Manufacturing process of mining composite casting and forging wear-resistant cutting pick

Abstract

The invention discloses a manufacturing process of a mining composite cast-forged wear-resistant cutting pick, which is characterized in that a cutting pick base body is made of 42CrMo steel, a tungsten-cobalt hard alloy tool bit is assembled on the base body after forging, quenching and low-temperature tempering, the tool bit and the base body are welded by adopting a laser cladding technology, ultrasonic impact treatment is carried out after welding, and finally the cutting pick is subjected to finish machining and shot blasting cleaning, so that the mining composite cast-forged wear-resistant cutting pick is obtained. And thus, a finished cutting pick workpiece is obtained. By designing the laser cladding process, the defect problems of uneven welding, cracks, holes and the like can be avoided, the process improvement is further combined, the wear resistance of the cladding layer is improved by optimizing the performance of the hard alloy for the wear-resistant part, and the high-strength mining composite casting and forging wear-resistant cutting pick can be obtained.

Description

Technical Field

[0001] The invention relates to the field of metal material processing, and in particular to a manufacturing process of a composite cast and forged wear-resistant mining pick. Background Art

[0002] The pick is a wear-resistant part made of cemented carbide. As a key component of tunnel boring machines and coal mining machines, it is responsible for cutting and crushing coal rocks during the coal mining process. However, in the process of coal mining, the pick is subject to severe impact and cyclic stress from the coal rocks. The pick is often prone to wear, fracture, deformation and other problems, leading to pick failure. According to incomplete statistics, wear and fracture at the weld of the pick accounts for 80% of its failure cases, and the vast majority of wear and fracture are due to defects in the connection between the carbide cutter head and the substrate, which reduces the strength of the pick. Therefore, improving the wear resistance of the pick has become an important issue that needs to be urgently addressed in the field of coal mining. Among the existing strengthening technologies, laser cladding technology has become a surface strengthening method that has attracted much attention due to its advantages such as high energy density, small heat-affected zone and rapid cooling.

[0003] CN101446199A discloses a diamond-impregnated composite high-wear-resistant pick and a manufacturing process thereof. The pick comprises a steel tooth body, a tooth head, and a composite tooth tip, wherein the composite tooth tip is brazed to the middle of the tooth head. The steel tooth body and the tooth head are directly sintered into one piece by powder metallurgy using a hot pressing process. The raw materials of the tooth head include matrix powder and diamond. The matrix powder contains a certain proportion of cobalt powder, nickel powder, iron powder, copper powder, manganese powder, tin powder, chromium powder, and tungsten carbide powder. The diamond particle size is 0.42mm to 0.074mm, and the volume of the diamond accounts for 5% to 50% of the volume of the tooth head. The process includes the steps of matrix powder mixing, working layer material mixing, hot pressing and sintering, sandblasting, and brazing. The pick of the present invention has high working efficiency and long service life and is suitable for use in equipment such as coal mining, mining, and drilling.

[0004] CN110026540A relates to a method for producing a composite cast and forged wear-resistant pick, comprising seven steps: mold preheating, alloy cutter head preparation, mold secondary processing, casting, forging, annealing, and finishing. The present invention has a simple production process, high production efficiency, and effectively improves the hardness and wear resistance of the pick, thereby achieving the purpose of extending the service life of the pick and the operating efficiency of the pick. In addition, the present invention overcomes the defects of poor connection structure stability and insufficient mechanical strength caused by the inconsistent material between the traditional cemented carbide body and the supporting metal body, effectively meeting the excavation and mining of various medium-hard rock formations and coal seams, and has good versatility and environmental adaptability. At the same time, it extends the service life of the pick, improves the efficiency of excavation and mining operations, reduces operating costs, effectively reduces the number of equipment repairs and replacements, and reduces the labor intensity and working time of workers, resulting in considerable economic and social benefits.

