Lap-joint tailor-welded structure of automobile integrated door ring and manufacturing method of lap-joint tailor-welded structure

Abstract

The invention discloses a lap joint tailor-welding structure of an automobile integrated door ring and a manufacturing method, and belongs to the technical field of tailor-welding of automobile spare parts, and the automobile integrated door ring is prepared through an integrated process of heating stamping and in-mold quenching after a composite coating is thermally sprayed on the surface of thermal forming steel. The composite coating comprises the following chemical components in percentage by weight: 3%-8% of Y2O3, 5%-15% of TiN, 2%-6% of HfO2, 20%-35% of Al, 5%-12% of Si and the balance of Fe and inevitable impurities. By means of the mode, the welding strength is effectively improved through the innovative tailor-welding process of the composite coating plate and lap resistance spot welding.

Description

Technical Field

[0001] This invention relates to the field of automotive parts welding technology, specifically to an lap welding structure and manufacturing method for an integrated automotive door ring. Background Technology

[0002] With the automotive industry's increasing demands for lightweighting, safety, and energy conservation and environmental protection, hot-formed ultra-high-strength steel has become a key material for manufacturing vehicle body safety structural components. Integrated door rings, as large components that integrate key load-bearing structures such as the upper sill, A-pillar, B-pillar, and door sill, can significantly improve the lateral stiffness and collision safety of the vehicle body, representing a significant trend in current high-end vehicle body design.

[0003] Existing technologies have made numerous improvements to the welding process of integrated automotive door rings. For example, Chinese patent CN116329753B discloses a laser welding device with adjustment function for automotive door rings. This device includes a mounting base connected to a welding robotic arm, a fixed base fixedly connected to the mounting base, a main drive column slidably disposed within a movable port, an assembly base fixedly connected to the end of the main drive column, and a horizontally positioned extrusion port within the assembly base. A front pressure plate is connected to the output end of an electric push rod. This invention precisely installs bolts through a bolt feed port and uses the extrusion column to drive the bolts forward, automatically installing the bolts to the automotive door ring and hinge. After installation, the combined action of the moving assembly base and the rotating bolt disc achieves automatic bolt installation. Furthermore, laser welders positioned around the assembly base effectively weld the joints between the automotive door ring and hinge, achieving an integrated bolt connection and welding formation, significantly improving automotive processing efficiency.

[0004] However, the aforementioned patents and existing technologies still have the following shortcomings: 1. When using laser welding to lap and weld automotive door rings, the splicing difficulty of laser welding is high and the allowable limit is small. At the same time, stress concentration points are easily formed at the weld, resulting in low weld strength. 2. In the existing technology, hot-formed steel generally adopts a continuous hot-dip galvanizing process to apply an aluminum-silicon coating. This coating can effectively prevent steel plate oxidation during conventional hot forming heating. However, the coating has low hardness and insufficient wear resistance, and is easily damaged in complex working conditions or subsequent assembly. At the same time, its upper limit for oxidation protection is usually around 900℃, and its protection capability for higher temperatures or more severe oxidation environments is limited.

[0005] Based on this, the present invention designs an overlapping and welding structure and manufacturing method for an integrated automotive door ring to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the existing technology, the present invention provides an lap welding structure and manufacturing method for an integrated door ring for automobiles.

[0007] To achieve the above objectives, the present invention provides the following technical solution: An integrated door ring for automobiles is manufactured through an integrated process of hot-formed steel surface thermal spraying composite coating followed by heating, stamping and in-mold quenching. The chemical composition of the composite coating by weight percentage is: Y2O3: 3%~8%, TiN: 5%~15%, HfO2: 2%~6%, Al: 20%~35%, Si: 5%~12%, with the balance being Fe and unavoidable impurities; The Al and Si are added in the form of gas-atomized Al-Si pre-alloyed powder, and the Fe is gas-atomized pure iron powder; The Y2O3 is a nano-sized spherical powder, D 50 The wavelength is 50~100nm; The TiN is a submicron-sized powder, D 50 The thickness is 0.5~2μm; The HfO2 is a mixed powder of monoclinic HfO2 and tetragonal HfO2, wherein the mass percentage of monoclinic HfO2 is 30%~50%.

