Production process of local hardening complex component

Abstract

The invention discloses a production technology of a local hardening complex component, and relates to the technical field of heat treatment, and the production technology specifically comprises the following steps: S1, placing a to-be-heated part of a basic component in an induction heating ring, and carrying out induction heating; s2, after induction heating is finished, quenching liquid is sprayed to the heated part, after the heated part is cooled to the room temperature, the heated part is taken out and subjected to low-temperature tempering, and a quenched component is obtained; s3, the to-be-quenched part of the quenched component is polished, degreased and dried, the surface of the to-be-quenched part is coated with the surface treatment liquid, solidification is conducted, induction cladding is conducted in the nitrogen atmosphere, and a local quenched component is obtained; according to tests, the complex component subjected to local hardening through the technology provided by the invention is relatively high in hardness, and the interior of the complex component is free of cracks.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment, in particular to a production process for locally hardened complex components. Background Art

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

[0003] Shaft components are key parts in mechanical transmission, and their comprehensive performance is crucial. Different areas require different mechanical properties. For example, some areas that bear greater stress require high hardness, and local quenching processes can meet this requirement. However, some complex shaft components, such as crankshafts, have complex shapes. Traditional processes use local high-temperature ablation heating with gas hot nozzles, but gas heating temperature control is difficult, oxidation is serious, efficiency is low, and operation is inconvenient; induction heating is limited by shape, components are heated unevenly, and local stress is easily excessive, cracks are formed, and it cannot meet the requirements.

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

[0005] The object of the present invention is to provide a production process for locally hardened complex components to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A production process for locally hardened complex components, comprising the following steps:

[0008] S1: placing the part of the basic component to be heated in the induction heating coil, adjusting the induction coil so that the induction coil covers the shape of the heated part of the component, and performing induction heating;

[0009] S2: After the induction heating is completed, the quenching liquid is sprayed on the heated part, and after cooling to room temperature, it is taken out and tempered at low temperature to obtain a quenched component;

[0010] S3: Grind, degrease, and dry the part of the quenching component to be hardened, apply the surface treatment liquid on the surface, solidify it, and perform induction cladding in a nitrogen atmosphere to obtain a partially hardened component.

[0011] Preferably, in step S1, the induction coil is an induction coil of a specific shape, the distances between the coil and the two ends of the component are different, and the surface temperatures of the proximal and distal components are different; during the induction heating process, the proximal heating temperature is the component quenching temperature + 50°C, and the distal heating temperature is the component quenching temperature ± 10°C.

[0012] Preferably, in step S2: during 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: during the coating process, the thickness is 0.5-0.7 mm; during the curing process, the temperature is 140-150°C and the time is 5-10 min; during the induction cladding process, the current is 1150-1250 A, the power is 25 KW, the oscillation frequency range is 50-80 kHz, the number of coil turns is 4, and the time is 40-50 s.

[0013] Preferably, the quenching liquid includes the following substances, calculated by mass: 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) mixing ethylene oxide, propylene oxide and epoxy propionic acid at a temperature of 3 to 5°C to obtain a polymerization monomer; (2) adding propylene glycol and a catalyst to a reaction kettle under a nitrogen atmosphere, heating to 75 to 85°C at a vacuum degree of ≤-0.09Mpa, then gradually introducing the polymerization monomer to ensure that the pressure is ≤0.3MPa, reacting at 125 to 135°C for 8 to 10 hours, purifying, and obtaining a PAG copolymer; (3) adding deionized water to the PAG copolymer and stirring evenly, adding chitosan and an activator, stirring at 80 to 85°C for 5 to 6 hours, purifying, and drying to obtain a modified PAG copolymer.

[0015] Preferably, the polymerization monomers include ethylene oxide, propylene oxide and glycidyl oxide in a mass ratio of 10:13-14:3-5; the mass ratio of propylene glycol and catalyst is 5-7:1; the mass ratio of the polymerization monomers and catalyst is 100:0.5-0.7; the modified PAG copolymer includes the following raw materials in parts by mass: 8-10 parts of PAG copolymer, 40-50 parts of deionized water, 3-5 parts of chitosan, and 3-4 parts of activator.

