency.

[0005] Based on this, the present invention designs a metal powder core welding wire and welding process for laser welding of thermoformed aluminum-silicon coated steel plates to solve the above problems. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a metal powder-cored welding wire and welding process for laser welding of thermoformed aluminum-silicon coated steel plates.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates comprises two parts: an outer metal sheath and an inner core filler. The welding wire contains the following chemical components by weight percentage: C: 0.05%~0.10%, Si: 0.20%~0.40%, Mn: 1.50%~1.75%, Cr: 23.0%~25.5%, Ni: 1.00%~3.50%, Mo: 0.10%~0.50%, Al: 0.01%~0.03%, B: 0.001%~0.005%, Cu: 0~0.20%, Ti: ≤0.05%, P: ≤0.012%, S: ≤0.008%, with the balance being Fe and unavoidable impurities; The core filler comprises the following raw materials by weight percentage: 15.0~18.0% low-carbon ferrochrome powder, 12.0~14.0% electrolytic manganese powder, 5.0~7.0% silica-alumina-barium-calcium powder, 3.0~5.0% nickel powder, 3.0~4.0% rutile powder, 2.5~3.5% cryolite powder, 0.8~1.5% calcium molybdate powder, 0.8~1.5% spodumene powder, 0.5~1.0% yttrium-stabilized zirconium oxide powder, and 0.1~0.3% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder.

[0008] Furthermore, the outer material of the metal sheath is low-carbon stainless steel strip, with a chromium content of 18-22%.

[0009] Furthermore, in the raw materials of the core filler, the mass ratio of rutile powder to spodumene powder is 2.9~3.1:1.0.

[0010] Furthermore, in the raw materials of the core filler, the mass ratio of hexagonal boron nitride powder, yttrium stabilized zirconium oxide powder and calcium molybdate powder is 0.15~0.25:0.75~0.85:0.95~1.05.

[0011] To better achieve the objectives of this invention, this invention also provides a method for preparing metal-cored welding wire for laser welding of hot-formed aluminum-silicon coated steel plates, specifically including the following steps: Step (1) Mix rutile powder and spodumene powder and ball mill at 250~300 rpm for 3~4 hours to obtain slurry. Dry the slurry and press it into a block. Under inert gas protection, heat the block to 1150~1250℃ at 8~12℃ / min and hold it for 1.5~2.5 hours. After the holding is completed, cool it with the furnace to obtain sintered block. Then crush, grind and sieve it to obtain mixed powder A. Step (2) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic and mechanical stirring for 1.5~2.0h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1350~1450℃ at a rate of 4~5℃ / min under vacuum conditions and keep it at the temperature for 1.0~1.5h to obtain mixed powder B; Step (3) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at a speed of 20-30 rpm for 80-100 minutes under an inert atmosphere. Then dry and sieve to obtain the core filler. Step (4) After the metal sheath of the low carbon stainless steel strip is precisely rolled into a U-shape, the powder core filler is filled in and then closed and rolled into a circle to obtain the metal powder core welding wire for laser welding of thermoformed aluminum silicon coated steel plates.

[0012] Furthermore, in step (2), the ultrasonic power is 400~500W, the ultrasonic frequency is 30~40kHz, and the mechanical stirring speed is 600~800rpm. The mass of the core filler in step (4) accounts for 34-36% of the total mass of the metal core welding wire used for laser welding of thermoformed aluminum-silicon coated steel plates.

[0013] To better achieve the objectives of this invention, the present invention also provides a welding process for metal-cored welding wire used in laser welding of hot-formed aluminum-silicon coated steel plates, with specific parameters as follows: Welding using metal-cored wire for laser welding of thermoformed aluminum-silicon coated steel plates must be carried out under the protection of inert gas. Each weld is composed of multiple weld segments, with an inert gas concentration of not less than 99.999% and a flow rate of 12~15L / min. During welding, the wire is heated to 890~920℃, the laser rated power is 6~8kW, and the wire feed speed is 0.6~3.0m / min.

