Electric arc additive remanufacturing repairing method for sliding bearing of LNG low-temperature immersed pump

Abstract

The invention belongs to the technical field of high-entropy alloy additive repairing, and particularly relates to an electric arc additive remanufacturing repairing method for an LNG low-temperature immersed pump sliding bearing. The high-entropy alloy with the general formula of (CrFeMnNi) xCuyAlzZw is adopted for repairing or manufacturing the bearing bush, the stability of the LNG low-temperature immersed pump bearing is effectively improved, the service life of the LNG low-temperature immersed pump bearing is effectively prolonged, the maintenance time is shortened, the use cost is reduced, and the electric arc additive remanufacturing repairing method is simple in operation process and low in cost. The repaired and remanufactured sliding bearing has high hardness and high low-temperature wear resistance, has great application potential in lubricating environments such as liquid oxygen, liquid nitrogen and liquefied natural gas, and can effectively prolong the service life of the LNG low-temperature immersed pump.

Description

Technical Field

[0001] The present invention belongs to the technical field of high entropy alloy additive repair, and more specifically relates to a method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps. Background Art

[0002] As a clean energy, liquefied natural gas (LNG) is gaining more and more attention in the current era of energy conservation and environmental protection. LNG cryogenic submersible pumps play a vital role in the transportation and transfer of LNG. However, the ball bearings commonly used in LNG cryogenic submersible pumps have a short lifespan under low temperature conditions. After working for a short time, the ball bearings will become unstable and fail. The failure of ball bearings seriously affects the efficiency of LNG transportation and transfer and the safety of equipment operation.

[0003] High entropy alloys have excellent low-temperature mechanical properties and wear resistance, so they are highly valued in materials science and engineering. In the past, alloys may have only one or two main metal components. In the past, the more types of metals added to the alloy, the more brittle the material will be. However, high entropy alloys are different from previous alloys, and many metals will not become brittle. High entropy alloys have excellent mechanical properties, mainly manifested as high strength and high hardness. This property enables high entropy alloys to perform well in various engineering applications and remain stable in a variety of corrosion and extremely low temperature environments. It has high wear resistance and is suitable for applications that need to withstand high wear. Remanufacturing bearings through laser repair of sliding bearings is of great significance to the realization of low-carbon economic development. Summary of the invention

[0004] The purpose of the present invention is to provide a method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps to solve the problems existing in the above-mentioned prior art.

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

[0006] One of the technical solutions of the present invention is to provide a high entropy alloy for arc additive remanufacturing and repair of sliding bearings of LNG cryogenic submersible pumps, wherein the general formula of the high entropy alloy is: (CrFeMnNi) x Cu y Al z Z w ;

[0007] Wherein, Z is selected from Si, Ti, Ca or RE; x is 0.550-0.800, y is 0.150-0.300, z is 0.100-0.150, w is 0.005-0.05, and the sum of x, y, z and w is 1.

[0008] The second technical solution of the present invention is to provide an application of the above-mentioned high entropy alloy in the arc additive remanufacturing, repair or preparation of bearing shells for sliding bearings.

[0009] The third technical solution of the present invention is to provide a method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, the steps comprising:

[0010] Pre-treating the bearing bush substrate of the LNG cryogenic submersible pump sliding bearing to obtain a pre-treated component;

[0011] According to the general formula of the high entropy alloy, a high entropy alloy raw material is prepared and set aside;

[0012] Processing the pre-treated component by arc additive manufacturing with the high entropy alloy raw material to obtain an arc additive manufacturing component;

[0013] The arc additively processed component is sequentially subjected to high-temperature short-time annealing, first low-temperature cooling, multiple medium-temperature annealing, second low-temperature cooling, deep cryogenic treatment, rough machining and fine machining to obtain a repaired bearing component.

[0014] Furthermore, the pretreatment step includes: the bearing shell substrate is polished, cleaned, and preheated in sequence to obtain a pretreated component.

[0015] Optionally, the cleaning is performed using acetone or ethanol.

[0016] Optionally, the preheating temperature is 100-200°C.

[0017] In the pretreatment step, wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface are removed by grinding.

[0018] Furthermore, the high entropy alloy raw material includes element powder and / or master alloy powder.

[0019] Among them, the high entropy alloy raw materials include Mn powder, Fe powder, Cr powder, Ni powder, Cu powder, Al powder, Ca powder, Si powder, Ti powder, Al-Ce powder, Al-La powder, Al-Y powder, aluminum-manganese alloy powder, aluminum-iron alloy powder, aluminum-chromium alloy powder, aluminum-nickel alloy powder, aluminum-copper alloy powder, aluminum-calcium alloy powder, aluminum-silicon alloy powder and aluminum-titanium alloy powder to support the general formula of the above-mentioned high entropy alloy.

[0020] Furthermore, the process parameters of the arc additive are: pulse energy is 0.5-2.5J, pulse frequency is 5-25Hz, working current is 40-65A, feed speed is 150-500mm / min; shielding gas is Ar, and flow rate is 10-20L / min.

[0021] Furthermore, in the arc additive process, two adjacent layers of cladding materials are rotated by 15°-45°.

[0022] Avoid stress concentration by rotating 15°-45°.

[0023] Furthermore, the high temperature short time annealing is performed by high frequency induction heating.

