Laser welding wire for press hardening steel having aluminum-containing coating and welding method using same

Abstract

Disclosed in the present disclosure are a laser welding wire for press hardening steel having an aluminum-containing coating and a welding method using same. Components of the laser welding wire satisfy the following relational expressions: 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15% and [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%, wherein [C], [Ni], [Mn], [Cr], [Mo], [Si], and [Nb] respectively represent the mass fractions of C, Ni, Mn, Cr, Mo, Si, and Nb in the welding wire.

Description

A laser welding wire for hot-formed steel with aluminum coating and its welding method Cross-references to related applications

[0001] This application claims priority to Chinese patent application No. 202410552197.3, filed on May 7, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of welding technology, and in particular to a laser welding wire for hot-formed steel with aluminum coating and a welding method thereof. Background Technology

[0003] Lightweight steel is an inevitable trend in materials development, and aluminum-coated hot-formed steel is the main way to achieve this, especially aluminum-coated products that are hot-stamped after welding, which have been widely used. Currently, the welding methods used for welding aluminum-coated hot-formed steel are mainly laser welding or laser filler wire welding.

[0004] The main problem encountered when laser welding hot-formed steel with aluminum coatings is that during the welding process, aluminum from the aluminum coating enters the molten pool and forms high-temperature ferrite after hot forming. The hardness of high-temperature ferrite is much lower than that of martensite, thus reducing the tensile strength of the weld. To solve this problem, related technologies typically use equipment to peel off the aluminum coating before welding to avoid the adverse effects of elements in the aluminum coating on weld quality, thereby addressing the issue of reduced weld strength. However, this process requires additional laser peeling equipment, increasing equipment and process costs. Summary of the Invention

[0005] The problem of reduced weld strength in aluminum-coated hot-formed steel is solved by utilizing one or more embodiments of the present disclosure.

[0006] In a first aspect, according to some embodiments of the present disclosure, a laser welding wire for hot-formed steel with an aluminum coating is provided, wherein the chemical composition of the laser welding wire satisfies: 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 15%, [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] ≤ 8%; wherein [C], [Ni], [Mn], [Cr], [Mo], [Si] and [Nb] are the mass fractions of C, Ni, Mn, Cr, Mo, Si and Nb in the welding wire, respectively.

[0007] Secondly, according to some embodiments of the present disclosure, a laser welding method for hot-formed steel with aluminum coating is performed using the laser welding wire for hot-formed steel with aluminum coating disclosed in the first aspect, comprising the following steps: splicing a first aluminum-coated sheet to be welded with a second aluminum-coated sheet to be welded; performing laser welding on the first aluminum-coated sheet to be welded with the second aluminum-coated sheet to be welded to form a welded blank with a weld seam; and heat-treating the welded blank to obtain a laser filler wire welded part; wherein the chemical composition of the weld seam satisfies: 7.8% ≤ 30 × [C] + [Ni] + 0. 5×[Mn]≤12%, [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al]≤12%, 30×[C]+[Ni]+0.5×[Mn]<-0.76×([Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al])+0.187; where [C], [Ni], [Mn], [Cr], [Mo], [Si], [Nb] and [Al] are the mass fractions of C, Ni, Mn, Cr, Si, Nb and Al in the weld, respectively. Attached Figure Description

[0008] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0009] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0010] Figure 1 shows a flowchart of a laser welding method for hot-formed steel with aluminum coating according to some embodiments of the present disclosure;

[0011] Figure 2 shows a schematic diagram of the structure of a laser filler wire welded part obtained by laser welding according to some embodiments of the present disclosure;

[0012] Figure 3 shows a tensile curve of the weld position of a laser-welded part according to Embodiment 1 of this disclosure;

[0013] Figure 4 shows the location of tensile fracture in the weld area of ​​a laser-welded part according to Embodiment 1 of this disclosure;

[0014] Figure 5 shows the location of tensile fracture in the weld area of ​​a laser-welded part according to Comparative Example 1 of this disclosure.

[0015] Figure 6 shows a schematic diagram of cracks in the weld of a laser-welded part according to Comparative Example 3 of this disclosure;

[0016] Figure 7 shows a schematic diagram of the form of a laser light source according to some embodiments of the present disclosure.

[0017] Figure label:

[0018] 1-First aluminum-containing coating on the substrate to be welded; 11-First substrate; 12-First aluminum-containing coating;

[0019] 2-Second aluminum-containing coating on the substrate to be welded; 21-Second substrate; 22-Second aluminum-containing coating;

[0020] 3-Weld;

[0021] 4-Laser; 41-Central light source; 42-Peripheral light source. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure 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 this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0023] Various embodiments of this disclosure may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this disclosure; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0024] In this disclosure, unless otherwise stated, terms including "comprising" and the like mean "including but not limited to". Relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this disclosure are available on the market or can be prepared by existing methods.

[0026] To address the issue of reduced weld strength in hot-formed steel with aluminum coatings, this disclosure proposes using laser filler wire welding to weld the steel. The aim is to add welding wire metal to the molten pool through laser filler wire welding, thereby diluting the aluminum element in the molten pool, expanding the austenite region, and providing a possibility for improving weld performance. Therefore, laser welding wire and laser welding method are the research focus of this disclosure.

[0027] In a first aspect, according to some embodiments of this disclosure, a laser welding wire for hot-formed steel with an aluminum coating is provided, the chemical composition of which satisfies:

[0028] 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15%,

[0029] [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%;

[0030] Wherein, [C], [Ni], [Mn], [Cr], [Mo], [Si] and [Nb] are the mass fractions of C, Ni, Mn, Cr, Mo, Si and Nb in the laser welding wire, respectively.

