A process for the production of a locally hardened complex component

Abstract

The application discloses a production process of a locally hardened complex component and relates to the technical field of heat treatment, and specifically comprises the following steps: S1, placing a to-be-heated part of a basic component in an induction heating ring for induction heating; S2, after the induction heating is completed, spraying a quenching liquid on the heated part, taking out the part after cooling to room temperature, and low-temperature tempering to obtain a quenched component; S3, grinding, degreasing and drying the quenched component, coating a surface treatment liquid on the surface of the quenched component, solidifying, and inductively cladding under a nitrogen atmosphere to obtain a locally hardened component; according to tests, the locally hardened complex component provided by the process has high hardness and no internal cracks.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat treatment, in particular to a production process of a locally hardened complex component. BACKGROUND

[0002] Quenching is a common process operation of metal components, which can significantly improve the hardness, strength of metal materials and fatigue life. The heating methods of quenching include furnace heating and induction heating. Induction heating is widely used in the heating process of quenching because of its high heating efficiency, accurate temperature control and pollution-free heating.

[0003] Shaft components are key parts in mechanical transmission, and their comprehensive performance is crucial. Different regions require different mechanical properties, such as high hardness in some regions that bear large stress. Local quenching process can meet this demand. However, some complex shaft components, such as crankshafts, have complex shapes. Traditional processes use gas heat nozzles for local high-temperature ablation heating, but gas heating temperature control is difficult, oxidation is serious, efficiency is low, and operation is inconvenient. Induction heating is limited by shape, and the component is not uniformly heated, which can easily lead to excessive local stress and cracks, and cannot meet the demand.

[0004] In summary, in order to solve the above problems, it is of great significance to provide a production process of a locally hardened complex component that can prevent cracking. SUMMARY

[0005] The purpose of the present application is to provide a production process of a locally hardened complex component to solve the problems in the prior art.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] A production process of a locally hardened complex component, comprising the following steps:

[0008] S1: placing the heating part of the base component in the induction heating ring, adjusting the induction ring to cover the shape of the component heating part, and performing induction heating;

[0009] S2: after the induction heating is completed, spraying quenching liquid on the heated part, cooling to room temperature, taking out, low temperature tempering, and obtaining a quenched component;

[0010] S3: grinding, degreasing and drying the quenched component, coating a surface treatment liquid on the surface, solidifying, and induction cladding in a nitrogen atmosphere to obtain a locally hardened component.

[0011] More preferably, in step S1, the induction coil is a special-shaped induction coil, the distance between the coil and the two ends of the component is different, and the surface temperatures of the proximal end and the distal end of the component are different; in the process of induction heating, the heating temperature of the proximal end is the quenching temperature of the component + 50℃, and the heating temperature of the distal end is the quenching temperature of the component ± 10℃.

[0012] More preferably, in step S2: in the spraying process, the water pressure is 100-120 kPa, and the water flow density is 70-80 L·m -2 s -1 ; in step S3: in the coating process, the thickness is 0.5-0.7 mm; in the solidification process, the temperature is 140-150℃, and the time is 5-10 min; in the induction cladding process, the current is 1150-1250 A, the power is 25 KW, the oscillation frequency range is 50-80 kHz, the coil turns are 4 turns, and the time is 40-50 s.

[0013] More preferably, the quenching liquid comprises the following substances by mass fraction: 30-35 parts of modified PAG copolymer, 0.3-0.4 parts of triethanolamine, 0.05-0.1 parts of monoethanolamine, 2.5-3.5 parts of calcium chloride, 1-3 parts of sorbitan monooleate, and 35-40 parts of deionized water.

[0014] The preparation method of the modified PAG copolymer comprises the following steps: (1) uniformly mixing ethylene oxide, propylene oxide and epoxy propionic acid at a temperature of 3-5℃ to obtain a polymerization monomer; (2) adding propylene glycol and a catalyst to a reaction kettle under a nitrogen atmosphere, heating to 75-85℃ under a vacuum degree of ≤-0.09 Mpa, then gradually introducing the polymerization monomer, ensuring that the pressure is ≤0.3 MPa, and reacting at 125-135℃ for 8-10 h, purifying, to obtain a PAG copolymer; (3) adding the PAG copolymer into deionized water to stir uniformly, adding chitosan and an activator, stirring at 80-85℃ for 5-6 h, purifying, and drying to obtain the modified PAG copolymer.