[0024] Optionally, the process parameters of the high-frequency induction heating are: power of 10-16KW, heating rate of 15-50°C / s, heating temperature of 950-1100°C, induction heating time of 10-60s, and frequency range of 200-250KHz.

[0025] Furthermore, the first low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank.

[0026] The first low temperature cooling in the present invention is rapid cooling to the temperature of liquid nitrogen or dry ice.

[0027] The present invention strengthens the lattice distortion energy through low-temperature rapid cooling (first low-temperature cooling) and increases the driving force of phase transformation during multi-pass medium-temperature annealing.

[0028] Furthermore, the multi-pass medium-temperature annealing is carried out in a vacuum resistance furnace or a gas-shielded resistance furnace.

[0029] Through multiple medium-temperature annealing steps, the high internal stress in the repaired and reconstructed area is reduced, the formation of nano-precipitation phase is induced, and the morphology and distribution of dislocations and twins are adjusted, thereby improving the hardness of the repaired bearing and its wear resistance at low temperatures.

[0030] Furthermore, the annealing temperature of the multi-pass medium-temperature annealing is 550-750° C., the annealing passes are 4-10 passes, and the total annealing time is 15-60 min.

[0031] Furthermore, the second low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank.

[0032] The second low temperature cooling in the present invention is rapid cooling to the temperature of liquid nitrogen or dry ice.

[0033] The present invention optimizes the material microstructure and improves the comprehensive mechanical properties of the material by combining multiple medium-temperature annealing and second low-temperature cooling.

[0034] Furthermore, the cryogenic treatment is carried out in liquid nitrogen for 2-50 hours.

[0035] It should be noted that the cryogenic treatment is carried out in liquid nitrogen, specifically, after the second cryogenic cooling, it is carried out alone in a liquid nitrogen tank.

[0036] Optionally, the cryogenic treatment is a one-time cryogenic treatment for 2-50 hours, or a treatment cycle of 2 hours, for 1-25 times.

[0037] The present invention can stabilize the high entropy alloy structure through deep cryogenic treatment, reduce the bearing size change caused by long-term service at low temperature, and improve the running stability of the bearing bush.

[0038] Furthermore, the rough machining is turning the arc additively processed part.

[0039] Among them, turning is used to make it slightly larger than the finished product size (approximately 0.3-0.5mm larger than the finished product size).

[0040] After rough machining, the arc additive treated parts are subjected to X-ray or ultrasonic testing. If there are still defects such as holes and cracks in the repaired area, repeat pretreatment, arc additive, high temperature short-time annealing, first low temperature cooling, multiple medium temperature annealing, second low temperature cooling, and deep cryogenic treatment until there are no defects in the repaired area.

[0041] Furthermore, the finishing process is grinding, milling and polishing the arc additive processing part.

[0042] Optionally, the milling process is to process equally spaced spiral grooves by milling, and the process parameters are: rotation speed of 1300r / min-1500r / min, feed rate of 300-350mm / min, grooves are semicircular or square, diameter or depth is 0.2-0.4mm±0.05mm, spiral line angle is 30°-60°, and groove spacing is 15-30mm.

[0043] Through grinding, the finished product size is within the allowable range; through milling, the finished product has high processing accuracy; through polishing, the bearing surface finish meets the requirements.

[0044] The fourth technical solution of the present invention is to provide a method for preparing a bearing bush for a sliding bearing of an LNG cryogenic submersible pump, the steps comprising:

[0045] According to the general formula of the high entropy alloy, a high entropy alloy raw material is prepared and set aside;

[0046] The high entropy alloy raw material is prepared by arc additive manufacturing to obtain a bearing bush precursor;

[0047] The bearing bush precursor for the LNG cryogenic submersible pump sliding bearing is sequentially subjected to high-temperature short-time annealing, first low-temperature cooling, multiple medium-temperature annealing, second low-temperature cooling, deep cryogenic treatment, rough machining and fine machining to obtain the bearing bush.

[0048] Furthermore, the high entropy alloy raw material includes element powder and / or master alloy powder.

[0049] Among them, the high entropy alloy raw materials include Mn powder, Fe powder, Cr powder, Ni powder, Cu powder, Al powder, Ca powder, Si powder, Ti powder, Al-Ce powder, Al-La powder, Al-Y powder, aluminum-manganese alloy powder, aluminum-iron alloy powder, aluminum-chromium alloy powder, aluminum-nickel alloy powder, aluminum-copper alloy powder, aluminum-calcium alloy powder, aluminum-silicon alloy powder and aluminum-titanium alloy powder to support the general formula of the above-mentioned high entropy alloy.

[0050] Furthermore, the process parameters of the arc additive are: pulse energy is 0.5-2.5J, pulse frequency is 5-25Hz, working current is 40-65A, feed speed is 150-500mm / min; shielding gas is Ar, and flow rate is 10-20L / min.

[0051] Optionally, in the arc additive process, two adjacent layers of cladding material are rotated 15°-45°.

[0052] Avoid stress concentration by rotating 15°-45°.

[0053] Furthermore, the high temperature short time annealing is performed by high frequency induction heating.

[0054] Optionally, the process parameters of the high-frequency induction heating are: power of 10-16KW, heating rate of 15-50°C / s, heating temperature of 950-1100°C, induction heating time of 10-60s, and frequency range of 200-250KHz.

