A sintered hard alloy welding rod containing rare earth for surface build-up welding of oil workover tools and a manufacturing method thereof

Abstract

The application provides a rare earth-containing hard alloy sintered electrode for surface surfacing of petroleum workover tools and a manufacturing method thereof, and comprises: obtaining a sintered electrode by hard alloy particles and soft metal sintering, wherein the component content of the hard alloy particles in the sintered electrode accounts for 60-75%, the component content of the soft metal accounts for 25wt%-40wt%, the hard alloy material is WC, TiC, NbC, Cr2C3, rare earth Ce and Co composite sintered material, the hardness, toughness and grinding performance of the sintered hard alloy particles are improved by optimizing the component and content of the hard alloy material, and then the milling effect on the high-strength pipe string is improved; the soft metal material is Cu-Ni-Zn-Mn system material powder, the strength and wear resistance of the matrix metal itself are improved, the WC particle falling phenomenon in the milling operation process is effectively solved, and the milling efficiency of the hard alloy surfacing material in the field workover operation is improved.

Description

Technical Field

[0001] The invention belongs to the field of well repair tool manufacturing in the petroleum and natural gas industry, and particularly relates to a rare earth-containing hard alloy sintered welding rod for surface welding of well repair tools and a manufacturing method thereof. Background Art

[0002] As a large number of oil and gas wells in my country enter the middle and late stages of production, downhole tubulars are frequently damaged, requiring the use of milling tools to repair the tubulars. Milling tools are usually made of alloy steel to form the base shape, and then large-sized hard alloy particles are welded at the position where the tool mills the tubular. The milling function of the milling tool on the damaged tubular is mainly achieved by the hard alloy particles welded on its surface. At present, the hard alloy particles welded on the surface of the milling tool are mainly WC particles. YD series welding rods are mostly used for welding in China. However, due to the high hardness and brittleness of WC particles, their hardness is relatively low, about HV1350-HV1450, and their impact resistance is weak. They are quite different from the properties of the steel matrix, and WC particles are prone to falling off during the milling operation. A method for manufacturing a composite tungsten-based tubular welding rod hardfacing material (CN201510384142.7) proposes to prepare the hardfacing material by combining multiple materials such as cast carbide and cemented carbide balls. However, the particle size of this material is small, and it is mechanically mixed and loaded into the tubular welding rod for use. It is mainly used in roller drill bits and perforating reamers, and is mainly used for rock layer grinding, but the milling effect on pipe string steel is very limited. In addition, with the extensive application of high-strength pipe strings, the pipe strings have higher strength and higher hardness, which puts higher requirements on the milling performance of milling tools. The milling efficiency of WC particles welded on the surface of milling tools is currently low and can no longer meet the needs of on-site well repair operations. There is an urgent need to develop a hard alloy welding material with higher milling efficiency for high-strength pipe strings. The present invention optimizes the composition and process of hard alloy particles, combines the special effects of rare earth elements, improves the bonding performance of hard alloy sintered particles, and reduces the falling of alloy particles during the milling process. Summary of the Invention

[0003] In response to the problems existing in the prior art, the present invention provides a rare earth-containing hard alloy sintered welding rod for surface welding of petroleum well repair tools and a manufacturing method thereof, which solves the problem of WC particles easily falling off during the milling operation and improves the milling efficiency of hard alloy welding materials during on-site well repair operations.

[0004] The present invention is achieved through the following technical solutions:

[0005] A rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools, comprising a sintered welding rod obtained by sintering hard alloy particles and soft metal, wherein the hard alloy particles in the sintered welding rod account for 60-75% of the component content, and the soft metal component content accounts for 25wt%-40wt%.

[0006] The composition of the hard alloy particles includes WC: 60wt%-70wt%, TiC: 12wt%-16wt%, NbC: 5wt%-7wt%, Cr2C3: 1wt%-2wt%, rare earth Ce: 0.6wt%-1.2wt%, and the rest is Co;

[0007] The soft metal is a Cu-Ni-Zn-Mn system material powder.

