Alloy protective coating, top hammer drill bit and preparation method thereof
By applying alloy protective coating on the top hammer drill head, the wear problem caused by the lack of protection of the edge teeth of the drill head is solved, the service life is extended, and the wear resistance and impact resistance are improved, achieving more efficient mining operations.
Patent Information
- Application Number
- CN202411337673.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2044-09-25
AI Technical Summary
Due to the lack of edge teeth protection measures during drilling, the existing top hammer drill bits have severe wear and short service life. Under cost limitations, all wear-resistant materials cannot be used.
Alloy protective coating is adopted, containing C: 1.5%-2.5%, Cr: 8%-12%, Fe: 1.5%-3%, Si: 1.5%-3.5%, B: 1.5%-2.5%, Mo: 0.5% Chemical components of -1.0%, Ti: 0.5%-1.0%, V: 0.5%-1.0%, W: 30%-35% and Ni are formed on the surface of the brazing head substrate through laser cladding technology. A corrosion-resistant and impact-resistant coating.
It significantly extends the service life of the top hammer drill head, reduces wear and maintenance frequency, improves the safety and success rate of operations, and reduces production costs.
Smart Images
Figure CN118854124B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of alloy materials, and particularly discloses an alloy protective coating, a top hammer drill bit and a preparation method thereof. Background Art
[0002] A top hammer drill bit is a tool used for drilling rock and is commonly found in rock drilling, mining, and construction. Typically made of high-strength steel and alloy buttons, it is durable and used for drilling or hammering holes in rock for tasks such as blasting, geological exploration, and installing fixed objects.
[0003] The top hammer drill bits produced by existing technology are usually used for drilling tunnels and rock breaking in surface and underground metal mines. Since metal ores are usually very hard and highly abrasive, the drill bit is subjected to continuous wear during the drilling process, and the existing products do not have any protection measures for the outer side of the side teeth, resulting in a reduction or even disappearance of the metal trousers used to wrap the side tooth alloy, and the alloy used for breaking rocks is exposed to the outside, and the tightening force it is subjected to is reduced, resulting in the alloy falling off and the product failure. More importantly, considering the cost issue, it is impossible to use wear-resistant materials to make the metal trousers. Therefore, there is an urgent need for a method to protect the alloy trousers of the side teeth of the top hammer drill bit without affecting the work efficiency of the product, reduce wear, and increase the service life of the top hammer drill bit. Summary of the Invention
[0004] In order to solve the problem that the outer side of the edge teeth of the existing top hammer drill bit has no protection measures for the edge teeth, and the metal trousers used to wrap the edge tooth alloy are easily worn, thereby reducing the service life of the top hammer drill bit, the present invention specifically discloses an alloy protective coating, a top hammer drill bit and a preparation method thereof.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] A first aspect of the present invention provides an alloy protective coating, which includes the following chemical components in percentage by mass: C: 1.5%-2.5%, Cr: 8%-12%, Fe: 1.5%-3%, Si: 1.5%-3.5%, B: 1.5%-2.5%, Mo: 0.5%-1.0%, Ti: 0.5%-1.0%, V: 0.5%-1.0%, W: 30%-35% and the remainder Ni and unavoidable impurities; wherein the percentage of the chemical components of the alloy protective coating satisfies 10%≤Cr+B+V≤14%, and 1%≤Mo+Ti≤1.6%.
[0007] The W in the alloy protective coating provided by the present invention is mainly in the form of tungsten carbide, which also gives the alloy protective coating high hardness and wear resistance, allowing the alloy side wall surface of the top hammer drill bit to maintain sharpness and durability for a long time in the harsh ore mining environment, which will greatly extend the service life of the top hammer drill bit, reduce the frequency of replacement and maintenance, and thus reduce production costs. The Cr, V and B elements provide the alloy protective coating with excellent corrosion resistance, allowing the alloy side wall surface of the top hammer drill bit to maintain a stable surface state when in contact with various corrosive media, ensuring that the top hammer drill bit can continue to operate efficiently under various geological conditions, reducing the chance of drill bit damage or performance degradation due to corrosion. Ni, Mo and Ti give the alloy protective coating excellent impact resistance and high-temperature stability, allowing the top hammer drill bit to withstand strong impact and vibration from rocks and soil layers during high-speed rotation and drilling, reducing the risk of fracture, collapse and other damage to the top hammer drill bit, improving the safety and stability of the operation, and improving the success rate and efficiency of the drilling operation.
