A method for laser cladding welding of high-entropy alloy mining picks

Abstract

The present invention relates to the technical field of clad welding of mining picks, and discloses a method for laser clad welding of mining picks with high-entropy alloy, including S1. Surface decontamination, cleaning the inner and outer surfaces of the hard alloy and the steel matrix seat of the mining pick; S2. Raw material preparation, using a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder and Ti elemental powder to form the original powder of CrCuFeNiTi high-entropy alloy; S3. Welding, synchronously sending the raw material of the laser clad layer to the middle connecting part between the hard alloy of the pick and the steel matrix seat, and melting the raw material of the laser clad layer by irradiation of a high-energy laser beam to form a welded joint of the CrCuFeNiTi high-entropy alloy laser clad layer; S4. Stress relief, soaking the laser clad welded joint in oil for quenching and ultrasonic stress relief to obtain the mining pick. The present invention can not only realize the control of the welding process, avoid thermal damage to the steel matrix seat and the hard alloy, and have a high welding efficiency, but also realize the effective chemical metallurgical bonding between the hard alloy of the pick and the steel matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of clad welding for mining picks, and particularly to a method for laser clad welding mining picks with high-entropy alloys. Background Art

[0002] Picks are widely used in the energy industry and are key components of mining machinery and equipment (such as roadheaders, shearers, etc.). By directly impacting and cutting ores, they achieve the crushing and collection of ores and are known as the "teeth" of mining machinery. Therefore, picks usually face harsh working environments such as severe impacts, complex stress and strain, and intense friction and wear. Their welding quality becomes a key factor in ensuring the stable operation of mining picks and has an important impact on the performance and service life of mining machinery and equipment.

[0003] Cemented carbide is the core material of mining picks and is connected to the steel base by welding. However, due to the significant difference in the thermal expansion coefficients of cemented carbide and steel, the welded joints of ordinary traditional processes are prone to defects (such as forming microcracks, pores, etc.) and have high brittleness, greatly reducing the strength of the welded joints. As a result, picks are prone to peeling from the steel base under high impact loads, causing pick failure. The invention patent (application number 201910270779.1) reported that by adding rare earth elements to the copper-based filler metal, the obtained welded joints have certain advantages (such as higher hardness), but also face the reality of high cost of rare earth elements resulting in low cost performance; the invention patent (application number 202410516369.1) proposed an improved connection structure between the cemented carbide and the steel base of the pick, but the overall wear resistance of the pick is limited; the laser welding process proposed in the invention patent (application number 202310992881.9) improves the welding efficiency, but the welding stress is not easy to control; the above factors ultimately lead to the welded joints being prone to fracture or cracking under impact loads.

[0004] Therefore, only by organically combining the selection of optimal filler metal components and the optimization of welding processes can the performance of the welded joints between the cemented carbide of the pick and the steel matrix base be further improved, ensuring the great potential of the "teeth" function of mining machinery is exerted. Summary of the Invention

[0005] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the problems existing in the above-mentioned existing method for laser clad welding mining picks with high-entropy alloys, the present invention is proposed.

[0007] The technical principle of the present invention is as follows: The CrCuFeNiTi high-entropy alloy has a stable multi-principal element solid solution structure and usually exhibits excellent physical and mechanical properties. By optimizing the special solder formula and laser cladding process, a CrCuFeNiTi high-entropy alloy clad layer welded joint is formed between the carbide of the pick and the steel matrix seat. At the same time, combined with subsequent quenching process and ultrasonic stress relief process, not only can a strong chemical metallurgical bond be formed between the carbide of the pick and the steel base, but also the hardness of the welded joint can be effectively improved. At the same time, the residual stress is greatly reduced, the generation of microcracks and pores is reduced, and the wear resistance of the mining pick is improved.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: A method for laser cladding welding of a mining pick with a high-entropy alloy. First, active elements Ti and Cr are added to the Ni-Cr-B-Si self-fluxing alloy, combined with Cu and Fe elements from the steel base, and the advantages of energy concentration, fast local heating, and easy control in the laser cladding welding process are fully utilized to avoid excessive heating and deformation of the steel base, so as to form a CrCuFeNiTi high-entropy alloy welded joint between the carbide and the steel base.