[0008] Preferably, the composition of the soft metal includes Cu: 76wt%-80wt%, Ni: 4wt%-8wt%, Mn: 5wt%-8wt%, and the rest is Zn.

[0009] Preferably, the hard alloy particles are in a multi-rib structure.

[0010] A manufacturing method of a rare earth-containing hard alloy sintered electrode for surface build-up welding of an oil workover tool, comprising,

[0011] S1, uniformly mix the components of the hard alloy particles in an oxygen-free environment by wet grinding, add a binder after drying, and then uniformly mix, and then press and form into a multi-rib shape through a multi-rib mold to obtain a multi-rib-shaped alloy material, and then sinter the pressed alloy material under high temperature conditions to obtain hard alloy particles;

[0012] S2, spread the hard alloy particles in the mold according to the proportion, heat the mold to 500±50℃ in a hydrogen environment, spread the soft metal powder around the hard alloy particles in the mold according to the proportion, heat the mold to 1200±50℃ in a hydrogen environment again, and then cool in a 200±50℃ environment after holding for 10-15min to obtain a rare earth-containing hard alloy sintered electrode.

[0013] Preferably, the temperature during the wet mixing process does not exceed 26℃, and the wet grinding time is 25h-30h.

[0014] Preferably, anhydrous alcohol is added during the wet mixing process to maintain humidity and temperature.

[0015] Preferably, the hardness of the hard alloy particles is HV1600-HV1800.

[0016] Preferably, the multi-rib mold adopts a trihedral, heptagonal star, or octagonal star.

[0017] Preferably, the specific process of sintering the pressed alloy material under high temperature conditions is as follows: first, place the pressed alloy material into a sintering device to form a vacuum environment, then raise the temperature from room temperature to 400±50℃, hold for 1h±0.2h, then raise the temperature to 1000±50℃, hold for 1h±0.2h, and finally raise the temperature to the sintering temperature of 1400±50℃, and hold for 8h±1h.

[0018] Preferably, a layer of borax release agent is spread on the bottom of the mold before spreading the hard alloy particles.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention provides a rare earth-containing hard alloy sintered welding rod for surface welding of petroleum well repair tools, comprising a sintered welding rod obtained by sintering hard alloy particles and soft metal, wherein the hard alloy particles in the sintered welding rod account for 60-75% of the component content, and the soft metal component content accounts for 25wt%-40wt%. By optimizing the composition of the hard alloy particles and the soft metal matrix material, introducing a ceramic reinforcement phase and rare earth elements, the strength and toughness of the hard alloy particles are improved, the occurrence of hard particle fracture and falling accidents is reduced, and the grinding and milling ability and service life of the sintered hard alloy welding material are improved. The hard alloy material in the present invention adopts a composite sintered material of WC, TiC, NbC, Cr2C3, rare earth Ce and Co. By optimizing the components and content of the hard alloy material, the hardness, toughness and grinding performance of the sintered hard alloy particles are improved, thereby improving its milling effect on high-strength pipe strings; the soft metal material adopts Cu-Ni-Zn-Mn material powder to improve the strength and wear resistance of the matrix metal itself, effectively solving the problem of WC particles easily falling off during the milling operation, and improving the milling efficiency of the hard alloy welding material during on-site well repair operations.

[0021] Furthermore, in the process of preparing the hard alloy particles, anhydrous alcohol is added in a timely manner during the wet grinding and mixing process to ensure a certain humidity of the powder, while reducing the ambient temperature to ensure that the wet grinding ambient temperature is within 26° C., thereby maintaining the hardness performance of the hard alloy particles to achieve the best effect;

[0022] Furthermore, the polygonal mold for pressing the hard alloy particles of the present invention should be a mold with sharp edges and corners such as a triangular prism, a seven-pointed star or an eight-pointed star. The size of the polygonal alloy material particles obtained by pressing is controlled in the range of 3mm-10mm, and the hardness of the hard alloy particles reaches HV1600-HV1800, which effectively improves the hardness, toughness and grinding performance of the hard alloy particles, thereby improving its grinding and milling effect on high-strength pipes. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0024] To help those skilled in the art better understand the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0025] The invention provides a hard alloy sintered welding rod for surface welding of a milling tool for milling a high-strength pipe column and a manufacturing process thereof.