[0005] In summary, although the current manufacturing process of wear-resistant mining picks has improved the service life of the picks to a certain extent, there is no strengthening process for the connection between the carbide cutter head of the pick and the matrix. This is the connection between two different materials and is prone to defects such as small cracks and holes. Once these defects occur, the wear resistance of the pick will be reduced, and the strength will be further reduced, causing the pick to break and fail to achieve the expected service life. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a manufacturing process for composite cast and forged wear-resistant mining picks, which strengthens the connection between the alloy cutter head and the substrate through laser cladding technology, and strengthens the surface of the connection between the pick substrate and the cutter head to eliminate hardness mutations and small cracks, holes and other defects at the connection between the alloy cutter head and the substrate. By optimizing the performance of cemented carbide for wear-resistant parts, an excellent cladding layer is formed on the surface of the pick, which can effectively improve the strength, wear resistance and corrosion resistance of the pick, thereby extending its service life, reducing the replacement frequency, and improving the efficiency and safety of coal mining.

[0007] To achieve the above object, the technical solution of the present invention is: A mining composite cast and forged wear-resistant pick, comprising a base and a cutter head connected to the base. The material of the substrate is 42CrMo steel, which is obtained by forging, quenching, and low-temperature tempering; The material of the cutter head is tungsten-cobalt hard alloy; The cutter head and the substrate are welded together by laser cladding. The cladding powder used in the laser cladding welding comprises, by weight, 55-75 parts of high entropy alloy powder, 20-30 parts of tungsten carbide powder, 5-10 parts of titanium carbide powder and 1-5 parts of rare earth powder.

[0008] The cutter head of the pick is used to mine hard ores, so it needs to be made of tungsten-cobalt cemented carbide with very high hardness. The matrix connected to the cutter head needs to have a certain strength and toughness. It uses 42CrMo steel, which is quenched after forging and tempered at low temperature. After that, a hole for assembling the cutter head is processed on the matrix. Due to the certain gap in hardness between the two, the traditional process of welding the cutter head and the matrix will cause a sudden change in hardness from the matrix to the cutter head. At the same time, cracks, holes and other defects are prone to appear at the connection, making the connection prone to breakage. The present invention adds high-entropy alloy powder, tungsten carbide powder, titanium carbide powder, and rare earth powder, pre-treats these powders before laser cladding, grinds these powders in a medium-free airflow to obtain pre-coated composite powder, and uses laser cladding technology to melt the powder and then cool and solidify it. Due to the friction between tungsten carbide and metal powder during the airflow grinding process, the tungsten carbide particles can be chamfered, making the particle surface smoother. At the same time, part of the metal is wrapped on the surface of the tungsten carbide particles with the help of frictional heat, thereby improving the compatibility with the high-entropy alloy powder body and better dispersing it after cladding. The performance is further improved through heat treatment and ultrasonic impact treatment, avoiding the sudden change of hardness from the matrix to the cutter head. At the same time, the addition of titanium carbide powder can strengthen the crystal structure and lattice, improve the mechanical properties of the connection, and enhance the wear resistance of the pick surface. The addition of rare earth powder can refine the grains and improve the overall strength of the material.

[0009] The powder pre-wrapping treatment disclosed in the present invention is followed by the use of laser cladding technology to weld the substrate and the carbide cutter head together. This has obvious advantages over the traditional brazing technology for connecting the carbide cutter head and the substrate. The traditional brazing technology may have defects such as uneven welding, cracks, and holes, which reduce the connection strength between the carbide head and the substrate and cause the pick to break.

[0010] In the manufacturing process of this solution, the substrate is made of 42CrMo steel. Through multiple forging processes such as upsetting and drawing, the internal structure of the steel is improved to make it more dense and uniform, thereby improving the comprehensive mechanical properties of the substrate. At the same time, the blank is forged into a shape and size close to the cutter body, quenched and low-temperature tempered, so that the hardness of the substrate is maintained at HRC45-50. A hole for assembling the cutter head is machined on the substrate. The cutter head uses tungsten-cobalt cemented carbide and is placed in the hole of the substrate to ensure a close fit with the substrate. The cutter head is welded to the substrate using laser cladding technology. The cladding powder used for laser cladding welding includes, by weight, 55-75 parts of high-entropy alloy powder, 20-30 parts of tungsten carbide powder, 5-10 parts of titanium carbide powder, and 1-5 parts of rare earth powder. The powder is pre-wrapped before welding and then dried. To prevent cracks in the cladding layer, the metal substrate must be heated to 200°C in a heating furnace before laser cladding. The cladding powder is then transported to the connection between the substrate and the cutter head through a coaxial powder feeding device. After laser cladding is completed, the pick is placed in quenching oil for cooling. This ensures that the cladding layer has high strength and hardness while avoiding quenching cracking caused by excessive quenching thermal stress. Ultrasonic impact treatment is then performed to eliminate the stress generated by laser cladding and improve fatigue performance. Finally, the pick is finely machined, shot blasted, and the surface of the processed pick blank is shot blasted to remove excess impurities, thereby obtaining a finished pick workpiece.