[0009] Secondly, through the B and Si elements in the Ni-Cr-B-Si self-fluxing alloy, the fluidity and wettability of the alloy in the high-temperature molten state are improved, so that chemical reactions occur between the Co, W, and C elements in the carbide and the Ti, Cr, etc. elements in the laser cladding layer raw material to form a compound layer.

[0010] Finally, combined with the ultrasonic stress relief process with the advantages of micro-amplitude, high frequency, and easy control, the CrCuFeNiTi high-entropy alloy clad layer welded joint after quenching is subjected to ultrasonic stress relief to improve the wear resistance of the welded joint and the overall service life of the pick.

[0011] As a preferred embodiment of the method for laser cladding welding of a mining pick with a high-entropy alloy of the present invention, it includes the following steps:

[0012] S1. Surface decontamination, cleaning the inner and outer surfaces of the carbide of the mining pick and the steel matrix seat, mechanically removing oxides with sandpaper, and removing oil stains and other impurities with alcohol and acetone;

[0013] S2. Raw material preparation, using a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder, and Ti elemental powder to form the original powder of the CrCuFeNiTi high-entropy alloy as the raw material for the laser cladding layer;

[0014] S3. Docking, synchronously sending the laser cladding layer raw material to the middle connection part between the carbide of the pick and the steel matrix seat, and irradiating it with a high-energy laser beam to melt the laser cladding layer raw material to form a CrCuFeNiTi high-entropy alloy laser cladding layer welded joint;

[0015] S4. Stress relief: Immerse the laser cladding welded joint in oil for quenching and perform ultrasonic stress relief to obtain a mining pick.

[0016] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S2, the mass ratio of Ni-Cr-B-Si, Cr, Cu, and Ti powders is (16~29):(22~31):(12~22):(19~34).

[0017] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S2, the original powder particle size ranges from 15 to 50 microns.

[0018] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S2, the purity of Cr elemental powder, Cu elemental powder, and Ti elemental powder is above 99%.

[0019] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S2, the mixing method is to ball mill the Ni-Cr-B-Si, Cr, Cu, and Ti mixed powders using a ball mill. The ball milling time is 8~10 h, and the rotational speed of the ball mill ranges from 60 to 200 r / min.

[0020] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S3, the laser cladding process conditions are that the argon shielding gas flow rate is 6~8 L / min, and the powder feeding rate is 8~12 g / min.

[0021] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S3, the spot diameter of the high-energy laser beam is 2~3 mm, the laser scanning speed is 1000~6000 mm / min, the power is 2~3 kW, and the overlapping rate is 40~60%. The thickness of the laser cladding layer is 2~3 mm.

[0022] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S4, the oil quenching temperature is room temperature, and the quenching time is 3~5 min.

[0023] As a preferred embodiment of the method for laser cladding welding a mining pick with a high-entropy alloy according to the present invention, wherein: in step S4, the ultrasonic stress relief parameters are ultrasonic power of 0.6~2 kW, ultrasonic amplitude of 1~10 microns, ultrasonic frequency of 20~40 kHz, and ultrasonic vibration aging treatment time of 10~40 min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. By forming a high-entropy alloy CrCuFeNiTi clad layer welded joint from Ni-Cr-B-Si self-fluxing alloy, Cu element, Ti and Cr active elements, and steel base Fe element in a high-temperature molten state, the present invention can not only chemically react with the carbide of the pick but also with the steel matrix base, thereby forming a stable compound layer at the bonding interface of the three components of carbide / CrCuFeNiTi clad layer / steel matrix base, which is beneficial to improving the bonding strength and firmness of the welded joint of the mining pick and significantly extending the service life of the mining pick.

[0026] 2. By optimizing the laser cladding welding process, the present invention can not only achieve welding process control, avoid thermal damage to the steel matrix base and carbide, and have a high welding efficiency, but also achieve effective chemical metallurgical bonding between the carbide of the pick and the steel matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. Among them:

[0028] Figure 1 It is the microhardness indentation and microstructure optical microscope image of the laser cladding welded joint area in Embodiment 1 of the present invention.