[0008] Furthermore, the preparation process of the composite coating is as follows: Step 1: Mechanical alloying to prepare Al-Si-Y2O3 composite powder: Gas-atomized Al-Si alloy powder and nano Y2O3 powder were placed in a high-energy ball mill and mechanically alloyed under argon protection. The ball milling time was 8-15 hours to obtain Al / Si / Y2O3 composite powder with a particle size of 15-45 μm. Step 2: Preparation of core-shell structured powders of Al-Si-Y2O3 and TiN by coating and sintering: The Al / Si / Y2O3 composite powder and TiN powder obtained in step one are placed in a fluidized bed coating device. The TiN powder is uniformly adhered to the surface of the Al / Si / Y2O3 composite powder by a binder. Then, the powder is heat-treated in a vacuum furnace at 500~600℃ to obtain a composite powder with a core-shell structure. Step 3: Spray granulation to prepare the final spray feed: The core-shell structured composite powder, HfO2 powder, and atomized pure iron powder obtained in step two are mixed together, and a water-based binder solution is added. A centrifugal spray granulation tower was used to atomize, dry, and sinter the mixed slurry to prepare spherical spray feed with a particle size distribution of 20~60μm; Step 4: Substrate Pretreatment and Thermal Spraying The hot-formed steel substrate is roughened by sandblasting, cleaned, and then preheated to 150~250℃. Using plasma spraying equipment, the spherical spraying feed prepared in step three is fed into a high-temperature jet to melt and then deposited onto the preheated substrate surface at high speed. Step 5, Post-coating treatment: After spraying, the coating is remelted to obtain a composite coating.

[0009] Furthermore, in step one, the ball-to-material ratio of the high-energy ball mill is 10:1 to 15:1, the rotation speed is 300 to 400 rpm, and the process control agent is anhydrous ethanol.

[0010] Furthermore, in step two, the fluidized bed coating temperature is 60~80℃, the binder is a polyvinyl alcohol aqueous solution, and during vacuum heat treatment, the heating rate is 5℃ / min and the holding time is 1~2 hours.

[0011] Furthermore, in step four, the main gas for plasma spraying is Ar, the auxiliary gas is H2, the spraying power is 35~45kW, and the spraying distance is 100~130mm.

[0012] Furthermore, the power of laser remelting is 1.5~3.0kW, the scanning speed is 5~20mm / s, and the overlap rate is 30%~50%.

[0013] To better achieve the objectives of this invention, this invention also provides a method for manufacturing a lap-welded structure for an integrated automotive door ring, specifically including the following steps: Step 1: Laser blanking Cut out the upper door beam, B-pillar, A-pillar and door sill according to the CAD drawings of the parts; Step 2: Material overlap The material sheets are overlapped on the resistance spot welding fixture. The material sheet overlap is selected on one side of the patch plate. The upper door beam overlaps with the upper ends of the B and A pillars, and the lower ends of the B and A pillars overlap with the door sill. The relationship between the thickness of the sheet material and the minimum overlap spacing is as follows: When the plate thickness is 0.65~1.09mm, the minimum overlap spacing is 19mm; When the plate thickness is 1.10~1.39mm, the minimum overlap spacing is 25mm; When the plate thickness is 1.40~1.59mm, the minimum overlap spacing is 36mm; When the plate thickness is 1.60~1.79mm, the minimum overlap spacing is 38mm; When the plate thickness is 1.80~2.09mm, the minimum overlap spacing is 45mm; When the plate thickness is 2.10~2.49mm, the minimum overlap spacing is 51mm; When the plate thickness is 2.50~2.79mm, the minimum overlap spacing is 53mm; When the plate thickness is 2.80~3.50mm, the minimum overlap spacing is 64mm; Step 3: Resistance spot welding Resistance spot welding is performed at the overlap, and the overlap welding of the integrated door ring of the car is completed after the spot welding is completed.