[0008] Preferably, the alloy protective coating includes a laser welding zone and a surface heat-affected zone, wherein the metallographic structure of the surface heat-affected zone comprises 85%-90% tempered bainite and 10%-15% quenched martensite in terms of area ratio.
[0009] The metallurgical structure of the heat-affected zone (HAZ) of the alloy protective coating provided by the present invention is primarily composed of tempered bainite and a small amount of quenched martensite. The tempered bainite imparts excellent mechanical properties to the alloy protective coating, resulting in high strength, high plasticity, and high toughness. This makes top hammer drill bits with the alloy protective coating more suitable for mining tunneling operations.
[0010] A second aspect of the present invention provides a top hammer drill bit comprising the alloy protective coating.
[0011] A third aspect of the present invention provides a method for preparing the top hammer drill bit, comprising the following steps:
[0012] Step 1: Weigh the alloy raw material powder according to the designed ratio, ball mill it, and vacuum dry it to obtain the pretreated alloy powder;
[0013] Step 2: Preheat the drill bit base at 170°C-190°C to obtain a preheated drill bit base; in an inert atmosphere, use laser cladding to clad the pretreated alloy powder on the surface of the preheated drill bit base to obtain an alloy protective coating; after passing the flaw detection, the surface of the alloy protective coating is sandblasted and painted in sequence to obtain a top hammer drill bit.
[0014] The present invention utilizes laser cladding to clad an alloy protective coating on the surface of a drill bit substrate. During the cladding process, the heat impact on the drill bit substrate is small, and the substrate temperature does not exceed 100°C, thereby avoiding the brittleness of the alloy protective coating caused by the heat impact of the drill bit substrate and reducing the service life of the top hammer drill bit.
[0015] Preferably, in step 1, the alloy raw material powder is any two or more of nickel-based alloy, cobalt-based alloy, nickel-based tungsten carbide or stainless steel.
[0016] Further preferably, in step 1, the nickel-based alloy is Ni60 alloy.
[0017] Further preferably, in step 1, the WC content in the nickel-based tungsten carbide is 30wt%-40wt%.
[0018] Preferably, in step 1, the rotation speed of the ball mill is 500 rpm-1000 rpm, and the ball milling time is 3 h-5 h.
[0019] Preferably, in step 1, the temperature of the vacuum drying is 140° C.-160° C., the vacuum degree of the vacuum drying is 0.7 MPa-0.75 MPa, and the time of the vacuum drying is 2 h-3 h.
[0020] Preferably, in step 1, the particle size of the pretreated alloy powder is 75 μm-85 μm.
[0021] Preferably, in step 2, the preheating time is 1 hour to 2 hours.
[0022] Preferably, in step 2, the process parameters of the laser cladding are: laser power of 5000W-7000W, spot diameter of 4mm-6mm, laser distance of 14mm-16mm, powder feeding rate of 18g / min-22g / min, powder feeding diameter of 0.9mm-1.1mm, powder feeder speed of 4rpm-6rpm, carrier gas flow rate of 7L / min-9L / min, and carrier gas pressure of 0.5MPa-0.7MPa.
[0023] Preferably, in step 2, the cladding thickness of the alloy protective coating is 0.3 mm to 0.5 mm.
[0024] Preferably, in step three, the sand particle size of the sand blasting is 50 mesh-70 mesh, the sand blasting pressure is 4 Bar-6 Bar, and the sand blasting speed is 4 m / s-6 m / s.