[0031] In the above embodiments, the laser welding wire is used as the welding material. By controlling the composition of the welding wire to meet the requirements of 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 15% and [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] ≤ 8%, the composition of the weld metal can be guaranteed, so that the weld is mainly composed of martensite, thereby improving the weld strength. On the other hand, when the composition of the laser welding wire meets the requirements, the formation range of martensite after the molten pool metal cools can be maximized, which can suppress the performance degradation caused by the non-uniformity of the weld composition to a certain extent. Therefore, even under extreme conditions, even if the welding wire does not fuse with the aluminum-coated hot-formed steel in some areas, the welding wire can still form a martensite structure after melting and resolidifying, thereby ensuring the mechanical properties of the joint of the aluminum-coated hot-formed steel.

[0032] It should be noted that, in some embodiments of this disclosure, the composition of the laser welding wire can be one of the following three:

[0033] Laser welding wire includes elements such as C, Ni, Mn, Mo, Cr, Si, and Nb, as well as other elements.

[0034] Laser welding wire contains only some or all of the elements C, Ni, Mn, Mo, Cr, Si and Nb. For example, the content of C, Cr, Nb or Mn can be 0, with the balance being Fe and unavoidable impurities.

[0035] Laser welding wire includes some elements from C, Ni, Mn, Cr, Mo, Si, and Nb. For example, the content of C, Cr, Nb, or Mn can be 0. Laser welding wire can also include other elements.

[0036] As an alternative implementation, the laser welding wire contains: [Ni]: >3%, [Si]: 0.15%–0.8%, and [Ti]: 0.05%–0.5%.

[0037] In some embodiments of this disclosure, controlling the Ni content in the welding wire composition to be greater than 3% can, on the one hand, offset the influence of the ferrite stabilizing element Al entering the molten pool. On the other hand, by making the Ni content in the laser welding wire composition greater than 3%, the C content in the laser welding wire can be reduced, thereby avoiding the presence of excessive C and other austenite stabilizing elements with stronger hardenability in the laser welding wire. If the C element in the welding wire is too high, it will not only increase the risk of cracking, but also cause the problem of pull-out fracture during the production process of laser welding wire.

[0038] In some embodiments of this disclosure, since the Si content in the laser welding wire is 0.15% to 0.8% and the Ti content is 0.05% to 0.5%, Si and Ti elements can be added to the molten pool through this laser welding wire. The Si and Ti elements can reduce the surface tension of the molten pool, increase fluidity, and promote uniform distribution of elements in the molten pool, thus avoiding localized enrichment of Al during welding. Furthermore, the addition of Si and Ti elements helps to change the direction of convection in the molten pool, changing it from "flowing from the center to the periphery" to "flowing from the periphery to the center."

[0039] In the research process of the laser welding wire for hot-formed steel with aluminum coating disclosed in this paper, welding tests after removing the coating from the upper and lower surfaces of the hot-formed steel with aluminum coating showed that the aluminum coating on the laser-irradiated side (upper surface) has a greater impact on the weld quality than the aluminum coating on the opposite side (lower surface). In related technologies, the molten pool of laser filler wire welding or laser welding exhibits a convection flow pattern "from the center to the periphery". On the laser-irradiated side, the molten aluminum coating around the molten pool moves downward along the fusion line. Due to the cooling effect of the surrounding metal, the high-temperature residence time near the fusion line is the shortest, which easily causes the Al element in the aluminum coating to not have time to be evenly distributed in the weld and instead agglomerates near the fusion line, resulting in a decrease in joint quality.

[0040] The laser welding wire for hot-formed steel with aluminum coating according to this disclosure can promote a convection direction in the molten pool on the laser irradiation side that flows "from the periphery to the center." This allows Al in the molten aluminum coating on the upper surface to move towards the center of the molten pool after entering the pool. Because the temperature in the center of the molten pool is higher, Al has sufficient time to fuse with other metals in the pool, thus preventing Al agglomeration near the fusion line and improving the uniformity of Al in the molten pool. Therefore, the laser welding wire for hot-formed steel with aluminum coating according to this disclosure can change the convection direction of the molten pool, facilitating a more uniform distribution of Al in the molten pool and reducing Al agglomeration near the fusion line.

[0041] Meanwhile, if the Si content is too high, oxide inclusions are prone to occur. Therefore, the Si content needs to be controlled at 0.15% to 0.8%. For example, the Si content can be set to 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, or 0.8%; the Ti content can be set to 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0042] As an optional implementation, the laser welding wire contains [Ti]: 0.08% to 0.5%.

[0043] As an alternative implementation, the laser welding wire is composed of C, Si, Mn, P, S, Cr, Ni, Mo, Ti, the balance Fe, and unavoidable impurities.

[0044] As an alternative implementation, the diameter of the laser welding wire is 0.9 mm to 1.2 mm.

[0045] Controlling the diameter of the laser welding wire from 0.9 mm to 1.2 mm helps to control the welding time and the volume of the weld. For example, the diameter of the laser welding wire can be set to 0.9 mm, 1.0 mm, 1.1 mm, or 1.2 mm.