[0014] Furthermore, the specific parameters for step three, resistance spot welding, are as follows: the resistance spot welding power supply uses medium-frequency DC, the electrode diameter is 16mm, the upsetting force is 4500 Newtons, and the current is 6000~8000 Amperes.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: 1. A novel composite coating has been successfully prepared. This coating achieves comprehensive performance of high hardness, excellent high temperature oxidation resistance, good steam oxidation resistance and excellent wear resistance through composition optimization and core-shell structure powder design, combined with plasma spraying and laser remelting processes. It is significantly better than the traditional hot-dip aluminized silicon coating. 2. The innovative composite coating plate with lap resistance spot welding process effectively avoids the strength reduction problem caused by the softening of the weld and heat-affected zone in laser welding. This ensures that the fracture location of the integrated door ring of the car occurs on the high-strength base material, thereby giving full play to the ultra-high strength of the steel substrate and the composite coating itself, and maximizing the overall structural strength. 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 This is a schematic diagram of the laser blanking process of the present invention; Figure 2 This is a schematic diagram of the lap welding structure of an integrated automotive door ring according to the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the lap welding structure of an integrated automotive door ring according to the present invention. Figure 2 . 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: A method for lap welding of an integrated automotive door ring, specifically including the following steps: I. Preparation of integrated automotive door rings with composite coatings: (1) The chemical composition of the hot-formed steel used, by weight percentage, is shown in Table 1: Table 1 Chemical composition of the hot-formed steel used

[0020] (2) Weigh the following raw materials by weight percentage: Y2O3: 3%, TiN: 15%, HfO2: 2%, Al: 35%, Si: 5%, balance Fe; The Y2O3 is a nano-sized spherical powder, D 50 It is 50nm; The TiN is a submicron-sized powder, D 50 It is 0.5μm; The HfO2 is a mixed powder of monoclinic HfO2 and tetragonal HfO2, wherein the mass percentage of monoclinic HfO2 is 30%.

[0021] (3) Preparation of Al-Si-Y2O3 composite powder by mechanical alloying: The gas-atomized Al-Si alloy powder and nano Y2O3 powder were placed in a high-energy ball mill. Al and Si were added in the proportion of step (2). Mechanical alloying was carried out in the high-energy ball mill under argon protection for 8 hours to obtain Al / Si / Y2O3 composite powder with a particle size of 45μm.

[0022] The ball-to-material ratio of the high-energy ball mill is 10:1, the rotation speed is 400 rpm, and the process control agent is anhydrous ethanol.

[0023] (4) Preparation of core-shell structured powders of Al-Si-Y2O3 and TiN by coating and sintering: Al / Si / Y2O3 composite powder and TiN powder were placed in a fluidized bed coating device. TiN powder was uniformly adhered to the surface of Al / Si / Y2O3 composite powder by a binder. Then, heat treatment was carried out in a vacuum furnace at 500℃ to decompose the binder and strengthen the bond between the TiN shell and the core, thus obtaining a composite powder with a core-shell structure. The fluidized bed coating temperature was 60℃, and the binder was an aqueous solution of polyvinyl alcohol (PVA). During vacuum heat treatment, the heating rate was 5℃ / min, and the holding time was 2 hours.

[0024] (5) Spray granulation to prepare the final spray feed: The core-shell structured composite powder, HfO2 powder, and atomized pure iron powder were mixed and then a water-based binder solution was added. A centrifugal spray granulation tower is used to atomize, dry, and sinter the mixed slurry to prepare spherical spray feed with good flowability and uniform composition. The inlet air temperature for spray granulation is 180℃, the outlet air temperature is 100℃, and the loose density of the feed is 1.2 g / cm³. 3 The angle of repose is less than 30 degrees.

[0025] (6) Substrate pretreatment and thermal spraying: The hot-formed steel substrate is roughened by sandblasting, cleaned and preheated to 150°C; a plasma spraying equipment is used to feed a spherical spray feed into a high-temperature jet to melt it, and then spray it at high speed onto the surface of the preheated substrate. The main gas for plasma spraying is Ar, the auxiliary gas is H2, the spraying power is 35kW, and the spraying distance is 130mm.

[0026] (7) Post-coating treatment: After the spraying is completed, the coating is remelted to obtain hot-formed steel with a composite coating.

