High-strength stainless steel for wheel hub cover and processing technology thereof

Abstract

The invention discloses a high-strength stainless steel for a wheel hub cap and a processing technology thereof, and relates to the technical field of stainless steel processing. The specific processing technology comprises: weighing a stainless steel raw material, melting and protectively pouring under nitrogen pressure to obtain an ingot, hot forging and hot rolling to obtain a hot-rolled plate, performing a solid solution treatment and water quenching, and then sequentially performing multiple cold rolling and a single liquid nitrogen heat-insulated cold rolling, annealing and aging treatment to obtain a stainless steel substrate, sequentially performing grinding and polishing, degreasing, and acid activation, and then placing the substrate in an electroplating solution to electrodeposit an alloy coating. After the electrodeposition is completed, the substrate is cleaned and laser clad, and finally heat treated and a thin layer is cut to obtain the high-strength stainless steel. The cladding powder used in the laser cladding comprises cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, zirconium powder, nano-carbon nitrogen metal and tungsten carbide.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel processing, in particular to high-strength stainless steel for wheel hub covers and a processing technology thereof. Background Art

[0002] In the field of automobile manufacturing, wheel hub covers, as important components for vehicle appearance and protection, not only need to have good decorative properties, but also need to meet performance requirements such as high strength, corrosion resistance, and lightweight. Traditional automobile wheel hub covers are often made of carbon steel or aluminum alloy. However, although carbon steel wheel hub covers have certain strength, their corrosion resistance is extremely poor. In daily use, especially in harsh environments such as humidity and salt, carbon steel wheel hub covers are very prone to rust and corrosion, resulting in a significant shortening of their service life. The processing technology of aluminum alloy wheel hub covers is complicated and cumbersome, the production cost is high, and they are prone to deformation and cracking during long-term use. Both are difficult to meet the high-strength requirements of modern automobiles for parts. At the same time, with the continuous increase in vehicle speed and the increase in complex road conditions, wheel hub covers face greater impact and load. Ordinary stainless steel wheel hub covers are prone to deformation and even cracking during long-term use, affecting the safety and stability of vehicle driving.

[0003] Therefore, with the current trend of vehicle weight reduction, the use of high-strength materials can reduce the thickness and weight of wheel hubcaps while maintaining performance, thereby achieving lightweighting and reducing energy consumption. Furthermore, during driving, wheel hubcaps are subject to corrosion from rain, sediment, acids, and alkalis, placing higher demands on the material's corrosion resistance. High-strength stainless steel, through optimized alloy composition and heat treatment processes, combines high strength with a dense oxide film formed on its surface, effectively preventing corrosion from external corrosive media and offering excellent corrosion resistance, making it superior to conventional stainless steel. Currently, automotive stainless steel is widely used in the manufacture of automotive parts due to its excellent corrosion resistance and good formability. However, existing high-strength stainless steels, when used in wheel hubcaps, still face challenges in achieving a balance between high strength, corrosion resistance, and processability. Therefore, the development of wheel hubcap materials and corresponding processing technologies that combine high strength, excellent corrosion resistance, and good processability is urgently needed to meet the growing demands of the automotive industry. Summary of the Invention

[0004] The object of the present invention is to provide a high-strength stainless steel for a wheel hub cap and a processing technology thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A processing technology for high-strength stainless steel for wheel hub caps includes the following processing steps:

[0007] S1: Weighing stainless steel raw materials, melting and protective casting under nitrogen pressure to obtain ingots, hot forging and hot rolling to obtain hot-rolled plates, solution treatment and water quenching, and then sequentially performing multiple cold rolling and single liquid nitrogen insulation cold rolling, annealing and aging treatment to obtain stainless steel substrates;

[0008] S2: A stainless steel substrate is pre-treated before plating, and is polished, degreased, and acid activated in sequence. The substrate is then placed in an electroplating solution and an alloy coating is electro-deposited. After the electroplating is completed, the substrate is cleaned and laser cladding is performed. After the cladding is completed, the substrate is heat treated, a thin layer is cold cut, and the substrate is polished to obtain the high-strength stainless steel.

[0009] Preferably, the nitrogen pressure in S2 is set to 0.2-0.4 MPa;

[0010] Preferably, the working conditions of the solution treatment are: temperature of 1000-1200°C and time of 2-3h;

[0011] Preferably, the annealing working conditions are: temperature of 800-1200°C, time of 2-3 minutes;

[0012] Preferably, the working conditions of the aging treatment are: temperature of 500-600°C and time of 18-24h;

[0013] Preferably, the thickness is reduced by 50-60% by multiple cold rolling passes, and the thickness is reduced by 70-80% by multiple cold rolling passes and a single liquid nitrogen insulation cold rolling pass.