[0015] More preferably, the polymerization monomer comprises ethylene oxide, propylene oxide and epoxy propionic acid in a mass ratio of 10:13-14:3-5; the mass ratio of the propylene glycol and the catalyst is 5-7:1; the mass ratio of the polymerization monomer and the catalyst is 100:0.5-0.7; and the modified PAG copolymer comprises the following raw materials by mass fraction: 8-10 parts of PAG copolymer, 40-50 parts of deionized water, 3-5 parts of chitosan, and 3-4 parts of activator.

[0016] The catalyst is a diimine iron complex and potassium hydroxide in a mass ratio of 1:3-4.

[0017] More preferably, the preparation method of the surface treatment liquid comprises the following steps: (1) adding sodium polymethacrylate into deionized water and stirring uniformly, adding dopamine and an activator, adjusting pH to 7.5-8.5, heating and stirring at 70-80℃ for 5-7h, separating, washing, and obtaining modified polymethacrylate; (2) mixing nano titanium carbide, tungsten powder and nickel powder to obtain metal powder; (3) mixing the metal powder, modified polymethacrylate, ethyl cellulose and acetone, and shearing and stirring at 40-45℃ for 1-1.5h to obtain the surface treatment liquid.

[0018] The modified polymethacrylate comprises the following raw materials by mass fraction: 4-5 parts of sodium polymethacrylate, 14-16 parts of dopamine and 7-8 parts of an activator; the metal powder comprises nano titanium carbide, tungsten powder and nickel powder in a mass ratio of 2:3-4:5-6; and the surface treatment liquid comprises the metal powder, modified polymethacrylate, ethyl cellulose and acetone in a mass ratio of 3:1-2:2.5-3.5:24-26.

[0019] The activator comprises 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide and succinimide in a mass ratio of 1:1-3; the sodium polymethacrylate has a molecular weight of 3000-4000; and the tungsten powder and nickel powder have a particle size of 1-4μm.

[0020] More preferably, the quenching liquid needs to be diluted three times with water for use.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] (1) The application can conveniently and accurately heat and treat specified parts of the component by using a local heating method, so that the parts that need to be heat treated can improve the corresponding performance, and the parts that do not participate in the heat treatment remain unchanged. Since the heating time is short, the internal grain size will not grow, and the oxidation scale is small, and the surface quality is good. The component treated by the method has the advantages of high hardness of the specified parts, fine internal structure, small size of the heating device and low energy consumption. It is easy to operate and has low cost, and is suitable for large-scale production. At the same time, the application uses a specific shape induction coil for induction heating. The distance between the coil and the two ends of the component is different, and the surface temperatures of the near-end and far-end components are different. The closer the distance, the greater the magnetic field density and the higher the temperature. The farther the distance, the smaller the magnetic field density and the lower the temperature. The near-end temperature is controlled to be the quenching temperature of the component +50℃, and the far-end heating temperature is the quenching temperature of the component ±10℃, which helps to improve the induction heating efficiency, makes the component quickly reach the quenching temperature, and also can meet the needs of some complex components for concentrated local heating, and provides better flexibility.

[0023] (2) The present application adopts water-based polymer PAG as quenching medium, because of its inverse solubility, solubility decreases with the temperature rising at 70-88℃, the polymer will be precipitated and attached to the surface of the component, forming an organic film, so as to adjust the temperature drop speed, control the cooling speed when the component temperature reaches Ms point (martensite start temperature), so as to solve the problem of component cracking and deformation caused by too fast cooling speed of water in low temperature zone. But the film generated by PAG copolymer in low temperature zone is discontinuous and has low strength. The cooling speed at Ms point is between water and oil, so the present application grafts chitosan on PAG copolymer, which has good film forming effect and can make up for the discontinuous film generated by PAG in low temperature zone, so as to reduce the possibility of component cracking.