[0026] Technical solution:

[0027] (1) The sintered welding rod of the present invention is obtained by sintering polygonal sintered hard alloy particles and a soft metal, wherein the hard alloy particles account for 60wt%-75wt% and the soft metal accounts for 25wt%-40wt%. The polygonal sintered hard alloy particles contain 60wt%-70wt% WC, 12wt%-16wt% TiC, 5wt%-7wt% NbC, 1wt%-2wt% Cr2C3, 0.6wt%-1.2wt% rare earth element Ce, and the remainder Co. The soft metal is a Cu-Ni-Zn-Mn based material powder, containing 76wt%-80wt% Cu, 4wt%-8wt% Ni, 5wt%-8wt% Mn, and the remainder Zn.

[0028] (2) First, WC: 60wt%-70wt%, TiC: 12wt%-16wt%, NbC: 5wt%-7wt%, Cr2C3: 1wt%-2wt%, rare earth Ce: 0.6wt%-1.2wt%, and the rest Co are mixed in proportion, and wet-milled in an oxygen-free environment for 25h-30h to fully mix the powders of different components. The temperature does not exceed 26°C during the wet-milling mixing process. The uniformly mixed alloy powder is dried, and a binder is added to the powder mixture, and the mixture is evenly mixed. The powder mixture is pressed into a polygonal mold to obtain a polygonal alloy material, and the pressed alloy material is sintered under high temperature conditions to obtain hard alloy particles.

[0029] (3) It should be further explained that during the wet grinding process, anhydrous alcohol should be added in time to ensure a certain humidity of the powder, and at the same time, the ambient temperature should be lowered to ensure that the wet grinding ambient temperature is within 26°C;

[0030] (4) It should be further explained that the polygonal mold for pressing hard alloy particles should be a mold with sharp corners such as a triangular prism, a seven-pointed star or an eight-pointed star, and the size of the polygonal alloy particles obtained by pressing should be controlled in the range of 3mm-10mm;

[0031] (5) The sintering of alloy particles needs to be performed in a vacuum environment using a gradient heating method. First, the alloy particles are placed in a sintering device to form a vacuum environment, then gradually heated from room temperature to 400±50℃, and kept for 1h±0.2h, then heated to 1000±50℃, and kept for 1h±0.2h, and finally heated to a sintering temperature of 1400±50℃, and kept for 8h±1h;

[0032] (6) After sintering, the hard alloy particles are slowly cooled in the furnace to obtain multi-prism hard alloy particles, and the hardness of the alloy particles is HV1600-HV1800.

[0033] (7) The sintered hard alloy particles are uniformly spread in the long groove mold according to a proportion of 60-75wt%, and a layer of borax release agent is spread on the bottom of the mold;

[0034] (8) The mold is placed in a hydrogen environment heating furnace and heated to 500±50℃;

[0035] (9) The soft metal powder is uniformly spread around the hard alloy particles in the mold according to a proportion of 25-40wt%, and the mold is placed back in the hydrogen environment heating furnace and heated to 1200±50℃, and kept for 10-15 minutes;

[0036] (10) It should be further noted that the soft metal composition is Cu: 76-80wt%, Ni: 4-8wt%, Mn: 5-8wt%, and the rest is Zn.

[0037] (11) The sintered hard alloy strip is slowly cooled in a 200±50℃ environment to obtain a hard alloy sintering welding strip product.