[0014] Preferably, the chemical composition of the stainless steel substrate is as follows by mass percentage: C: 0.04-0.07%, N: 0.40-0.60%, Cr: 17.00-19.00%, Mn: 10.00-12.50%, Ni: 1.00-1.20%, Si: 0.10-0.20%, Nb: 0.15-0.20%, Ti: 0.03-0.05%, V: 0.60-0.80%, P+S: 0.010%, and the balance is Fe and unavoidable impurities;

[0015] Preferably, the electroplating solution in S2 comprises the following components: 10-20 g / L ferrous sulfate, 100-120 g / L nickel sulfate, 100-120 g / L chromium sulfate, 10-30 g / L nano-carbon nitrogen metal, 20-30 g / L boric acid, 100-120 g / L complexing agent, 1-2 g / L surfactant, and the remainder is deionized water; wherein ferrous sulfate, nickel sulfate, and chromium sulfate are all hydrates;

[0016] Preferably, the preparation steps of the nano-carbon nitrogen metal are: placing glucose in a mixed solvent of deionized water and ethanol, hydrothermally reacting at 180° C. for 6 hours, cooling and centrifuging, drying the primary precipitate, placing it in a mixed solvent of deionized water and ethanol, adding a metal salt to prepare a metal salt solution, stirring for 24 hours and then centrifuging, drying the secondary precipitate and calcining it, heating it to 250° C. and keeping it warm for 30 minutes under an argon atmosphere, adjusting the gas flow to an acetonitrile bubbler, passing argon after 2-3 hours, heating it to 600-800° C. and keeping it warm for 1-2 hours, and cooling it to obtain the nano-carbon nitrogen metal;

[0017] Preferably, the metal salt is one or more of chromium nitrate, nickel nitrate, molybdenum nitrate, cerium nitrate, and zirconium nitrate;

[0018] Preferably, the metal salt solution comprises 0.2-0.5 mol / L metal salt, 2-3 g / L primary precipitate, and the remainder is deionized water and ethanol;

[0019] Preferably, the electrodeposition is carried out using a graphite plate as the anode and a direct current electrodeposition with a current density of 100-200 mA / cm 2 , the temperature is 35-45℃, and the electrodeposition treatment time is 10-30min;

[0020] The specific process steps and parameters of laser cladding in S2 are as follows: cladding powder is pre-placed on the surface of the electrodeposited stainless steel substrate with a binder, and then laser cladding is performed after drying. Nitrogen is used as the shielding gas with a shielding gas flow rate of 15L / min, a laser power of 1600-2000W, a cladding rate of 8-10mm / s, a spot size of 5mm, and an overlap rate of 30-50%;

[0021] Preferably, the cladding powder is prepared by the steps of: ball milling cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano-carbon nitrogen metal and WC powder at a speed of 150-200 r / min for 1-2 hours; wherein the cladding powder comprises, by mass, 13-15 parts of cobalt powder, 12-15 parts of chromium powder, 13-15 parts of nickel powder, 5-8 parts of aluminum powder, 10-25 parts of molybdenum powder, 8-10 parts of titanium powder, 4-6 parts of zirconium powder, 6-8 parts of nano-carbon nitrogen metal and 10-12 parts of WC powder;

[0022] Preferably, the process parameters of the heat treatment in S2 are: keeping at 800-1000°C for 10 minutes and then air cooling, and then keeping at 500-600°C for 2-3 hours and air cooling;

[0023] The high-strength stainless steel for the wheel hub cover is prepared by the above processing technology.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The stainless steel substrate produced by the present invention is an austenitic stainless steel. Some trace elements, such as titanium, vanadium, and niobium, are added to refine the grains and delay the precipitation of precipitated phases. A small amount of niobium forms nano-second phase particles to improve the strength of the steel. At the same time, high nitrogen is introduced through a coupling method of high-pressure nitrogen nitriding and nitriding alloy nitriding to increase nitrogen, thereby achieving high strength of the stainless steel. During cold rolling, the substrate steel is sequentially cold-rolled and liquid nitrogen-rolled, which helps to form a high-density and intertwined dislocation structure, resulting in high strength and plastic processing.