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

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

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

[0019] Wherein, the activator comprises 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and succinimide in a mass ratio of 1:1 to 3; the molecular weight of the sodium polymethacrylate is 3000 to 4000; and the particle size of the tungsten powder and the nickel powder is 1 to 4 μm.

[0020] Preferably, the quenching liquid needs to be diluted three times with water before use.

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

[0022] (1) The scheme of the present invention can be used to heat the designated parts of the components by local heating in an easy and accurate manner, so that the corresponding performance of the parts that need to be heat treated is improved, and the performance of the parts that do not participate in the heat treatment remains unchanged. Due to the short heating time, the internal grain size will not grow, and there is less oxide scale and good surface quality. The components subjected to surface heat treatment by this method have the advantages of high hardness of the designated parts, fine internal structure, small size of the heating device and low energy consumption. It is highly operable, low cost and suitable for large-scale production. At the same time, the present invention 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 temperature of the near and far ends of the component is 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. In addition, the present invention controls the near-end temperature to be the component quenching temperature + 50°C, and the far-end heating temperature to be the component quenching temperature ± 10°C, which helps to improve the efficiency of induction heating, so that the component can quickly reach the quenching temperature, and can also meet the concentrated local heating required by some complex components, providing better flexibility.

[0023] (2) The present invention uses water-based polymer PAG as a quenching medium. Due to its reverse solubility, the solubility decreases with the increase of temperature at 70-88°C, and the polymer will be precipitated and attached to the surface of the component to form an organic film, thereby adjusting the temperature drop rate. When the temperature of the component reaches the Ms point (the temperature at which martensite begins to transform), the cooling rate can be reduced. This solves the problem of cracking and deformation of components caused by excessive cooling of water in the low temperature zone. However, the film generated by the PAG copolymer in the low temperature zone is discontinuous and has low strength. The cooling rate at the Ms point is between that of water and oil. Therefore, the present invention grafts chitosan onto the PAG copolymer. Chitosan has a good film-forming effect, which can make up for the discontinuous film generated by PAG in the low temperature zone, resulting in fast and uneven cooling, and reduces the possibility of component cracking.

[0024] (3) In order to further improve the hardness of the hardened area, the present invention coats a layer of surface treatment liquid containing metal powder on its surface, and induction clads it after solidification to form a hardened layer on the surface, thereby improving the hardness, wear resistance and corrosion resistance of the material. At the same time, since the present invention only needs to be applied to the part that needs to be hardened and adopts induction cladding, the operation is convenient and the heating time is short. It can locally harden complex components without having a significant impact on the surface of the component that has been quenched. Since the treatment liquid is relatively viscous, it is difficult to stably disperse the metal powder in the system. The present invention modifies polymethacrylic acid and grafts dopamine. Its catechol group has a good attraction to metals, so that the metal particles are evenly loaded on the polymethacrylic acid, thereby improving the dispersibility of the metal powder. The excess catechol groups can combine with the metal on the surface of the component, thereby improving the tightness of the treatment liquid and the component, and facilitating subsequent operations. DETAILED DESCRIPTION

[0025] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0026] It should be noted that there is no special restriction on the purchase manufacturers of all raw materials involved in the present invention, which exemplarily include: triethanolamine; monoethanolamine; calcium chloride; sorbitan monooleate; ethylene oxide; propylene oxide; epoxy propionic acid; dopamine; tungsten powder: particle size is 1 to 4 μm; nickel powder: particle size is 1 to 4 μm; in the following embodiments, parts are by mass, and raw materials are all commercially purchased.

[0027] Among them, the crankshafts of each embodiment include the following elements, calculated by 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 are Fe and other inevitable impurities; at the same time, the quenching temperature of the crankshaft is 840-860°C.

[0028] Among them, the quenching liquid of each embodiment includes the following substances: by mass, 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; the quenching liquid needs to be diluted three times with water before use.