[0038] Example 1

[0039] (1) The sintering welding strip of the present application is obtained from multi-prism sintered hard alloy particles and soft metal sintering, and the proportion of hard alloy particles is 60wt%, and the proportion of soft metal is 40wt%. The composition of the multi-prism sintered hard alloy particles is WC: 60wt%, TiC: 12wt%, NbC: 5wt%, Cr2C3: 1wt%, rare earth Ce: 0.6wt%, and the rest is Co. The soft metal is a Cu-Ni-Zn-Mn system material powder, and the composition is Cu: 76wt%, Ni: 4wt%, Mn: 5wt%, and the rest is Zn.

[0040] (2) First, WC: 60wt%, TiC: 12wt%, NbC: 5wt%, Cr2C3: 1wt%, rare earth Ce: 0.6wt%, and the rest Co are mixed in proportion, and wet-milled in an oxygen-free environment for 25 hours to fully mix the powders of different components. The temperature does not exceed 26°C during the wet-milling mixing process. The uniformly mixed alloy powder is dried, and a binder is added to the powder mixture and mixed evenly. The powder mixture is pressed into a polygonal mold to obtain a polygonal alloy material. The pressed alloy material is sintered under high temperature conditions to obtain hard alloy particles.

[0041] (3) It should be further explained that during the wet grinding process, anhydrous alcohol should be added in time to ensure a certain humidity of the powder, and at the same time, the ambient temperature should be lowered to ensure that the wet grinding ambient temperature is within 26°C;

[0042] (4) It should be further explained that the polygonal mold for pressing the hard alloy particles should be a triangular prism-shaped mold, and the size of the triangular prism alloy particles obtained by pressing should be controlled in the range of 3mm-5mm;

[0043] (5) Alloy particle sintering needs to be carried out in a vacuum environment using a gradient temperature increase method. First, the alloy particles are placed in the sintering equipment to form a vacuum environment. Then the temperature is gradually increased from room temperature to 400 °C and kept at this temperature for 1 hour. Then the temperature is increased to 800 °C and kept at this temperature for 1 hour. Finally, the temperature is increased to the sintering temperature of 1400 °C and kept at this temperature for 8 hours.

[0044] (6) After sintering, the hard alloy particles are slowly cooled in the furnace to obtain polyhedral hard alloy particles with a hardness of HV1600-HV1680.

[0045] (7) Spreading the sintered hard alloy particles in a ratio of 60 wt% evenly in a long groove mold, and spreading a layer of borax release agent on the bottom of the mold;

[0046] (8) Place the mold in a hydrogen environment heating furnace and heat it to 500°C;

[0047] (9) Sprinkle the soft metal powder evenly around the hard alloy particles in the mold at a ratio of 40 wt %. Place the mold back into a hydrogen environment heating furnace and heat it to 1200°C for 10-13 minutes.

[0048] (10) It should be further explained that the soft metal composition is Cu: 76 wt%, Ni: 4 wt%, Mn: 5 wt%, and the rest is Zn.

[0049] (11) The sintered hard alloy bar is placed in a low temperature environment of 200°C for slow cooling to obtain a finished hard alloy sintered welding rod.

[0050] Example 2

[0051] (1) The sintered welding rod of the present invention is obtained by sintering polygonal sintered hard alloy particles and a soft metal, wherein the hard alloy particles account for 75wt% and the soft metal accounts for 25wt%. The polygonal sintered hard alloy particles are composed of WC: 70wt%, TiC: 16wt%, NbC: 7wt%, Cr2C3: 2wt%, rare earth Ce: 1.2wt%, and the balance is Co. The soft metal is a Cu-Ni-Zn-Mn material powder, composed of Cu: 80wt%, Ni: 8wt%, Mn: 8wt%, and the balance is Zn.