[0027] The laser remelting power is 1.5kW, the scanning speed is 20mm / s, and the overlap rate is 30%.

[0028] (8) A one-piece automotive door ring can be obtained by heating, stamping, and in-mold quenching hot-formed steel coated with a composite coating, such as... Figure 1 As shown, the integrated door ring of a car includes an upper door beam, B-pillar, A-pillar, and door sill.

[0029] II. Lap welding of integrated door rings in automobiles: (1) Laser blanking: like Figure 1 As shown, the upper door beam, B-pillar, A-pillar and door sill are cut out according to the CAD drawings of the parts; Step 2: Material overlap: The material sheets are overlapped on the resistance spot welding fixture. The material sheet overlap is selected on one side of the patch plate. The upper door beam overlaps with the upper ends of the B and A pillars, and the lower ends of the B and A pillars overlap with the door sill. The relationship between the thickness of the sheet material and the minimum overlap spacing is shown in Table 2: Table 2 Relationship between sheet thickness and minimum overlap spacing

[0030] In this embodiment, the plate thickness is 2.15mm, so the overlap spacing is selected as 51mm.

[0031] Step 3: Resistance spot welding Resistance spot welding is performed at the lap joint. The resistance spot welding power supply is medium frequency DC, the electrode diameter is 16mm, the upsetting force is 4500 Newtons, and the current is 6000 Amperes. After the spot welding is completed, the lap welding of the integrated door ring of the car is completed.

[0032] Example 2: A method for lap welding of an integrated automotive door ring, specifically including the following steps: I. Preparation of integrated automotive door rings with composite coatings: (1) The chemical composition of the hot-formed steel used is the same as that in Example 1; (2) Weigh the following raw materials by weight percentage: Y2O3: 8%, TiN: 5%, HfO2: 6%, Al: 20%, Si: 12%, balance Fe; The Y2O3 is a nano-sized spherical powder, D 50 It is 100nm; The TiN is a submicron-sized powder, D 50 It is 2μm; The HfO2 is a mixed powder of monoclinic HfO2 and tetragonal HfO2, wherein the mass percentage of monoclinic HfO2 is 50%.

[0033] (3) Preparation of Al-Si-Y2O3 composite powder by mechanical alloying: The gas-atomized Al-Si alloy powder and nano Y2O3 powder were placed in a high-energy ball mill. Al and Si were added in the proportions in step (2). Mechanical alloying was carried out in the high-energy ball mill under argon protection for 15 hours to obtain Al / Si / Y2O3 composite powder with a particle size of 15μm.

[0034] The ball-to-material ratio of the high-energy ball mill is 15:1, the rotation speed is 300 rpm, and the process control agent is anhydrous ethanol.

[0035] (4) Preparation of core-shell structured powders of Al-Si-Y2O3 and TiN by coating and sintering: Al / Si / Y2O3 composite powder and TiN powder were placed in a fluidized bed coating device. TiN powder was uniformly adhered to the surface of Al / Si / Y2O3 composite powder by a binder. Then, heat treatment was carried out in a vacuum furnace at 600℃ to decompose the binder and strengthen the bond between the TiN shell and the core, thus obtaining a composite powder with a core-shell structure. The fluidized bed coating temperature was 80℃, the binder was an aqueous solution of polyvinyl alcohol (PVA), and the theoretical thickness of the TiN powder coating layer accounted for 10% of the total mass of the composite powder. During vacuum heat treatment, the heating rate was 5℃ / min, and the holding time was 2 hours.

[0036] (5) Spray granulation to prepare the final spray feed: The core-shell structured composite powder, HfO2 powder, and atomized pure iron powder were mixed and then a water-based binder solution was added. A centrifugal spray granulation tower is used to atomize, dry, and sinter the mixed slurry to prepare spherical spray feed with good flowability and uniform composition. The inlet air temperature for spray granulation is 220℃, the outlet air temperature is 80℃, and the loose density of the feed is 1.8 g / cm³. 3 The angle of repose is less than 30 degrees.