[0025] In summary, the alloy protective coating provided by the present invention can effectively reduce the wear of the top hammer drill bit, improve the surface hardness and wear resistance of the top hammer drill bit, and the alloy protective coating gives the top hammer drill bit excellent impact resistance and high-temperature stability, reduces the risk of breakage, collapse and other damage to the top hammer drill bit, extends its service life, and improves the safety and stability of the operation. The technical solution of the present invention effectively solves the problem that the existing top hammer drill bit has no protection measures on the outer side of the edge teeth, and the metal trousers used to wrap the edge tooth alloy are easily worn, thereby reducing the service life of the top hammer drill bit. According to tests, the service life of the top hammer drill bit containing the alloy protective coating is increased by 70%-98% compared with the top hammer drill bit without coating. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is a 200-fold metallographic structure diagram of the heat-affected zone of the alloy protective coating described in Example 1;
[0027] Figure 2 This is a 200-fold metallographic structure diagram of the heat-affected zone of the alloy protective coating described in Example 5;
[0028] Figure 3 50x magnification metallographic structure comparison diagram of the laser welding area of the alloy protective coating described in Example 1 and the laser welding area of the alloy protective coating described in Example 5; wherein (a) is the laser welding area of the alloy protective coating described in Example 1; (b) is the laser welding area of the alloy protective coating described in Example 5;
[0029] Figure 4 100-fold comparison of the metallographic structures of the laser welding area of the alloy protective coating described in Example 1 and the laser welding area of the alloy protective coating described in Example 5; wherein (a) is the laser welding area of the alloy protective coating described in Example 1; (b) is the laser welding area of the alloy protective coating described in Example 5;
[0030] Figure 5 200x magnification metallographic structure comparison diagram of the laser welding area of the alloy protective coating described in Example 1 and the laser welding area of the alloy protective coating described in Example 5; wherein (a) is the laser welding area of the alloy protective coating described in Example 1; (b) is the laser welding area of the alloy protective coating described in Example 5;
[0031] Figure 6 This is a 500x metallographic structure comparison diagram of the laser welding area of the alloy protective coating described in Example 1 and the laser welding area of the alloy protective coating described in Example 5; wherein (a) is the laser welding area of the alloy protective coating described in Example 1; (b) is the laser welding area of the alloy protective coating described in Example 5. DETAILED DESCRIPTION
[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0033] Example 1
[0034] This embodiment provides a top hammer drill bit, the surface of which is clad with an alloy protective coating, specifically including the following:
[0035] The alloy protective coating includes the following chemical components in percentage by mass: C: 2.0%, Cr: 10.0%, Fe: 2.5%, Si: 2.5%, B: 2.0%, Mo: 0.8%, Ti: 0.8%, V: 0.6%, W: 32.0% and the balance Ni.
[0036] Step 1: Ni60 alloy and 35 wt% nickel-based tungsten carbide were weighed according to the designed ratio, ball-milled at 800 rpm for 3.5 h, and vacuum-dried at 150 ° C and 0.7 MPa for 2.5 h to obtain a pretreated alloy powder with a particle size of 80 μm;
[0037] Step 2: Grind and clean the surface of the position where the top hammer drill bit needs to be clad to ensure that the surface is clean and flat without attachments, and then preheat the position where the top hammer drill bit needs to be clad at 180°C for 1 hour to obtain a preheated metal substrate; under an inert atmosphere, align the laser head of the laser with the surface of the position where the top hammer drill bit needs to be clad, and use a coaxial carrier gas powder feeder to evenly spray the pretreated alloy powder onto the surface. The high-energy laser beam emitted by the laser is irradiated on the cladding material, causing it to melt instantly to form molten droplets. Then, the laser continuously scans the cladding range according to a pre-set trajectory, gradually forming a uniform cladding coating to obtain an alloy protective coating precursor with a cladding thickness of 0.3 mm;
[0038] The power of the laser is 6000W, the core diameter of the laser is 1000μm, the obtained spot diameter is 5mm, the powder feeding amount of the carrier gas powder feeder is 20g / min, the gas flow rate of the carrier gas powder feeder is 8L / min, the gas pressure of the carrier gas powder feeder is 0.6Mpa, the speed of the carrier gas powder feeder is 5r / min, the working distance of the laser gun head is 15mm, and the powder feeding diameter of the laser gun head is 1mm.
[0039] Step 3: After the alloy protective coating precursor is naturally cooled, a portable flaw detector is used to detect whether there are defects such as cracks, pores or collapse; after passing the inspection, the alloy protective coating precursor is sandblasted using a sandblasting machine, and the sand blasting sand particle size is 60 mesh, the sandblasting pressure is 5 Bar, the sandblasting speed is 5 m / s, and the sandblasting angle is 70° to the coating surface; after the sandblasting is completed, the alloy protective coating precursor is painted to obtain a hammer drill bit.