[0046] Secondly, according to some embodiments of the present disclosure, a laser welding method for hot-formed steel with an aluminum coating is provided, as shown in FIG1. ​​This laser welding method uses the laser welding wire for hot-formed steel with an aluminum coating disclosed in the first aspect for welding. The laser welding method includes the following steps:

[0047] S1: Splice the first aluminum-coated plate to be welded with the second aluminum-coated plate to be welded;

[0048] S2: Laser welding is performed on the first aluminum-coated sheet material and the second aluminum-coated sheet material to be welded to form a weld blank with a weld seam; and,

[0049] S3: Heat-treat the welded blank to obtain laser filler wire welded parts;

[0050] The chemical composition of the weld meets the following requirements:

[0051] 7.8% ≤ 30×[C]+[Ni]+0.5×[Mn]≤12%, [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al]≤12%, 30×[C]+[Ni]+0.5×[Mn]<-0.76×([Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al])+0.187; where [C], [Ni], [Mn], [Cr], [Mo], [Si], [Nb] and [Al] are the mass fractions of C, Ni, Mn, Cr, Si, Nb and Al in the weld, respectively.

[0052] In some embodiments of this disclosure, when the weld composition meets the following conditions during laser welding: 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 12%, [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al] ≤ 12%, and 30×[C] + [Ni] + 0.5×[Mn] < -0.76×([Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al]) + 0.187, the weld can be predominantly martensitic, thereby improving weld strength. C, Ni, and Mn are all austenite stabilizing elements, which prevents Al from entering the molten pool and forming high-temperature ferrite.

[0053] It should be noted that, due to the certain inhomogeneity of the microstructure in the weld, the laser welding method disclosed herein, by ensuring that the weld composition meets 7.8% ≤ 30 × [C] + [Ni] + 0.5 × [Mn] ≤ 12%, can maximize the formation range of martensite after the molten pool metal cools, thereby suppressing the performance degradation caused by the inhomogeneity of the weld composition and ensuring the improvement of the joint's mechanical properties. When the weld composition does not meet the above conditions, ferrite or austenite structures are easily formed in the weld, thereby reducing the mechanical properties of the joint.

[0054] As an optional implementation, the volume ratio of laser welding wire in the weld is 10% to 70%.

[0055] In some embodiments of this disclosure, the volume ratio of laser welding wire in the weld is controlled to be 10% to 70%. The purpose is to control the main components in the weld during laser welding. If the volume of laser welding wire in the weld is too large, the energy required to melt the laser welding wire will increase, which will lead to insufficient energy to melt the plate to be welded, reduced welding efficiency, increased wire consumption, and easy formation of defects such as poor fusion. If the volume of laser welding wire in the weld is too small, that is, the amount of welding wire used is too small, the components in the weld mainly come from the plate to be welded, especially from the aluminum-containing coating of the plate to be welded, which has a high aluminum content. This leads to a high aluminum content in the molten pool and a low amount of beneficial elements from the laser welding wire in the molten pool, which may lead to the formation of ferrite in the weld, thereby reducing the mechanical properties of the joint.

[0056] As an optional implementation, when splicing the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded, the bottoms of the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded are aligned.

[0057] As an optional implementation, the first aluminum-coated substrate to be welded includes a first substrate and a first aluminum-coated layer disposed on the first substrate, and the second aluminum-coated substrate to be welded includes a second substrate and a second aluminum-coated layer disposed on the second substrate. The chemical compositions of the first and second aluminum-coated layers, by mass fraction, are respectively: [Al]: 85%–95%, [Si]: 5%–15%. The chemical compositions of the first and second substrates respectively include C, Si, Mn, Cr, Ti, and Fe.

[0058] In some embodiments of this disclosure, the chemical composition of the first aluminum-containing coating, by mass fraction, comprises: [Al]: 85%–95%, [Si]: 5%–15%. Exemplarily, the chemical composition of the first aluminum-containing coating may be set to: [Al]: 85%, [Si]: 15%; or, [Al]: 90%, [Si]: 10%; or, [Al]: 95%, [Si]: 5%.

[0059] In some embodiments of this disclosure, the chemical composition of the second aluminum-containing coating, by mass fraction, comprises: [Al]: 85%–95%, [Si]: 5%–15%. Exemplarily, the chemical composition of the second aluminum-containing coating may be set to: [Al]: 85%, [Si]: 15%; or, [Al]: 90%, [Si]: 10%; or, [Al]: 95%, [Si]: 5%.

[0060] It should be noted that the chemical composition of the first aluminum-containing coating may be the same as or different from that of the first aluminum-containing coating.

[0061] As an optional implementation, the thicknesses of the first aluminum-containing coating and the second aluminum-containing coating are 10 μm to 100 μm, respectively.

[0062] In some embodiments of this disclosure, the thickness of the first aluminum-containing coating can be from 10 μm to 100 μm. For example, the thickness of the first aluminum-containing coating can be set to 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0063] In some disclosed embodiments, the thickness of the second aluminum-containing coating can be from 10 μm to 100 μm. For example, the thickness of the second aluminum-containing coating can be set to 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0064] It should be noted that the thickness of the first aluminum-containing coating can be the same as or different from that of the first aluminum-containing coating.

[0065] In some embodiments of this disclosure, the aluminum content and thickness of the aluminum-containing coating are controlled in order to avoid oxidation and decarburization at high temperatures during the subsequent heating process of the welded blank.

[0066] As an optional implementation, the carbon equivalent of the laser welding wire is Ceq0, and the carbon equivalent of the aluminum-coated welding plate with higher tensile strength in the first aluminum-coated welding plate and the second aluminum-coated welding plate is Ceq1, satisfying Ceq1≤Ceq0≤(Ceq1+1), where Ceq is calculated as Ceq={[C]+[Mn] / 6+([Cr]+[Mo]) / 5+[Ni] / 15}×100%.