[0037] (6) Substrate pretreatment and thermal spraying: The hot-formed steel substrate is roughened by sandblasting, cleaned and preheated to 250°C; a plasma spraying equipment is used to feed spherical spraying feed into a high-temperature jet to melt and then deposit it onto the preheated substrate surface at high speed. The main gas for plasma spraying is Ar, the auxiliary gas is H2, the spraying power is 45kW, and the spraying distance is 100mm.

[0038] (7) Post-coating treatment: After the spraying is completed, the coating is remelted to obtain hot-formed steel with a composite coating.

[0039] The laser remelting power is 3.0kW, the scanning speed is 5mm / s, and the overlap rate is 50%.

[0040] (8) A one-piece automotive door ring can be obtained by heating, stamping, and in-mold quenching hot-formed steel coated with a composite coating, such as... Figure 1 As shown, the integrated door ring of a car includes an upper door beam, B-pillar, A-pillar, and door sill.

[0041] II. Lap welding of integrated door rings in automobiles: (1) Laser blanking: like Figure 1 As shown, the upper door beam, B-pillar, A-pillar and door sill are cut out according to the CAD drawings of the parts; Step 2: Material overlap: The material sheets are overlapped on the resistance spot welding fixture. The material sheet overlap is selected on one side of the patch plate. The upper door beam overlaps with the upper ends of the B and A pillars, and the lower ends of the B and A pillars overlap with the door sill. In this embodiment, the plate thickness is 2.15mm, so the overlap spacing is selected as 51mm.

[0042] Step 3: Resistance spot welding Resistance spot welding is performed at the lap joint. The resistance spot welding power supply is medium frequency DC, the electrode diameter is 16mm, the upsetting force is 4500 Newtons, and the current is 8000 Amperes. After the spot welding is completed, the lap welding of the integrated door ring of the car is completed.

[0043] Example 3: A method for lap welding of an integrated automotive door ring, specifically including the following steps: I. Preparation of integrated automotive door rings with composite coatings: (1) The chemical composition of the hot-formed steel used is the same as that in Example 1; (2) Weigh the following raw materials by weight percentage: Y2O3: 5%, TiN: 10%, HfO2: 4%, Al: 30%, Si: 8%, balance Fe; The Y2O3 is a nano-sized spherical powder, D 50 It is 75nm; The TiN is a submicron-sized powder, D 50 It is 1μm; The HfO2 is a mixed powder of monoclinic HfO2 and tetragonal HfO2, wherein the mass percentage of monoclinic HfO2 is 35%.

[0044] (3) Preparation of Al-Si-Y2O3 composite powder by mechanical alloying: The gas-atomized Al-Si alloy powder and nano Y2O3 powder were placed in a high-energy ball mill. Al and Si were added in the proportion in step (2). Mechanical alloying was carried out in the high-energy ball mill under argon protection for 10 hours to obtain Al / Si / Y2O3 composite powder with a particle size of 25μm.

[0045] The ball-to-material ratio of the high-energy ball mill is 12:1, the rotation speed is 350 rpm, and the process control agent is anhydrous ethanol.

[0046] (4) Preparation of core-shell structured powders of Al-Si-Y2O3 and TiN by coating and sintering: Al / Si / Y2O3 composite powder and TiN powder were placed in a fluidized bed coating device. TiN powder was uniformly adhered to the surface of Al / Si / Y2O3 composite powder by a binder. Then, heat treatment was carried out in a vacuum furnace at 550℃ to decompose the binder and strengthen the bond between the TiN shell and the core, thus obtaining a composite powder with a core-shell structure. The fluidized bed coating temperature was 65℃, the binder was an aqueous solution of polyvinyl alcohol (PVA), and the theoretical thickness of the TiN powder coating layer accounted for 15% of the total mass of the composite powder. During vacuum heat treatment, the heating rate was 5℃ / min, and the holding time was 1.5 hours.

[0047] (5) Spray granulation to prepare the final spray feed: The core-shell structured composite powder, HfO2 powder, and atomized pure iron powder were mixed and then a water-based binder solution was added. A centrifugal spray granulation tower is used to atomize, dry, and sinter the mixed slurry to prepare spherical spray feed with good flowability and uniform composition. The inlet air temperature for spray granulation is 200℃, the outlet air temperature is 90℃, and the loose density of the feed is 1.5g / cm³. 3 The angle of repose is less than 30 degrees.