[0040] Example 2
[0041] This embodiment provides a top hammer drill bit, the surface of which is clad with an alloy protective coating, specifically including the following:
[0042] The alloy protective coating includes the following chemical components in percentage by mass: C: 2.2%, Cr: 11.0%, Fe: 2.3%, Si: 3.0%, B: 2.1%, Mo: 0.7%, Ti: 0.6%, V: 0.7%, W: 33.4% and the balance Ni.
[0043] Step 1: Ni60 alloy and 35 wt% nickel-based tungsten carbide were weighed according to the designed ratio, ball-milled at 750 rpm for 4 h, and vacuum-dried at 160°C and 0.7 MPa for 2.5 h to obtain a pretreated alloy powder with a particle size of 80 μm;
[0044] Step 2: Grind and clean the surface of the position where the top hammer drill bit needs to be clad to ensure that the surface is clean and flat without any attachments, and then preheat the position where the top hammer drill bit needs to be clad at 175°C for 1 hour to obtain a preheated metal matrix;
[0045] In an inert atmosphere, the laser head is aligned with the surface of the hammer drill bit where cladding is required, and the pretreated alloy powder is evenly sprayed onto the surface using a coaxial carrier gas powder feeder. The high-energy laser beam emitted by the laser irradiates the cladding material, causing it to instantly melt and form molten droplets. The laser then continuously scans the cladding range according to a pre-set trajectory, gradually forming a uniform cladding coating, resulting in an alloy protective coating precursor with a cladding thickness of 0.4 mm.
[0046] The power of the laser is 6500W, the core diameter of the laser is 1000μm, the obtained spot diameter is 6mm, the powder feeding rate of the carrier gas powder feeder is 22g / min, the gas flow rate of the carrier gas powder feeder is 7L / min, the gas pressure of the carrier gas powder feeder is 0.6Mpa, the speed of the carrier gas powder feeder is 6r / min, the working distance of the laser gun head is 15mm, and the powder feeding diameter of the laser gun head is 1mm.
[0047] Step 3: After the alloy protective coating precursor is naturally cooled, a portable flaw detector is used to detect whether there are defects such as cracks, pores or collapse; after passing the inspection, the alloy protective coating precursor is sandblasted using a sandblasting machine, and the sand blasting sand particle size is 60 mesh, the sandblasting pressure is 5 Bar, the sandblasting speed is 5 m / s, and the sandblasting angle is 70° to the coating surface; after the sandblasting is completed, the alloy protective coating precursor is painted to obtain a hammer drill bit.
[0048] Example 3
[0049] This embodiment provides a top hammer drill bit, the surface of which is clad with an alloy protective coating, specifically including the following:
[0050] The alloy protective coating includes the following chemical components in percentage by mass: C: 1.8%, Cr: 9.6%, Fe: 2.5%, Si: 2.5%, B: 2.4%, Mo: 0.8%, Ti: 0.5%, V: 0.5%, W: 33.7% and the balance Ni.
[0051] Step 1: Ni60 alloy and 35 wt% nickel-based tungsten carbide were weighed according to the designed ratio, ball-milled at 900 rpm for 3 h, and vacuum-dried at 140°C and 0.75 MPa for 3 h to obtain a pretreated alloy powder with a particle size of 80 μm;
[0052] Step 2: Grind and clean the surface of the location where the top hammer drill bit needs to be clad to ensure that the surface is clean and flat without any attachments, and then preheat the location where the top hammer drill bit needs to be clad at 185°C for 1 hour to obtain a preheated metal matrix;
[0053] In an inert atmosphere, the laser head is aligned with the surface of the hammer drill bit where cladding is required, and the pretreated alloy powder is evenly sprayed onto the surface using a coaxial carrier gas powder feeder. The high-energy laser beam emitted by the laser irradiates the cladding material, causing it to instantly melt and form molten droplets. The laser then continuously scans the cladding range according to a pre-set trajectory, gradually forming a uniform cladding coating, resulting in an alloy protective coating precursor with a cladding thickness of 0.4 mm.