[0026] 2. Electrodeposition + laser cladding is achieved on the surface of stainless steel substrate. A uniform Fe-Cr-Ni alloy coating is introduced on the surface of the stainless steel substrate as a transition buffer layer through electrodeposition. The added nano-carbon and nitrogen metal promotes grain refinement. Glucose is used as a carbon source to introduce a variety of metal ions, such as Ce and Zr, to synergistically improve wear resistance and corrosion resistance. At the same time, the introduction of metal ions effectively improves the dispersion of carbon materials, increases the co-deposition rate, and improves the uniformity of the coating. Nitrogen doping is performed during calcination, which brings about a carbonitriding effect during subsequent laser cladding, strengthening the interface metallurgical structure. Laser cladding introduces a small amount of Fe element into the cladding layer through dilution, and adds aluminum powder and titanium powder to introduce Al and Ti elements to change the single-phase FCC structure of the alloy to FCC+BCC structure, promoting the formation of high-hardness BCC phase. At the same time, Mo and Zr will dissolve into the BCC phase due to their large atomic radius, causing lattice distortion, hindering dislocation slip deformation, and further improving the strength and hardness of the BCC phase. The larger dislocation density has the effect of optimizing the hardness and strength of the cladding layer and improving the wear resistance. The increase of Al element also makes the cladding layer have a high hardness. - A dense passive film is formed in the environment, and a small amount of Mo enhances the density of the passive film, and the Zr element improves the stability of the passive film, thereby improving the corrosion resistance of the CrCoNi series alloy of the cladding layer;

[0027] 3. Reinforcement phase particles WC and nano-carbon nitrogen metal are added during laser cladding. The nano-carbon nitrogen metal forms nitrides through cladding and is dispersed in the cladding layer, which has the effect of dispersion strengthening and fine grain strengthening. The reinforcement phase particles improve the hardness and wear resistance and corrosion resistance of the cladding layer, and at the same time enhance the interface bonding strength between the cladding layer and the electroplating layer. Finally, heat treatment is performed to release stress and optimize the comprehensive performance of the cladding layer and the substrate. DETAILED DESCRIPTION

[0028] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0029] In the experiment, the chemical composition of the stainless steel substrate is as follows by mass percentage: C: 0.04%, N: 0.53%, Cr: 18.87%, Mn: 10.09%, Ni: 1.15%, Si: 0.15%, Nb: 0.20%, Ti: 0.05%, V: 0.65%, P+S=0.010%, and the balance is Fe and unavoidable impurities;

[0030] Iron powder, cobalt powder, nickel powder, aluminum powder, titanium powder, molybdenum powder, niobium powder, and zirconium powder were purchased from Changsha Tianjiu Metal Materials Co., Ltd. with a purity of 99.99% and a particle size of 50-100 μm. WC powder with a particle size of 45-50 μm was also purchased from Changsha Tianjiu Metal Materials Co., Ltd.

[0031] The electroplating solution includes the following components: 20 g / L ferrous sulfate heptahydrate, 100 g / L nickel sulfate hexahydrate, 100 g / L chromium sulfate hexahydrate, 20 g / L nano-carbon nitrogen metal, 30 g / L boric acid, 120 g / L complexing agent, 2 g / L surfactant, and the remainder is deionized water; the complexing agent is citric acid monohydrate and sodium citrate dihydrate with a concentration ratio of 2:1; the surfactant is sodium lauryl sulfate;

[0032] The laser cladding equipment was an IPG-YLS-10000 fiber laser. The adhesive was a 4% aqueous solution of polyvinyl alcohol (PVA), 1788 type with an average MW of 88,000, purchased from Shanghai Koraman.

[0033] Example 1: This example provides a processing technology for high-strength stainless steel for wheel hub caps, and the specific steps are as follows:

[0034] S1: Stainless steel raw materials were weighed, melted and cast under nitrogen pressure at 0.2 MPa to obtain ingots, which were then hot-forged and hot-rolled to obtain hot-rolled plates. The plates were solution-treated at 1200°C for 2 h and water-quenched. The plates were then cold-rolled in multiple passes to reduce the thickness by 50%, followed by single-pass liquid nitrogen cold rolling to reduce the thickness by 20%, annealed at 800°C for 2 min, and aged at 500°C for 20 h to obtain a 6 mm stainless steel substrate.