[0048] (6) Substrate pretreatment and thermal spraying: The hot-formed steel substrate is roughened by sandblasting, cleaned and preheated to 200°C; a plasma spraying equipment is used to feed spherical spraying feed into a high-temperature jet to melt and then deposit it onto the preheated substrate surface at high speed. The main gas for plasma spraying is Ar, the auxiliary gas is H2, the spraying power is 40kW, and the spraying distance is 120mm.

[0049] (7) Post-coating treatment: After the spraying is completed, the coating is remelted to obtain hot-formed steel with a composite coating.

[0050] The laser remelting power is 2.5kW, the scanning speed is 15mm / s, and the overlap rate is 40%.

[0051] (8) A one-piece automotive door ring can be obtained by heating, stamping, and in-mold quenching hot-formed steel coated with a composite coating, such as... Figure 1 As shown, the integrated door ring of a car includes an upper door beam, B-pillar, A-pillar, and door sill.

[0052] II. Lap welding of integrated door rings in automobiles: (1) Laser blanking: like Figure 1 As shown, the upper door beam, B-pillar, A-pillar and door sill are cut out according to the CAD drawings of the parts; Step 2: Material overlap: The material sheets are overlapped on the resistance spot welding fixture. The material sheet overlap is selected on one side of the patch plate. The upper door beam overlaps with the upper ends of the B and A pillars, and the lower ends of the B and A pillars overlap with the door sill. In this embodiment, the plate thickness is 2.15mm, so the overlap spacing is selected as 51mm.

[0053] Step 3: Resistance spot welding Resistance spot welding is performed at the lap joint. The resistance spot welding power source is medium frequency DC, the electrode diameter is 16mm, the upsetting force is 4500 Newtons, and the current is 7000 Amperes. After the spot welding is completed, the lap welding of the integrated door ring of the car is completed.

[0054] Comparative Example 1: Compared with Example 3, the proportions of the composite coating raw materials were changed: Y2O3: 10%, TiN: 3%, HfO2: 8%, Al: 40%, Si: 15%, balance Fe.

[0055] The other steps are the same as in Example 3.

[0056] Comparative Example 2: Compared with Example 3, the stepwise coating, sintering, and granulation processes were no longer performed in the preparation of the composite coating. Instead, the raw materials were directly mixed and granulated. The specific process is as follows: A mixture of gas-atomized Al-Si alloy powder, nano-Y2O3 powder, TiN powder, HfO2 powder, and gas-atomized pure iron powder was prepared, and a water-based binder solution was added. The mixture was then atomized, dried, and sintered using a centrifugal spray granulation tower to produce spherical spray feed.

[0057] The other steps are the same as in Example 3.

[0058] Comparative Example 3: Compared with Example 3, instead of using plasma spraying composite coating, a conventional continuous hot-dip galvanizing process was used to cover the surface of hot-formed steel with an aluminum-silicon coating.

[0059] The lap welding steps for the integrated door ring of the car are the same as in Example 3.

[0060] Comparative Example 4: Compared with Example 3, the lap welding method of the integrated door ring of the car was not used, but traditional laser welding was used.

[0061] Experimental example: (1) The following performance tests were performed on the composite coatings prepared in Examples 1-3 and Comparative Examples 1-2, as well as the aluminum-silicon coating of Comparative Example 3: Hardness: GB / T 4340.1-2024; Steam oxidation resistance: Weight gain per unit area (mg / cm²) after 500 hours in a steam environment at 650℃.2 ); High-temperature oxidation resistance: Weight gain per unit area (mg / cm²) after oxidation at 1000℃ for 100 hours. 2 ); Wear resistance: Friction and wear tests were conducted using an MG-2000 high-speed high-temperature friction and wear testing machine. The total number of revolutions of the coatings prepared in Examples 1-3 and Comparative Examples 1-3 on the friction pair was 2000 revolutions, the motor speed was controlled at 250 revolutions / minute, the total sliding distance was 0.38km, the sliding speed was 0.8m / s, the applied load was 10N, and the wear amount (mg) was recorded.