[0067] In some embodiments of this disclosure, the carbon equivalent Ceq0 of the laser welding wire is controlled to satisfy Ceq1≤Ceq0, the purpose of which is to ensure that the joint has higher hardenability than the base material with higher tensile strength; the carbon equivalent Ceq0 of the laser welding wire is controlled to satisfy Ceq0≤(Ceq1+1) to prevent the joint from having excessive hardenability, thereby increasing the tendency to crack.

[0068] As an optional implementation, the step of heat-treating the welding blank to obtain the laser filler wire welded part includes: heating the welding blank sequentially, hot stamping and quenching to obtain the laser filler wire welded part.

[0069] As an optional implementation, the heating temperature is greater than or equal to the austenitizing temperature AC3.

[0070] In some embodiments of this disclosure, the heating temperature is controlled to be above the austenitizing temperature AC3. The purpose is that the welded blank can only achieve complete austenitization when the temperature is above AC3, laying the foundation for the formation of martensite and the achievement of the specified strength in the later cooling stage.

[0071] As an optional implementation, the quenching cooling rate is >27°C / s.

[0072] In some embodiments of this disclosure, the quenching cooling rate is controlled to be >27°C / s. The purpose of this is that the aluminum-coated sheet material with a high carbon equivalent needs to reach this cooling rate during cooling in order to transform it into a certain amount of martensite structure and achieve the specified strength.

[0073] As an alternative implementation, the laser used in laser welding includes a central light source and a peripheral light source.

[0074] In some embodiments of this disclosure, as shown in FIG7, the laser source used for laser welding includes a central light source and a peripheral light source, that is, the central light source and the peripheral light source work together as a laser source. The central light source is used to form a narrow weld seam, and the peripheral light source is used to form a high-temperature region. By adding the peripheral light source, on the one hand, the temperature of the molten pool, especially the area near the fusion line, is increased, thereby increasing the residence time of the molten pool, especially the area near the fusion line, in the liquid state. This avoids the agglomeration of Al in the aluminum-containing coating near the fusion line after entering the molten pool, further improving the uniformity of Al element distribution in the molten pool. On the other hand, the peripheral light source can reduce the cooling rate of the molten pool, effectively preventing welding cracks from appearing in the weld seam.

[0075] As an optional implementation, the width of the weld on the laser-irradiated side is greater than that on the other side. The purpose is to further reduce the total amount of Al in the aluminum-containing coating on the lower surface (the other side opposite to the laser-irradiated side) entering the molten pool. Combined with the control of the laser welding wire and the weld composition, the uniformity of Al in the weld can be improved, which can reduce the impact of Al entering the molten pool on the joint performance and improve the weld strength.

[0076] The present disclosure is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the disclosure. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0077] Example 1

[0078] This embodiment discloses a laser welding wire for hot-formed steel with aluminum coating. The diameter of the laser welding wire is 1.2 mm, and the composition of the laser welding wire by mass percentage includes: C: 0.104%, Si: 0.250%, Mn: 1.62%, P: 0.008%, S: 0.001%, Cr: 1.07%, Ni: 5.99%, Mo: 1.39%, and Ti: 0.08%, with the balance being Fe.

[0079] Calculations show that 30×[C]+[Ni]+0.5×[Mn]=9.92% and [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]=2.84%. Therefore, the composition of the laser welding wire meets the following requirements: 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15% and [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%.

[0080] Laser welding was performed using the aforementioned laser welding wire to prepare laser-filled wire welded parts. The structural schematic diagram of the obtained filler wire welded parts is shown in Figure 2. The preparation method includes the following steps:

[0081] S1: The first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded are spliced ​​together so that the bottom of the first aluminum-coated plate to be welded is aligned with the bottom of the second aluminum-coated plate to be welded.

[0082] The first aluminum-containing coating on the substrate to be welded has a thickness of 1.8 mm and consists of a first substrate and a first aluminum-containing coating. The first substrate has the following composition: C: 0.24%, Si: 0.25%, Mn: 1.19%, Cr: 0.21%, and Ti: 0.03%, with the balance being Fe. The first aluminum-containing coating has a thickness of 30 μm and its composition is: Al: 88%, Si: 12%.

[0083] The second aluminum-containing coating has a thickness of 1.8 mm and consists of a second substrate and a second aluminum-containing coating. The second substrate has the following composition: C: 0.24%, Si: 0.25%, Mn: 1.19%, Cr: 0.21%, and Ti: 0.03%, with the balance being Fe. The second aluminum-containing coating has a thickness of 30 μm and its composition is: Al: 88% and Si: 12%.

[0084] Calculations show that the carbon equivalent of the laser welding wire, Ceq0, is 1.27, and the carbon equivalent of the first aluminum-coated welding plate and the second aluminum-coated welding plate, Ceq1, is 0.48, satisfying Ceq1≤Ceq0≤Ceq1+1.

[0085] S2: Laser filler wire welding is performed on the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded to form a weld blank with a weld seam.