[0014] Furthermore, each weld is composed of four weld segments, with argon as the inert gas, the concentration of which is not less than 99.999%, and the flow rate of which is 12~15L / min. The parameters for each weld segment are different, specifically: The weld length is 10~120mm, the welding speed is 5.3~5.8m / min, and the welding power is 76~97% of the laser's rated power.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The welding wire prepared by the present invention, through the metal powder core welding wire structure and the high Cr and appropriate amount of Ni components, enhances the compatibility with the coating, reduces the defects caused by coating burn-off, and improves the overall performance of the weld. 2. The wire feeding speed of this invention is matched with the laser power, and the segmented welding parameters are adapted to different weld lengths, so as to realize the deposition control under high-speed welding and improve the process adaptability to thick plates or long welds. 3. The ratio of raw materials for the core filler and the preparation process of the core filler have a synergistic effect on the maximum hardness of the weld and the number of spatter points formed by the welding wire. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 These are schematic diagrams showing the weld positions and composition in embodiments 1-5 of the present invention; Figure 2 This is a schematic diagram of the metallographic structure of the weld formed in Embodiment 3 of the present invention; Figure 3 This is a weld strength test diagram using the welding wire and process of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Preparation and welding process of metal-cored welding wire for laser welding of hot-formed aluminum-silicon coated steel plates, specifically including: I. Preparation of Powder Core Filler (1) Weigh the following raw materials by weight percentage: 15.0% low-carbon ferrochrome powder, 14.0% electrolytic manganese powder, 5.0% silica-alumina-barium-calcium powder, 5.0% nickel powder, 3.0% rutile powder, 3.5% cryolite powder, 1.3% calcium molybdate powder, 0.9% spodumene powder, 0.8% yttrium-stabilized zirconium oxide powder, and 0.3% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder; (2) After mixing rutile powder and spodumene powder, place them in a high-energy ball mill, add ethanol as a process control agent, and ball mill at 250 rpm for 4 hours to obtain a slurry. Dry the slurry, press it into a block, place the block in an atmosphere sintering furnace, and heat it to 1250℃ at 8℃ / min under argon protection. Hold it for 1.5 hours. After the holding is completed, cool it with the furnace to obtain a sintered block. Then crush, grind and sieve it to obtain mixed powder A. (3) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic (power 350W, frequency 35kHz) and mechanical stirring (speed 700rpm) for 1.8h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1400℃ at a rate of 4.5℃ / min under vacuum and keep it at the temperature for 1.2h to obtain mixed powder B; (4) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at 20 rpm for 100 min under an inert atmosphere. Then dry and sieve to obtain the core filler.

[0020] II. Preparation of Welding Wire and Welding Process (1) After the metal sheath of the low-carbon stainless steel strip is precisely rolled into a U-shape, a core filler is filled in and then closed and rolled into a circle. The mass of the core filler accounts for 35% of the total mass of the welding wire, thus obtaining a metal core welding wire for laser welding of thermoformed aluminum-silicon coated steel plates. The chemical composition of the welding wire by weight percentage is as follows: C: 0.05%, Si: 0.40%, Mn: 1.50%, S: 0.008%, P: 0.008%, Cr: 25.5%, Ni: 1.0%, Mo: 0.50%, Ti: ≤0.03%, Al: 0.03%, B: 0.001%, Cu: 0.20%, balance Fe and unavoidable impurities; (2) The diameter of the welding wire is 1.2mm, the base material is 1.6mm thick (aluminum silicon coating HC800 / 1000HS) and 2.1mm thick (aluminum silicon coating 950 / 1300HS+AS) is welded together. The welding method is disc laser-filler wire welding with a rated power of 6kW. The welding process parameters are shown in Table 1.

[0021]

[0022] Example 2: Preparation and welding process of metal-cored welding wire for laser welding of hot-formed aluminum-silicon coated steel plates, specifically including: I. Preparation of Powder Core Filler (1) Weigh the following raw materials by weight percentage: 18.0% low-carbon ferrochrome powder, 12.0% electrolytic manganese powder, 7.0% silica-alumina-barium-calcium powder, 3.0% nickel powder, 4.7% rutile powder, 2.5% cryolite powder, 0.8% calcium molybdate powder, 1.5% spodumene powder, 0.6% yttrium-stabilized zirconium oxide powder, and 0.1% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder; (2) After mixing rutile powder and spodumene powder, place them in a high-energy ball mill, add ethanol as a process control agent, and ball mill at 300 rpm for 3 hours to obtain a slurry. Dry the slurry, press it into a block, place the block in an atmosphere sintering furnace, and heat it to 1150℃ at 12℃ / min under argon protection. Hold it for 2.5 hours. After the holding is completed, cool it with the furnace to obtain a sintered block. Then crush, grind and sieve it to obtain mixed powder A. (3) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic (power 400W, frequency 40kHz) and mechanical stirring (speed 600rpm) for 2.0h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1450℃ at a rate of 4℃ / min under vacuum and keep it at that temperature for 1.0h to obtain mixed powder B; (4) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at 30 rpm for 80 min under an inert atmosphere. Then dry and sieve to obtain the core filler.