[0011] The present invention further discloses a manufacturing process of the above-mentioned composite cast and forged wear-resistant mining pick, which comprises the following steps: Step (1): 42CrMo steel is selected as the substrate, which is quenched and low-temperature tempered after forging to maintain its hardness at HRC45-50. A hole for assembling the cutter head is machined on the substrate. The cutter head is made of tungsten-cobalt cemented carbide. The cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): welding the cutter head to the substrate using laser cladding welding technology, wherein the cladding powder used for laser cladding welding comprises, by weight, 55-75 parts of high entropy alloy powder, 20-30 parts of tungsten carbide powder, 5-10 parts of titanium carbide powder and 1-5 parts of rare earth powder; Step (3): The cladding powder obtained in step (2) is transported to the surface of the pick to be strengthened through a coaxial powder feeding device, the laser power is 1.5-2.0kW, the scanning speed is 0.6-3.0mm / s, the spot diameter is 2-4mm, the powder feeding rate is 40-50g / min, the protective gas is argon, and the flow rate is 10-20L / min. After the laser cladding is completed, the pick is placed in quenching oil for cooling, and then the pick is subjected to ultrasonic impact treatment; Step (4): Finishing, shot blasting and cleaning the pick.

[0012] Preferably, in step (1), the forging temperature of the forging process is 1050-1150°C, the forging ratio is 3:1, the quenching temperature is 920°C, the quenching medium is quenching oil, and the tempering temperature is 200°C; Preferably, in step (2), the high entropy alloy powder is a FeCoCrNiAl alloy, and its composition by mass is: 25-35 parts of iron powder, 20-30 parts of cobalt powder, 15-25 parts of chromium powder, 10-20 parts of nickel powder, and 5-10 parts of aluminum powder; The particle size of the tungsten carbide powder is 100-150 μm, and the purity is ≥99.5%; The titanium carbide powder has a particle size of 1-10 μm and a purity of ≥99.9%; The rare earth powder is a rare earth containing yttrium or lanthanum, and has a particle size of 1-5 μm; preferably, the preparation method of the cladding powder is: high entropy alloy powder, tungsten carbide powder, titanium carbide powder and rare earth powder are put into a medium-free airflow in proportion and ground, the grinding pressure is 0.8-1 MPa, and the average particle size is ground to 80-120 μm, the working gas flow rate is ≥400 m / s, and inert gas protection is used to finally obtain pre-wrapped composite powder; the pre-wrapped composite powder contains tungsten carbide particles, which avoids the sudden change of hardness from the matrix to the cutter head. At the same time, the addition of titanium carbide powder can strengthen the crystal structure and lattice, improve the mechanical properties of the connection, and enhance the wear resistance of the pick surface. The addition of rare earth powder can refine the grains and improve the overall strength of the material. The pre-wrapped composite powder needs to be dried at a temperature of 80-120°C for 1-3 hours, with the moisture content controlled at ≤0.1%. If the grinding pressure is too high, the pre-wrapped composite powder particles will be too fine and easily agglomerated. If the grinding pressure is too low, the pre-wrapped composite powder particles will be too coarse and still have or have a small amount of edges and corners, which will lead to a decrease in performance.

[0013] Preferably, in step (3), in order to avoid cracks after cladding, the pick base is preheated to 200°C before laser cladding. The pre-wrapped composite powder obtained in step (2) is delivered to the surface of the pick to be strengthened through a coaxial powder feeding device, with a laser power of 1.5-2.0kW, an overlap rate of 30-50%, a scanning speed of 0.6-3.0mm / s, a spot diameter of 2-4mm, a powder feeding rate of 40-50g / min, and a protective gas of argon at a flow rate of 10-20L / min.

[0014] Preferably, in step (3), after the laser cladding is completed, the material is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment, with an ultrasonic frequency of 20-40 kHz, an amplitude of 10-30 μm, and a duration of 5-15 min.