[0029] Figure 2 It is the scanning electron microscope image of the bonding area between the carbide and the high-entropy alloy clad layer of the present invention.

[0030] Figure 3 It is one of the enlarged views of the bonding area between the carbide and the high-entropy alloy clad layer of the present invention.

[0031] Figure 4 It is the second enlarged view of the bonding area between the carbide and the high-entropy alloy clad layer of the present invention, where the yellow line is the scanning path.

[0032] Figure 5 For Figure 4 the path of the yellow line in, it is the element analysis diagram obtained by scanning with an energy dispersive spectrometer (EDS) in the bonding area.

[0033] Figure 6 It is the optical microscope image of the laser cladding welding interface welded joint area of the comparative example of the present invention.

[0034] Figure 7SEM image of the welded joint area of the laser cladding welding interface in the comparative example of the present invention.

[0035] Figure 8 One of the SEM images of the Ni-Cu material in the comparative example of the present invention at the joint between the hard alloy of the mining pick and the steel matrix seat.

[0036] Figure 9 Another SEM image of the Ni-Cu material in the comparative example of the present invention at the joint between the hard alloy of the mining pick and the steel matrix seat.

[0037] Figure 10 Histogram comparing the microhardness of the laser cladding welding areas in the examples and comparative examples of the present invention. Detailed implementation manners

[0038] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present invention in conjunction with the accompanying drawings of the specification.

[0039] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0040] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that mutually excludes other embodiments.

[0041] Furthermore, the present invention is described in detail in conjunction with schematic diagrams. When detailing the embodiments of the present invention, for the sake of convenience of explanation, the cross-sectional views showing the device structure will be enlarged locally not in accordance with the general scale, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0042] Embodiment 1

[0043] Referring to Figures 1 to 5 , which is the first embodiment of the present invention, a method for laser cladding welding a mining pick with a high-entropy alloy is provided, including the following steps:

[0044] S1. Surface decontamination, cleaning the inner and outer surfaces of the hard alloy of the mining pick and the steel matrix seat, mechanically removing oxides with sandpaper, and removing oil stains and other impurities with alcohol and acetone;

[0045] S2. Raw material preparation: Use a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder, and Ti elemental powder to form the original powder of CrCuFeNiTi high-entropy alloy, which is used as the raw material for the laser cladding layer.

[0046] S3. Butt joint: Synchronously send the raw material of the laser cladding layer to the middle connection part between the pick carbide and the steel matrix seat. After being irradiated by a high-energy laser beam, the raw material of the laser cladding layer melts to form a welded joint of the CrCuFeNiTi high-entropy alloy laser cladding layer.

[0047] S4. Stress relief: Immerse the laser cladding welded joint in oil for quenching and use ultrasonic to relieve stress to obtain a mining pick.

[0048] Furthermore, in step S2, the mass ratio of the Ni-Cr-B-Si, Cr, Cu, and Ti powders is (16~29):(22~31):(12~22):(19~34).

[0049] Furthermore, in step S2, the particle size of the original powder is between 15 and 50 microns.

[0050] Furthermore, in step S2, the purity of the Cr elemental powder, Cu elemental powder, and Ti elemental powder is above 99%.

[0051] Furthermore, in step S2, the mixing method is to use a ball mill to ball mill the Ni-Cr-B-Si, Cr, Cu, and Ti mixed powders. The ball milling time is 8 to 10 h, and the rotation speed of the ball mill is between 60 and 200 r / min.

[0052] Furthermore, in step S3, the process conditions of the laser cladding are that the flow rate of the argon shielding gas is 6 to 8 L / min, and the powder feeding rate is 8 to 12 g / min.

[0053] Furthermore, in step S3, the spot diameter of the high-energy laser beam is 2 to 3 mm, the laser scanning speed is 1000 to 6000 mm / min, the power is 2 to 3 kW, and the overlapping rate is 40 to 60%. The thickness of the laser cladding layer is 2 to 3 mm.