[0086] In some embodiments, the laser light source used in laser welding includes a central light source and a peripheral light source. The energy of the peripheral light source is 50% of that of the central light source. The central light source is used to perform welding to form a narrow weld, and the peripheral light source is used to perform heating to form a high-temperature region that at least covers the fusion line. The width of the upper surface of the weld is greater than that of the lower surface. The volume ratio of the metal component of the laser welding wire in the weld is 10%. The average composition of the obtained weld includes: C: 0.23%, Si: 0.258%, Mn: 1.23%, Cr: 0.30%, Ni: 0.60%, Mo: 0.14%, Al: 1.02%, Ti: 0.03%. Calculations show that the weld composition meets the requirements of 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 12%, [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al] ≤ 12%, and 30×[C] + [Ni] + 0.5×[Mn] < -0.76×([Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al]) + 0.187.

[0087] S3: The welding blank is heated, hot-stamped, and quenched to obtain a laser-welded part. The heating temperature is 930℃ (>AC3), and the holding time is 5 minutes. After heating, it is quickly transferred to a flat mold for quenching and cooling. The quenching cooling rate is >27℃ / s.

[0088] Finally, the laser-welded parts were prepared into tensile samples. The tensile curve of the tensile samples is shown in Figure 3. The tensile strength of the tensile samples is 1639 MPa, and the elongation after fracture is above 7.2%. As shown in Figure 4, the fracture location after the tensile test is located in the base material, indicating that the tensile strength of the weld of the laser-welded parts obtained in this embodiment is greater than that of the base material, and the weld strength performance is good, meeting the test requirements.

[0089] Example 2

[0090] This embodiment discloses a laser welding wire for hot-formed steel with aluminum coating. The diameter of the laser welding wire is 1.2 mm. By mass percentage, the composition of the laser welding wire includes: C: 0.08%, Si: 0.40%, Mn: 1.5%, P: 0.008%, S: 0.001%, Cr: 1%, Ni: 5%, Mo: 1%, and Ti: 0.08%, with the balance being Fe.

[0091] Calculations show that 30×[C]+[Ni]+0.5×[Mn]=8.15%, [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]=2.6%, and the laser welding wire meets the following requirements: 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15%, [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%.

[0092] The laser welding process using the aforementioned laser welding wire to prepare laser filler wire welded parts includes the following steps:

[0093] S1: The first aluminum-coated substrate to be welded is spliced ​​with the second aluminum-coated substrate to be welded, aligning the bottom edges of the first aluminum-coated substrate to be welded with those of the second aluminum-coated substrate. The first aluminum-coated substrate has a thickness of 1.2 mm and consists of a first substrate and a first aluminum-coated layer. The composition of the first substrate is: C: 0.23%, Si: 0.22%, Mn: 1.2%, Cr: 0.18%, and Ti: 0.03%, with the balance being Fe; the first aluminum-coated layer has a thickness of 30 μm and a composition of: Al: 88% and Si: 12%.

[0094] The second aluminum-containing coating has a thickness of 1.2 mm and consists of a second substrate and a second aluminum-containing coating. The second substrate comprises: C: 0.23%, Si: 0.22%, Mn: 1.2%, Cr: 0.18%, and Ti: 0.03%, with the balance being Fe. The second aluminum-containing coating has a thickness of 30 μm and comprises: Al: 88% and Si: 12%.

[0095] Calculations show that the carbon equivalent of the laser welding wire, Ceq0, is 1.06, and the carbon equivalent of the first aluminum-coated welding plate and the second aluminum-coated welding plate, Ceq1, is 0.47, satisfying Ceq1≤Ceq0≤Ceq1+1.

[0096] S2: Laser filler wire welding is performed on the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded to form a weld blank with a weld seam.

[0097] The laser welding process utilizes a central laser source and peripheral laser sources. The peripheral laser sources have 50% of the energy of the central laser source. The central laser source is used to perform the welding to form a narrow weld bead, while the peripheral laser sources are used to heat the weld to create a high-temperature zone that at least covers the fusion line. The upper surface of the weld bead is wider than the lower surface. The metal composition of the laser welding wire accounts for 40% of the volume of the weld bead. The average composition of the obtained weld bead includes: C: 0.18%, Si: 0.31%, Mn: 1.3%, Cr: 0.5%, Ni: 2%, Mo: 0.4%, Al: 1.2%, Ti: 0.04%.

[0098] Calculations show that the weld composition meets the requirements of 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 12%, [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al] ≤ 12%, and 30×[C] + [Ni] + 0.5×[Mn] < -0.76×([Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al]) + 0.187.

[0099] S3: The welding blank is heated, hot-stamped, and quenched to obtain a laser-welded part. The heating temperature is 930℃ (>AC3), and the holding time is 5 minutes. After heating, it is quickly transferred to a flat mold for quenching and cooling. The quenching cooling rate is >27℃ / s.

[0100] Finally, the laser-welded parts were prepared into tensile samples. After tensile testing, the fracture location of the tensile samples was still located in the base material, and the tensile strength was 1577 MPa, indicating that the weld strength performance obtained in this embodiment is good and meets the test requirements.

[0101] Comparative Example 1

[0102] This comparative example discloses a laser welding wire for hot-formed steel with aluminum coating. The diameter of the laser welding wire is 1.2 mm, and the composition of the laser welding wire by mass percentage includes: C: 0.08%, Si: 0.52%, Mn: 1.05%, P: 0.015%, S: 0.008%, Cr: 0.21%, Ni: 0.95%, and Mo: 0.12%, with the balance being Fe.

[0103] Calculations show that 30×[C]+[Ni]+0.5×[Mn]=3.88% and [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]=1.11%. The composition of the laser welding wire meets the requirement of [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%, but does not meet the requirement of 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15%. Furthermore, the Ni content in the laser welding wire used for laser filler wire welding is 0.95%, which does not meet the requirement of >3%.

