A pick and a method of manufacturing the same

Abstract

The present application relates to a kind of pick and its preparation method, it is related to pick processing technical field;The pick includes pick body and composite alloy head;The composite alloy head includes bottom cylinder shell and titanium alloy core;The bottom cylinder shell, the mass fraction of including: hard phase 76-84 parts, cobalt 16-24 parts;The hard phase includes tungsten carbide;The titanium alloy core, the mass fraction of including: titanium 52-55 parts, nickel 18-22 parts, cobalt 9-12 parts, molybdenum 5-7 parts, tungsten carbide 4-16 parts;Preparation step includes: preparation bottom cylinder shell embryo, press forming, vacuum sintering, brazing assembly step;The present application provides wear resistance strength and pressure hardness by using tungsten carbide, cobalt fills gap between particles, guarantees the overall density and structural toughness of shell;Nickel, cobalt, molybdenum in titanium alloy core are dissolved in titanium matrix, alloy grain is refined, welding strength is improved, and the cost of production and manufacture is reduced.

Description

Technical Field

[0001] This invention relates to the field of cutting tool processing technology, and in particular to a cutting tool and its preparation method. Background Technology

[0002] Cutting teeth are major consumable components in coal mining, tunneling, and mining exploration. They are subjected to high-frequency impacts and wear during mining operations. The comprehensive performance of the wear-resistant alloy at the head of the cutting teeth directly determines mining efficiency, equipment downtime frequency, and overall mining costs.

[0003] Chinese invention patent application with publication number CN120719162A and publication date of September 30, 2025 proposes a method for manufacturing cemented carbide for hard rock cutting tools. The technical solution uses powder raw materials such as tungsten carbide and optimizes the internal grain structure of cemented carbide through a stepwise sintering process to improve the hardness and wear resistance of tungsten carbide cemented carbide.

[0004] However, tungsten carbide is a product of deep processing of tungsten resources. Since March 2025, the market price of tungsten carbide materials has risen sharply, with an overall increase of over 900%. The raw material production costs of downstream enterprises in the entire industrial chain, such as cutting teeth, cutting tools, and wear-resistant parts, have risen sharply. The industry urgently needs to develop low-cost, mass-producible wear-resistant materials that can replace tungsten carbide while meeting performance standards.

[0005] Among them, titanium alloys have abundant reserves and lower raw material procurement costs. After alloying modification, their wear resistance is improved, making them a potential alternative material for wear-resistant cutting teeth. However, due to the high chemical reactivity of titanium, which easily reacts with elements such as oxygen, nitrogen, and carbon at high temperatures, its application has been limited. In particular, the brazing bond strength with the cutting tooth base material is insufficient. For example, tungsten carbide can achieve a shear strength of 180 MPa when brazed with copper-based solder, while conventional titanium alloys can only achieve a shear strength of 60 MPa when brazed with copper-based solder, which is far from meeting the strength standards for use in mining operations. Summary of the Invention

[0006] In order to improve the brazing strength between titanium alloy and the base material of the cutting tooth, and to achieve the goal of replacing part of tungsten carbide with titanium alloy, thereby reducing the production cost of raw materials, this invention provides a cutting tooth and its preparation method.

[0007] Firstly, the cutting tooth provided in this application adopts the following technical solution: A cutting tooth includes a cutting tooth body and a composite alloy head; the composite alloy head includes a bottom cylindrical shell and a titanium alloy core; the bottom cylindrical shell comprises, by mass, 76-84 parts of hard phase and 16-24 parts of cobalt; the hard phase includes tungsten carbide. The titanium alloy core (2) comprises the following components by mass: 52-55 parts titanium, 18-22 parts nickel, 9-12 parts cobalt, 5-7 parts molybdenum, and 4-16 parts tungsten carbide.