[0054] Furthermore, in step S4, the oil quenching temperature is room temperature, and the quenching time is 3 to 5 min.

[0055] Furthermore, in step S4, the ultrasonic stress relief parameters are ultrasonic power of 0.6 to 2 kW, ultrasonic amplitude of 1 to 10 microns, ultrasonic frequency of 20 to 40 KHz, and ultrasonic vibration aging treatment time of 10 to 40 min.

[0056] Example 2

[0057] Refer to Figures 1 to 5, which is the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the content in Embodiment 1 is specified. Among them,

[0058] S1. Clean the inner and outer surfaces of the hard alloy and steel matrix seat of the mining pick. Mechanically remove oxides with sandpaper, and remove oil stains and other impurities with alcohol and acetone.

[0059] S2. Use a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder, and Ti elemental powder to form the original powder of CrCuFeNiTi high-entropy alloy as the raw material for the laser cladding layer. The mass ratio of the Ni-Cr-B-Si, Cr, Cu, and Ti powders is (16~29):(22~31):(12~22):(19~34). The purity of the Cr elemental powder, Cu elemental powder, and Ti elemental powder is above 99%. The particle size of the original powder is between 15 and 50 microns. Use a ball mill to ball mill the Ni-Cr-B-Si, Cr, Cu, and Ti mixed powders. The ball milling time is 8~10h, and the rotation speed of the ball mill is between 60 and 200r / min.

[0060] S3. Synchronously send the raw material of the laser cladding layer to the middle connection part between the hard alloy of the pick and the steel matrix seat, and melt the raw material of the laser cladding layer by irradiation with a high-energy laser beam to form a welded joint of the CrCuFeNiTi high-entropy alloy laser cladding layer. The laser cladding process conditions are that the argon shielding gas flow rate is 6~8L / min, and the powder feeding rate is 8~12g / min. The spot diameter of the high-energy laser beam is 2~3mm, the laser scanning speed is 1000~6000mm / min, the power is 2~3kw, and the overlapping rate is 40~60%. The thickness of the laser cladding layer is 2~3mm.

[0061] S4. Immerse the laser cladding welded joint in oil for quenching and remove stress by ultrasonic to obtain a mining pick. The oil quenching temperature is room temperature, and the quenching time is 3~5min. The ultrasonic stress relief parameters are ultrasonic power of 0.6~2kW, ultrasonic amplitude of 1~10 microns, ultrasonic frequency of 20~40KHz, and ultrasonic vibration aging treatment time of 10~40min.

[0062] The remaining steps are the same as those in the structure of Embodiment 1.

[0063] Embodiment 3

[0064] Refer to Figures 1 to 5 , which is the third embodiment of the present invention. The difference between this embodiment and the second embodiment is that it includes the following steps:

[0065] S1. Clean the inner and outer surfaces of the hard alloy and steel matrix seat of the mining pick. Mechanically remove oxides with sandpaper, and remove oil stains and other impurities with alcohol and acetone.

[0066] S2. The Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder, and Ti elemental powder are mixed using a ball mill to form the high-entropy alloy original powder as the raw material for the laser cladding layer. The chemical composition of the Ni-Cr-B-Si powder includes the following components by mass percentage: Cr: 17.6%, B: 3.5%, Si: 3.2%, C: 0.56%, and the rest is Ni. The particle size of the powder is less than 50 microns. The purity of the Cr elemental powder, Cu elemental powder, and Ti elemental powder is 99% - 99.7%. The mass ratio of Ni-Cr-B-Si, Cr, Cu, and Ti powders is 24:29:13:34. The Ni-Cr-B-Si, Cr, Cu, and Ti mixed powders are ball milled using a ball miller. The ball milling time is 7.5 h, and the rotational speed of the ball mill is 70 r / min.

[0067] S3. The raw material for the laser cladding layer is synchronously fed to the intermediate connection part between the pick carbide and the steel matrix seat, and is melted by irradiation with a high-energy laser beam to form a laser cladding welding layer. The process conditions for laser cladding are as follows: the flow rate of argon shielding gas is 6 L / min, and the powder feeding rate is 8 g / min. The spot diameter of the high-energy laser beam is 2 mm, the laser scanning speed is 1000 mm / min, the power is 2 kW, and the overlapping rate is 40%. The thickness of the laser cladding layer is 2.2 mm.