[0104] The laser welding wire provided above is used to weld and prepare filler wire welded parts. The preparation method includes the following steps:

[0105] S1: The first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded are spliced ​​together so that the bottom of the first aluminum-coated plate to be welded is aligned with the bottom of the second aluminum-coated plate to be welded.

[0106] The first aluminum-containing coating on the substrate to be welded has a thickness of 1.8 mm and consists of a first substrate and a first aluminum-containing coating. The first substrate has the following composition: C: 0.24%, Si: 0.25%, Mn: 1.19%, Cr: 0.21%, and Ti: 0.03%, with the balance being Fe. The first aluminum-containing coating has a thickness of 30 μm and its composition is: Al: 88% and Si: 12%.

[0107] The second aluminum-containing coating on the substrate to be welded has a thickness of 1.8 mm and consists of a second substrate and a second aluminum-containing coating. The second substrate has the following composition: C: 0.24%, Si: 0.25%, Mn: 1.19%, Cr: 0.21%, and Ti: 0.03%, with the balance being Fe. The second aluminum-containing coating has a thickness of 30 μm and its composition is: Al: 88% and Si: 12%.

[0108] Calculations show that the carbon equivalent Ceq0 of the laser welding wire is 0.38, and the carbon equivalent Ceq1 of the first aluminum-coated welding plate and the second aluminum-coated welding plate is 0.48. This satisfies Ceq0≤Ceq1+1, but does not satisfy Ceq1≤Ceq0.

[0109] S2: Laser filler wire welding is performed on the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded to form a weld blank with a weld seam.

[0110] In this comparative example, only the central laser light source is used, meaning that welding is performed solely using the central light source. The width of the upper surface of the weld is greater than that of the lower surface. The volume percentage of the metallic component of the laser welding wire in the weld is 10%. The average composition of the obtained weld includes: C: 0.22%, Si: 0.28%, Mn: 1.18%, Cr: 0.21%, Ni: 0.1%, Mo: 0.02%, Al: 1%, Ti: 0.01%. Calculations show that the weld composition meets the requirements of [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al]≤12% and 30×[C]+[Ni]+0.5×[Mn]<-0.76×([Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al])+0.187, but does not meet the requirement of 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤12%.

[0111] S3: The welding blank is heated, hot-stamped, and quenched to obtain a laser-welded part. The heating temperature is 930℃ (>AC3), and the holding time is 5 minutes. After heating, it is quickly transferred to a flat mold for quenching and cooling. The quenching cooling rate is >27℃ / s.

[0112] Finally, the obtained laser-welded parts were prepared into tensile samples, as shown in Figure 5. After the tensile test, the fracture location of the tensile sample was located at the weld, that is, the tensile strength of the weld was 1295 MPa. The tensile strength of the weld was less than that of the base material, indicating that the weld strength was insufficient and did not meet the test requirements.

[0113] Comparative Example 2

[0114] This comparative example discloses a laser welding wire for hot-formed steel with aluminum coating. The diameter of the laser welding wire is 1.2 mm, and the composition of the laser welding wire by mass percentage includes: C: 0.08%, Si: 0.52%, Mn: 1.05%, P: 0.015%, S: 0.008%, Cr: 0.21%, Ni: 0.95%, and Mo: 0.12%, with the balance being Fe.

[0115] Calculations show that 30×[C]+[Ni]+0.5×[Mn]=3.88% and [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]=1.11%. The composition of the laser welding wire meets the requirement of [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%, but does not meet the requirement of 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15%. Furthermore, the Ni content in the laser welding wire used for laser filler wire welding is 0.95%, which does not meet the requirement of >3%.

[0116] The laser welding wire provided above is used to weld and prepare filler wire welded parts. The preparation method includes the following steps:

[0117] S1: The first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded are spliced ​​together, so that the bottom of the first aluminum-coated plate to be welded is aligned with the bottom of the second aluminum-coated plate to be welded. The thickness of the first aluminum-coated plate to be welded is 1.8 mm, and it consists of a first substrate and a first aluminum-coated layer. The composition of the first substrate is: C: 0.24%, Si: 0.25%, Mn: 1.19%, Cr: 0.21%, and Ti: 0.03%, with the balance being Fe. The thickness of the first aluminum-coated layer is 30 μm, and the composition of the first aluminum-coated layer is: Al: 88%, Si: 12%.

[0118] The second aluminum-containing coating on the substrate to be welded has a thickness of 1.8 mm and consists of a second substrate and a second aluminum-containing coating. The second substrate has the following composition: C: 0.24%, Si: 0.25%, Mn: 1.19%, Cr: 0.21%, and Ti: 0.03%, with the balance being Fe. The second aluminum-containing coating has a thickness of 30 μm and its composition is: Al: 88% and Si: 12%.

[0119] Calculations show that the carbon equivalent of the laser welding wire, Ceq0, is 0.38, and the carbon equivalents of the first aluminum-coated welding plate and the first aluminum-coated welding plate, Ceq1, are both 0.48, satisfying Ceq0 ≤ Ceq1 + 1, but not satisfying Ceq1 ≤ Ceq0.