[0029] Embodiment 1:

[0030] Step 1: Preparation of surface treatment liquid: (1) Add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir evenly, add 15 parts of dopamine and 7.5 parts of activator, adjust the pH to 8, heat and stir at 45°C for 6 hours, separate the liquids, 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 metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, shear and stir at 40°C for 1.5 hours to obtain a surface treatment liquid;

[0031] Step 2: Preparation of modified PAG copolymer: (1) At a temperature of 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed in a mass ratio of 10:13.5:4 to obtain a polymerization monomer; (2) Under a nitrogen atmosphere, propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reactor in a mass ratio of 6:1, and heated to 80°C under a vacuum degree of ≤-0.09Mpa, and then the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) is gradually introduced to ensure that the pressure is ≤0.3MPa, and the reaction is carried out at 130°C for 9h, and purified to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred evenly, 4 parts of chitosan and 3.5 parts of an activator are added, stirred at 80°C for 5.5h, purified, and dried to obtain a modified PAG copolymer;

[0032] Step 3: Local hardening of complex components:

[0033] S1: In a nitrogen atmosphere, place the part of the base component to be heated in an induction heating coil, adjust the induction coil so that it covers the shape of the heated part of the component, and perform induction heating at 900°C at the proximal end and 850°C at the distal end for 50s;

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

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

[0036] Embodiment 2:

[0037] Step 1: Preparation of surface treatment liquid: (1) Add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir evenly, add 15 parts of dopamine and 7.5 parts of activator, adjust the pH to 8, heat and stir at 45°C for 6 hours, separate the liquids, 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 metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, shear and stir at 40°C for 1.5 hours to obtain a surface treatment liquid;

[0038] Step 2: Preparation of modified PAG copolymer: (1) At a temperature of 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed in a mass ratio of 10:13.5:4 to obtain a polymerization monomer; (2) Under a nitrogen atmosphere, propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reactor in a mass ratio of 6:1, and heated to 80°C under a vacuum degree of ≤-0.09Mpa, and then the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) is gradually introduced to ensure that the pressure is ≤0.3MPa, and the reaction is carried out at 130°C for 9h, and purified to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred evenly, 4 parts of chitosan and 3.5 parts of an activator are added, stirred at 80°C for 5.5h, purified, and dried to obtain a modified PAG copolymer;

[0039] Step 3: Local hardening of complex components:

[0040] S1: In a nitrogen atmosphere, place the part of the base component to be heated in an induction heating coil, adjust the induction coil so that it covers the shape of the heated part of the component, and perform induction heating at 900°C at the proximal end and 850°C at the distal end for 40s;

[0041] S2: After the induction heating is completed, the water pressure is 100 kPa and the water flow density is 70 L·m -2 s -1 The heated part is sprayed with quenching liquid, cooled to room temperature, taken out, and tempered at 200°C for 2.5h to obtain a quenched component;

[0042] S3: The part of the quenched component to be hardened is polished, degreased, and dried, and the surface treatment liquid is coated on its surface with a thickness of 0.6 mm. It is cured at 140°C for 5 minutes, and induction cladding is performed in a nitrogen atmosphere (induction cladding parameters are: current is 1150-1250A, power is 25KW, oscillation frequency range is 50-80kHz, coil turns are 4 turns, and time is 40s) to obtain a locally hardened component.

[0043] Embodiment 3:

[0044] Step 1: Preparation of surface treatment liquid: (1) Add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir evenly, add 15 parts of dopamine and 7.5 parts of activator, adjust the pH to 8, heat and stir at 45°C for 6 hours, separate the liquids, 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 metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, shear and stir at 40°C for 1.5 hours to obtain a surface treatment liquid;

[0045] Step 2: Preparation of modified PAG copolymer: (1) At a temperature of 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed in a mass ratio of 10:13.5:4 to obtain a polymerization monomer; (2) Under a nitrogen atmosphere, propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reactor in a mass ratio of 6:1, and heated to 80°C under a vacuum degree of ≤-0.09Mpa, and then the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) is gradually introduced to ensure that the pressure is ≤0.3MPa, and the reaction is carried out at 130°C for 9h, and purified to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred evenly, 4 parts of chitosan and 3.5 parts of an activator are added, stirred at 80°C for 5.5h, purified, and dried to obtain a modified PAG copolymer;

[0046] Step 3: Local hardening of complex components:

[0047] S1: In a nitrogen atmosphere, place the part of the base component to be heated in an induction heating coil, adjust the induction coil so that it covers the shape of the heated part of the component, and perform induction heating at 900°C at the proximal end and 850°C at the distal end for 60s;

[0048] S2: After the induction heating is completed, the water pressure is 120 kPa and the water flow density is 80 L·m -2 s -1 The heated part is sprayed with quenching liquid, cooled to room temperature, taken out, and tempered at 200°C for 2.5h to obtain a quenched component;

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

[0050] Comparative Example 1: Based on Example 1, circular coil induction heating is adopted, and the other processes remain unchanged, as follows:

[0051] Step 1: Preparation of surface treatment liquid: (1) Add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir evenly, add 15 parts of dopamine and 7.5 parts of activator, adjust the pH to 8, heat and stir at 45°C for 6 hours, separate the liquids, 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 metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, shear and stir at 40°C for 1.5 hours to obtain a surface treatment liquid;

[0052] Step 2: Preparation of modified PAG copolymer: (1) At a temperature of 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed in a mass ratio of 10:13.5:4 to obtain a polymerization monomer; (2) Under a nitrogen atmosphere, propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reactor in a mass ratio of 6:1, and heated to 80°C under a vacuum degree of ≤-0.09Mpa, and then the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) is gradually introduced to ensure that the pressure is ≤0.3MPa, and the reaction is carried out at 130°C for 9h, and purified to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred evenly, 4 parts of chitosan and 3.5 parts of an activator are added, stirred at 80°C for 5.5h, purified, and dried to obtain a modified PAG copolymer;

[0053] Step 3: Local hardening of complex components:

[0054] S1: In a nitrogen atmosphere, place the part of the base component to be heated in an induction heating coil, adjust the induction coil so that it covers the shape of the heated part of the component, and perform induction heating at 850°C for 50s;

[0055] S2: After the induction heating is completed, the water pressure is 100 kPa and the water flow density is 75 L·m -2 s -1 The heated part is sprayed with quenching liquid, cooled to room temperature, taken out, and tempered at 200°C for 2.5h to obtain a quenched component;

[0056] S3: The part of the quenched component to be hardened is polished, degreased, and dried, and the surface treatment liquid is coated on its surface with a thickness of 0.6 mm. It is cured at 145°C for 5 minutes, and induction cladding is performed in a nitrogen atmosphere (induction cladding parameters are: current is 1150-1250A, power is 25KW, oscillation frequency range is 50-80kHz, coil turns are 4 turns, and time is 45s) to obtain a locally hardened component.

[0057] Comparative Example 2: Based on Example 1, commercially available PAG quenching liquid was used, and the other processes remained unchanged, as follows:

[0058] Step 1: Preparation of surface treatment liquid: (1) Add 4.5 parts of sodium polymethacrylate to 50 parts of deionized water and stir evenly, add 15 parts of dopamine and 7.5 parts of activator, adjust the pH to 8, heat and stir at 45°C for 6 hours, separate the liquids, 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 metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1.5:3:25, shear and stir at 40°C for 1.5 hours to obtain a surface treatment liquid;

[0059] Step 2: Local hardening of complex components:

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

[0061] S2: After the induction heating is completed, the water pressure is 100 kPa and the water flow density is 75 L·m -2 s -1 The heated part was sprayed with commercially available PAG quenching liquid, cooled to room temperature, taken out, and tempered at 200°C for 2.5h to obtain a quenched component;

[0062] S3: The part of the quenched component to be hardened is polished, degreased, and dried, and the surface treatment liquid is coated on its surface with a thickness of 0.6 mm. It is cured at 145°C for 5 minutes, and induction cladding is performed in a nitrogen atmosphere (induction cladding parameters are: current is 1150-1250A, power is 25KW, oscillation frequency range is 50-80kHz, coil turns are 4 turns, and time is 45s) to obtain a locally hardened component.