[0015] Preferably, in step (4), the pick is finely processed, shot blasted, and cleaned.

[0016] Conduct bonding strength test on the pick and observe whether there are defects such as cracks and holes on the cross section of the cladding layer.

[0017] Compared with the prior art, the present invention has the following advantages: 1. The present invention can avoid the occurrence of defects such as uneven welding, cracks and holes through laser cladding. By optimizing the composition of the cladding powder and the pretreatment process to optimize the performance of cemented carbide for wear-resistant parts, the quality of the cladding layer is significantly improved, and it has better strength and hardness.

[0018] 2. After cladding, ultrasonic impact is used for stress relief treatment to further remove residual stress and improve fatigue performance, greatly extending the service life of the cutting teeth. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a microscopic morphology of the cladding layer described in Example 1 of the present invention; Figure 2 This is a microscopic morphology of the cladding layer described in Comparative Example 1 of the present invention; Figure 3 This is a microscopic morphology of the soldering layer described in Comparative Example 2 of the present invention; Figure 4 This is a microscopic morphology of the cladding layer described in Comparative Example 8 of the present invention. DETAILED DESCRIPTION

[0020] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention. Example 1

[0021] A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 60 parts of FeCoCrNiAl high entropy alloy powder, 28 parts of tungsten carbide powder, 9 parts of titanium carbide powder, and 3 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 100 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0022] The bonding strength test of the pick was conducted, and the result was 460MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are no defects such as cracks and holes in the cladding layer, and the tungsten carbide particles are evenly distributed in the cladding layer. Figure 1 . Example 2

[0023] A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 55 parts of FeCoCrNiAl high entropy alloy powder, 30 parts of tungsten carbide powder, 10 parts of titanium carbide powder, and 5 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa and a grinding time of 100 to 2000 rpm. The average particle size is 80 μm and an inert gas is used for protection to finally obtain a pre-wrapped composite powder. The pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 h and a moisture content is controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0024] The bonding strength test of the pick was conducted, and the result was 440MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are no defects such as cracks and holes in the cladding layer, and the tungsten carbide particles are evenly distributed in the cladding layer. Example 3

[0025] A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 74 parts of FeCoCrNiAl high entropy alloy powder, 20 parts of tungsten carbide powder, 5 parts of titanium carbide powder, and 1 part of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 120 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0026] The bonding strength test of the pick was conducted, and the result was 450MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are no defects such as cracks and holes in the cladding layer, and the tungsten carbide particles are evenly distributed in the cladding layer.

[0027] Comparative Example 1 The difference from Example 1 is that the powder is not pre-packaged: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): Take 60 parts of FeCoCrNiAl high entropy alloy powder, 28 parts of tungsten carbide powder, 9 parts of titanium carbide powder, and 3 parts of rare earth powder, mix them evenly and dry them at a drying temperature of 100°C for 2 hours, and control the moisture content to ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0028] The bonding strength test of the pick was conducted and the result was 280MPa. The cross-section sample of the pick was taken and observed under an optical microscope after being inlaid, ground and polished. It can be clearly seen that the tungsten carbide particles in the cladding layer are irregular. Figure 2 As shown by the arrows, there are a large number of sharp corners and holes on the surface of some particles.

[0029] Comparative Example 2 The difference from Example 1 is that a traditional welding process is used: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): preheating the cutter base to 200°C and welding the cutter head and base using a conventional brazing process; Step (4): Finishing, shot blasting and cleaning the pick.

[0030] The bonding strength test of the pick was conducted and the result was 200MPa. The cross-section sample of the pick was taken and observed under an optical microscope after being inlaid, ground and polished. It can be clearly seen that there are holes in the cladding layer. Figure 3 As indicated by the arrow.

[0031] Comparative Example 3 The difference from Example 1 is that the substrate is not preheated to 200°C before laser cladding: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 60 parts of FeCoCrNiAl high entropy alloy powder, 28 parts of tungsten carbide powder, 9 parts of titanium carbide powder, and 3 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 80 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): The cladding powder obtained in step (2) is transported to the surface of the pick to be strengthened through a coaxial powder feeding device, the laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment, the ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min; Step (4): Finishing, shot blasting and cleaning the pick.