[0008] By adopting the above technical solution, tungsten carbide serves as a high-hardness, wear-resistant skeleton, providing wear resistance and compressive hardness. Cobalt fully wets the tungsten carbide particles, filling the gaps between the particles and ensuring the overall density and structural toughness of the outer shell. The internal core adopts a titanium, nickel, cobalt, and molybdenum composite titanium alloy system with tungsten carbide hard phase incorporated. On the one hand, the raw material costs of titanium, nickel, and molybdenum are much lower than those of tungsten carbide and cobalt, reducing the overall raw material cost. On the other hand, the tungsten carbide particles doped in the core uniformly disperse and strengthen the titanium alloy matrix, compensating for the strength of the lightweight titanium alloy matrix. At the same time, nickel, cobalt, and molybdenum are dissolved in the titanium matrix, refining the alloy grains and producing a solid solution strengthening effect, giving the core a good buffering and energy absorption effect.

[0009] Optionally, the hard phase further includes 3 to 8 parts of titanium carbide and 1 to 4 parts of tantalum carbide.

[0010] By employing the above technical solution, titanium carbide and tantalum carbide dissolve into the tungsten carbide lattice to form a composite carbide, which suppresses abnormal grain growth during sintering and refines the grain structure. Grain refinement not only improves hardness but also increases the tortuosity of crack propagation paths, thereby increasing the hardness and compressive strength of the shell without increasing the cobalt content. In addition, tantalum carbide segregates at the grain boundaries of tungsten carbide and tungsten carbide-cobalt during liquid-phase sintering, exhibiting a grain boundary pinning effect, which enhances the bonding force between tungsten carbide particles and the cobalt binder phase and reduces phase interface defects.

[0011] Optionally, the hard phase further includes 0.5 to 2 parts of chromium carbide.

[0012] By adopting the above technical solution, chromium carbide plays a role in inhibiting grain growth. During the sintering process, chromium carbide is uniformly distributed at the grain boundaries of tungsten carbide, titanium carbide, and tantalum carbide. The trace amount of chromium carbide can hinder the Ostwald ripening process of carbide particles, resulting in a finer grain structure. The strengthened fine grains enable the shell material to maintain high hardness while improving its fracture toughness.

[0013] Meanwhile, the addition of chromium improves the wettability of liquid cobalt on tungsten carbide particles, reduces sintering porosity, and makes it easier for the shell to reach the theoretical density under the same pressing pressure.

[0014] Secondly, this application provides a method for preparing cutting teeth, which adopts the following technical solution: A method for preparing a cutting tooth includes the following steps: Preparation of the bottom cylindrical shell blank: The bottom cylindrical shell blank is formed by powder metallurgy process; Compression molding: The bottom cylindrical shell blank is placed into the mold, titanium alloy core powder is filled into the inner cavity of the bottom cylindrical shell blank, and secondary compression molding is performed to obtain an integral pressed blank; Vacuum sintering: The integral pressed blank is placed in a vacuum sintering furnace for sintering and cooling to obtain a composite alloy head; Brazing assembly: Using copper-based brazing filler metal, the composite alloy head is welded to the cutting tooth body through a cutting tooth brazing process to obtain the cutting tooth.

[0015] By adopting the above technical solution, a cylindrical outer shell blank is first prepared by powder metallurgy pressing. Then, the core and outer shell are integrally formed by filling the outer shell blank with powder and pressing it again. This eliminates the interface gaps between the separate structures, allowing the composite alloy head to form a complete and dense overall structure, improving the bonding strength of the composite layer and avoiding interlayer delamination and failure. Vacuum sintering isolates air oxidation and reduces alloy sintering defects. Finally, copper-based brazing is used for assembly, ensuring the overall connection strength between the composite alloy head and the cutting tooth body. At the same time, the brazing layer acts as a flexible buffer layer, absorbing the impact vibration between the cutting tooth body and the alloy head, fundamentally ensuring the overall structural strength and toughness.