[0062] The results of coating performance testing for Examples 1-3 and Comparative Examples 1-3 are shown in Table 3.

[0063] Table 3 Summary of coating performance test results for Examples 1-3 and Comparative Examples 1-3

[0064] As can be seen from Comparative Example 1 and Example 3, if the proportion of the composite coating raw materials is changed, the hardness of the prepared composite coating decreases, and the oxidation resistance (especially the high temperature oxidation resistance) and wear resistance deteriorate significantly.

[0065] As can be seen from Comparative Example 2 and Example 3, if the step-by-step coating, sintering and granulation are no longer carried out in the process of preparing composite coatings, but the raw materials are directly mixed and granulated, the hardness of the prepared composite coating will decrease, and the antioxidant and wear resistance properties will be significantly worse.

[0066] As can be seen from Comparative Example 3 and Example 3, the traditional hot-dip aluminized silicon coating has the lowest weight gain under medium-temperature steam oxidation environment, which is even better than Example 3. However, it has a sharp weight gain under high-temperature oxidation, indicating that the traditional aluminized silicon coating has insufficient oxidation resistance at high temperatures. At the same time, its hardness and wear resistance are far lower than those of the plasma sprayed composite coating.

[0067] (2) Tensile tests were conducted on the integrated automotive door rings obtained by lap welding in Examples 1-3 and Comparative Examples 1-3, as well as the integrated automotive door ring obtained by laser welding in Comparative Example 4: The results of the tensile tests on the integrated door rings of automobiles in Examples 1-3 and Comparative Examples 1-4 are shown in Table 4.

[0068] Table 4 Summary of tensile test results for Examples 1-3 and Comparative Examples 1-4

[0069] As can be seen from Comparative Example 1 and Example 3, if the proportion of the composite coating material is changed, the yield strength and tensile strength of the lap-welded automotive integrated door ring decrease, and the fracture location is in the composite coating substrate, proving that the welding performance is good.

[0070] As can be seen from Comparative Example 2 and Example 3, if the step-by-step coating, sintering and granulation are no longer carried out in the process of preparing the composite coating, but the raw materials are directly mixed and granulated, the yield strength and tensile strength of the lap-welded automotive integrated door ring will decrease, and the fracture location will be in the composite coating substrate, which proves that the welding performance is good.

[0071] As can be seen from Comparative Example 3 and Example 3, if a traditional aluminum-silicon coating is used, the yield strength and tensile strength of the lap-welded automotive integrated door ring will decrease significantly, and the fracture location will be in the aluminum-silicon coated substrate, proving that the welding performance is good.

[0072] As can be seen from Comparative Example 4 and Example 3, if a one-piece door ring for automobiles is obtained by laser welding, the yield strength remains almost unchanged, but the tensile strength decreases significantly, and the fracture occurs at the laser weld seam. This proves that the lap welding of the present invention can effectively avoid the weld seam becoming the weakest link compared with the traditional laser welding method, so that the fracture returns to the base material, giving full play to the ultra-high strength of the steel matrix and the composite coating itself, and maximizing the overall structural strength.

[0073] 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. An automotive integrated door ring, characterized by, The automobile integrated door ring is prepared by an integrated process of heating stamping and in-mold quenching after thermal spraying a composite coating on the surface of a hot-formed steel material; The chemical composition of the composite coating is as follows in terms of percentage by weight: Y2O3: 3-8%, TiN: 5-15%, HfO2: 2-6%, Al: 20-35%, Si: 5-12%, and the balance of Fe and unavoidable impurities; The Al and Si are added in the form of gas-atomized Al-Si pre-alloyed powder, and the Fe is gas-atomized pure iron powder; The Y2O3 is a nanoscale spherical powder, D 50 50-100 nm; The TiN is a sub-micron powder, D 50 0.5-2 μm; The HfO2 is a mixed powder of monoclinic HfO2 and tetragonal HfO2, wherein the mass percentage of the monoclinic HfO2 is 30-50%.