[0032] The bonding strength test of the pick was conducted, and the result was 380MPa. The cross-section sample of the pick was taken, inlaid, polished and then observed under an optical microscope. It can be clearly observed that there are defects such as cracks and holes in the cladding layer, and tungsten carbide particles are aggregated.

[0033] Comparative Example 4 The difference from Example 1 is that 30 parts of FeCoCrNiAl high entropy alloy powder, 50 parts of tungsten carbide powder, 15 parts of titanium carbide powder, and 5 parts of rare earth powder are taken: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 30 parts of FeCoCrNiAl high entropy alloy powder, 50 parts of tungsten carbide powder, 15 parts of titanium carbide powder, and 5 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 80 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0034] The bonding strength test of the pick was conducted, and the result was 290MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are cracks and holes in the cladding layer, and tungsten carbide particles are aggregated.

[0035] Comparative Example 5 The difference from Example 1 is that 40 parts of FeCoCrNiAl high entropy alloy powder, 40 parts of tungsten carbide powder, 15 parts of titanium carbide powder, and 5 parts of rare earth powder are taken: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 40 parts of FeCoCrNiAl high entropy alloy powder, 40 parts of tungsten carbide powder, 15 parts of titanium carbide powder, and 5 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 80 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0036] The bonding strength of the pick was tested and the result was 300MPa. The cross-section sample of the pick was taken, inlaid, polished and then observed under an optical microscope. It can be clearly observed that there are cracks and holes in the cladding layer, and tungsten carbide particles are aggregated.

[0037] Comparative Example 6 The difference from Example 1 is that 80 parts of FeCoCrNiAl high entropy alloy powder, 10 parts of tungsten carbide powder, 8 parts of titanium carbide powder, and 2 parts of rare earth powder are taken: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 80 parts of FeCoCrNiAl high entropy alloy powder, 10 parts of tungsten carbide powder, 8 parts of titanium carbide powder, and 2 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 80 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0038] The bonding strength of the pick was tested and the result was 330MPa. A cross-section sample of the pick was taken, inlaid, polished and then observed under an optical microscope. It can be clearly observed that there are cracks and holes in the cladding layer, and tungsten carbide particles are aggregated.

[0039] Comparative Example 7 The difference from Example 1 is that 85 parts of FeCoCrNiAl high entropy alloy powder, 5 parts of tungsten carbide powder, 6 parts of titanium carbide powder, and 4 parts of rare earth powder are taken: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 85 parts of FeCoCrNiAl high entropy alloy powder, 5 parts of tungsten carbide powder, 6 parts of titanium carbide powder, and 4 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 80 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0040] The bonding strength test of the pick was conducted, and the result was 320MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are cracks and holes in the cladding layer, and tungsten carbide particles are aggregated.

[0041] Comparative Example 8 The difference from Example 1 is that the grinding pressure is too large: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 60 parts of FeCoCrNiAl high entropy alloy powder, 28 parts of tungsten carbide powder, 9 parts of titanium carbide powder, and 3 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 1.2 MPa to an average particle size of 70 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0042] The bonding strength test of the pick was conducted, and the result was 390MPa. The cross-section sample of the pick was taken, inlaid, polished and then observed under an optical microscope. It can be clearly observed that there are no defects such as cracks and holes in the cladding layer. The tungsten carbide particles are distributed in the cladding layer, and some particles are agglomerated. Figure 4 shown.

[0043] Comparative Example 9 The difference from Example 1 is that the grinding pressure is too small: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 60 parts of FeCoCrNiAl high entropy alloy powder, 28 parts of tungsten carbide powder, 9 parts of titanium carbide powder, and 3 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.7 MPa to an average particle size of 130 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0 kW, the overlap rate is 30%, the scanning speed is 1.5 mm / s, the spot diameter is 2 mm, the powder feeding rate is 40 g / min, the protective gas is argon, and the flow rate is 10 L / min. After the laser cladding is completed, it is placed in quenching oil for cooling, and then subjected to ultrasonic impact treatment. The ultrasonic frequency is 30 kHz, the amplitude is 20 μm, and the duration is 10 min. Step (4): Finishing, shot blasting and cleaning the pick.

[0044] The bonding strength test of the pick was conducted, and the result was 380MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are no defects such as cracks and holes in the cladding layer, and the tungsten carbide particles are evenly distributed in the cladding layer.