[0055] Furthermore, the first low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank.

[0056] The present invention strengthens the lattice distortion energy through low-temperature rapid cooling (first low-temperature cooling) and increases the driving force of phase transformation during multi-pass medium-temperature annealing.

[0057] Furthermore, the multi-pass medium-temperature annealing is carried out in a vacuum resistance furnace or a gas-shielded resistance furnace.

[0058] Through multiple medium-temperature annealing steps, the high internal stress of the bearing precursor is reduced, the formation of nano-precipitation phase is induced, and the morphology and distribution of dislocations and twins are adjusted, thereby improving the hardness of the bearing and the wear resistance at low temperatures.

[0059] Furthermore, the annealing temperature of the multi-pass medium-temperature annealing is 550-750° C., the annealing passes are 4-10 passes, and the total annealing time is 15-60 min.

[0060] Furthermore, the second low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank.

[0061] The present invention optimizes the material microstructure and improves the material performance by combining multiple medium-temperature annealing and second low-temperature cooling.

[0062] Furthermore, the cryogenic treatment is carried out in liquid nitrogen for 2-50 hours.

[0063] Optionally, the cryogenic treatment is a one-time cryogenic treatment for 2-50 hours, or a treatment cycle of 2 hours, for 1-25 times.

[0064] It should be noted that the cryogenic treatment is carried out in liquid nitrogen, specifically, after the second cryogenic cooling, it is carried out alone in a liquid nitrogen tank.

[0065] Furthermore, the rough machining is turning the bearing shell precursor.

[0066] Among them, turning is used to make it slightly larger than the finished product size (approximately 0.3-0.5mm larger than the finished product size).

[0067] Furthermore, the finishing process is grinding, milling and polishing the arc additively processed part.

[0068] Optionally, the milling process is to process equally spaced spiral grooves by milling, and the process parameters are: rotation speed of 1300r / min-1500r / min, feed rate of 300-350mm / min, grooves are semicircular or square, diameter or depth is 0.2-0.4mm±0.05mm, spiral line angle is 30°-60°, and groove spacing is 15-30mm.

[0069] The sliding bearing repaired, remanufactured or prepared by the present invention can be used for LNG cryogenic submersible pumps and other equipment working in low-temperature environments.

[0070] The present invention discloses the following technical effects:

[0071] The present invention can effectively improve the stability and service life of the bearing of the LNG cryogenic submersible pump, and is beneficial to reducing maintenance time and use cost.

[0072] The operation process of the arc additive remanufacturing and repairing of the present invention is simple, and the repaired and remanufactured sliding bearing has higher hardness and stronger low-temperature wear resistance.

[0073] The present invention not only improves the strength and low-temperature characteristics of the sliding bearing bushing through arc additive remanufacturing and repair of the sliding bearing, but also has high corrosion resistance, wear resistance and fatigue resistance. It can be used in lubricated environments such as liquid oxygen, liquid nitrogen and liquefied natural gas, and has excellent performance in reliability and life.

[0074] The invention stabilizes the dimensional accuracy of the bearing bush through deep cryogenic treatment, thereby improving the service reliability and safety of the sliding bearing.

[0075] The present invention can realize one-time forming of the sliding bearing of the LNG low-temperature submersible pump, does not require the induction melting furnace, forging press and other equipment used in conventional production, and reduces the production cost of the sliding bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0077] Figure 1 It is the bearing combination diagram;

[0078] Figure 2 This is a bearing split diagram;

[0079] Figure 3 For the bearing. DETAILED DESCRIPTION

[0080] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0081] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0082] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0083] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0084] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0085] The raw materials used for the high entropy alloy of the present invention are all commercially available products with a purity of not less than 99.9%.

[0086] The room temperature and normal temperature involved in the specific implementation scheme of the present invention are both 20-30°C.

[0087] The specifications and dimensions of the bearing bush substrate of the LNG cryogenic submersible pump sliding bearing to be repaired in the present invention are: inner diameter 36mm, length 26mm, thickness 4.5mm.

[0088] Figure 1 It is the bearing combination diagram; Figure 2 This is a bearing split diagram; Figure 3 For the bearing.

[0089] Example 1

[0090] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0091] S1, according to the general formula (CrFeMnNi) 0.65 Cu 0.2 Al 0.12 Si 0.03 Prepare raw materials, wherein the raw materials are: Mn powder, Fe powder, Cr powder, Ni powder, Cu powder, Si powder, Al powder;

[0092] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0093] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 0.8 J; pulse frequency 10 Hz; working current 45 A; feed speed 150 mm / min; shielding gas Ar, shielding gas flow rate 12 L / min;

[0094] S4, performing a high-temperature short-time annealing treatment on the arc additively processed component by high-frequency induction heating, and performing a first low-temperature cooling directly in a liquid nitrogen tank after the high-temperature short-time annealing treatment is completed, cooling to the liquid nitrogen temperature;

[0095] The parameters of high-frequency induction heating are: power 10KW, heating rate 46℃ / s, heating temperature 920℃, induction heating time 20s, frequency 220KHz;

[0096] S5, after the first low-temperature cooling, perform a multi-pass medium-temperature annealing treatment in a gas-shielded resistance furnace, and after the multi-pass medium-temperature annealing treatment, perform a second low-temperature cooling directly in a liquid nitrogen tank for rapid cooling to the liquid nitrogen temperature;