[0024] (3) The present application further improves the hardness of hardened area, and a surface treatment liquid containing metal powder is coated on the surface, and a hardened layer is formed on the surface after solidification and induction cladding, so as to improve the hardness, wear resistance and corrosion resistance of the material. At the same time, the present application only needs to be applied to the part needing hardening, and induction cladding is adopted, so that the operation is convenient, the heating time is short, and the complex component can be locally hardened without affecting the surface of the component which has been quenched. Because the treatment liquid is relatively viscous, it is difficult for the metal powder to be stably dispersed in the system, the present application grafts dopamine on modified polymethyl methacrylate, the catechol group has good attraction to metal, so that the metal particles are uniformly loaded on polymethyl methacrylate, so as to improve the dispersibility of the metal powder, and the excess catechol group can be combined with the metal on the surface of the component, so as to improve the tightness of the treatment liquid and the component, and facilitate subsequent operation. DETAILED DESCRIPTION

[0025] Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] It should be noted that there is no special limitation on the purchase manufacturer of all raw materials involved in the present application, which exemplarily includes: triethanolamine; monoethanolamine; calcium chloride; sorbitan monooleate; ethylene oxide; propylene oxide; epoxy propionic acid; dopamine; tungsten powder: particle size 1-4 μm; nickel powder: particle size 1-4 μm; in the following examples, parts are mass parts, and the raw materials are commercially available.

[0027] Each of the embodiments of the crankshaft comprises the following elements in terms of mass fraction: C: 0.46%, Si: 0.25%, Mn: 1.16%, P: 0.01%, S: 0.012%, Cr: 0.17%, V: 0.07%, Ni: 0.01%, Cu: 0.1%, Mo: 0.01%, Ti: 0.016%, and the rest is Fe and other inevitable impurities; and the quenching temperature of the crankshaft is 840-860°C.

[0028] Each of the embodiments of the quenching liquid comprises the following substances: 30 parts of modified PAG copolymer, 0.35 parts of triethanolamine, 0.05 parts of monoethanolamine, 3 parts of calcium chloride, 2 parts of sorbitan monooleate, and 35 parts of deionized water in terms of mass parts; and the quenching liquid needs to be diluted with water by three times before use.

[0029] Embodiment 1:

[0030] Step one: preparation of the surface treatment liquid: (1) 4.5 parts of sodium polymethacrylate is added to 50 parts of deionized water and stirred uniformly, 15 parts of dopamine and 7.5 parts of activator are added, the pH is adjusted to 8, and heating and stirring are carried out at 45°C for 6h, and then separation, washing, and modification are carried out to obtain modified polyacrylic acid; (2) nano titanium carbide, tungsten powder, and nickel powder are mixed in a mass ratio of 2:3.5:5.5 to obtain metal powder; (3) the metal powder, modified polymethacrylate, ethyl cellulose, and acetone are mixed in a mass ratio of 3:1.5:3:25, and shearing stirring is carried out at 40°C for 1.5h to obtain the surface treatment liquid;

[0031] Step two: preparation of the modified PAG copolymer: (1) at 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed uniformly in a mass ratio of 10:13.5:4 to obtain polymer monomer; (2) under a nitrogen atmosphere, propylene glycol and a catalyst (diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reaction kettle in a mass ratio of 6:1, heating is carried out to 80°C under a vacuum degree of ≤-0.09Mpa, then the polymer monomer is gradually introduced (the mass ratio of the polymer monomer and the catalyst is 100:0.6), the pressure is ensured to be ≤0.3MPa, and reaction is carried out at 130°C for 9h, and then purification, drying, and modification are carried out to obtain the PAG copolymer; (3) 9 parts of the PAG copolymer is added to 45 parts of deionized water and stirred uniformly, 4 parts of chitosan and 3.5 parts of activator are added, stirring is carried out at 80°C for 5.5h, and then purification, drying, and modification are carried out to obtain the modified PAG copolymer;