[0035] S2: The stainless steel substrate is pre-treated before plating, and is polished, degreased, and acid activated in sequence. The alloy coating is then deposited in the plating solution. The graphite plate is used as the anode and DC electrodeposition is adopted with a current density of 150 mA / cm 2, the temperature is 35℃, the electrodeposition treatment time is 20min, after the electrodeposition is completed, cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano carbon nitrogen metal and WC powder are ball milled at a speed of 150r / min for 2h to obtain cladding powder, the cladding powder is pre-placed on the surface of the electrodeposited stainless steel with a binder, and then laser cladding is performed after drying, with nitrogen as the protective gas, the protective gas flow rate is 15L / min, the laser power is 1800W, the cladding rate is 10mm / s, the spot size is 5mm, the overlap rate is 50%, and the cladding layer thickness is 2mm; finally, heat treatment is performed, the temperature is kept at 800℃ for 10min and then air-cooled, and then the temperature is kept at 500℃ for 2h and air-cooled, a 1mm thin layer is cold cut and then polished to obtain the finished steel;

[0036] The cladding powder includes 14.73 parts of cobalt powder, 13.00 parts of chromium powder, 14.67 parts of nickel powder, 6.75 parts of aluminum powder, 23.99 parts of molybdenum powder, 8.97 parts of titanium powder, 5.80 parts of zirconium powder, 6 parts of nano-carbon and nitrogen metal, and 12 parts of WC powder by mass.

[0037] The preparation steps of nano carbon nitrogen metal are as follows: 12.5g of glucose is placed in a mixed solvent of 240mL of deionized water and 10mL of ethanol, hydrothermally reacted at 180°C for 6h, cooled and centrifuged at 10000r / min for 10min, the precipitate is dried once, placed in a mixed solvent of 1.25L of deionized water and 1.25L of ethanol, and then 86.85g of cerium nitrate hexahydrate and 128.80g of zirconium nitrate pentahydrate are added to prepare a metal salt solution, stirred for 24h and then centrifuged, the secondary precipitate is dried and calcined, and under an argon atmosphere, the temperature is raised to 250°C and kept warm for 30min, the gas flow is adjusted to the acetonitrile bubbler, argon is introduced after 3h, the temperature is raised to 650°C and kept warm for 2h, and the product is obtained by cooling.

[0038] Example 2: This example provides a processing technology for high-strength stainless steel for wheel hub caps, and the specific steps are as follows:

[0039] S1: Stainless steel raw materials were weighed, melted and cast under nitrogen pressure at 0.2 MPa to obtain ingots, which were then hot-forged and hot-rolled to obtain hot-rolled plates. The plates were solution-treated at 1200°C for 2 h and water-quenched. The plates were then cold-rolled in multiple passes to reduce the thickness by 50%, followed by single-pass liquid nitrogen cold rolling to reduce the thickness by 20%, annealed at 800°C for 2 min, and aged at 500°C for 20 h to obtain a 6 mm stainless steel substrate.

[0040] S2: The stainless steel substrate is pre-treated before plating, and is polished, degreased, and acid activated in sequence. The alloy coating is then deposited in the plating solution. The graphite plate is used as the anode and DC electrodeposition is adopted with a current density of 150 mA / cm 2, the temperature is 35℃, the electrodeposition treatment time is 20min, after the electrodeposition is completed, cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano carbon nitrogen metal and WC powder are ball milled at a speed of 150r / min for 2h to obtain cladding powder, the cladding powder is pre-placed on the surface of the electrodeposited stainless steel with a binder, and after drying, secondary laser cladding is carried out, with nitrogen as the protective gas, the protective gas flow rate is 15L / min, the laser power is 1800W, the cladding rate is 10mm / s, the spot size is 5mm, the overlap rate is 50%, and the cladding layer thickness is 2mm; finally, heat treatment is carried out, the temperature is kept at 800℃ for 10min and then air-cooled, and then the temperature is kept at 500℃ for 2h and air-cooled, a 1mm thin layer is cold cut and then polished to obtain the finished steel;

[0041] The cladding powder includes 14.72 parts of cobalt powder, 13.01 parts of chromium powder, 14.67 parts of nickel powder, 3.37 parts of aluminum powder, 11.99 parts of molybdenum powder, 9.57 parts of titanium powder, 4.56 parts of zirconium powder, 8 parts of nano-carbon and nitrogen metal, and 10 parts of WC powder by mass.