[0120] S2: Laser filler wire welding is performed on the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded to form a weld blank with a weld seam;

[0121] The laser light source used in this comparative example includes a central light source and a peripheral light source; that is, welding is carried out using both central and peripheral light sources. The width of the upper surface of the weld is greater than that of the lower surface. The volume percentage of the metallic component of the laser welding wire in the weld is 10%. The average composition of the obtained weld is C: 0.22%, Si: 0.28%, Mn: 1.18%, Cr: 0.21%, Ni: 0.1%, Mo: 0.02%, Al: 1%, Ti: 0.01%. Calculations show that the weld composition meets the requirements of [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al]≤12% and 30×[C]+[Ni]+0.5×[Mn]<-0.76×([Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al])+0.187, but does not meet the requirement of 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤12%.

[0122] S3: The welding blank is heated, hot-stamped, and quenched to obtain a laser-welded part. The heating temperature is 930℃ (>AC3), and the holding time is 5 minutes. After heating, it is quickly transferred to a flat mold for quenching and cooling. The quenching cooling rate is >27℃ / s.

[0123] Finally, the obtained laser-welded parts were prepared into tensile samples. After tensile testing, the fracture location of the tensile samples was located at the weld, that is, the tensile strength of the weld was 1379 MPa. The tensile strength of the weld was less than that of the base material. Although the tensile strength was higher than that of Comparative Example 1, it still did not meet the test requirements.

[0124] Comparative Example 3

[0125] This comparative example discloses a laser welding wire for hot-formed steel with aluminum coating. The diameter of the laser welding wire is 1.2 mm, and the composition of the laser welding wire by mass percentage includes: C: 0.08%, Si: 0.5%, Mn: 1.3%, P: 0.006%, S: 0.001%, Cr: 12%, Ni: 6%, and Mo: 1%, with the balance being Fe.

[0126] Calculations show that 30×[C]+[Ni]+0.5×[Mn]=9.05% and [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]=13.75%. Therefore, the welding wire meets the requirement of 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤15%, but does not meet the requirement of [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]≤8%. Furthermore, the laser welding wire used in laser filler wire welding has a Ni content of 6%, which meets the requirement of >3%.

[0127] The laser welding wire provided above is used to prepare filler wire welded parts, and the preparation method includes the following steps:

[0128] S1: The first aluminum-coated plate to be welded is spliced ​​with the second aluminum-coated plate to be welded, so that the bottom of the first aluminum-coated plate to be welded is aligned with the bottom of the second aluminum-coated plate to be welded. The thickness of the first aluminum-coated plate to be welded is 1.2 mm, and it consists of a first substrate and a first aluminum-coated layer. The composition of the first substrate is: C: 0.23%, Si: 0.22%, Mn: 1.2%, Cr: 0.18%, and Ti: 0.03%, with the balance being Fe. The thickness of the first aluminum-coated layer is 30 μm, and the composition of the first aluminum-coated layer is: Al: 88% and Si: 12%.

[0129] The second aluminum-containing coating has a thickness of 1.2 mm and consists of a second substrate and a second aluminum-containing coating. The second substrate comprises: C: 0.23%, Si: 0.22%, Mn: 1.2%, Cr: 0.18%, and Ti: 0.03%, with the balance being Fe. The second aluminum-containing coating has a thickness of 30 μm and comprises: Al: 88% and Si: 12%.

[0130] Calculations show that the carbon equivalent of the laser welding wire, Ceq0, is 3.3, while the carbon equivalents of the first aluminum-coated welding plate and the second aluminum-coated welding plate are both 0.47, which does not satisfy the condition Ceq1≤Ceq0≤Ceq1+1.

[0131] S2: Laser filler wire welding is performed on the first aluminum-coated plate to be welded and the second aluminum-coated plate to be welded to form a weld blank with a weld seam;

[0132] In this comparative example, only the central laser light source was used, and welding was performed solely using the central laser light source. The width of the upper surface of the weld was greater than that of the lower surface. The volume ratio of the metal component of the laser welding wire in the weld was 40%, and the average composition of the obtained weld was C: 0.17%, Si: 0.33%, Mn: 1.2%, Cr: 4.9%, Ni: 2.4%, Mo: 0.4%, Al: 1.2%. This satisfies the requirements of 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 12% and 30×[C] + [Ni] + 0.5×[Mn] < -0.76×([Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al]) + 0.187, but does not meet the requirement of [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] + 5.5×[Al] ≤ 12%.

[0133] S3: The welding blank is heated, hot-stamped, and quenched to obtain a laser-welded part. The heating temperature is 930℃ (>AC3), and the holding time is 5 minutes. After heating, it is quickly transferred to a flat mold for quenching and cooling. The quenching cooling rate is >27℃ / s.

[0134] Finally, tensile samples were prepared from the laser-welded parts. After tensile testing, the fracture location was located in the weld, that is, the tensile strength of the weld was 1498 MPa. The tensile strength of the weld was less than that of the base material, indicating that the strength of the weld was still insufficient. As shown in Figure 6, cracks were found in the weld, so the test requirements were not met.

[0135] In summary, Examples 1 and 2 both used the laser welding wire disclosed herein for hot-formed steel with aluminum coating to prepare laser-filled wire welded parts. The tensile fracture points of the obtained products were not located at the weld seam, indicating that the weld joint strength was high. However, the welding performance of the laser welding wires used in Comparative Examples 1-3 was inferior to that of the laser welding wire disclosed herein. When the laser welding wires of the comparative examples were applied to prepare filler wire welded parts, although they also had a certain tensile strength, the fracture points were all located at the weld seam, indicating that the strength of the obtained weld joint was insufficient. Furthermore, in Comparative Examples 1 and 2, the same laser welding wire was used, but different laser light sources were employed for welding. Although the filler wire welded parts all fractured at the weld seam, the tensile strengths they withstood differed. In Comparative Example 2, a laser with a central light source and peripheral light sources was used for welding, and the highest tensile strength reached 1379 MPa, significantly higher than the 1295 MPa in Comparative Example 1. This demonstrates that using a central light source and peripheral light sources as the laser for welding is more beneficial to the welding process.