[0068] S4. The cladding welding layer is oil quenched and ultrasonically stress relieved to obtain a mining pick. The oil quenching temperature is room temperature, and the quenching time is 3 min. The ultrasonic stress relief parameters are: ultrasonic power 0.6 kW, ultrasonic amplitude 2 microns, ultrasonic frequency 20 KHz, and the ultrasonic vibration aging treatment time is 10 min.

[0069] The results show that with this high-entropy alloy laser cladding process, a dense metallurgical bond is formed at the connection between the cladding layer and the pick carbide and the steel matrix seat of the mining pick. The interfacial bonding strength is high, and there are no obvious crack or pore defects. The structure of the cladding layer is uniform and fine. The high-entropy alloy cladding layer has high hardness, good toughness and plasticity, ensuring that the connection is not prone to cracking under strong wear and impact loads, and significantly extending the service life of the welding joint of the mining pick.

[0070] Example 4

[0071] Refer to Figures 1 to 5 , which is the fourth embodiment of the present invention. The difference between this embodiment and the third embodiment is: A method for laser cladding welding of a mining pick with a high-entropy alloy, including the following steps:

[0072] S1. Clean the inner and outer surfaces of the pick carbide and the steel matrix seat of the mining pick. Mechanically remove oxides using sandpaper, and remove impurities such as oil stains using alcohol and acetone.

[0073] S2. Use a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder and Ti elemental powder to form the original high-entropy alloy powder as the raw material for the laser cladding layer. The chemical composition of the Ni-Cr-B-Si powder includes the following components by mass percentage: Cr: 16%, B: 3.6%, Si: 2.8%, C: 0.46%, and the rest is Ni. The particle size of the powder is less than 38 microns. The purity of the Cr elemental powder, Cu elemental powder and Ti elemental powder is 99.5% - 99.9%. The mass ratio of Ni-Cr-B-Si, Cr, Cu and Ti powders is 25:31:19:25. Use a ball mill to ball mill the Ni-Cr-B-Si, Cr, Cu, Ti mixed powder. The ball milling time is 10 h, and the rotation speed of the ball mill is 200 r / min.

[0074] S3. Synchronously feed the laser cladding layer raw material to the middle connection part between the pick carbide and the steel matrix seat, and irradiate it with a high-energy laser beam to melt the laser cladding layer raw material to form a laser cladding welding layer. The process conditions for laser cladding are that the argon shielding gas flow rate is 8 L / min, and the powder feeding rate is 12 g / min. The spot diameter of the high-energy laser beam is 3 mm, the laser scanning speed is 3000 mm / min, the power is 3 kw, and the overlapping rate is 60%. The thickness of the laser cladding layer is 3 mm.

[0075] S4. Oil quench and ultrasonically relieve stress on the cladding welding layer to obtain a mining pick. The oil quenching temperature is room temperature, and the quenching time is 5 min. The ultrasonic stress relief parameters are ultrasonic power 2 kW, ultrasonic amplitude 10 microns, ultrasonic frequency 40 KHz, and the ultrasonic vibration aging treatment time is 30 min.

[0076] The results show that using this high-entropy alloy material, a stable metallurgical bond is formed at the connection between the pick carbide and the steel matrix seat of the mining pick. The cladding layer is tightly and evenly bonded to the matrix without delamination. The strength and hardness of the connection area are significantly improved, the wear resistance and corrosion resistance are enhanced, effectively improving the overall performance of the mining pick, especially showing excellent anti-fatigue performance at the connection part.

[0077] Example 5

[0078] Refer to Figures 1 to 10 , which is the fifth embodiment of the present invention. The difference between this embodiment and the fourth embodiment is as follows: It includes the following steps:

[0079] S1. Clean the inner and outer surfaces of the mining pick carbide and the steel matrix seat, mechanically remove oxides with sandpaper, and remove oil stains and other impurities with alcohol and acetone.