[0032] Step three: local hardening of the complex component:

[0033] S1: under a nitrogen atmosphere, the part to be heated of the base component is placed in an induction heating coil, the induction coil is adjusted so that the induction coil covers the shape of the heated part of the component, and then induction heating is carried out at a proximal end of 900°C and a distal end of 850°C for 50s;

[0034] S2: After the induction heating is completed, water pressure is 100 kPa, and water flow density is 75 L·m -2 s -1 Spray quenching liquid on the heated part, and after cooling to room temperature, the quenched component is taken out and tempered at 200℃ for 2.5h to obtain a quenched component;

[0035] S3: The quenched component is polished, degreased, and dried, and a surface treatment liquid is coated on the surface thereof with a thickness of 0.6mm, and is cured at 145℃ for 5min, and is induction cladded in a nitrogen atmosphere (induction cladding parameters: current is 1150-1250A, power is 25KW, oscillation frequency range is 50-80kHz, coil turns is 4 turns, and time is 45s) to obtain a locally hardened component.

[0036] Example 2:

[0037] Step one: preparation of the surface treatment liquid: (1) 4.5 parts of sodium polymethacrylate are added to 50 parts of deionized water and stirred uniformly, 15 parts of dopamine and 7.5 parts of activator are added, the pH is adjusted to 8, and heating and stirring are carried out at 45℃ for 6h, and then separation, washing are carried out to obtain modified polyacrylic acid; (2) nano titanium carbide, tungsten powder, and nickel powder are mixed in a mass ratio of 2:3.5:5.5 to obtain metal powder; (3) the metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone are mixed in a mass ratio of 3:1.5:3:25, and shearing stirring is carried out at 40℃ for 1.5h to obtain a surface treatment liquid;

[0038] Step two: preparation of the modified PAG copolymer: (1) ethylene oxide, propylene oxide, and epoxy propionic acid are mixed uniformly at a mass ratio of 10:13.5:4 at 4℃ to obtain a polymerization monomer; (2) under a nitrogen atmosphere, propylene glycol and a catalyst (diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reaction kettle in a mass ratio of 6:1, heating is carried out to 80℃ under a vacuum degree ≤-0.09Mpa, then the polymerization monomer is gradually introduced (the mass ratio of the polymerization monomer and the catalyst is 100:0.6), and the pressure is ensured to be ≤0.3MPa, and reaction is carried out at 130℃ for 9h, and then purification is carried out to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred uniformly, 4 parts of chitosan and 3.5 parts of an activator are added, stirring is carried out at 80℃ for 5.5h, and then purification, drying are carried out to obtain a modified PAG copolymer;

[0039] Step three: local hardening of the complex component

[0040] S1: the part to be heated of the base component is placed in an induction heating coil under a nitrogen atmosphere, the induction coil is adjusted so that the induction coil covers the shape of the heated part of the component, and the near end is heated at 900℃ and the far end is heated at 850℃ for 40s by induction;

[0041] S2: After the induction heating is completed, water pressure is 100 kPa, and water flow density is 70 L·m -2 s -1 Spray quenching liquid on the heated part, cool to room temperature, take out, temper at 200℃ for 2.5h, and quenching component is obtained;

[0042] S3: Grind the quenching component to be hardened, degrease, dry, coat the surface treatment liquid on the surface with a thickness of 0.6mm, solidify at 140℃ for 5min, and induction cladding (induction cladding parameters: current is 1150-1250A, power is 25KW, oscillation frequency range is 50-80kHz, coil turns is 4 turns, time is 40s) in nitrogen atmosphere to obtain a locally hardened component.