[0097] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 550°C, the annealing passes are 4 passes, and the treatment time of each pass is 5 minutes;

[0098] S6. After the second low temperature cooling, deep cryogenic treatment is performed in a liquid nitrogen tank for 15 hours;

[0099] S7. After the cryogenic treatment, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S7 processes can be repeated until there are no defects in the remanufactured area;

[0100] S8. After turning, grinding is performed to make it reach the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0101] Example 2

[0102] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0103] S1, according to the general formula (CrFeMnNi) 0.6 Cu 0.21 Al 0.15 Ti 0.04 Prepare raw materials, wherein the raw materials are: Ti powder, Cr powder, Fe powder, Mn powder, Ni powder, Cu powder and Al powder and AlFe alloy powder, AlCr alloy powder and AlTi alloy powder;

[0104] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0105] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 2J; pulse frequency 10Hz; working current 55A; feed speed 300mm / min; shielding gas Ar, shielding gas flow rate 16L / min;

[0106] S4, performing a high-temperature short-time annealing treatment on the arc additively processed component by high-frequency induction heating, and performing a first low-temperature cooling directly in a liquid nitrogen tank after the high-temperature short-time annealing treatment is completed, cooling to the liquid nitrogen temperature;

[0107] The parameters of high-frequency induction heating are: power 12KW, heating rate 30℃ / s, heating temperature 960℃, induction heating time 32s, frequency 225KHz;

[0108] S5, after the first low-temperature cooling, perform a multi-pass medium-temperature annealing treatment in a gas-shielded resistance furnace, and after the multi-pass medium-temperature annealing treatment, perform a second low-temperature cooling directly in a liquid nitrogen tank for rapid cooling to the liquid nitrogen temperature;

[0109] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 550°C, the number of annealing passes is 5, and the treatment time of each pass is 5 minutes;

[0110] S6. After the second low temperature cooling, deep cryogenic treatment is performed in a liquid nitrogen tank for 10 hours;

[0111] S7. After the cryogenic treatment, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S7 processes can be repeated until there are no defects in the remanufactured area;

[0112] S8. After turning, grinding is performed to make it reach the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0113] Example 3

[0114] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0115] S1, according to the general formula (CrFeMnNi) 0.7 Cu 0.16 Al 0.125 Ti 0.015 Prepare raw materials, wherein the raw materials are: FeCr powder, FeMn powder, FeNi powder, CuCr powder and AlTi alloy powder, AlFe alloy powder, AlMn alloy powder, AlNi alloy powder;

[0116] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0117] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 2J; pulse frequency 15Hz; working current 55A; feed speed 300mm / min; shielding gas Ar, shielding gas flow rate 16L / min;

[0118] S4, performing a high-temperature short-time annealing treatment on the arc additively processed component by high-frequency induction heating, and performing a first low-temperature cooling directly in a liquid nitrogen tank after the high-temperature short-time annealing treatment is completed, cooling to the liquid nitrogen temperature;

[0119] The parameters of high-frequency induction heating are: power 14KW, heating rate 20℃ / s, heating temperature 1000℃, induction heating time 50s, frequency 230KHz;

[0120] S5, after the first low-temperature cooling, perform a multi-pass medium-temperature annealing treatment in a gas-shielded resistance furnace, and after the multi-pass medium-temperature annealing treatment, perform a second low-temperature cooling directly in a liquid nitrogen tank for rapid cooling to the liquid nitrogen temperature;

[0121] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 650℃, the number of annealing passes is 5, and the treatment time of each pass is 4 minutes;

[0122] S6. After the second low temperature cooling, cryogenic treatment is performed in a liquid nitrogen tank for 20 hours, wherein the cryogenic treatment takes 2 hours as one cryogenic treatment cycle, and a total of 10 cycles are performed;

[0123] S7. After the cryogenic treatment, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S7 processes can be repeated until there are no defects in the remanufactured area;

[0124] S8. After turning, grinding is performed to make it reach the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0125] Example 4

[0126] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0127] S1, according to the general formula (CrFeMnNi) 0.67 Cu 0.17 Al 0.12 Ca 0.04 Prepare raw materials, wherein the raw materials are: Cr powder, Fe powder, Mn powder, Ni powder, Cu powder, AlCr alloy powder, AlFe alloy powder and AlCa alloy powder;

[0128] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0129] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 2.2J; pulse frequency 15Hz; working current 60A; feed speed 350mm / min; shielding gas Ar, shielding gas flow rate 16L / min;

[0130] S4, performing a high-temperature short-time annealing treatment on the arc additively processed component by high-frequency induction heating, and performing a first low-temperature cooling directly in a liquid nitrogen tank after the high-temperature short-time annealing treatment is completed, cooling to the liquid nitrogen temperature;

[0131] The parameters of high-frequency induction heating are: power 16KW, heating rate 26℃ / s, heating temperature 1040℃, induction heating time 40s, frequency 220KHz;

[0132] S5, after the first low-temperature cooling, medium-temperature annealing treatment is performed in a gas-shielded resistance furnace, and after the medium-temperature annealing treatment, the medium-temperature annealing treatment is directly and rapidly cooled in a liquid nitrogen tank for a second low-temperature cooling to the liquid nitrogen temperature;