[0023] II. Preparation of Welding Wire and Welding Process (1) After the metal sheath of the low-carbon stainless steel strip is precisely rolled into a U-shape, a core filler is filled in and then closed and rolled into a circle. The mass of the core filler accounts for 35% of the total mass of the welding wire, thus obtaining a metal core welding wire for laser welding of thermoformed aluminum-silicon coated steel plates. The chemical composition of the welding wire by weight percentage is as follows: C: 0.10%, Si: 0.20%, Mn: 1.75%, S: 0.003%, P: 0.012%, Cr: 23%, Ni: 3.50%, Mo: 0.10%, Ti: 0.05%, Al: 0.01%, B: 0.005%, balance Fe and unavoidable impurities; (2) The diameter of the welding wire is 1.2mm, the base material is 1.9mm thick (aluminum silicon coating 950 / 1300HS+AS) and 2.0mm thick (aluminum silicon coating HC800 / 1000HS). The welding method is disc laser-filler wire welding with a rated power of 6kW. The welding process parameters are shown in Table 2.

[0024]

[0025] Example 3: Preparation and welding process of metal-cored welding wire for laser welding of hot-formed aluminum-silicon coated steel plates, specifically including: I. Preparation of Powder Core Filler (1) Weigh the following raw materials by weight percentage: 15.5% low-carbon ferrochrome powder, 12.5% ​​electrolytic manganese powder, 5.5% silica-alumina-barium-calcium powder, 3.5% nickel powder, 3.5% rutile powder, 3.0% cryolite powder, 1.0% calcium molybdate powder, 1.1% spodumene powder, 0.8% yttrium-stabilized zirconium oxide powder, and 0.2% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder; (2) After mixing rutile powder and spodumene powder, place them in a high-energy ball mill, add ethanol as a process control agent, and ball mill at 280 rpm for 3.5 h to obtain a slurry. Dry the slurry, press it into a block, place the block in an atmosphere sintering furnace, and heat it to 1200℃ at 10℃ / min under argon protection. Hold it for 2 h. After the holding is completed, cool it with the furnace to obtain a sintered block. Then crush, grind and sieve it to obtain mixed powder A. (3) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic (power 500W, frequency 30kHz) and mechanical stirring (speed 800rpm) for 1.5h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1350℃ at a rate of 5℃ / min under vacuum and keep it at that temperature for 1.5h to obtain mixed powder B. (4) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at 25 rpm for 90 min under an inert atmosphere. Then dry and sieve to obtain the core filler.

[0026] II. Preparation of Welding Wire and Welding Process (1) After the metal sheath of the low-carbon stainless steel strip is precisely rolled into a U-shape, a core filler is filled in and then closed and rolled into a circle. The mass of the core filler accounts for 34% of the total mass of the welding wire, thus obtaining a metal core welding wire for laser welding of thermoformed aluminum-silicon coated steel plates. The chemical composition of the welding wire by weight percentage is as follows: C: 0.08%, Si: 0.3%, Mn: 1.65%, S: 0.005%, P: 0.010%, Cr: 24%, Ni: 2%, Mo: 0.3%, Ti: 0.03%, Al: 0.02%, B: 0.003%, Cu: 0.1%, balance Fe and unavoidable impurities; (2) The diameter of the welding wire is 1.2mm, the base material is 2.0mm thick (aluminum silicon coating HC800 / 1000HS) and 1.0mm thick (aluminum silicon coating 950 / 1300HS+AS) is welded together. The welding method is disc laser-filler wire welding, the rated power is 4kW, and the welding process parameters are shown in Table 3.