[0043] Example 3:

[0044] Step one: preparation of surface treatment liquid: (1) add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir until uniform, add 15 parts of dopamine and 7.5 parts of activator, adjust pH to 8, heat and stir at 45℃ for 6h, separate, wash, and obtain modified polyacrylic acid; (2) mix nano titanium carbide, tungsten powder, and nickel powder in a mass ratio of 2:3.5:5.5 to obtain metal powder; (3) mix the metal powder, modified polymethacrylate, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, and shear stir at 40℃ for 1.5h to obtain the surface treatment liquid;

[0045] Step two: preparation of modified PAG copolymer: (1) mix ethylene oxide, propylene oxide, and epoxy propionic acid in a mass ratio of 10:13.5:4 uniformly at 4℃ to obtain polymer monomer; (2) add propylene glycol and catalyst (diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) in a mass ratio of 6:1 to a reaction kettle under nitrogen atmosphere, heat to 80℃ under a vacuum degree ≤-0.09Mpa, then gradually introduce polymer monomer (mass ratio of polymer monomer and catalyst is 100:0.6) to ensure that the pressure is ≤0.3MPa, and react at 130℃ for 9h, purify, and obtain PAG copolymer; (3) add 9 parts of PAG copolymer to 45 parts of deionized water and stir until uniform, add 4 parts of chitosan and 3.5 parts of activator, stir at 80℃ for 5.5h, purify, dry, and obtain modified PAG copolymer;

[0046] Step three: local quenching of complex component

[0047] S1: place the part to be heated of the base component in the induction heating coil under nitrogen atmosphere, adjust the induction coil to cover the shape of the heated part of the component, and induction heat at near end 900℃ and far end 850℃ for 60s;

[0048] S2: After the induction heating is completed, water pressure is 120 kPa, and water flow density is 80 L·m -2 s -1 After the heating part is sprayed with quenching liquid, the quenching member is taken out after being cooled to room temperature, tempered at 200 DEG C for 2.5 h, and the quenching member is obtained;

[0049] S3: The quenched member is polished, degreased, and dried, and a surface treatment liquid is coated on the surface thereof with a thickness of 0.7 mm, cured at 150 DEG C for 10 min, and induction cladded in a nitrogen atmosphere (induction cladding parameters: current is 1150-1250 A, power is 25 KW, oscillation frequency range is 50-80 kHz, coil turns is 4 turns, and time is 50 s) to obtain a locally hardened member.

[0050] Comparative Example 1: Based on Example 1, a circular coil is used for induction heating, and the rest of the process remains unchanged, as follows:

[0051] Step one: preparation of surface treatment liquid: (1) 4.5 parts of sodium polymethacrylate are added to 50 parts of deionized water and stirred uniformly, 15 parts of dopamine and 7.5 parts of activator are added, the pH is adjusted to 8, and heating and stirring are carried out at 45 DEG C for 6 h, and then separation, washing, and modification are carried out to obtain modified polyacrylic acid; (2) nano-titanium carbide, tungsten powder, and nickel powder are mixed in a mass ratio of 2:3.5:5.5 to obtain metal powder; (3) the metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone are mixed in a mass ratio of 3:1.5:3:25, and shearing stirring is carried out at 40 DEG C for 1.5 h to obtain a surface treatment liquid;

[0052] Step two: preparation of modified PAG copolymer: (1) at 4 DEG C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed uniformly in a mass ratio of 10:13.5:4 to obtain polymer monomer; (2) under a nitrogen atmosphere, propylene glycol and a catalyst (diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reaction kettle in a mass ratio of 6:1, heated to 80 DEG C under a vacuum degree of ≤-0.09 Mpa, and then gradually introduce the polymer monomer (mass ratio of polymer monomer and catalyst is 100:0.6) to ensure that the pressure is ≤0.3 MPa, and react at 130 DEG C for 9 h, and then purify and dry to obtain a PAG copolymer; (3) 9 parts of PAG copolymer are added to 45 parts of deionized water and stirred uniformly, 4 parts of chitosan and 3.5 parts of activator are added, stirring is carried out at 80 DEG C for 5.5 h, and then purification, drying, and modification are carried out to obtain a modified PAG copolymer;

[0053] Step three: local quenching of complex member:

[0054] S1: under a nitrogen atmosphere, the heating part of the base member is placed in the induction heating coil, the induction coil is adjusted so that the induction coil covers the shape of the heating part of the member, and induction heating is carried out at 850 DEG C for 50 s;