[0133] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 600°C, the annealing passes are 5, and the treatment time of each pass is 4 minutes;

[0134] S6. After the second low temperature cooling, cryogenic treatment is performed in a liquid nitrogen tank for 32 hours, wherein the cryogenic treatment takes 2 hours as one cryogenic treatment cycle, and a total of 16 cycles are performed;

[0135] S7. After the cryogenic treatment, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S7 processes can be repeated until there are no defects in the remanufactured area;

[0136] S8. After turning, grinding is performed to make it reach the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0137] Example 5

[0138] The preparation steps of the bearing bush for the sliding bearing of the LNG cryogenic submersible pump include:

[0139] S1, according to the general formula (CrFeMnNi) 0.7 Cu 0.15 Al 0.12 Si 0.03 preparing raw materials, wherein the raw materials are: Mn powder, Fe powder, Cr powder, Ni powder, Cu powder, Al powder, Si powder and AlFe alloy powder, AlCr alloy powder, AlCu alloy powder, AlSi alloy powder and AlTi alloy powder;

[0140] S2. 9Cr18 steel was selected as the substrate, and the above powder was used as the raw material to prepare the bearing bush for the sliding bearing of the LNG cryogenic submersible pump by arc additive technology, wherein the parameters of the arc additive processing were: pulse energy 0.8J; pulse frequency 10Hz; working current 45A; feed speed 150mm / min; shielding gas Ar, shielding gas flow rate 12L / min;

[0141] S3, performing a high-temperature short-time annealing treatment on the arc additive processing component by high-frequency induction heating, and performing a first low-temperature cooling directly in a liquid nitrogen tank after the high-temperature short-time annealing treatment is completed, cooling to the liquid nitrogen temperature;

[0142] The parameters of high-frequency induction heating are: power 10KW, heating rate 46℃ / s, heating temperature 920℃, induction heating time 20s, frequency 220KHz;

[0143] S4, after the first low-temperature cooling, perform a multi-pass medium-temperature annealing treatment in a gas-shielded resistance furnace, and after the multi-pass medium-temperature annealing treatment, perform a second low-temperature cooling directly in a liquid nitrogen tank for rapid cooling to liquid nitrogen temperature;

[0144] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 550°C, the annealing passes are 4 passes, and the treatment time of each pass is 5 minutes;

[0145] S5. After the second low temperature cooling, deep cryogenic treatment is performed in a liquid nitrogen tank for 15 hours;

[0146] S6. After the cryogenic treatment, the arc-added area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); then the part is ground to make it within the allowable range of the finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then the ground surface is milled with equally spaced spiral grooves by a CNC milling machine. The milling cutter is made of alloy steel, with a speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the bearing surface roughness reach Ra≤1.6μm.

[0147] Comparative Example 1

[0148] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0149] S1, according to the general formula (CrFeMnNi) 0.65 Cu 0.2 Al 0.12 Si 0.03 Prepare raw materials, wherein the raw materials are: Mn powder, Fe powder, Cr powder, Ni powder, Cu powder, Si powder and Al powder;

[0150] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface to obtain a pre-treated bearing component;

[0151] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 0.8 J; pulse frequency 10 Hz; working current 45 A; feed speed 150 mm / min; shielding gas Ar, shielding gas flow rate 12 L / min;

[0152] S4. The arc additively treated component is not subjected to high-temperature short-time annealing treatment, but is directly subjected to medium-temperature annealing treatment in a gas-shielded resistance furnace. After the medium-temperature annealing treatment, it is directly rapidly cooled in a liquid nitrogen tank for a second low-temperature cooling to the liquid nitrogen temperature;

[0153] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 550°C, the annealing passes are 4 passes, and the treatment time of each pass is 5 minutes;

[0154] S5. After the second low temperature cooling, deep cryogenic treatment is performed in a liquid nitrogen tank for 15 hours;

[0155] S6. After the cryogenic treatment, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S6 processes can be repeated until there are no defects in the remanufactured area;

[0156] S7. After turning, grinding is performed to achieve the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0157] Comparative Example 2

[0158] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0159] S1, according to the general formula (CrFeMnNi) 0.6 Cu 0.16 Al 0.2 Ti 0.04 Prepare raw materials, wherein the raw materials are: Ti powder, Cr powder, Fe powder, Mn powder, Ni powder, Cu powder and Al powder and AlFe alloy powder, AlCr alloy powder and AlTi alloy powder;

[0160] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0161] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 2J; pulse frequency 10Hz; working current 55A; feed speed 300mm / min; shielding gas Ar, shielding gas flow rate 16L / min;

[0162] S4, performing a high-temperature short-time annealing treatment on the arc additively processed component by high-frequency induction heating, and performing a first low-temperature cooling directly in a liquid nitrogen tank after the high-temperature short-time annealing treatment is completed, cooling to the liquid nitrogen temperature;

[0163] The parameters of high-frequency induction heating are: power 12KW, heating rate 30℃ / s, heating temperature 960℃, induction heating time 32s, frequency 225KHz;

[0164] S5, after the first low-temperature cooling, a single-pass long-term medium-temperature annealing treatment is performed in a gas-shielded resistance furnace, wherein the annealing temperature is 550° C. and the annealing time is 25 min;