[0080] S2. The Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder, and Ti elemental powder are mixed by a ball mill to form the raw powder of the high-entropy alloy as the raw material for the laser cladding layer. The chemical composition of the Ni-Cr-B-Si powder includes the following components by mass percentage: Cr: 13%, B: 2.8%, Si: 3.2%, C: 0.55%, and the rest is Ni. The particle size of the powder is less than 40 microns. The purity of the Cr elemental powder, Cu elemental powder, and Ti elemental powder is above 99% - 99.9%. The mass ratio of the Ni-Cr-B-Si, Cr, Cu, and Ti powders is 25:29:16:30. The Ni-Cr-B-Si, Cr, Cu, and Ti mixed powders are ball-milled by a ball mill. The ball-milling time is 9 h, and the rotation speed of the ball mill is 130 r / min.

[0081] S3. The raw material for the laser cladding layer is synchronously fed to the intermediate connection part between the pick cemented carbide and the steel matrix seat, and is melted by the irradiation of a high-energy laser beam to form a laser cladding welding layer. The process conditions for laser cladding are that the argon shielding gas flow rate is 7 L / min, and the powder feeding rate is 10 g / min. The spot diameter of the high-energy laser beam is 2.5 mm, the laser scanning speed is 6000 mm / min, the power is 2.5 kw, and the overlapping rate is 50%. The thickness of the laser cladding layer is 2.5 mm.

[0082] S4. The cladding welding layer is oil quenched and ultrasonically stress-relieved to obtain a mining pick. The oil quenching temperature is room temperature, and the quenching time is 4 min. The ultrasonic stress-relieving parameters are an ultrasonic power of 1.3 kW, an ultrasonic amplitude of 5 microns, an ultrasonic frequency of 30 KHz, and an ultrasonic vibration aging treatment time of 25 min.

[0083] The results show that through laser cladding, a strong metallurgical bond is formed between the high-entropy alloy and the connection part between the mining pick cemented carbide and the steel matrix seat. The interface transition is smooth and defect-free. The cladding layer is dense and uniform, and the hardness and wear resistance of the connection area are significantly improved, enhancing the impact resistance and wear resistance of the connection part, ensuring the stability and durability of the mining pick under complex working conditions. Energy dispersive spectrometer (EDS) analysis shows that element diffusion such as Al, Ti, and W occurs in the laser cladding layer area, proving the occurrence of chemical metallurgical bonding between the cemented carbide and the high-entropy alloy materials. Using this high-entropy alloy laser cladding process, a dense chemical metallurgical bond is formed between the cladding layer and the connection part between the mining pick cemented carbide and the steel matrix seat, with high interface bonding strength and no obvious crack or pore defects. The structure of the cladding layer is uniform and fine.

[0084] Comparative Example 1

[0085] Refer to Figures 5 to 10 , which is the first comparative example of the present invention. The difference between this example and the previous five examples is as follows: The steps include,

[0086] S1. Clean the inner and outer surfaces of the hard alloy and steel matrix seat of the mining pick. Mechanically remove oxides with sandpaper and remove oil stains and other impurities with alcohol and acetone.

[0087] S2. Use a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder and Cu elemental powder to form a commonly used Ni-Cu alloy solder as the raw material for the laser cladding layer. The chemical composition of the Ni-Cr-B-Si powder includes the following components by mass percentage: Cr: 14%, B: 3.4%, Si: 2.1%, C: 0.44%, and the rest is Ni. The particle size of the powder is less than 50 microns. The purity of the Cu elemental powder is 99% - 99.9% or more. The mass ratio of Ni-Cr-B-Si to Cu powder is 55:45. Use a ball mill to ball mill the Ni-Cr-B-Si and Cu mixed powder. The ball milling time is 8 h, and the rotation speed of the ball mill is 100 r / min.

[0088] S3. Synchronously send the raw material of the laser cladding layer to the middle connection part between the hard alloy of the pick and the steel matrix seat, and melt the raw material of the laser cladding layer by irradiation with a high-energy laser beam to form a welded joint. The process conditions of the laser cladding are as follows: the flow rate of the argon shielding gas is 7 L / min, and the powder feeding rate is 8 g / min. The spot diameter of the high-energy laser beam is 2.5 mm, the laser scanning speed is 5000 mm / min, the power is 2.5 kw, and the overlapping rate is 45%. The thickness of the laser cladding layer is 2 mm.