[0027]

[0028] Example 4: Preparation and welding process of metal-cored welding wire for laser welding of hot-formed aluminum-silicon coated steel plates, specifically including: I. Preparation of Powder Core Filler (1) Weigh the following raw materials by weight percentage: 16.5% low-carbon ferrochrome powder, 13.0% electrolytic manganese powder, 6.0% silica-alumina-barium-calcium powder, 4.0% nickel powder, 3.3% rutile powder, 3.0% cryolite powder, 1.1% calcium molybdate powder, 1.0% spodumene powder, 0.9% yttrium-stabilized zirconium oxide powder, and 0.2% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder; (2) After mixing rutile powder and spodumene powder, place them in a high-energy ball mill, add ethanol as a process control agent, and ball mill at 260 rpm for 3.2 h to obtain a slurry. Dry the slurry, press it into a block, place the block in an atmosphere sintering furnace, and heat it to 1180℃ at 9℃ / min under argon protection. Hold it for 1.8 h. After the holding is completed, cool it with the furnace to obtain a sintered block. Then crush, grind and sieve it to obtain mixed powder A. (3) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic (power 350W, frequency 35kHz) and mechanical stirring (speed 700rpm) for 1.8h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1400℃ at a rate of 4.5℃ / min under vacuum and keep it at the temperature for 1.2h to obtain mixed powder B; (4) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at 22 rpm for 85 min under an inert atmosphere. Then dry and sieve to obtain the core filler.

[0029] II. Preparation of Welding Wire and Welding Process (1) After the metal sheath of the low-carbon stainless steel strip is precisely rolled into a U-shape, a core filler is filled in and then closed and rolled into a circle. The mass of the core filler accounts for 35% of the total mass of the welding wire, thus obtaining a metal core welding wire for laser welding of thermoformed aluminum-silicon coated steel plates. The chemical composition of the welding wire by weight percentage is as follows: C: 0.06%, Si: 0.25%, Mn: 1.55%, S: 0.004%, P: 0.009%, Cr: 23.5%, Ni: 1.5%, Mo: 0.2%, Ti: 0.01%, Al: 0.015%, B: 0.0015%, Cu: 0.05%, balance Fe and unavoidable impurities; (2) The diameter of the welding wire is 1.2mm, the base material is 1.6mm thick (aluminum silicon coating HC800 / 1000HS) and 1.0mm thick (aluminum silicon coating 950 / 1300HS+AS) is welded together. The welding method is disc laser-filler wire welding with a rated power of 5kW. The welding process parameters are shown in Table 4.

[0030]

[0031] Example 5: Preparation and welding process of metal-cored welding wire for laser welding of hot-formed aluminum-silicon coated steel plates, specifically including: I. Preparation of Powder Core Filler (1) Weigh the following raw materials by weight percentage: 17.5% low-carbon ferrochrome powder, 13.5% electrolytic manganese powder, 6.5% silica-alumina-barium-calcium powder, 4.5% nickel powder, 3.6% rutile powder, 3.2% cryolite powder, 1.0% calcium molybdate powder, 1.2% spodumene powder, 0.8% yttrium-stabilized zirconium oxide powder, and 0.1% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder; (2) After mixing rutile powder and spodumene powder, place them in a high-energy ball mill, add ethanol as a process control agent, and ball mill at 280 rpm for 3.7 h to obtain a slurry. Dry the slurry, press it into a block, place the block in an atmosphere sintering furnace, and heat it to 1230℃ at 11℃ / min under argon protection. Hold it for 2.2 h. After the holding is completed, cool it with the furnace to obtain a sintered block. Then crush, grind and sieve it to obtain mixed powder A. (3) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic (power 350W, frequency 35kHz) and mechanical stirring (speed 700rpm) for 1.8h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1400℃ at a rate of 4.5℃ / min under vacuum and keep it at the temperature for 1.2h to obtain mixed powder B; (4) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at 28 rpm for 95 minutes under an inert atmosphere. Then dry and sieve to obtain the core filler.

[0032] II. Preparation of Welding Wire and Welding Process (1) After the metal sheath of the low-carbon stainless steel strip is precisely rolled into a U-shape, a core filler is filled in and then closed and rolled into a circle. The mass of the core filler accounts for 35% of the total mass of the welding wire, thus obtaining a metal core welding wire for laser welding of thermoformed aluminum-silicon coated steel plates. The chemical composition of the welding wire by weight percentage is as follows: C: 0.08%, Si: 0.35%, Mn: 1.6%, S: 0.006%, P: 0.01%, Cr: 25%, Ni: 3%, Mo: 0.4%, Ti: 0.04%, Al: 0.025%, B: 0.004%, Cu: 0.15%, balance Fe and unavoidable impurities; (2) The diameter of the welding wire is 1.2mm, the base material is 1.9mm thick (aluminum silicon coating 950 / 1300HS+AS) and 2.1mm thick (aluminum silicon coating 950 / 1300HS+AS) is welded together. The welding method is disc laser-filler wire welding with a rated power of 6kW. The welding process parameters are shown in Table 5.