[0165] S6. After the second low temperature cooling, deep cryogenic treatment is performed in a liquid nitrogen tank for 10 hours;

[0166] S7. After the cryogenic treatment, the arc-added area is turned to make it slightly larger than the finished product size (approximately 0.3 mm larger than the finished product size);

[0167] S8. After turning, grinding is performed to make it reach the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0168] Comparative Example 3

[0169] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0170] S1, according to the general formula (CrFeMnNi) 0.7 Cu 0.16 Al 0.125 Ti 0.015 preparing raw materials, wherein the raw materials are: Ti powder, Cr powder, Fe powder, Mn powder, Ni powder, Cu powder and Al powder;

[0171] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0172] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 2J; pulse frequency 15Hz; working current 55A; feed speed 300mm / min; shielding gas Ar, shielding gas flow rate 16L / min;

[0173] S4, subjecting the arc additively processed component to a multi-pass medium-temperature annealing treatment in a gas-shielded resistance furnace, and directly cooling it in a liquid nitrogen tank for a second low-temperature cooling after the multi-pass medium-temperature annealing treatment, cooling it to a liquid nitrogen temperature;

[0174] Among them, the temperature of the multi-pass medium-temperature annealing treatment is 650℃, the number of annealing passes is 5, and the treatment time of each pass is 4 minutes;

[0175] S5. After the second low temperature cooling, cryogenic treatment is performed in a liquid nitrogen tank for 20 hours, wherein the cryogenic treatment takes 2 hours as one cryogenic treatment cycle, and a total of 10 cycles are performed;

[0176] S6. After the cryogenic treatment, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S6 processes can be repeated until there are no defects in the remanufactured area;

[0177] S7. After turning, grinding is performed to achieve the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0178] Comparative Example 4

[0179] A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, comprising the steps of:

[0180] S1, according to the general formula (CrFeMnNi) 0.67 Cu 0.17 Al 0.12 Ca 0.04 Prepare raw materials, wherein the raw materials are: Cr powder, Fe powder, Mn powder, Ni powder, Cu powder, AlCr alloy powder, AlFe alloy powder and AlCa alloy powder;

[0181] S2. Grind the bearing base material of the LNG cryogenic submersible pump sliding bearing to be repaired to remove the wear, ablation, cracks, deformation, flanging, peeling, corrosion pits, etc. on the bearing surface, then remove the dust, impurities and dirt on the surface, clean it with high-concentration ethanol, and then preheat the bearing base material to 160° C. to obtain a pretreated bearing component;

[0182] S3, performing arc additive processing on the pre-treated bearing shell component to be repaired to obtain an arc additive processed component, wherein the parameters of the arc additive processing are: pulse energy 2.2J; pulse frequency 15Hz; working current 60A; feed speed 350mm / min; shielding gas Ar, shielding gas flow rate 16L / min;

[0183] S4, performing high-temperature short-time annealing treatment on the arc additively processed component by high-frequency induction heating, and water cooling after the high-temperature short-time annealing treatment;

[0184] The parameters of high-frequency induction heating are: power 16KW, heating rate 26℃ / s, heating temperature 1040℃, induction heating time 40s, frequency 220KHz;

[0185] S5, subjecting the sample to medium-temperature annealing in a gas-shielded resistance furnace, and directly air-cooling after the medium-temperature annealing;

[0186] Among them, the temperature of medium temperature annealing treatment is 600℃ and the time is 20min;

[0187] S6. After the medium-temperature annealing is completed, the arc additive area is turned to make it slightly larger than the finished product size (about 0.3mm larger than the finished product size); the processed cladding area is subjected to X-ray or ultrasonic flaw detection to check whether there are defects such as holes and cracks in the repaired area; if obvious defects are found, the aforementioned grinding, cleaning and arc additive remanufacturing S2-S6 processes can be repeated until there are no defects in the remanufactured area;

[0188] S7. After turning, grinding is performed to achieve the allowable range of finished product size (inner diameter 35mm, length 25mm, thickness 4mm); then, the surface after grinding is milled with equally spaced spiral grooves by CNC milling machine. The milling cutter is made of alloy steel, with a rotation speed of 1400r / min and a feed rate of 320mm / min. The groove is semicircular with a radius of 0.25mm, a helix angle of 35°, and a groove spacing of 15mm; then fine grinding is performed to make the surface roughness of the bearing reach Ra≤1.6μm.

[0189] Comparative Example 5

[0190] Compared with Example 5, the selected raw material ratio, arc additive processing parameters, heat treatment parameters and cryogenic treatment parameters are all the same. The difference is that this process adds X-ray flaw detection, polishing of the part to be repaired, inspection of the repair area, repeated polishing and repair process, which is suitable for the repair and remanufacturing of LNG cryogenic submersible pump sliding bearings.

[0191] Comparative Examples 6-13

[0192] Compared with Example 1, the only difference is that the element ratio is different, as shown in Table 1.