[0045] Comparative Example 10 The difference from Example 1 is that after the laser cladding is completed, the sample is placed in quenching oil for cooling and no ultrasonic impact treatment is performed afterwards: A manufacturing process for a composite cast and forged wear-resistant mining pick is described through the following steps: Step (1): a 42CrMo steel substrate is forged at 1100°C with a forging ratio of 3:1, then heated to 920°C, cooled in quenching oil, and then tempered in a heat treatment furnace at a tempering temperature of 200°C. A hole for assembling a cutter head is machined on the substrate, and a tungsten-cobalt carbide cutter head is placed in the hole of the substrate and is tightly fitted to the substrate. Step (2): 60 parts of FeCoCrNiAl high entropy alloy powder, 28 parts of tungsten carbide powder, 9 parts of titanium carbide powder, and 3 parts of rare earth powder are taken and ground in a medium-free airflow at a grinding pressure of 0.8 MPa to an average particle size of 100 μm. Inert gas protection is used to finally obtain a pre-wrapped composite powder, and the pre-wrapped composite powder is dried at a drying temperature of 100°C for 2 hours, with the moisture content controlled at ≤0.1%; Step (3): preheat the pick base to 200°C, and deliver the cladding powder obtained in step (2) to the surface of the pick to be strengthened through a coaxial powder feeding device. The laser power is 2.0kW, the overlap rate is 30%, the scanning speed is 1.5mm / s, the spot diameter is 2mm, the powder feeding rate is 40g / min, the protective gas is argon, and the flow rate is 10L / min. After the laser cladding is completed, it is placed in quenching oil for cooling; Step (4): Finishing, shot blasting and cleaning the pick.

[0046] The bonding strength test of the pick was conducted, and the result was 370MPa. The cross-section sample of the pick was taken, inlaid, ground and polished, and then observed under an optical microscope. It can be clearly observed that there are no defects such as cracks and holes in the cladding layer, and the tungsten carbide particles are evenly distributed in the cladding layer.

[0047] Detect the hardness of the cladding layer and substrate; Test the wear resistance of the cladding layer: Based on the actual working conditions of the pick in coal mining, which is subjected to coal and rock cutting and scraping, a friction and wear test is conducted (in accordance with GB / T12444-2006 "Metallic Materials Wear Test Methods - Test Ring-Test Block Sliding Wear Test"). The specific operation is as follows: Sample preparation: Samples were taken from the cladding layer area of ​​the picks of each embodiment / comparative example and processed into block samples of 12 mm × 12 mm × 19 mm. The surface was polished in stages with 400#-1200# sandpaper to a roughness Ra ≤ 0.8 μm, cleaned, and dried for later use.

[0048] Test parameter setting: Experimental temperature: 23℃±5℃; Experimental environment: should be carried out in an environment without vibration, corrosive gas and dust; Load: 200N (corresponding to the average contact load when the pick cuts coal and rock); Test ring speed: 180r / min; Wear time: 30 min (to avoid excessive wear that may lead to substrate exposure, while ensuring that the wear volume can be quantified); Cleaning and weighing: Clean with cleaning solution, dry at 60℃ for 2h after cleaning, put into desiccator after cooling to room temperature, and weigh immediately after 2h.

[0049] Data collection and calculation: Use an electronic balance with an accuracy of 0.1 mg to measure the mass of the sample before and after wear (recorded as m1 and m2), and calculate the mass loss Δm=m1-m2; Taking Example 1 as the benchmark (its cladding layer has the best performance, and the relative wear amount is set to 1.0), the relative wear amount of other groups = (Δm of this group / Δm of Example 1). The smaller the value, the better the wear resistance.

[0050] The performance data comparison of the embodiment and the comparative example is shown in Table 1.