[0054] The power of the laser is 7000W, the core diameter of the laser is 1000μm, the obtained spot diameter is 5mm, the powder feeding rate of the carrier gas powder feeder is 18g / min, the gas flow rate of the carrier gas powder feeder is 9L / min, the gas pressure of the carrier gas powder feeder is 0.6Mpa, the speed of the carrier gas powder feeder is 5r / min, the working distance of the laser gun head is 15mm, and the powder feeding diameter of the laser gun head is 1mm.
[0055] Step 3: After the alloy protective coating precursor is naturally cooled, a portable flaw detector is used to detect whether there are defects such as cracks, pores or collapse; after passing the inspection, the alloy protective coating precursor is sandblasted using a sandblasting machine, and the sand blasting sand particle size is 60 mesh, the sandblasting pressure is 5 Bar, the sandblasting speed is 5 m / s, and the sandblasting angle is 70° to the coating surface; after the sandblasting is completed, the alloy protective coating precursor is painted to obtain a hammer drill bit.
[0056] Example 4
[0057] This embodiment provides a top hammer drill bit, the surface of which is clad with an alloy protective coating. The difference from Example 1 is that the cladding thickness of the alloy protective coating precursor is 0.8 mm, and other components and processes remain unchanged. Specifically, the embodiment includes the following contents:
[0058] The alloy protective coating includes the following chemical components in percentage by mass: C: 2.0%, Cr: 10.0%, Fe: 2.5%, Si: 2.5%, B: 2.0%, Mo: 0.8%, Ti: 0.8%, V: 0.6%, W: 32.0% and the balance Ni.
[0059] Step 1: Ni60 alloy and 35 wt% nickel-based tungsten carbide were weighed according to the designed ratio, ball-milled at 800 rpm for 3.5 h, and vacuum-dried at 150 ° C and 0.7 MPa for 2.5 h to obtain a pretreated alloy powder with a particle size of 80 μm;
[0060] Step 2: Grind and clean the surface of the position where the top hammer drill bit needs to be clad to ensure that the surface is clean and flat without any attachments, and then preheat the position where the top hammer drill bit needs to be clad at 180°C for 1 hour to obtain a preheated metal matrix;
[0061] In an inert atmosphere, the laser head of the laser is aimed at the surface of the hammer drill bit where cladding is required, and the pretreated alloy powder is evenly sprayed onto the surface using a coaxial carrier gas powder feeder. The high-energy laser beam emitted by the laser irradiates the cladding material, causing it to instantly melt and form molten droplets. Then, the laser continuously scans the cladding range according to a pre-set trajectory, gradually forming a uniform cladding coating, thereby obtaining an alloy protective coating precursor with a cladding thickness of 0.8 mm.
[0062] The power of the laser is 6000W, the core diameter of the laser is 1000μm, the obtained spot diameter is 5mm, the powder feeding amount of the carrier gas powder feeder is 20g / min, the gas flow rate of the carrier gas powder feeder is 8L / min, the gas pressure of the carrier gas powder feeder is 0.6Mpa, the speed of the carrier gas powder feeder is 5r / min, the working distance of the laser gun head is 15mm, and the powder feeding diameter of the laser gun head is 1mm.
[0063] Step 3: After the alloy protective coating precursor is naturally cooled, a portable flaw detector is used to detect whether there are defects such as cracks, pores or collapse; after passing the inspection, the alloy protective coating precursor is sandblasted using a sandblasting machine, and the sand blasting sand particle size is 60 mesh, the sandblasting pressure is 5 Bar, the sandblasting speed is 5 m / s, and the sandblasting angle is 70° to the coating surface; after the sandblasting is completed, the alloy protective coating precursor is painted to obtain a hammer drill bit.
[0064] Example 5
[0065] This embodiment provides a top hammer drill bit, the surface of which is clad with an alloy protective coating. The difference from the first embodiment is that the alloy protective coating is clad using a plasma cladding process, and the other components and processes remain unchanged. Specifically, the following contents are included:
[0066] The alloy protective coating includes the following chemical components in percentage by mass: C: 2.0%, Cr: 10%, Fe: 2.5%, Si: 2.5%, B: 2%, Mo: 0.8%, Ti: 0.8%, V: 0.6%, W: 32% and the balance Ni.