[0055] S2: After the induction heating is completed, water pressure is 100 kPa, and water flow density is 75 L·m -2 -1 Spray the quenching liquid on the heated part, cool to room temperature, take out, temper at 200 DEG C for 2.5 h, and obtain a quenched component;

[0056] S3: Grind the quenched component to be hardened, degrease, dry, coat the surface treatment liquid on the surface to a thickness of 0.6 mm, solidify at 145 DEG C for 5 min, and induction cladding in a nitrogen atmosphere (induction cladding parameters: current is 1150-1250 A, power is 25 KW, oscillation frequency range is 50-80 kHz, coil turns is 4 turns, time is 45 s) to obtain a locally hardened component.

[0057] Comparative Example 2: Based on Example 1, a commercially available PAG quenching liquid is used, and the rest of the process remains unchanged, as follows:

[0058] Step one: preparation of the surface treatment liquid: (1) add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir until uniform, add 15 parts of dopamine and 7.5 parts of activator, adjust the pH to 8, heat and stir at 45 DEG C for 6 h, separate, wash, and obtain modified polyacrylic acid; (2) mix nano titanium carbide, tungsten powder, and nickel powder in a mass ratio of 2:3.5:5.5 to obtain metal powder; (3) mix the metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, and shear stir at 40 DEG C for 1.5 h to obtain the surface treatment liquid;

[0059] Step two: local hardening of the complex component:

[0060] S1: Place the part to be heated of the base component in the induction heating coil in a nitrogen atmosphere, adjust the induction coil so that the induction coil covers the shape of the heated part of the component, and induction heat at a proximal end of 900 DEG C and a distal end of 850 DEG C for 50 s;

[0061] S2: After the induction heating is completed, water pressure is 100 kPa, and water flow density is 75 L·m -2 -1 Spray the commercially available PAG quenching liquid on the heated part, cool to room temperature, take out, temper at 200 DEG C for 2.5 h, and obtain a quenched component;

[0062] S3: Grind the quenched component to be hardened, degrease, dry, coat the surface treatment liquid on the surface to a thickness of 0.6 mm, solidify at 145 DEG C for 5 min, and induction cladding in a nitrogen atmosphere (induction cladding parameters: current is 1150-1250 A, power is 25 KW, oscillation frequency range is 50-80 kHz, coil turns is 4 turns, time is 45 s) to obtain a locally hardened component.​​

[0063] Comparative Example 3: Based on Example 1, no coating treatment liquid is used, and the rest of the process remains unchanged, as follows:

[0064] Step one: preparation of modified PAG copolymer: (1) mix ethylene oxide, propylene oxide, and epoxy propionic acid at a mass ratio of 10:13.5:4 uniformly at a temperature of 4°C to obtain polymer monomer; (2) under a nitrogen atmosphere, add propylene glycol and catalyst (diimine iron complex and potassium hydroxide at a mass ratio of 1:3.5) to the reaction kettle at a mass ratio of 6:1, heat to 80°C under a vacuum degree of ≤-0.09 Mpa, then gradually introduce the polymer monomer (mass ratio of polymer monomer and catalyst is 100:0.6) to ensure that the pressure is ≤0.3 MPa, and react at 130°C for 9 h, purify, and dry to obtain the modified PAG copolymer;

[0065] Step two: local hardening of complex components:

[0066] S1: under a nitrogen atmosphere, place the part to be heated of the base component in the induction heating coil, adjust the induction coil so that the induction coil covers the shape of the heated part of the component, and heat at a proximal end of 900°C and a distal end of 850°C for 50 s;

[0067] S2: after the induction heating is completed, spray the quenched liquid at a water pressure of 100 kPa and a water flow density of 75 L·m -2 s -1 Spray the heated part with the quenched liquid, cool to room temperature, remove, and temper at 200°C for 2.5 h to obtain a locally hardened component.