[0052] (2) First, WC: 70wt%, TiC: 16wt%, NbC: 7wt%, Cr2C3: 2wt%, rare earth Ce: 1.2wt%, and the rest Co are mixed in proportion, and wet-milled in an oxygen-free environment for 30 hours to fully mix the powders of different components. The temperature does not exceed 26°C during the wet-milling mixing process. The uniformly mixed alloy powder is dried, and a binder is added to the powder mixture and mixed evenly. The powder mixture is pressed into a polygonal mold to obtain a polygonal alloy material. The pressed alloy material is sintered under high temperature conditions to obtain hard alloy particles.

[0053] (3) It should be further explained that during the wet grinding process, anhydrous alcohol should be added in time to ensure a certain humidity of the powder, and at the same time, the ambient temperature should be lowered to ensure that the wet grinding ambient temperature is within 26°C;

[0054] (4) It should be further explained that the polygonal die for pressing the hard alloy particles should be a seven-pointed star-shaped die, and the size of the polygonal alloy particles obtained by pressing should be controlled in the range of 6mm-8mm;

[0055] (5) Alloy particle sintering needs to be carried out in a vacuum environment using a gradient temperature increase method. First, the alloy particles are placed in the sintering equipment to form a vacuum environment. Then the temperature is gradually increased from room temperature to 450 ° C, kept at this temperature for 1.2 h, then increased to 850 ° C, kept at this temperature for 1.2 h, and finally increased to the sintering temperature of 1450 ° C, kept at this temperature for 9 h.

[0056] (6) After sintering, the hard alloy particles are slowly cooled in the furnace to obtain polyhedral hard alloy particles with a hardness of HV1750-HV1800.

[0057] (7) Spreading the sintered hard alloy particles evenly in a long groove mold at a ratio of 75 wt%, and spreading a layer of borax release agent at the bottom of the mold;

[0058] (8) Place the mold in a hydrogen environment heating furnace and heat it to 550°C;

[0059] (9) Sprinkle the soft metal powder evenly around the hard alloy particles in the mold at a ratio of 25 wt %. Place the mold back into a hydrogen environment heating furnace and heat it to 1250°C for 13-15 minutes.

[0060] (10) It should be further explained that the soft metal composition is Cu: 80 wt%, Ni: 8 wt%, Mn: 8 wt%, and the rest is Zn.

[0061] (11) The sintered hard alloy bar is placed in a low temperature environment of 250°C for slow cooling to obtain a finished hard alloy sintered welding rod.

[0062] Example 3

[0063] (1) The sintered welding rod of the present invention is obtained by sintering polygonal sintered hard alloy particles and a soft metal, wherein the hard alloy particles account for 70wt% and the soft metal accounts for 30wt%. The polygonal sintered hard alloy particles are composed of WC: 65wt%, TiC: 14wt%, NbC: 6wt%, Cr2C3: 1.5wt%, rare earth Ce: 1.0wt%, and the balance is Co. The soft metal is a Cu-Ni-Zn-Mn material powder, composed of Cu: 78wt%, Ni: 5wt%, Mn: 7wt%, and the balance is Zn.

[0064] (2) First, WC: 65wt%, TiC: 14wt%, NbC: 6wt%, Cr2C3: 1.5wt%, rare earth Ce: 1.0wt%, and the rest Co are mixed in proportion, and wet-milled in an oxygen-free environment for 28 hours to fully mix the powders of different components. The temperature does not exceed 26°C during the wet-milling mixing process. The uniformly mixed alloy powder is dried, and a binder is added to the powder mixture and mixed evenly. The powder mixture is pressed into a polygonal mold to obtain a polygonal alloy material. The pressed alloy material is sintered under high temperature conditions to obtain hard alloy particles.