[0033]

[0034] The weld segmentation diagrams in Examples 1-5 are as follows: Figure 1 As shown.

[0035] The mechanical properties of the welded welds according to the parameters in Examples 1 to 5 are shown in Tables 6 and 7. Different sample fragments were cut from the welds of each example for performance testing. A total of 16 samples were selected from the five examples. Four samples were selected for Example 1 (weld No. 01) and Example 2 (weld No. 02), two samples were selected for Example 3 (weld No. 03), and three samples were selected for Example 4 (weld No. 04) and Example 5 (weld No. 05).

[0036]

[0037]

[0038]

[0039] Table 7. Test results of mechanical properties (hardness) of Examples 1-5

[0040] Comparative Example 1: Compared with Example 3, the difference is that the ratio of the raw materials for the core filler was changed: 15.5% low-carbon ferrochrome powder, 12.5% ​​electrolytic manganese powder, 5.5% silica-alumina-barium-calcium powder, 3.5% nickel powder, 4.0% rutile powder, 3.0% cryolite powder, 1.5% calcium molybdate powder, 1.0% spodumene powder, 0.4% yttrium-stabilized zirconium oxide powder, and 0.4% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder; The remaining steps are the same as in Example 3.

[0041] Comparative Example 2: Compared with Example 3, the difference is that in the process of preparing the core filler, the raw materials were directly mixed into a three-dimensional mixer and mixed at 25 rpm for 90 min under an inert atmosphere. After drying and sieving, the core filler was obtained.

[0042] The remaining steps are the same as in Example 3.

[0043] Comparative Example 3: Compared with Example 3, the difference is that the ratio of the raw materials of the core filler was changed, and the preparation process of the core filler was also changed. The remaining steps were the same as in Example 3.

[0044] Comparative Example 4: Compared with Example 3, commercially available welding wire was used instead of the welding wire prepared in this invention, and the remaining steps were the same as in Example 3.

[0045] Experimental example: The following performance tests were conducted on Examples 1-3 and Comparative Examples 1-4, and the performance test results are shown in Table 8.

[0046] The tensile strength (MPa) and weld hardness (HV) were the maximum values ​​of the four weld segments in each example and comparative example. Meanwhile, spatter tests were performed on the welding wires prepared in Examples 1-3 and Comparative Examples 1-4, and the number of spatter points was recorded as the results.

[0047]

[0048] The weld formed using the welding wire prepared in Example 3 has the following metallographic structure: Figure 2 As shown, the martensite content exceeds 95%, and there is no Fe-A structure. This achieves the basic mechanical properties of high strength and high hardness of the weld, while effectively suppressing the formation of Fe-Al brittle phases, thus ensuring the plasticity and toughness of the weld.

[0049] As shown in Table 7, when welding with different grades of materials, the average hardness of the weld area is higher than the average hardness of the softer substrate, but does not exceed 50 HV of the average hardness of the harder material. When welding with the same grade of materials, the average hardness of the weld area does not deviate from the average hardness of the base material by more than 50 HV. That is, when welding with the welding wire prepared by the method of the present invention, the hardness index of the weld is qualified.

[0050] As can be seen from Examples 1-3, the tensile strength of the welded joints obtained by using the metal powder-cored welding wire and welding process provided by the present invention is higher than that of the base material, the fracture location is the base material, the hardness of the weld is also at a high strength level, and the number of spatter points is controlled at an extremely low level, indicating that the welding process is very stable and the weld formation quality is good.

[0051] As can be seen from Example 3 and Comparative Example 1, if the ratio of the raw materials of the core filler is changed, the strength and hardness of the weld formed by the prepared welding wire will decrease, and the welding spatter will increase significantly.

[0052] As can be seen from Example 3 and Comparative Example 2, if the key powder pretreatment step is omitted and the raw materials are directly mixed, although the decrease in tensile strength and hardness is relatively small, the fracture location shifts to the weld and spatter increases.

[0053] As can be seen from Example 3 and Comparative Example 3, the ratio of the raw materials of the core filler and the preparation process of the core filler have a synergistic effect on the maximum hardness of the weld and the number of spatter points formed by the welding wire.