[0193] Table 1

[0194] project general formula difference Comparative Example 6 <![CDATA[(CrFeMnNi) 0.82 With 0.03 the 0.12 And 0.03 ]]> The ratio of (CrFeMnNi) is higher than 0.8 Comparative Example 7 <![CDATA[(CrFeMnNi) 0.5 With 0.25 the 0.135 And 0.115 ]]> The ratio of (CrFeMnNi) is less than 0.55 Comparative Example 8 <![CDATA[(CrFeMnNi) 0.55 With 0.32 the 0.115 And 0.015 ]]> The proportion of Cu is higher than 0.3 Comparative Example 9 <![CDATA[(CrFeMnNi) 0.7 With 0.14 the 0.145 And 0.015 ]]> The proportion of Cu is less than 0.15 Comparative Example 10 <![CDATA[(CrFeMnNi) 0.675 With 0.15 the 0.16 And 0.015 ]]> The proportion of Al is higher than 0.15 Comparative Example 11 <![CDATA[(CrFeMnNi) 0.7 With 0.25 the 0.035 And 0.015 ]]> The proportion of Al is less than 0.1 Comparative Example 12 <![CDATA[(CrFeMnNi) 0.6 With 0.165 the 0.135 And 0.1 ]]> The proportion of Si is higher than 0.05 Comparative Example 13 <![CDATA[(CrFeMnNi) 0.6 With 0.25 the 0.147 And 0.003 ]]> The proportion of Si is less than 0.005

[0195] Test example

[0196] The performance parameters of the bearings prepared in Examples 1-5 and Comparative Examples 1-13 were tested, and the results are shown in Table 2.

[0197] The microhardness test method is to press the diamond indenter of the microhardness tester into the material surface under a certain test force (6N), and measure the diagonal length of the indentation to calculate the hardness value;

[0198] The method for detecting the average friction coefficient is to use a reciprocating friction tester to simulate the reciprocating motion in actual use and measure the change of friction force with time and number of times.

[0199] Table 2

[0200] Sliding bearings Microhardness(HV) Average friction coefficient Example 1 536.1 0.23 Example 2 495.8 0.21 Example 3 498.2 0.29 Example 4 525.7 0.26 Example 5 512.3 0.26 Comparative Example 1 486.5 0.32 Comparative Example 2 478.2 0.39 Comparative Example 3 502.3 0.33 Comparative Example 4 482.4 0.48 Comparative Example 5 498.6 0.39 Comparative Example 6 513.5 0.36 Comparative Example 7 496.6 0.28 Comparative Example 8 522.5 0.33 Comparative Example 9 477.4 0.26 Comparative Example 10 466.3 0.25 Comparative Example 11 485.6 0.34 Comparative Example 12 478.3 0.26 Comparative Example 13 488.9 0.30

[0201] It can be seen from the data of the embodiments and comparative examples in Table 2 that the repair method of the bearing substrate pretreatment, arc additive, high-temperature short-time annealing, first low-temperature cooling, multi-pass medium-temperature annealing, second low-temperature cooling, deep cryogenic treatment, rough machining and fine machining provided by the present invention achieves the purpose of good combination of the cladding layer and the substrate; by performing high-temperature short-time annealing after the arc additive treatment, the surface structure of the high-entropy alloy cladding layer is refined; by deep cryogenic treatment to regulate the morphology and distribution of defects such as dislocations and stacking faults in the cladding layer, the hardness and wear resistance of the repaired bearing are enhanced; under the joint action of the above-mentioned processes, the purpose of arc additive remanufacturing of the sliding bearing is achieved, the service life of the bearing is improved, and the microhardness of the sliding bearing is ≥595.8HV, and the average friction coefficient is ≤0.29, which meets the requirements of high strength and high wear resistance, and is conducive to application in low-temperature applications.

[0202] It can be seen from the data of Example 5 that the bearing bush substrate prepared by the preparation method of the present invention has good wear resistance in a low temperature environment.

[0203] Comparison of the data of Comparative Example 5 with that of Example 1 shows that when other high entropy alloy powders are used to repair the bearing, the hardness of the bearing will be reduced and the friction coefficient will be increased.

[0204] From the comparison of the data of Comparative Examples 6-13 and Example 1, it can be seen that when the element ratio is changed, the hardness and friction coefficient of the bearing will change, wherein the change of the value of x in the general formula will bring about the change of the hardness and compressive yield strength of the bearing; the change of the value of y will bring about the change of the yield strength and hardness of the bearing, and change the plasticity of the bearing alloy; the change of the value of z will bring about the change of the hardness and tensile strength of the bearing; the change of the value of w will bring about the change of the hardness, strength, wear resistance and corrosion resistance of the bearing.

[0205] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0206] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high entropy alloy for arc additive remanufacturing and repair of sliding bearings of LNG cryogenic submersible pumps, characterized in that: The general formula of the high entropy alloy is: (CrFeMnNi) x Cu y Al z Z w ; Wherein, Z is selected from Si, Ti, Ca or RE; x is 0.550-0.800, y is 0.150-0.300, z is 0.100-0.150, w is 0.005-0.05, and the sum of x, y, z and w is 1.

2. An application of the high entropy alloy described in claim 1 in arc additive remanufacturing, repair or preparation of bearing shells for sliding bearings.

3. A method for arc additive remanufacturing and repairing of sliding bearings of LNG cryogenic submersible pumps, characterized in that the steps include: Pre-treating the bearing bush substrate of the LNG cryogenic submersible pump sliding bearing to obtain a pre-treated component; Prepare a high entropy alloy raw material according to the general formula of the high entropy alloy of claim 1, and set aside; Processing the pre-treated component by arc additive manufacturing with the high entropy alloy raw material to obtain an arc additive manufacturing component; The arc additively processed component is sequentially subjected to high-temperature short-time annealing, first low-temperature cooling, multiple medium-temperature annealing, second low-temperature cooling, deep cryogenic treatment, rough machining and fine machining to obtain a repaired bearing component.