[0063] Comparative Example 3: Based on Example 1, the treatment liquid is not applied, and the other processes remain unchanged, as follows:

[0064] Step 1: Preparation of modified PAG copolymer: (1) At a temperature of 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed in a mass ratio of 10:13.5:4 to obtain a polymerization monomer; (2) Under a nitrogen atmosphere, propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reactor in a mass ratio of 6:1, and heated to 80°C under a vacuum degree of ≤-0.09Mpa, and then the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) is gradually introduced to ensure that the pressure is ≤0.3MPa, and the reaction is carried out at 130°C for 9h, and purified to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred evenly, 4 parts of chitosan and 3.5 parts of an activator are added, stirred at 80°C for 5.5h, purified, and dried to obtain a modified PAG copolymer;

[0065] Step 2: Local hardening of complex components:

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

[0067] S2: After the induction heating is completed, the water pressure is 100 kPa and the water flow density is 75 L·m -2 s -1 The heated part was sprayed with quenching liquid, cooled to room temperature, taken out, and tempered at 200°C for 2.5h to obtain a locally hardened component.

[0068] Comparative Example 4: Based on Example 1, the sodium polymethacrylate in the treatment solution is not modified, and the other processes remain unchanged, as follows:

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

[0070] Step 2: Preparation of modified PAG copolymer: (1) At a temperature of 4°C, ethylene oxide, propylene oxide, and epoxy propionic acid are mixed in a mass ratio of 10:13.5:4 to obtain a polymerization monomer; (2) Under a nitrogen atmosphere, propylene glycol and a catalyst (a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5) are added to a reactor in a mass ratio of 6:1, and heated to 80°C under a vacuum degree of ≤-0.09Mpa, and then the polymerization monomer (the mass ratio of the polymerization monomer and the catalyst is 100:0.6) is gradually introduced to ensure that the pressure is ≤0.3MPa, and the reaction is carried out at 130°C for 9h, and purified to obtain a PAG copolymer; (3) 9 parts of the PAG copolymer are added to 45 parts of deionized water and stirred evenly, 4 parts of chitosan and 3.5 parts of an activator are added, stirred at 80°C for 5.5h, purified, and dried to obtain a modified PAG copolymer;

[0071] Step 3: Local hardening of complex components:

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

[0073] S2: After the induction heating is completed, the water pressure is 100 kPa and the water flow density is 75 L·m -2 s -1 The heated part is sprayed with quenching liquid, cooled to room temperature, taken out, and tempered at 200°C for 2.5h to obtain a quenched component;

[0074] S3: The part of the quenched component to be hardened is polished, degreased, and dried, and the surface treatment liquid is coated on its surface with a thickness of 0.6 mm. It is cured at 145°C for 5 minutes, and induction cladding is performed in a nitrogen atmosphere (induction cladding parameters are: current is 1150-1250A, power is 25KW, oscillation frequency range is 50-80kHz, coil turns are 4 turns, and time is 45s) to obtain a locally hardened component.

[0075] Performance test: (1) According to the document GB / T 5617-2005, the surface hardness of the crankshafts of each embodiment after quenching was measured using a surface hardness meter. The experimental data are shown in Table 1; (2) According to the document GB / T 39240-2020, the crankshafts of each embodiment after quenching were ultrasonically tested, and the number of cracks inside the component was rated as A, B, C, and D (A: no cracks were found on the surface and inside the component; B: the number of cracks in the component was small; C: a certain number of cracks existed in the component, but it was still within an acceptable range; D: there were many cracks in the component and the structural integrity was low)

[0076] Table 1

[0077] project 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: It can be seen from Table 1 that Comparative Example 1 uses a circular coil induction coil for heating, and the heating efficiency is slow, and the strength of the part to be hardened is not as good as that of Example 1; Comparative Example 2: Using commercially available PAG quenching liquid, the resulting film is discontinuous, low in strength, the temperature drops rapidly at the Ms point, tiny cracks are generated, and the hardness is not as good as that of Example 1; Comparative Example 3: No treatment liquid is applied, and the local quenching hardness is lower than the hardness of the hardened layer of Example 1; Comparative Example 4: Sodium polymethacrylate in the treatment liquid is not modified, the metal powder has poor dispersion in the system, there is agglomeration after induction cladding, and the hardness decreases.

[0079] Conclusion: The present invention adopts induction heating of a coil of a specific shape, quenching with chitosan-modified PAG quenching liquid and induction cladding hardening layer after coating with surface treatment liquid, successfully providing a production process for locally hardened complex components, which can prevent cracking and has a higher hardness of the hardened part of the product.