[0067] Step 1: Ni60 alloy and 35 wt% nickel-based tungsten carbide were weighed according to the designed ratio, ball-milled at 800 rpm for 3.5 h, and vacuum-dried at 150 ° C and 0.7 MPa for 2.5 h to obtain a pretreated alloy powder with a particle size of 80 μm;
[0068] Step 2: Grind and clean the surface of the position where the top hammer drill bit needs to be clad to ensure that the surface is clean and flat without any attachments, and then preheat the position where the top hammer drill bit needs to be clad at 180°C for 1 hour to obtain a preheated metal matrix;
[0069] Under an inert atmosphere, the preheated metal substrate is placed in a plasma spray chamber, the pretreated alloy powder is fed into the plasma spray chamber at a powder feeding rate of 20 g / min through a powder feeder, the pretreated alloy powder is atomized into molten droplets using a plasma spray gun, and then sprayed onto the surface of the preheated metal substrate, gradually forming a uniform cladding coating to obtain an alloy protective coating precursor with a cladding thickness of 3 mm;
[0070] The power output of the plasma spray gun is 10000W, the output current is 300A, the carrier gas is a mixture of argon and helium, the flow rate of argon is 50L / min, the flow rate of helium is 50L / min, the moving speed of the plasma spray gun is 300mm / s, and the spraying distance between the nozzle of the plasma spray gun and the preheated metal substrate surface is 50mm;
[0071] Step 3: After the alloy protective coating precursor is naturally cooled, a portable flaw detector is used to detect whether there are defects such as cracks, pores or collapse; after passing the inspection, the alloy protective coating precursor is sandblasted using a sandblasting machine, and the sand blasting sand particle size is 60 mesh, the sandblasting pressure is 5 Bar, the sandblasting speed is 5 m / s, and the sandblasting angle is 70° to the coating surface; after the sandblasting is completed, the alloy protective coating precursor is painted to obtain a hammer drill bit.
[0072] Comparative Example 1
[0073] This comparative example provides a top hammer drill bit, the surface of which is clad with an alloy protective coating. The difference from Example 1 is that the chemical composition percentage of the alloy protective coating satisfies Cr+B+V>14%, and the preparation process and parameters remain unchanged, specifically including the following:
[0074] The alloy protective coating includes the following chemical components in percentage by mass: C: 2.0%, Cr: 11.5%, Fe: 2.5%, Si: 2.5%, B: 2.2%, Mo: 0.8%, Ti: 0.8%, V: 0.6%, W: 32.0% and the balance Ni.
[0075] The preparation process will not be described in detail here.
[0076] Comparative Example 2
[0077] This comparative example provides a top hammer drill bit, the surface of which is clad with an alloy protective coating. The difference from Example 1 is that the chemical composition percentage of the alloy protective coating satisfies Mo+Ti>1.7%, and the preparation process and parameters remain unchanged, specifically including the following:
[0078] The alloy protective coating includes the following chemical components in percentage by mass: C: 2.0%, Cr: 11.5%, Fe: 2.5%, Si: 2.5%, B: 2.2%, Mo: 0.9%, Ti: 0.9%, V: 0.6%, W: 32.0% and the balance Ni.
[0079] The preparation process will not be described in detail here.
[0080] In order to further demonstrate the technical effects of the present invention, the present invention conducted performance tests on the top hammer drill bits obtained in Examples 1-5 and Comparative Examples 1-2 and the top hammer drill bits without alloy protective coating on the surface. They were used in tunnel excavation tests with rock hardnesses of f7 and f12, respectively. The service life was tested, the number of holes drilled and the excavation length were counted, and tooth loss and tooth breakage were used as failure evaluation. The specific test results are shown in Table 1.
[0081] Table 1 Test results of the tunneling test of each hammer drill bit
[0082]
[0083] As can be seen from Table 1, the top hammer drill bit with an alloy protective coating provided by the embodiment of the present invention has a long service life. For excavating rocks with a hardness of f7, its service life can reach up to 345 meters; for excavating rocks with a hardness of f12, its service life can reach up to 103 meters.