[0042] The preparation steps of nano carbon nitrogen metal are as follows: 12.5g of glucose is placed in a mixed solvent of 240mL of deionized water and 10mL of ethanol, hydrothermally reacted at 180°C for 6h, cooled and centrifuged at 10000r / min for 10min, the precipitate is dried once, placed in a mixed solvent of 1.25L of deionized water and 1.25L of ethanol, and then 86.85g of cerium nitrate hexahydrate and 128.80g of zirconium nitrate pentahydrate are added to prepare a metal salt solution, stirred for 24h and then centrifuged, the secondary precipitate is dried and calcined, and under an argon atmosphere, the temperature is raised to 250°C and kept warm for 30min, the gas flow is adjusted to the acetonitrile bubbler, argon is introduced after 3h, the temperature is raised to 650°C and kept warm for 2h, and the product is obtained by cooling.

[0043] Example 3: This example provides a processing technology for high-strength stainless steel for wheel hub caps, and the specific steps are as follows:

[0044] S1: Stainless steel raw materials were weighed, melted and cast under nitrogen pressure at 0.2 MPa to obtain ingots, which were then hot-forged and hot-rolled to obtain hot-rolled plates. The plates were solution-treated at 1200°C for 2 h and water-quenched. The plates were then cold-rolled in multiple passes to reduce the thickness by 50%, followed by single-pass liquid nitrogen cold rolling to reduce the thickness by 20%, annealed at 800°C for 2 min, and aged at 500°C for 20 h to obtain a 6 mm stainless steel substrate.

[0045] S2: The stainless steel substrate is pre-treated before plating, and is polished, degreased, and acid activated in sequence. The alloy coating is then deposited in the plating solution. The graphite plate is used as the anode and DC electrodeposition is adopted with a current density of 150 mA / cm 2, the temperature is 35°C, the electrodeposition treatment time is 20 minutes, after the electrodeposition is completed, cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano carbon nitrogen metal and WC powder are ball-milled at a speed of 150r / min for 2 hours to obtain cladding powder, the cladding powder is pre-placed on the surface of the electrodeposited stainless steel with a binder, and laser cladding is performed after drying, nitrogen is used as the protective gas, the protective gas flow rate is 15L / min, the laser power is 1800W, the cladding rate is 10mm / s, the spot size is 5mm, the overlap rate is 50%, and the cladding layer thickness is 2mm; finally, heat treatment is performed, the mixture is kept at 800°C for 10 minutes and then air-cooled, and then kept at 500°C for 2 hours and air-cooled, a thin layer is cold-cut and then polished to obtain the high-strength stainless steel;

[0046] The cladding powder includes 14.74 parts of cobalt powder, 12.99 parts of chromium powder, 14.67 parts of nickel powder, 5.39 parts of aluminum powder, 19.19 parts of molybdenum powder, 8.97 parts of titanium powder, 5.70 parts of zirconium powder, 7 parts of nano-carbon and nitrogen metal, and 11 parts of WC powder by mass.

[0047] The preparation steps of nano carbon nitrogen metal are as follows: 12.5g of glucose is placed in a mixed solvent of 240mL of deionized water and 10mL of ethanol, hydrothermally reacted at 180°C for 6h, cooled and centrifuged at 10000r / min for 10min, the precipitate is dried once, placed in a mixed solvent of 1.25L of deionized water and 1.25L of ethanol, and then 86.85g of cerium nitrate hexahydrate and 128.80g of zirconium nitrate pentahydrate are added to prepare a metal salt solution, stirred for 24h and then centrifuged, the secondary precipitate is dried and calcined, and under an argon atmosphere, the temperature is raised to 250°C and kept warm for 30min, the gas flow is adjusted to the acetonitrile bubbler, argon is introduced after 3h, the temperature is raised to 650°C and kept warm for 2h, and the product is obtained by cooling.

[0048] Comparative Example 1: As a control experiment of Example 1, the electrodeposition was omitted, and the specific steps were as follows:

[0049] S1: Stainless steel raw materials were weighed, melted and cast under nitrogen pressure at 0.2 MPa to obtain ingots, which were then hot-forged and hot-rolled to obtain hot-rolled plates. The plates were solution-treated at 1200°C for 2 h and water-quenched. The plates were then cold-rolled in multiple passes to reduce the thickness by 50%, followed by single-pass liquid nitrogen cold rolling to reduce the thickness by 20%, annealed at 800°C for 2 min, and aged at 500°C for 20 h to obtain a 6 mm stainless steel substrate.