[0089] S4. Immerse the laser cladding welded joint in oil for quenching and remove stress by ultrasonic, and obtain the mining pick. The oil quenching temperature is room temperature, and the quenching time is 4 min. The ultrasonic stress removal parameters are as follows: the ultrasonic power is 1.2 kW, the ultrasonic amplitude is 4 microns, the ultrasonic frequency is 23 KHz, and the ultrasonic vibration aging treatment time is 30 min.

[0090] The results show that using Ni-Cu material can form a relatively stable metallurgical bond at the connection between the hard alloy of the mining pick and the steel matrix seat, but there are microcracks in the bonding interface area, resulting in the hardness of the connection area being similar to that of the steel matrix, and the hardness improvement is not as obvious as that in the embodiment of the present invention. Therefore, the strength of the welded joint is not effectively enhanced. Using Ni-Cu material can form a metallurgical bond at the connection between the hard alloy of the mining pick and the steel matrix seat, but the microstructure in this area is stratified and the bonding area is narrow, and there are microcracks at the bonding interface.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for laser cladding welding of high-entropy alloy mining picks, characterized in that: It includes the following steps: S1. Surface decontamination: Clean the inner and outer surfaces of the hard alloy and steel matrix seat of the mining pick. Mechanically remove oxides with sandpaper, and remove oil stains and other impurities with alcohol and acetone. S2. Raw material preparation: Use a ball mill to mix Ni-Cr-B-Si self-fluxing alloy powder, Cr elemental powder, Cu elemental powder, and Ti elemental powder to form the original powder of CrCuFeNiTi high-entropy alloy, which is used as the raw material for the laser cladding layer. S3. Welding: Synchronously send the raw material of the laser cladding layer to the middle connection part between the hard alloy of the pick and the steel matrix seat. The raw material of the laser cladding layer is melted by high-energy laser beam irradiation to form a welded joint of CrCuFeNiTi high-entropy alloy laser cladding layer. S4. Use a composite post-treatment process to relieve stress on the welded joint. The specific process is as follows: Immerse the laser cladding welded joint in oil for quenching. The oil quenching temperature is room temperature, and the quenching time is 3 - 5 minutes. Then, perform ultrasonic stress relief on the quenched welded joint. The ultrasonic power is 0.6 - 2 kW, the ultrasonic amplitude is 1 - 10 microns, the ultrasonic frequency is 20 - 40 KHz, and the ultrasonic vibration aging treatment time is 10 - 40 minutes to finally obtain the mining pick. In step S2, the mass ratio of the Ni-Cr-B-Si, Cr, Cu, and Ti powders is: (16 - 29):(22 - 31):(12 - 22):(19 - 34). In step S2, the particle size of the original powder is between 15 - 50 microns. In step S2, the purity of the Cr elemental powder, Cu elemental powder, and Ti elemental powder is above 99%.

2. The method for laser cladding and welding a mining pick with a high-entropy alloy according to claim 1, characterized in that: In step S2, the mixing method is to use a ball mill to ball mill the Ni-Cr-B-Si, Cr, Cu, and Ti mixed powders. The ball milling time is 8 - 10 hours, and the rotation speed of the ball mill is between 60 - 200 r / min.

3. The method for laser cladding welding of high-entropy alloy mining picks according to claim 2, characterized in that: In step S3, the process conditions of the laser cladding are that the argon shielding gas flow rate is 6 - 8 L / min, and the powder feeding rate is 8 - 12 g / min.

4. The method for laser cladding welding of high-entropy alloy mining picks according to claim 3, characterized in that: In step S3, the spot diameter of the high-energy laser beam is 2 - 3 mm, the laser scanning speed is 1000 - 6000 mm / min, the power is 2 - 3 kW, the overlapping rate is 40 - 60%, and the thickness of the laser cladding layer is 2 - 3 mm.

Images