[0051] Table 2 Performance data of examples and comparative examples Group Bonding strength (MPa) crack holes Tungsten carbide distribution shape Matrix hardness (HRC) Cladding layer hardness (HRC) Wear resistance (relative wear amount) Example 1 460 none none Uniform 48±2 60±1 1.0 (baseline) Example 2 440 none none Uniform 48±2 61±1 1.05 Example 3 450 none none Uniform 48±2 59±1 0.98 Comparative Example 1 280 have Small amount Various shapes, multi-angle 48±2 55±1 2.3 Comparative Example 2 200 have many / 48±2 38±1 3.8 Comparative Example 3 380 Small amount Small amount Uniform 48±2 56±1 1.8 Comparative Example 4 290 none none Uniform 48±2 57±1 1.9 Comparative Example 5 300 none none Uniform 48±2 58±1 1.7 Comparative Example 6 330 none none Uniform 48±2 54±1 2.1 Comparative Example 7 320 none none Uniform 48±2 53±1 2.4 Comparative Example 8 390 none none reunion 48±2 57±1 1.6 Comparative Example 9 380 none none Coarse particles with a few edges and corners 48±2 56±1 1.5 Comparative Example 10 400 none none Uniform 48±2 59±1 1.4 The embodiment uses a powder pre-wrapping treatment of medium-free airflow grinding to not only make the tungsten carbide particles chamfered and smooth under the action of friction, but also use frictional heat to wrap part of the metal on its surface, which greatly improves the compatibility with high-entropy alloy powder and lays the foundation for the uniform dispersion of particles during subsequent laser cladding. At the same time, the substrate is preheated to a specific temperature before laser cladding, which effectively relieves the thermal stress generated during the rapid heating and cooling process of the laser and avoids crack initiation. After cladding, quenching and oil cooling ensure the strength and hardness of the cladding layer. Subsequent ultrasonic impact treatment further eliminates residual stress and optimizes tissue stability. In addition, the reasonable ratio of high-entropy alloy, tungsten carbide, titanium carbide and rare earth powder - high-entropy alloy provides basic toughness and bonding ability, tungsten carbide and titanium carbide provide basic toughness and bonding ability. Titanium as a reinforcing phase improves hardness and wear resistance, and rare earth refines grains to strengthen overall performance, ultimately forming a crack-free, hole-free, and tightly bonded cladding layer; while in Comparative Example 1, since no powder pre-wrapping treatment was performed, the tungsten carbide particles retained a large number of edges and corners, and had poor compatibility with high-entropy alloy powders. During laser cladding, stress concentration was easily generated at the edges and corners, which in turn caused cracks. Uneven particle dispersion also led to local holes, which destroyed the organizational integrity of the cladding layer, making the performance far inferior to that of the embodiment; Comparative Example 2 adopted traditional brazing technology, relying on low-melting-point brazing material to connect the cutter head and the substrate, and could not form a metallurgical bond like laser cladding. The brazing material itself had low strength, and a large number of pores and cracks were easily generated due to uneven temperature control during welding, resulting in poor connection between the cutter head and the substrate. The bonding strength dropped significantly, and the performance gap was significant; in Comparative Example 3, the substrate was not preheated before laser cladding, and the substrate and the cladding layer generated huge thermal stress under the laser rapid thermal cycle. When the thermal stress exceeded the material's bearing limit, cracks in the cladding layer would be caused. At the same time, the thermal stress would also destroy the bonding state between the particles and the substrate, resulting in a small number of holes, which weakened the overall performance of the cladding layer; Comparative Examples 4-7 deviated from the optimized powder ratio in the embodiment, wherein the proportion of high entropy alloy powder in Comparative Example 4-5 was too low, and the proportion of tungsten carbide and titanium carbide was too high. Excessive hard particles exceeded the bearing capacity of the high entropy alloy substrate, and stress concentration was easily formed between the particles, causing cracks and holes, and the particles were difficult to disperse evenly. In Comparative Examples 6-7, the proportion of high entropy alloy powder was too high , the proportion of tungsten carbide is too low, and the insufficient reinforcement phase cannot provide sufficient hardness and wear resistance support for the cladding layer. At the same time, the excessive amount of high-entropy alloy will also lead to a decrease in the overall organizational stability of the cladding layer, which makes the performance weaker than that of the embodiment; Comparative Example 8 has too high a grinding pressure, the pre-wrapped composite powder particles are too fine, the surface energy of the fine particles is high, and they are prone to agglomeration. During laser cladding, the agglomerated particles cannot be evenly dispersed, forming local weak performance areas in the cladding layer, reducing the overall bonding strength and wear resistance; Comparative Example 9 has too low a grinding pressure, the pre-wrapped composite powder particles are too coarse and still retain some edges and corners, the coarse particles are difficult to fully combine with the substrate, stress concentration is easily generated at the edges and corners, and the gaps between the particles will also affect the density of the cladding layer, resulting in performance inferior to that of the embodiment;Although Comparative Example 10 exhibits good hardness and metallographic structure, the absence of ultrasonic impact treatment after laser cladding results in residual stresses not being eliminated, resulting in slightly poor structural stability. Localized stress concentration during wear and stress loading can accelerate material loss, and bonding and wear resistance are also somewhat lower than those of the examples.