[0050] S2: The stainless steel substrate was pre-treated before plating, and polishing, degreasing, and acid activation were carried out in sequence. Then, cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano-carbon nitrogen metal and WC powder were ball-milled at a speed of 150r / min for 2h to obtain cladding powder. The cladding powder was pre-placed on the surface of the electrodeposited stainless steel with a binder. After drying, laser cladding was performed, using nitrogen as the protective gas with a protective gas flow rate of 15L / min, a laser power of 1800W, a cladding rate of 10mm / s, a spot size of 5mm, an overlap rate of 50%, and a cladding layer thickness of 2mm. Finally, heat treatment was performed, keeping the temperature at 800℃ for 10min and then air cooling, and then keeping the temperature at 500℃ for 2h and air cooling. A 1mm thin layer was cold cut and then polished to obtain the finished steel.

[0051] The cladding powder includes, by mass, 14.73 parts of cobalt powder, 13.00 parts of chromium powder, 14.67 parts of nickel powder, 6.75 parts of aluminum powder, 23.99 parts of molybdenum powder, 8.97 parts of titanium powder, 5.80 parts of zirconium powder, 6 parts of nano-carbon nitrogen metal and 12 parts of WC powder.

[0052] Comparative Example 2: As a control experiment of Example 1, no nano-carbon-nitrogen metal is added during laser cladding. The specific steps are as follows:

[0053] S1: Stainless steel raw materials were weighed, melted and cast under nitrogen pressure at 0.2 MPa to obtain ingots, which were then hot-forged and hot-rolled to obtain hot-rolled plates. The plates were solution-treated at 1200°C for 2 h and water-quenched. The plates were then cold-rolled in multiple passes to reduce the thickness by 50%, followed by single-pass liquid nitrogen cold rolling to reduce the thickness by 20%, annealed at 800°C for 2 min, and aged at 500°C for 20 h to obtain a 6 mm stainless steel substrate.

[0054] S2: The stainless steel substrate is pre-treated before plating, and is polished, degreased, and acid activated in sequence. The alloy coating is then deposited in the plating solution. The graphite plate is used as the anode and DC electrodeposition is adopted with a current density of 150 mA / cm 2 , the temperature is 35℃, the electrodeposition treatment time is 20min, after the electrodeposition is completed, cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder and WC powder are ball-milled at a speed of 150r / min for 2h to obtain cladding powder, the cladding powder is pre-placed on the surface of the electrodeposited stainless steel with a binder, and then laser cladding is performed after drying, with nitrogen as the protective gas, the protective gas flow rate is 15L / min, the laser power is 1800W, the cladding rate is 10mm / s, the spot size is 5mm, the overlap rate is 50%, and the cladding layer thickness is 2mm; finally, heat treatment is performed, the temperature is kept at 800℃ for 10min and then air-cooled, and then the temperature is kept at 500℃ for 2h and air-cooled, a 1mm thin layer is cold-cut and then polished to obtain the finished steel;

[0055] The cladding powder includes, by mass, 14.73 parts of cobalt powder, 13.00 parts of chromium powder, 14.67 parts of nickel powder, 6.75 parts of aluminum powder, 23.99 parts of molybdenum powder, 8.97 parts of titanium powder, 5.80 parts of zirconium powder and 12 parts of WC powder;

[0056] The preparation steps of nano carbon nitrogen metal are as follows: 12.5g of glucose is placed in a mixed solvent of 240mL of deionized water and 10mL of ethanol, hydrothermally reacted at 180°C for 6h, cooled and centrifuged at 10000r / min for 10min, the precipitate is dried once, placed in a mixed solvent of 1.25L of deionized water and 1.25L of ethanol, and then 86.85g of cerium nitrate hexahydrate and 128.80g of zirconium nitrate pentahydrate are added to prepare a metal salt solution, stirred for 24h and then centrifuged, the secondary precipitate is dried and calcined, and under an argon atmosphere, the temperature is raised to 250°C and kept warm for 30min, the gas flow is adjusted to the acetonitrile bubbler, argon is introduced after 3h, the temperature is raised to 650°C and kept warm for 2h, and the product is obtained by cooling.

[0057] Comparative Example 3: As a control experiment of Example 1, no heat treatment is performed after laser cladding. The specific steps are as follows:

[0058] S1: Stainless steel raw materials were weighed, melted and cast under nitrogen pressure at 0.2 MPa to obtain ingots, which were then hot-forged and hot-rolled to obtain hot-rolled plates. The plates were solution-treated at 1200°C for 2 h and water-quenched. The plates were then cold-rolled in multiple passes to reduce the thickness by 50%, followed by single-pass liquid nitrogen cold rolling to reduce the thickness by 20%, annealed at 800°C for 2 min, and aged at 500°C for 20 h to obtain a 6 mm stainless steel substrate.