2. The automotive integrated door ring of claim 1, wherein, The preparation process of the composite coating is as follows: Step one: preparing Al-Si-Y2O3 composite powder by mechanical alloying Put the gas-atomized Al-Si alloy powder and nano Y2O3 powder into a high-energy ball mill and perform mechanical alloying under argon protection for 8-15 hours to obtain Al / Si / Y2O3 composite powder with a particle size of 15-45 μm; Step two: preparing Al-Si-Y2O3 and TiN core-shell structure powder by coating sintering Put the Al / Si / Y2O3 composite powder obtained in step one and TiN powder into a fluidized bed coating device, uniformly adhere the TiN powder to the surface of the Al / Si / Y2O3 composite powder by a binder, and then perform heat treatment in a vacuum furnace at 500-600 ℃ to obtain a composite powder with a core-shell structure; Step three: preparing the final spraying feedstock by spray granulation Mix the composite powder with a core-shell structure obtained in step two, HfO2 powder and gas-atomized pure iron powder, and add a water-based binder solution; Use a centrifugal spray granulation tower to atomize, dry and sinter the mixed slurry to prepare spherical spraying feedstock with a particle size distribution of 20-60 μm; Step four: substrate pretreatment and thermal spraying Perform sand blasting roughening treatment on the hot-formed steel substrate, and then clean and preheat to 150-250 ℃; Use a plasma spraying device to melt the spherical spraying feedstock prepared in step three in a high-temperature jet and deposit it at high speed onto the surface of the preheated substrate; Step five: coating post-treatment After spraying, perform remelting treatment on the coating to obtain the composite coating.

3. The automotive integrated door ring of claim 2, wherein, In step one, the ball-to-material ratio of the high-energy ball mill is 10:1-15:1, and the rotation speed is 300-400 rpm, and the process control agent is anhydrous ethanol.

4. The automotive integrated door ring of claim 2, wherein, In step two, the fluidized bed coating temperature is 60-80 ℃, the binder is a polyvinyl alcohol aqueous solution, and during vacuum heat treatment, the heating rate is 5 ℃ / min and the holding time is 1-2 hours.

5. The automotive integrated door ring of claim 2, wherein, In step four, the main gas for plasma spraying is Ar, the auxiliary gas is H2, the spraying power is 35-45 kW, and the spraying distance is 100-130 mm.

6. The automotive integrated door ring of claim 2, wherein, In step five, the power for laser remelting is 1.5-3.0 kW, the scanning speed is 5-20 mm / s, and the overlap rate is 30-50%.

7. A method of manufacturing the lap-welded structure of the integrated door ring of an automobile according to any one of claims 1 to 6, characterized by, Specifically, the following steps are included: Step one: laser blanking Blank the upper door beam, B column, A column and door sill according to the CAD drawings of the parts; Step two: sheet lapping The sheet is overlapped on the resistance spot welding tool, and the sheet overlap is selected on one side of the patch panel, wherein the upper door beam is overlapped with the upper end of the B column and the A column, and the lower end of the B column and the A column is overlapped with the rocker panel; The relationship between the thickness of the sheet and the minimum overlap distance is as follows: When the plate thickness is 0.65-1.09mm, the minimum overlap distance is 19mm; When the plate thickness is 1.10-1.39mm, the minimum overlap distance is 25mm; When the plate thickness is 1.40-1.59mm, the minimum overlap distance is 36mm; When the plate thickness is 1.60-1.79mm, the minimum overlap distance is 38mm; When the plate thickness is 1.80-2.09mm, the minimum overlap distance is 45mm; When the plate thickness is 2.10-2.49mm, the minimum overlap distance is 51mm; When the plate thickness is 2.50-2.79mm, the minimum overlap distance is 53mm; When the plate thickness is 2.80-3.50mm, the minimum overlap distance is 64mm; Step three: resistance spot welding Resistance spot welding is performed at the overlap, and after the spot welding is completed, the overlap welding of the automobile integrated door ring is completed.

8. The method of manufacturing a lap welded structure of an automobile integrated door ring according to claim 7, characterized in that, The specific parameters of step three resistance spot welding are as follows: the resistance spot welding power source adopts medium frequency direct current, the electrode diameter is 16mm, the top forging force is 4500 Newton, and the current is 6000-8000 amperes.

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