4. The method according to claim 3, characterized in that The pretreatment step comprises: the bearing bush substrate is polished, cleaned and preheated in sequence to obtain a pretreated component; and / or, the high entropy alloy raw material comprises element powder and / or master alloy powder; and / or, the process parameters of the arc additive are: pulse energy of 0.5-2.5J, pulse frequency of 5-25Hz, working current of 40-65A, feed speed of 150-500mm / min; shielding gas is Ar, flow rate of 10-20L / min; and / or, the two adjacent layers of cladding material in the arc additive are rotated 15°-45 °; and / or, the high-temperature short-time annealing is carried out by high-frequency induction heating; and / or, the first low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank; and / or, the multi-pass medium-temperature annealing is carried out in a vacuum resistance furnace or a gas-shielded resistance furnace; and / or, the annealing temperature of the multi-pass medium-temperature annealing is 550-750°C, the annealing passes are 4-10 passes, and the total annealing time is 15-60min; and / or, the second low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank; and / or, the deep cryogenic treatment is carried out in liquid nitrogen for 2-50h.

5. The method according to claim 4, characterized in that The cleaning is performed using acetone or ethanol; and / or the preheating temperature is 100-200°C; and / or the process parameters of the high-frequency induction heating are: power of 10-16KW, heating rate of 15-50°C / s, heating temperature of 950-1100°C, induction heating time of 10-60s, frequency range of 200-250KHz; and / or the cryogenic treatment is a one-time cryogenic treatment of 2-50h, or a treatment cycle of 2h for 1-25 times.

6. The method according to claim 3, characterized in that The rough machining is to perform turning on the part processed by the arc additive process; and / or, it also includes, after the rough machining, performing X-ray or ultrasonic flaw detection on the part processed by the arc additive process. If there are still holes and cracks in the repaired area, repeating pretreatment, arc additive process, high temperature short-time annealing, first low temperature cooling, multiple medium temperature annealing, second low temperature cooling, and deep cryogenic treatment until there are no defects in the repaired area; and / or, the fine machining is to perform grinding, milling and polishing on the part processed by the arc additive process.

7. The method according to claim 6, characterized in that The milling process is to process equally spaced spiral grooves through milling, and the process parameters are: rotation speed of 1300r / min-1500r / min, feed rate of 300-350mm / min, grooves are semicircular or square, diameter or depth is 0.2-0.4mm, spiral line angle is 30°-60°, and groove spacing is 15-30mm.

8. A method for preparing a bearing bush for a sliding bearing of an LNG cryogenic submersible pump, characterized in that the steps include: Prepare a high entropy alloy raw material according to the general formula of the high entropy alloy of claim 1, and set aside; The high entropy alloy raw material is prepared by arc additive manufacturing to obtain a bearing bush precursor; The bearing bush precursor for the LNG cryogenic submersible pump sliding bearing is sequentially subjected to high-temperature short-time annealing, first low-temperature cooling, multiple medium-temperature annealing, second low-temperature cooling, deep cryogenic treatment, rough machining and fine machining to obtain the bearing bush.

9. The preparation method according to claim 8, characterized in that: The high entropy alloy raw material includes element powder and / or master alloy powder; and / or, the process parameters of the arc additive are: pulse energy of 0.5-2.5J, pulse frequency of 5-25Hz, working current of 40-65A, feed speed of 150-500mm / min; shielding gas is Ar, and flow rate is 10-20L / min; and / or, two adjacent layers of cladding materials in the arc additive are rotated by 15°-45°; and / or, the high temperature short time annealing is processed by high frequency induction heating; and / or, the first low temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank; And / or, the multi-pass medium-temperature annealing is carried out in a vacuum resistance furnace or a gas-shielded resistance furnace; and / or, the annealing temperature of the multi-pass medium-temperature annealing is 550-750°C, the annealing passes are 4-10 passes, and the total annealing time is 15-60min; and / or, the second low-temperature cooling is cooling in a liquid nitrogen tank or a dry ice tank; and / or, the deep cryogenic treatment is carried out in liquid nitrogen for 2-50h; and / or, the rough machining is turning the bearing precursor; and / or, the fine machining is grinding, milling and polishing the bearing precursor.

10. The preparation method according to claim 9, characterized in that: The process parameters of the high-frequency induction heating are: power of 10-16KW, heating rate of 15-50℃ / s, heating temperature of 950-1100℃, induction heating time of 10-60s, and frequency range of 200-250KHz; and / or, the cryogenic treatment is a one-time cryogenic treatment of 2-50h, or a treatment cycle of 2h, and a treatment of 1-25 times; and / or, the milling process is a process of processing equidistant spiral grooves by milling, and the process parameters are: rotation speed of 1300r / min-1500r / min, feed rate of 300-350mm / min, the groove is semicircular or square, the diameter or depth is 0.2-0.4mm±0.05mm, the spiral line angle is 30°-60°, and the groove spacing is 15-30mm.

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