[0059] S2: The stainless steel substrate is pre-treated before plating, and is polished, degreased, and acid activated in sequence. The alloy coating is then deposited in the plating solution. The graphite plate is used as the anode and DC electrodeposition is adopted with a current density of 150 mA / cm 2 , the temperature is 35℃, the electrodeposition treatment time is 20min, after the electrodeposition is completed, cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano carbon nitrogen metal and WC powder are ball milled at a speed of 150r / min for 2h to obtain cladding powder, the cladding powder is pre-placed on the surface of the electrodeposited stainless steel with a binder, and then laser cladding is performed after drying, with nitrogen as the shielding gas, the shielding gas flow rate is 15L / min, the laser power is 1800W, the cladding rate is 10mm / s, the spot size is 5mm, the overlap rate is 50%, and the cladding layer thickness is 2mm; finally, a 1mm thin layer is cold cut and then polished to obtain the finished steel;

[0060] The cladding powder includes 14.73 parts of cobalt powder, 13.00 parts of chromium powder, 14.67 parts of nickel powder, 6.75 parts of aluminum powder, 23.99 parts of molybdenum powder, 8.97 parts of titanium powder, 5.80 parts of zirconium powder, 6 parts of nano-carbon and nitrogen metal, and 12 parts of WC powder by mass.

[0061] The preparation steps of nano carbon nitrogen metal are as follows: 12.5g of glucose is placed in a mixed solvent of 240mL of deionized water and 10mL of ethanol, hydrothermally reacted at 180°C for 6h, cooled and centrifuged at 10000r / min for 10min, the precipitate is dried once, placed in a mixed solvent of 1.25L of deionized water and 1.25L of ethanol, and then 86.85g of cerium nitrate hexahydrate and 128.80g of zirconium nitrate pentahydrate are added to prepare a metal salt solution, stirred for 24h and then centrifuged, the secondary precipitate is dried and calcined, and under an argon atmosphere, the temperature is raised to 250°C and kept warm for 30min, the gas flow is adjusted to the acetonitrile bubbler, argon is introduced after 3h, the temperature is raised to 650°C and kept warm for 2h, and the product is obtained by cooling.

[0062] Detection test

[0063] 1. Hardness test: The hardness of the stainless steel substrate S1 in Example 1 was measured using a Vickers hardness tester and was found to be 642.1 HV. The microhardness of the steel products prepared in Examples 1-3 and Comparative Examples 1-3 was further measured, and the data are recorded in the table below.

[0064] 2. Wear test: A friction and wear tester was used to measure the friction resistance of the finished steel surface at room temperature (25°C). The load was 10N, the test length was 8mm, and the test time was 30min. The wear rate was calculated and the data was recorded in the table below.

[0065] 3. Electrochemical test: Electrochemical test was carried out in 3.5wt% NaCl solution at 25℃ using an electrochemical workstation with a standard three-electrode system. Pt was used as the auxiliary electrode and a saturated calomel electrode was used as the reference electrode. At open circuit potential, the scan range was -0.5~1V and the scan speed was 1m / s. The self-corrosion potential was calculated by fitting the curve. The data are recorded in the table below.

[0066]

[0067] Conclusion: It can be seen from the above data that the finished steel produced by the processing method and ingredient ratio of Example 1 has better hardness, wear resistance and corrosion resistance than the other examples; Comparative Example 1 does not perform electrodeposition, and the interface bonding between the stainless steel and the cladding layer decreases, resulting in an increase in the wear rate; Comparative Example 2 does not add nano-carbon nitrogen metal during laser cladding, resulting in a significant decrease in the hardness of the cladding layer. The decrease in hardness leads to an increase in the wear rate, a decrease in wear resistance, and a decrease in corrosion resistance; Comparative Example 3 does not perform heat treatment after laser cladding, and the comprehensive performance of the finished steel decreases.