[0080] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is 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 can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A production process for locally hardened complex components, characterized in that: The following steps are involved: S1: placing the part of the basic component to be heated in the induction heating coil for induction heating; S2: After the induction heating is completed, the quenching liquid is sprayed on the heated part, and after cooling to room temperature, it is taken out and tempered at low temperature to obtain a quenched component; S3: Grind, degrease, and dry the part of the quenching component to be hardened, apply the surface treatment liquid on the surface, solidify it, and perform induction cladding in a nitrogen atmosphere to obtain a partially hardened component.

2. A production process for a partially hardened complex component according to claim 1, characterized in that: In step S1, the induction coil is an induction coil of a specific shape, the distances between the coil and the two ends of the component are different, and the surface temperatures of the proximal and distal components are different; during the induction heating process, the proximal heating temperature is the component quenching temperature + 50°C, and the distal heating temperature is the component quenching temperature ± 10°C.

3. The production process of a partially 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·m -2 s -1 ; In step S3: during the coating process, the thickness is 0.5-0.7 mm; during the curing process, the temperature is 140-150°C and the time is 5-10 min; during the induction cladding process, the current is 1150-1250 A, the power is 25 KW, the oscillation frequency range is 50-80 kHz, the number of coil turns is 4, and the time is 40-50 s.

4. The production process of a partially hardened complex component according to claim 1, characterized in that: The quenching liquid comprises the following substances, calculated by mass: 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.

5. A production process for a partially hardened complex component according to claim 4, characterized in that: The preparation method of the modified PAG copolymer comprises the following steps: (1) mixing ethylene oxide, propylene oxide and epoxy propionic acid uniformly at a temperature of 3 to 5° C. to obtain a polymerization monomer; (2) adding propylene glycol and a catalyst into a reaction kettle under a nitrogen atmosphere, heating to 75 to 85° C. at a vacuum degree of ≤-0.09 MPa, then gradually introducing the polymerization monomer to ensure that the pressure is ≤0.3 MPa, reacting at 125 to 135° C. for 8 to 10 hours, purifying, and obtaining a PAG copolymer; (3) adding deionized water to the PAG copolymer and stirring uniformly, adding chitosan and an activator, stirring at 80 to 85° C. for 5 to 6 hours, purifying, and drying to obtain a modified PAG copolymer.

6. A production process for a partially hardened complex component according to claim 5, characterized in that: The polymerization monomers include ethylene oxide, propylene oxide and epoxy propionic acid in a mass ratio of 10:13-14:3-5; the mass ratio of propylene glycol and catalyst is 5-7:1; the mass ratio of the polymerization monomer and catalyst is 100:0.5-0.7; the modified PAG copolymer includes the following raw materials in parts by mass: 8-10 parts of PAG copolymer, 40-50 parts of deionized water, 3-5 parts of chitosan, and 3-4 parts of activator.

7. The production process of a partially hardened complex component according to claim 1, characterized in that: The preparation method of the surface treatment liquid comprises the following steps: (1) adding sodium polymethacrylate to deionized water and stirring evenly, adding dopamine and an activator, adjusting the pH to 7.5-8.5, heating and stirring at 70-80° C. for 5-7 hours, separating the liquids, washing, and obtaining modified polymethacrylic acid; (2) mixing nano titanium carbide, tungsten powder, and nickel powder to obtain metal powder; (3) mixing metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone, and shearing and stirring at 40-45° C. for 1-1.5 hours to obtain a surface treatment liquid.

8. The production process of a partially hardened complex component according to claim 7, characterized in that: The modified polymethacrylic acid comprises the following raw materials in parts by mass: 4 to 5 parts of sodium polymethacrylate, 14 to 16 parts of dopamine, and 7 to 8 parts of an activator; the metal powder comprises nano titanium carbide, tungsten powder, and nickel powder in a mass ratio of 2:3 to 4:5 to 6; and the surface treatment liquid comprises metal powder, modified polymethacrylic acid, ethyl cellulose, and acetone in a mass ratio of 3:1 to 2:2.5 to 3.5:24 to 26.