[0068] Comparative Example 4: Based on Example 1, the sodium polymethacrylate in the treatment liquid is not modified, and the rest of the process remains unchanged, as follows:

[0069] Step one: preparation of surface treatment liquid: (1) mix nano titanium carbide, tungsten powder, and nickel powder at a mass ratio of 2:3.5:5.5 to obtain metal powder; (2) mix the metal powder, sodium polymethacrylate, ethyl cellulose, and acetone at a mass ratio of 3:1.5:3:25, and shear stir at 40°C for 1.5 h to obtain the surface treatment liquid;

[0070] Step two: preparation of modified PAG copolymer: (1) mix ethylene oxide, propylene oxide and epoxy propionic acid uniformly at a mass ratio of 10:13.5:4 at a temperature of 4°C to obtain a polymerization monomer; (2) under a nitrogen atmosphere, add propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide at a mass ratio of 1:3.5) to a reaction kettle at a mass ratio of 6:1, heat to 80°C under a vacuum degree ≤-0.09 Mpa, then gradually introduce the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) to ensure that the pressure is ≤0.3 MPa, and react at 130°C for 9 h, purify, and dry to obtain the PAG copolymer; (3) add 9 parts of the PAG copolymer to 45 parts of deionized water and stir uniformly, add 4 parts of chitosan and 3.5 parts of an activator, stir at 80°C for 5.5 h, purify, dry, and obtain the modified PAG copolymer;

[0071] Step three: local hardening of complex components

[0072] S1: under a nitrogen atmosphere, place the part to be heated of the base component in an induction heating coil, adjust the induction coil so that the induction coil covers the shape of the heated part of the component, and inductively heat at a proximal end of 900°C and a distal end of 850°C for 50 s;

[0073] S2: after the induction heating is completed, spray the quenched liquid on the heated part at a water pressure of 100 kPa and a water flow density of 75 L·m -2 s -1 After cooling to room temperature, remove the quenched component, temper it at 200°C for 2.5 h, and obtain a quenched component;

[0074] S3: polish, degrease, and dry the quenched component, apply a surface treatment liquid to the surface of the component at a thickness of 0.6 mm, cure it at 145°C for 5 min, and inductively clad it under a nitrogen atmosphere (the inductive cladding parameters are: a current of 1150-1250 A, a power of 25 KW, a shock frequency range of 50-80 kHz, a coil turn number of 4 turns, and a time of 45 s) to obtain a locally hardened component.

[0075] Performance test: (1) measure the surface hardness of the crankshafts of each example after quenching according to the file GB / T 5617-2005, and the experimental data are shown in Table 1; (2) perform ultrasonic detection on the crankshafts of each example after quenching according to the file GB / T 39240-2020, and grade the number of internal cracks of the components as A, B, C, and D (A: no cracks are found on the surface and inside of the component; B: a small number of cracks are found in the component; C: a certain number of cracks exist in the component, but are still within an acceptable range; and D: a large number of cracks exist in the component, and the structural integrity is low)

[0076] Table 1

[0077] Item Hardness HRC Number of cracks Example 1 60.2 A Example 2 58.7 A Example 3 59.1 A Comparative Example 1 54.2 B- Comparative Example 2 53.5 B Comparative Example 3 48.2 B+ Comparative Example 4 50.1 B

[0078] Conclusion: From Table 1, it can be seen that the heating efficiency of Comparative Example 1 using a circular coil induction coil is slow, and the strength of the hardened part is not as good as that of Example 1; in Comparative Example 2, a commercially available PAG quenching liquid is used, and the film produced is discontinuous, the strength is low, the temperature at the Ms point decreases rapidly, small cracks are produced, and the hardness is not as good as that of Example 1; in Comparative Example 3, no surface treatment liquid is coated, and the local quenching hardness is lower than the hardness of the hardened layer of Example 1; in Comparative Example 4, the sodium polymethacrylate in the treatment liquid is not modified, the dispersibility of the metal powder in the system is poor, agglomeration occurs after induction cladding, and the hardness decreases.

[0079] Conclusion: The present application uses a specific shape of coil induction heating, simultaneously uses a chitosan modified PAG quenching liquid for quenching and uses a surface treatment liquid for induction cladding of the hardened layer, successfully providing a production process for local quenching of complex components, which can prevent cracking, and the hardness of the quenched part of the product is higher.