[0065] (3) It should be further explained that during the wet grinding process, anhydrous alcohol should be added in time to ensure a certain humidity of the powder, and at the same time, the ambient temperature should be lowered to ensure that the wet grinding ambient temperature is within 26°C;

[0066] (4) It should be further explained that the polygonal die for pressing the hard alloy particles should be an octagonal star-shaped die, and the size of the polygonal alloy particles obtained by pressing should be controlled in the range of 7mm-10mm;

[0067] (5) Alloy particle sintering needs to be carried out in a vacuum environment using a gradient temperature increase method. First, the alloy particles are placed in the sintering equipment to form a vacuum environment. Then the temperature is gradually increased from room temperature to 350 ° C, kept at this temperature for 0.8 h, then increased to 750 ° C, kept at this temperature for 0.8 h, and finally increased to the sintering temperature of 1350 ° C, kept at this temperature for 7 h.

[0068] (6) After sintering, the hard alloy particles are slowly cooled in the furnace to obtain polyhedral hard alloy particles with a hardness of HV1670-HV1750.

[0069] (7) Evenly spread the sintered hard alloy particles in a ratio of 70 wt% in a long groove mold, and spread a layer of borax release agent on the bottom of the mold;

[0070] (8) Place the mold in a hydrogen environment heating furnace and heat it to 450°C;

[0071] (9) Sprinkle 30 wt% of soft metal powder evenly around the hard alloy particles in the mold, place the mold back into a hydrogen environment heating furnace and heat to 1150°C for 11-14 minutes;

[0072] (10) It should be further explained that the soft metal composition is Cu: 78 wt%, Ni: 5 wt%, Mn: 7 wt%, and the rest is Zn.

[0073] (11) The sintered hard alloy bar is placed in a 150°C environment for slow cooling to obtain a finished hard alloy sintered welding rod.

[0074] Example 4

[0075] (1) The sintered welding rod of the present invention is obtained by sintering polygonal sintered hard alloy particles and a soft metal, wherein the hard alloy particles account for 65wt% and the soft metal accounts for 35wt%. The polygonal sintered hard alloy particles are composed of 68wt% WC, 15wt% TiC, 5wt% NbC, 2wt% Cr2C3, 1.2wt% rare earth element Ce, and the remainder Co. The soft metal is a Cu-Ni-Zn-Mn material powder composed of 78wt% Cu, 7wt% Ni, 5wt% Mn, and the remainder Zn.

[0076] (2) First, WC: 68wt%, TiC: 15wt%, NbC: 5wt%, Cr2C3: 2wt%, rare earth Ce: 1.2wt%, and the rest Co are mixed in proportion, and wet-milled in an oxygen-free environment for 30 hours to fully mix the powders of different components. The temperature does not exceed 26°C during the wet-milling mixing process. The uniformly mixed alloy powder is dried, and a binder is added to the powder mixture and mixed evenly. The powder mixture is pressed into a polygonal mold to obtain a polygonal alloy material. The pressed alloy material is sintered under high temperature conditions to obtain hard alloy particles.

[0077] (3) It should be further explained that anhydrous alcohol should be added in time during the wet grinding process to ensure a certain humidity of the powder, and at the same time the ambient temperature should be lowered to ensure that the wet grinding ambient temperature is within 30°C;

[0078] (4) It needs to be further explained that the polygonal die for pressing the hard alloy particles should be a seven-star-shaped die, and the size of the polygonal alloy particles obtained by pressing is controlled in the range of 5mm-8mm;

[0079] (5) The alloy particle sintering needs to be carried out in a vacuum environment by using a gradient heating method, first, the alloy particles are put into the sintering equipment to form a vacuum environment, then gradually heated from room temperature to 400℃, and kept for 1.1h, then heated to 850℃, and kept for 1h, and finally heated to the sintering temperature of 1400℃, and kept for 8h;

[0080] (6) The hard alloy particles after sintering are slowly cooled in the furnace to obtain polygonal hard alloy particles, and the hardness of the alloy particles is HV1720-HV1770.

