Methods for producing locally hardened components

1 . A method for producing a locally hardened component, comprising:

S1: placing a to-be-heated portion of a base component in an induction coil and performing induction heating to form a heated portion, wherein the induction heating is gradient heating, a first heating temperature and a second heating temperature are formed in a cross-section of the to-be-heated portion of the base component wherein during the induction heating the first heating temperature is equal to a component quenching temperature +50° C., and the second heating temperature is equal to the component quenching temperature ±10° C. wherein the first heating temperature is the maximum temperature during the gradient heating, and the second heating temperature is the minimum temperature during the gradient heating;

S2: after a completion of the induction heating, spraying a quenching solution on the heated portion, cooling the heated portion down to room temperature, removing the base component from the induction coil, and tempering the base component at a temperature of 100° C. to 250° C. to obtain a quenched component wherein the quenching solution comprises substances including: modified polyalkylene glycol PAG) copolymer, triethanolamine, monoethanolamine, calcium chloride, sorbitan monooleate, and deionized water in a mass ratio of 30 to 35):(0.3 to 0.4):(0.05 to 0.1:(2.5 to 3.5):1 to 3):(35 to 40); and

S3: grinding, degreasing, and drying a hardened portion of the quenched component, coating a surface treatment solution on a surface of the hardened portion, curing the surface treatment solution, and performing an induction cladding on the hardened portion in a nitrogen atmosphere to obtain the locally hardened component.

2 . The method of claim 1 , wherein:

in S2, a water pressure for spraying the quenching solution is in a range of 100 to 120 kPa, and a water flow density is in a range of 70 to 80 L·m −2 s −1 .

3 . The method of claim 1 , wherein:

in S3, a coating thickness of the surface treatment solution is in a range of 0.5 to 0.7 mm.

4 . The method of claim 1 , wherein:

in S3, a temperature for curing the surface treatment solution is in a range of 140 to 150° C., and a time for curing the surface treatment solution is in a range of 5 to 10 min.

5 . The method of claim 1 , wherein:

in S3, the induction cladding is operated at a current of 1150 to 1250 A, a power of 25 kW, an oscillation frequency in a range of 50 to 80 kHz, a coil turn count of 4, and a time of 40 to 50 s.

6 . The method of claim 1 , wherein the modified PAG copolymer is prepared by:

(1) obtaining a polymerized monomer by mixing ethylene oxide, propylene oxide, and glycidic acid at a temperature of 3 to 5° C.;

(2) under the nitrogen atmosphere, adding propylene glycol and catalyst to a reactor, and heating to 75 to 85° C. under a vacuum degree≤−0.09 MPa, after which the polymerized monomer is gradually introduced to ensure that a pressure is 0.3 MPa, carrying out a reaction at 125 to 135° C. for 8 to 10 h, and obtaining a PAG copolymer after purification; and

(3) adding the PAG copolymer to deionized water and mixing, adding chitosan and an activator, stirring at 80 to 85° C. for 5 to 6 h, and obtaining the modified PAG copolymer after purification and drying.

7 . The method of claim 1 , wherein the surface treatment solution is prepared by:

(1) adding sodium polymethacrylate to deionized water and mixing, adding dopamine and an activator, adjusting pH to 7.5 to 8.5, heating and stirring at 70 to 80° C. for 5 to 7 h, and obtaining modified polymethacrylic acid after liquid separation and washing;

(2) obtaining metal powder by mixing nano titanium carbide, tungsten powder, and nickel powder; and

(3) mixing the metal powder, the modified polymethacrylic acid, ethyl cellulose, and acetone, and shear stirring at 40 to 45° C. for 1 to 1.5 h to obtain the surface treatment solution.

8 . The method of claim 6 , wherein:

the polymerized monomer comprises the ethylene oxide, the propylene oxide, and the glycidic acid in a mass ratio of 10:(13 to 14):(3 to 5);

a mass ratio of the propylene glycol and the catalyst is (5 to 7):1;

a mass ratio of the polymerized monomer and the catalyst is 100:(0.5 to 0.7); and

the modified PAG copolymer comprises raw materials including: the PAG copolymer, the deionized water, the chitosan, the activator in a mass ratio of (8 to 10):(40 to 50):(3 to 5):(3 to 4).

9 . The method of claim 8 , wherein

the catalyst comprises a diimine iron complex and potassium hydroxide in a mass ratio of 1:3.5.

10 . The method of claim 7 , wherein the modified polymethacrylic acid comprises:

the sodium polymethacrylate, the dopamine, and the activator in a mass ratio of (4 to 5):(14 to 16):(7 to 8).

11 . The method of claim 7 , wherein the sodium polymethacrylate has a molecular weight of 3000 to 4000.

12 . The method of claim 7 , wherein the activator comprises 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and succinimide in a mass ratio of 1:1 to 3.

13 . The method of claim 7 , wherein the metal powder comprises the nano titanium carbide, the tungsten powder, the nickel powder in a mass ratio of 2:(3 to 4):(5 to 6).

14 . The method of claim 7 , wherein the tungsten powder and the nickel powder have a particle size of 1-4 μm.

15 . The method of claim 7 , wherein the surface treatment solution comprises the metal powder, the modified polymethacrylic acid, the ethyl cellulose, and the acetone in a mass ratio of 3:(1 to 2):(2.5 to 3.5):(24 to 26).