[0080] Finally, it should be noted that: the above only describes the preferred embodiments of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements for some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A manufacturing process for locally hardened complex components, characterized in that, Includes the following steps: S1: Place the part of the base component to be heated in the induction heating coil for induction heating; S2: After induction heating is completed, the heated part is sprayed with quenching liquid, cooled to room temperature, taken out, and tempered at low temperature to obtain the quenched component. S3: Grind, degrease, and dry the hardened parts of the quenched component, apply surface treatment liquid to its surface, cure, and induction cladding in a nitrogen atmosphere to obtain a locally hardened component. In step S1, the induction heating coil is a specific-shaped induction coil with different distances between the coil and the two ends of the component, resulting in different surface temperatures at the near and far ends of the component. During the induction heating process, the near-end heating temperature is the component quenching temperature +50℃, and the far-end heating temperature is the component quenching temperature ±10℃. The quenching fluid comprises the following substances, by mass: 30-35 parts modified PAG copolymer, 0.3-0.4 parts triethanolamine, 0.05-0.1 parts monoethanolamine, 2.5-3.5 parts calcium chloride, 1-3 parts dehydrated sorbitan monooleate, and 35-40 parts deionized water. The preparation method of the modified PAG copolymer includes the following steps: (1) Ethylene oxide, propylene oxide and epoxy propionic acid are mixed evenly at 3~5℃ to obtain a polymer monomer; (2) Propylene glycol and catalyst are added to the reactor under a nitrogen atmosphere, heated to 75~85℃ under a vacuum of ≤-0.09Mpa, and then the polymer monomer is gradually introduced to ensure that the pressure is ≤0.3MPa. The reaction is carried out at 125~135℃ for 8~10h, purified, and PAG copolymer is obtained; (3) PAG copolymer is added to deionized water and stirred evenly, chitosan and activator are added, stirred at 80~85℃ for 5~6h, purified, dried, and modified PAG copolymer is obtained. The polymerizing monomers include ethylene oxide, propylene oxide, and epoxypropionic acid in a mass ratio of 10:13~14:3~5; the mass ratio of propylene glycol to catalyst is 5~7:1; the mass ratio of polymerizing monomers to catalyst is 100:0.5~0.7; the modified PAG copolymer includes the following raw materials in parts by mass: 8~10 parts PAG copolymer, 40~50 parts deionized water, 3~5 parts chitosan, and 3~4 parts activator; The preparation method of the surface treatment liquid includes the following steps: (1) Sodium polymethacrylate is added to deionized water and stirred evenly, dopamine and activator are added, the pH is adjusted to 7.5~8.5, heated and stirred at 70~80℃ for 5~7h, separated, washed, and modified polymethacrylate is obtained; (2) Nano titanium carbide, tungsten powder and nickel powder are mixed to obtain metal powder; (3) Metal powder, modified polymethacrylate, ethyl cellulose and acetone are mixed and sheared and stirred at 40~45℃ for 1~1.5h to obtain surface treatment liquid; The modified polymethyl methacrylate comprises the following raw materials in parts by weight: 4-5 parts sodium polymethyl methacrylate, 14-16 parts dopamine, and 7-8 parts activator; the metal powder comprises nano-titanium carbide, tungsten powder, and nickel powder in a mass ratio of 2:3-4:5-6; and the surface treatment liquid comprises metal powder, modified polymethyl methacrylate, ethyl cellulose, and acetone in a mass ratio of 3:1-2:2.5-3.5:24-26.

2. The manufacturing process for a locally hardened complex component according to claim 1, characterized in that: In step S2: During the spraying process, the water pressure is 100~120 kPa and the water flow density is 70~80 L·m³. -2 s -1 In step S3: during the coating process, the thickness is 0.5~0.7mm; during the curing process, the temperature is 140~150℃ and the time is 5~10min; during the induction cladding process, the current is 1150~1250A, the power is 25KW, the oscillation frequency range is 50~80kHz, the number of coil turns is 4, and the time is 40~50s.