[0081] (7) The sintered hard alloy particles are uniformly spread in the long groove die according to the proportion of 65wt%, and a layer of borax release agent is spread on the bottom of the die;

[0082] (8) The die is placed in a hydrogen environment heating furnace and heated to 520℃;

[0083] (9) The soft metal powder is uniformly spread around the hard alloy particles in the die according to the proportion of 35wt%, and the die is re-placed in the hydrogen environment heating furnace and heated to 1220℃, and kept for 12-15 minutes;

[0084] (10) It needs to be further explained that the soft metal composition is Cu: 78wt%, Ni: 7wt%, Mn: 5wt%, and the rest is Zn.

[0085] (11) The sintered hard alloy strip is slowly cooled in a 220℃ environment to obtain the finished hard alloy sintering electrode.

[0086] Table 1 Welding rod material composition and mass percentage

[0087]

[0088] The above is only a preferred embodiment of the present application, and does not limit the present application in any form; any ordinary skilled person in the industry can easily implement the present application according to the description and the above; however, any equivalent changes, modifications and evolution made by those skilled in the art without departing from the scope of the technical solution of the present application, using the technical content disclosed above, are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above embodiments according to the essence of the present application are still within the protection scope of the technical solution of the present application.

Claims

1. A rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools, characterized in that: The method comprises: obtaining a rare earth-containing hard alloy sintered welding rod by sintering hard alloy particles and soft metal, wherein the hard alloy particles in the rare earth-containing hard alloy sintered welding rod have a component content of 60 wt%-75 wt% and the soft metal component content of 25 wt%-40wt%; The components of the hard alloy particles include WC: 60 wt%-70 wt%, TiC: 12 wt%-16 wt%, NbC: 5 wt%-7wt%, Cr2C3: 1 wt%-2 wt%, rare earth Ce: 0.6 wt%-1.2 wt%, and the rest is Co; The soft metal is Cu-Ni-Zn-Mn system material powder; The soft metal composition includes Cu: 76 wt%-80 wt%, Ni: 4 wt%-8 wt%, Mn: 5 wt%-8 wt%, and the remainder is Zn; The hard alloy particles are of a polygonal structure; The hardness of the hard alloy particles is HV1600-HV1800.

2. A method for manufacturing a rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools according to claim 1, characterized in that: include, S1. Wet-grinding and mixing the components of the hard alloy particles in an oxygen-free environment, drying and then adding a binder to mix the mixture evenly, pressing the mixture through a polygonal mold to obtain a polygonal alloy material, and sintering the pressed alloy material at a high temperature to obtain hard alloy particles; S2. Spread the hard alloy particles in the mold in proportion, place the mold in a hydrogen environment and heat it to 500±50°C, then spread the soft metal in proportion around the hard alloy particles in the mold, place the mold in a hydrogen environment again and heat it to 1200±50°C, keep it warm for 10-15 minutes, and then place it in a 200±50°C environment to cool it to obtain a rare earth-containing hard alloy sintered welding rod.

3. The method for manufacturing a rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools according to claim 2, characterized in that: The temperature during the wet grinding and mixing process does not exceed 26° C., and the wet grinding time is 25 h to 30 h.

4. The method for manufacturing a rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools according to claim 2, characterized in that: Anhydrous alcohol is added during the wet grinding and mixing process to maintain humidity and temperature.

5. The method for manufacturing a rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools according to claim 2, characterized in that: The polygonal mold is a triangular prism, a seven-pointed star or an eight-pointed star.

6. The method for manufacturing a rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools according to claim 2, characterized in that: The specific process of sintering the pressed alloy material under high temperature conditions is as follows: first, the pressed alloy material is placed in a sintering device to form a vacuum environment, then the temperature is raised from room temperature to 400±50°C, kept warm for 1h±0.2h, then the temperature is raised to 1000±50°C, kept warm for 1h±0.2h, and finally the temperature is raised to a sintering temperature of 1400±50°C, and the holding time is 8h±1h.

7. The method for manufacturing a rare earth-containing hard alloy sintered welding rod for surface welding of oil well repair tools according to claim 2, characterized in that: Before spreading the hard alloy particles, a layer of borax release agent is first spread on the bottom of the mold.

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