[0052] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A composite cast and forged wear-resistant mining pick, characterized in that: including a base and a cutting head connected to the base, The material of the substrate is 42CrMo steel, which is quenched after forging and tempered at low temperature to obtain a hardness of HRC45-50; The material of the cutter head is tungsten-cobalt hard alloy; The cutter head and the substrate are welded together by laser cladding. The cladding powder used in the laser cladding welding comprises, by weight, 55-75 parts of high entropy alloy powder, 20-30 parts of tungsten carbide powder, 5-10 parts of titanium carbide powder and 1-5 parts of rare earth powder.

2. A process for manufacturing a composite cast and forged wear-resistant mining pick according to claim 1, characterized in that: The following steps are involved: Step (1): 42CrMo steel is selected as the substrate, which is quenched and low-temperature tempered after forging to maintain its hardness at HRC45-50, a hole for assembling the cutter head is machined on the substrate, and the cutter head made of tungsten-cobalt cemented carbide is placed into the hole of the substrate and is tightly fitted to the substrate; Step (2): welding the cutter head to the substrate using laser cladding welding technology, wherein the cladding powder used for laser cladding welding comprises, by weight, 55-75 parts of high entropy alloy powder, 20-30 parts of tungsten carbide powder, 5-10 parts of titanium carbide powder and 1-5 parts of rare earth powder; Step (3): The cladding powder obtained in step (2) is transported to the surface of the pick to be strengthened through a coaxial powder feeding device, the laser power is 1.5-2.0kW, the scanning speed is 0.6-3.0mm / s, the spot diameter is 2-4mm, the powder feeding rate is 40-50g / min, the protective gas is argon, and the flow rate is 10-20L / min. After the laser cladding is completed, the pick is placed in quenching oil for cooling, and then the pick is subjected to ultrasonic impact treatment; Step (4): Finishing, shot blasting and cleaning the pick to obtain the mining composite cast and forged wear-resistant pick.

3. The manufacturing process of the composite casting and forging wear-resistant mining pick according to claim 2, characterized in that: In step (1), the forging temperature of the forging process is 1050-1150°C, the forging ratio is 3:1, the quenching temperature is 920°C, the quenching medium is quenching oil, and the tempering temperature is 200°C.

4. The manufacturing process of the composite casting and forging wear-resistant mining pick according to claim 2 is characterized in that: In step (2), the high entropy alloy powder is a FeCoCrNiAl alloy, and its composition by mass is: 25-35 parts of iron powder, 20-30 parts of cobalt powder, 15-25 parts of chromium powder, 10-20 parts of nickel powder, and 5-10 parts of aluminum powder.

5. The manufacturing process of the composite cast and forged wear-resistant mining pick according to claim 2, characterized in that: In step (3), the pick base is preheated to 200°C before laser cladding.

6. The manufacturing process of the composite cast and forged wear-resistant mining pick according to claim 2, characterized in that: During the ultrasonic impact treatment, the ultrasonic frequency is 20-40 kHz, the amplitude is 10-30 μm, and the duration is 5-15 minutes.

7. The manufacturing process of the composite casting and forging wear-resistant mining pick according to claim 2, characterized in that: The preparation method of the cladding powder is as follows: high entropy alloy powder, tungsten carbide powder, titanium carbide powder and rare earth powder are put into a medium-free airflow in proportion and ground at a grinding pressure of 0.8-1 MPa to an average particle size of 80-120 μm to obtain the cladding powder.

8. The manufacturing process of the composite casting and forging wear-resistant mining pick according to claim 7, characterized in that: The cladding powder also needs to be dried at a temperature of 80-120° C. for 1-3 hours, with the moisture content controlled at ≤0.1%.

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