[0084] The present invention also carried out metallographic structure test on the alloy protective coatings described in Example 1 and Example 5, and the results were as follows: Figure 1-6 As shown. Figure 1-2 As shown in the figure, the metallographic structure of the surface heat-affected zone of the alloy protective coating prepared by laser cladding process in Example 1 is mainly tempered martensite (90%) and a small amount of quenched martensite (10%), and the crystal structure is more uniform and has fewer defects. However, the metallographic structure of the surface heat-affected zone of the alloy protective coating prepared by plasma cladding process in Example 5 contains a large amount of quenched martensite (>50%), and the crystal structure is uneven. Figure 3-6 It can be seen that the laser welding area of the alloy protective coating prepared by the laser cladding process in Example 1 is basically free of cracks; no cracks appear in the surface heat-affected zone; while the laser welding area and the surface-affected zone of the alloy protective coating prepared by the plasma cladding process in Example 5 are cracked. This is due to the large amount of quenched martensite, which makes the alloy protective coating more brittle and less tough, thus generating a large number of cracks, which easily leads to the coating breaking and collapse. The top hammer drill bit with the cracked alloy protective coating is not suitable for mining operations. In Example 1, the coating is basically tempered bainite. The tempered bainite gives the alloy protective coating better mechanical properties, making it have the characteristics of high strength, high toughness and high plasticity, which is more conducive to the top hammer drill bit in mining excavation operations.
[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. An alloy protective coating, Features: The alloy protective coating comprises the following chemical components in percentage by mass: C: 1.5%-2.5%, Cr: 8%-12%, Fe: 1.5%-3%, Si: 1.5%-3.5%, B: 1.5%-2.5%, Mo: 0.5%-1.0%, Ti: 0.5%-1.0%, V: 0.5%-1.0%, W: 30%-35% and the balance of Ni and unavoidable impurities; wherein the percentage of the chemical components of the alloy protective coating satisfies 10%≤Cr+B+V≤14%, 1%≤Mo+Ti≤1.6%; The alloy protective coating includes a laser welding zone and a surface heat-affected zone, wherein the metallographic structure of the surface heat-affected zone includes 85%-90% of tempered troostite and 10%-15% of quenched martensite in terms of area ratio; The raw materials of the alloy protective coating are nickel-based alloy and nickel-based tungsten carbide.
2. A top hammer drill bit, Features: The invention comprises the alloy protective coating as claimed in claim 1.
3. The method for preparing a top hammer drill bit according to claim 2, Features: The steps include: Step 1: weighing alloy raw material powder according to the designed ratio, ball milling, and vacuum drying to obtain pretreated alloy powder; Step 2: preheat the drill bit base at 170°C-190°C to obtain a preheated drill bit base; in an inert atmosphere, laser clad the pretreated alloy powder on the surface of the preheated drill bit base to obtain an alloy protective coating; after passing the flaw detection, the surface of the alloy protective coating is sandblasted and painted in turn to obtain a top hammer drill bit.
4. The method for preparing a top hammer drill bit according to claim 3, Features: In step 1, the rotation speed of the ball mill is 500rpm-1000rpm, and the time of the ball mill is 3h-5h.
5. The method for preparing a top hammer drill bit according to claim 3, Features: In step 1, the particle size of the pretreated alloy powder is 75 μm-85 μm.
6. The method for preparing a top hammer drill bit according to claim 3, Features: In step 2, the preheating time is 1h-2h.
7. The method for preparing a top hammer drill bit according to claim 3, Features: In step 2, the process parameters of the laser cladding are: laser power is 5000W-7000W, spot diameter is 4mm-6mm, laser distance is 14mm-16mm, powder feeding rate is 18g / min-22g / min, powder feeding diameter is 0.9mm-1.1mm, powder feeder speed is 4rpm-6rpm, carrier gas flow rate is 7L / min-9L / min, and carrier gas pressure is 0.5MPa-0.7MPa.
8. The method for preparing a top hammer drill bit according to claim 3, Features: In step 2, the cladding thickness of the alloy protective coating is 0.3 mm-0.5 mm.
9. The method for preparing a top hammer drill bit according to claim 3, Features: In step 2, the sand particle size of the sand blasting is 50 mesh-70 mesh, the sand blasting pressure is 4 Bar-6 Bar, and the sand blasting speed is 4 m / s-6 m / s.