[0054] As can be seen from Example 3 and Comparative Example 4, when commercially available ordinary welding wire is used, all properties of the weld are the worst, and the fracture is located in the weld.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates, characterized in that, It consists of two parts: an outer metal sheath and an inner powder core filler. The welding wire comprises the following chemical components by weight percentage: C: 0.05%~0.10%, Si: 0.20%~0.40%, Mn: 1.50%~1.75%, Cr: 23.0%~25.5%, Ni: 1.00%~3.50%, Mo: 0.10%~0.50%, Al: 0.01%~0.03%, B: 0.001%~0.005%, Cu: 0~0.20%, Ti: ≤0.05%, P: ≤0.012%, S: ≤0.008%, with the balance being Fe and unavoidable impurities; The core filler comprises the following raw materials by weight percentage: 15.0~18.0% low-carbon ferrochrome powder, 12.0~14.0% electrolytic manganese powder, 5.0~7.0% silica-alumina-barium-calcium powder, 3.0~5.0% nickel powder, 3.0~4.0% rutile powder, 2.5~3.5% cryolite powder, 0.8~1.5% calcium molybdate powder, 0.8~1.5% spodumene powder, 0.5~1.0% yttrium-stabilized zirconium oxide powder, and 0.1~0.3% hexagonal boron nitride powder, with the balance being low-carbon ferrochrome powder.

2. The metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to claim 1, characterized in that, The outer metal sheath is made of low-carbon stainless steel strip, with a chromium content of 18-22%.

3. The metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to claim 2, characterized in that, In the raw materials of the core filler, the mass ratio of rutile powder to spodumene powder is 2.9~3.1:1.

0.

4. The metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to claim 3, characterized in that, In the raw materials of the core filler, the mass ratio of hexagonal boron nitride powder, yttrium-stabilized zirconium oxide powder and calcium molybdate powder is 0.15~0.25:0.75~0.85:0.95~1.

05.

5. A method for preparing a metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to any one of claims 1-4, characterized in that, Specifically, the following steps are included: Step (1) Mix rutile powder and spodumene powder and ball mill at 250~300 rpm for 3~4 hours to obtain slurry. Dry the slurry and press it into a block. Under inert gas protection, heat the block to 1150~1250℃ at 8~12℃ / min and hold it for 1.5~2.5 hours. After the holding is completed, cool it with the furnace to obtain sintered block. Then crush, grind and sieve it to obtain mixed powder A. Step (2) Disperse hexagonal boron nitride powder and yttrium stable zirconium oxide powder in a solution containing tetraethyl orthosilicate and ethanol, and treat it under ultrasonic and mechanical stirring for 1.5~2.0h to obtain a suspension. Add dilute ammonia water to the suspension and stir to form a gel. After drying the gel, heat it to 1350~1450℃ at a rate of 4~5℃ / min under vacuum conditions and keep it at the temperature for 1.0~1.5h to obtain mixed powder B; Step (3) Mix powder A, mixed powder B and other raw materials and put them into a three-dimensional mixer. Mix them at a speed of 20-30 rpm for 80-100 minutes under an inert atmosphere. Then dry and sieve to obtain the core filler. Step (4) After the metal sheath of the low carbon stainless steel strip is precisely rolled into a U-shape, the powder core filler is filled in and then closed and rolled into a circle to obtain the metal powder core welding wire for laser welding of thermoformed aluminum silicon coated steel plates.

6. The method for preparing the metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to claim 5, characterized in that: In step (2), the ultrasonic power is 400~500W, the ultrasonic frequency is 30~40kHz, and the mechanical stirring speed is 600~800rpm. The mass of the core filler in step (4) accounts for 34-36% of the total mass of the metal core welding wire used for laser welding of thermoformed aluminum-silicon coated steel plates.

7. A welding process for a metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to any one of claims 1-4, characterized in that, The specific parameters are as follows: Welding using metal-cored wire for laser welding of thermoformed aluminum-silicon coated steel plates must be carried out under the protection of inert gas. Each weld is composed of multiple weld segments, with an inert gas concentration of not less than 99.999% and a flow rate of 12~15L / min. During welding, the wire is heated to 890~920℃, the laser rated power is 6~8kW, and the wire feed speed is 0.6~3.0m / min.

8. The welding process of the metal-cored welding wire for laser welding of thermoformed aluminum-silicon coated steel plates according to claim 7, characterized in that, Each weld is composed of four weld segments, with argon as the inert gas, the concentration of which is not less than 99.999%, and the flow rate of which is 12~15L / min. The parameters for each weld segment are different, specifically: The weld length is 10~120mm, the welding speed is 5.3~5.8m / min, and the welding power is 76~97% of the laser's rated power.

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