[0068] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A processing technology for high-strength stainless steel for wheel hub cap, characterized in that: The processing steps include: S1: Weighing stainless steel raw materials, melting and protective casting under nitrogen pressure to obtain ingots, hot forging and hot rolling to obtain hot-rolled plates, solution treatment and water quenching, and then sequentially performing multiple cold rolling and single liquid nitrogen insulation cold rolling, annealing and aging treatment to obtain stainless steel substrates; S2: Pre-treatment of the stainless steel substrate before plating, including grinding and polishing, degreasing, and acid activation, followed by electrodeposition of an alloy coating in an electroplating solution. After the electrodeposition, the substrate is cleaned and laser clad. After the cladding is completed, the substrate is heat treated, a thin layer is cold cut, and the substrate is ground and polished to obtain the high-strength stainless steel. The chemical composition of the stainless steel substrate is as follows by mass percentage: the chemical composition of the stainless steel substrate is as follows by mass percentage: C: 0.04-0.07%, N: 0.40-0.60%, Cr: 17.00-19.00%, Mn: 10.00-12.50%, Ni: 1.00-1.20%, Si: 0.10-0.20%, Nb: 0.15-0.20%, Ti: 0.03-0.05%, V: 0.60-0.80%, P+S: 0.010%, and the balance is Fe and unavoidable impurities; In step S2, the electroplating solution includes the following components: 10-20 g / L ferrous sulfate, 100-120 g / L nickel sulfate, 100-120 g / L chromium sulfate, 10-30 g / L nano-carbon nitrogen metal, 20-30 g / L boric acid, 100-120 g / L complexing agent, 1-2 g / L surfactant, and the rest is deionized water; The preparation steps of the nano-carbon nitrogen metal are as follows: placing glucose in a mixed solvent of deionized water and ethanol, hydrothermally reacting at 180°C for 6 hours, cooling and centrifuging, drying a primary precipitate, placing it in a mixed solvent of deionized water and ethanol, adding a metal salt, stirring for 24 hours, and then centrifuging, drying a secondary precipitate, and calcining it; heating it to 250°C under an argon atmosphere and holding it for 30 minutes; adjusting the gas flow to an acetonitrile bubbler, introducing argon after 2-3 hours, heating it to 600-800°C and holding it for 1-2 hours, and cooling it to obtain the nano-carbon nitrogen metal; wherein the metal salt is one or more combinations of chromium nitrate, nickel nitrate, molybdenum nitrate, cerium nitrate, and zirconium nitrate; The specific process steps and parameters of laser cladding in S2 are as follows: cladding powder is pre-placed on the surface of the electrodeposited stainless steel substrate with a binder, and then laser cladding is performed after drying. Nitrogen is used as the shielding gas with a shielding gas flow rate of 15L / min, a laser power of 1600-2000W, a cladding rate of 8-10mm / s, a spot size of 5mm, and an overlap rate of 30-50%; The cladding powder is prepared by ball milling cobalt powder, chromium powder, nickel powder, aluminum powder, molybdenum powder, titanium powder, niobium powder, zirconium powder, nano-carbon nitrogen metal and WC powder at a rotation speed of 150-200 r / min for 1-2 hours; the cladding powder comprises, by mass, 13-15 parts of cobalt powder, 12-15 parts of chromium powder, 13-15 parts of nickel powder, 5-8 parts of aluminum powder, 10-25 parts of molybdenum powder, 8-10 parts of titanium powder, 4-6 parts of zirconium powder, 6-8 parts of nano-carbon nitrogen metal and 10-12 parts of WC powder.

2. The processing technology of high-strength stainless steel for wheel hub cap according to claim 1, characterized in that: In step S1, the nitrogen pressure is set to 0.2-0.4 MPa; the working conditions of the solution treatment are: temperature of 1000-1200° C., time of 2-3 hours; the working conditions of the annealing are: temperature of 800-1200° C., time of 2-3 minutes; the working conditions of the aging treatment are: temperature of 500-600° C., time of 18-24 hours; multiple passes of cold rolling are performed until the thickness is reduced by 50-60%, and multiple passes of cold rolling and single pass of liquid nitrogen insulation cold rolling are performed until the thickness is reduced by 70-80% in total.

3. The processing technology of high-strength stainless steel for wheel hub cap according to claim 1, characterized in that: Electrodeposition uses graphite plate as anode and adopts direct current deposition with a current density of 100-200mA / cm 2 , the temperature is 35-45℃, and the electrodeposition treatment time is 10-30min.

4. The processing technology of high-strength stainless steel for wheel hub cap according to claim 1, characterized in that: The process parameters of the heat treatment in S2 are: keeping at 800-1000℃ for 10 minutes and then air cooling, and then keeping at 500-600℃ for 2-3 hours and air cooling.

5. High-strength stainless steel for wheel hub caps prepared by the processing technology according to any one of claims 1 to 4.

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