[0136] The technical solution disclosed in this paper has the following advantages compared with related technologies:

[0137] This paper discloses a laser welding wire for hot-formed steel with aluminum coating and its welding method. The composition of the laser welding wire meets the requirements of 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 15% and [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] ≤ 8%. By using this welding wire as the welding material and controlling its composition, the composition of the weld metal can be guaranteed, ensuring that the weld is mainly composed of martensite, thereby improving the weld strength. On the other hand, when the composition of the laser welding wire meets the requirements, the formation range of martensite after the molten pool metal cools is the widest, which can suppress the performance degradation caused by the non-uniformity of the weld composition. Therefore, even under extreme conditions, even if the welding wire does not fuse with the hot-formed steel with aluminum coating in some areas, martensite can still be formed after the welding wire melts and resolidifies, thus ensuring the mechanical properties of the joint.

[0138] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser welding wire for hot-formed steel with aluminum coating, wherein the chemical composition of the laser welding wire satisfies: 7.8% ≤ 30×[C] + [Ni] + 0.5×[Mn] ≤ 15%, [Cr] + [Mo] + 1.5×[Si] + 0.5×[Nb] ≤ 8%; in, [C], [Ni], [Mn], [Cr], [Mo], [Si], and [Nb] represent the mass fractions of C, Ni, Mn, Cr, Mo, Si, and Nb in the laser welding wire, respectively.

2. The laser welding wire for hot-formed steel with aluminum coating according to claim 1, wherein, In the laser welding wire, [Ni]: >3%, [Si]: 0.15%–0.8%, [Ti]: 0.05%–0.5%.

3. The laser welding wire for hot-formed steel with aluminum coating according to claim 2, wherein, In the laser welding wire, [Ti]: 0.08%–0.5%.

4. The laser welding wire for hot-formed steel with aluminum coating according to claim 2 or 3, wherein, The laser welding wire is composed of C, Si, Mn, P, S, Cr, Ni, Mo, Ti, the balance Fe, and unavoidable impurities.

5. A laser welding method for hot-formed steel with aluminum coating, comprising the following steps: using the laser welding wire for hot-formed steel with aluminum coating as described in any one of claims 1 to 4. The first aluminum-coated plate to be welded is spliced ​​with the second aluminum-coated plate to be welded. The first aluminum-coated sheet material to be welded and the second aluminum-coated sheet material to be welded are laser welded to form a weld blank with a weld seam; and, The welded blank is heat-treated to obtain a laser filler wire welded part; The chemical composition of the weld meets the following requirements: 7.8%≤30×[C]+[Ni]+0.5×[Mn]≤12%, [Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al]≤12%, 30×[C]+[Ni]+0.5×[Mn]<-0.76× ([Cr]+[Mo]+1.5×[Si]+0.5×[Nb]+5.5×[Al])+0.187; Wherein, [C], [Ni], [Mn], [Cr], [Mo], [Si], [Nb], and [Al] are the mass fractions of C, Ni, Mn, Cr, Si, Nb, and Al in the weld, respectively.

6. The laser welding method for hot-formed steel with aluminum coating according to claim 5, wherein, The volume ratio of the laser welding wire in the weld is 10% to 70%.

7. The laser welding method for hot-formed steel with aluminum coating according to claim 5, wherein, The first aluminum-coated plate to be welded includes a first aluminum-coated layer, and the second aluminum-coated plate to be welded includes a second aluminum-coated layer. By mass fraction, the chemical composition of the first aluminum-coated layer and the second aluminum-coated layer includes: [Al]: 85% to 95%, [Si]: 5% to 15%.

8. The laser welding method for hot-formed steel with aluminum coating according to claim 7, wherein, The thicknesses of the first aluminum-containing coating and the second aluminum-containing coating are 10 μm to 100 μm, respectively.

9. The laser welding method for hot-formed steel with aluminum coating according to claim 7, wherein, The carbon equivalent of the laser welding wire is Ceq0. The carbon equivalent of the aluminum-coated welding plate with higher tensile strength in the first aluminum-coated welding plate and the second aluminum-coated welding plate is Ceq1, which satisfies Ceq1≤Ceq0≤(Ceq1+1). The calculation method of Ceq is Ceq={[C]+[Mn] / 6+([Cr]+[Mo]) / 5+[Ni] / 15}×100%.

10. The laser welding method for hot-formed steel with aluminum coating according to claim 5, wherein, The step of heat-treating the welding blank to obtain the laser filler wire welded part includes: heating the welding blank sequentially, hot stamping and quenching it to obtain the laser filler wire welded part. Wherein, the heating temperature is greater than or equal to the austenitizing temperature AC3; and / or, The quenching cooling rate is >27℃ / s.

11. The laser welding method for hot-formed steel with aluminum coating according to claim 5, wherein, The laser light source used in the laser welding includes a central light source and a peripheral light source.

12. The laser welding method for hot-formed steel with aluminum coating according to claim 5, wherein, The weld seam is wider on the laser-irradiated side than on the other side.

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