[0016] More importantly, during vacuum sintering, elements such as cobalt and nickel will interdiffusion at the interface between the shell and the core, forming a composition transition zone. This can alleviate the residual stress caused by the difference in thermal expansion coefficients, ensuring that the core provides strong support for the shell under impact loads, preventing the shell from cracking, and thus maintaining high overall strength and toughness at low cost.

[0017] Optionally, in the compression molding step, the pressure of the secondary compression is 100-600 MPa, and the holding time is 5-30 seconds.

[0018] By adopting the above technical solution, the arching effect between powder particles is eliminated, the gas between particles is discharged, and the bottom cylindrical shell and the core powder achieve a better filling density, further reducing shrinkage deformation and porosity after sintering; at the same time, the core powder will not be embedded too deeply into the shell due to excessive pressure, and the interface delamination or micro-cracks caused by the difference in elastic rebound during demolding are avoided.

[0019] Optionally, in the pressing step, a transition layer is provided between the bottom cylindrical shell and the titanium alloy core; the powder of the transition layer includes, by mass parts: 30-40 parts cobalt, 20-30 parts nickel, and 30-50 parts tungsten carbide; wherein, the radial thickness ratio of the bottom cylindrical shell, the transition layer and the titanium alloy core is 1-3:0.2-1:3-8.

[0020] By adopting the above technical solution, the cobalt and nickel in the transition layer are plastic buffer phases, which are used to absorb the thermal stress generated during sintering and cooling, and reduce the stress concentration between layers. At the same time, the transition layer is located between the shell and the core, which avoids the formation of brittle phases at the interface. Meanwhile, the cobalt-nickel composite binder phase improves the wettability and bonding force of the interface, so that the three-layer structure forms a metallurgical bond after sintering, reduces interface defects, and improves the overall strength of the composite structure.

[0021] Optionally, in the vacuum sintering step, the sintering method is as follows: Degreasing: Heat to 400-600℃ at a heating rate of 3-5℃ / min, and hold for 30-60 minutes; Pre-sintering: Continue heating to 900-1000℃ and hold for 20-40 minutes; High-temperature sintering: Continue heating to 1350-1400℃ and hold for 120-150 minutes.

[0022] By adopting the above technical solution, the degreasing stage involves slow heating to prevent the green body from cracking due to rapid volatilization of the binder; the pre-sintering stage removes adsorbed gases and initially forms a particle skeleton structure, allowing the inner and outer layers and transition layer powders to initially bond and form, releasing residual molding stress and stabilizing the green body structure; the high-temperature sintering stage achieves densification, thereby minimizing defects such as pores and microcracks, and ensuring the density and mechanical properties of the material.

[0023] The pre-sintering stage allows solid-state diffusion between powder particles to form sintering necks, preventing excessive rearrangement of tungsten carbide particles when the liquid phase appears, which would lead to excessive diffusion of titanium elements from the core to the shell, generating a brittle η phase. In addition, the high-temperature sintering section is slightly lower than the conventional sintering temperature of tungsten carbide and cobalt, preventing β-grain coarsening of the titanium alloy core at excessively high temperatures. At this temperature, nickel, cobalt, and molybdenum in the core are activated, generating a high-strength solid solution and fine titanium carbide precipitates, achieving precipitation strengthening and improving the core strength.

[0024] Optionally, in the vacuum sintering step, the cooling method is as follows: First, the temperature is reduced to 900±5℃ at a cooling rate of 1.5~2.0℃ / min; then it is reduced to 550±10℃ at a cooling rate of 2.5~3℃ / min; then it is reduced to 300±20℃ at a cooling rate of 4~5℃ / min; finally, it is allowed to cool naturally to room temperature with the furnace.

[0025] By adopting the above technical solution, the residual stress from sintering at high temperature is released slowly by slow cooling to avoid microcrack defects caused by thermal stress concentration and stabilize the primary structure; then the temperature is lowered to 550℃ at 2.5-3℃ / min to prevent microcracks from being generated due to uneven release of latent heat of martensitic phase transformation; then the temperature is lowered slightly faster to allow the metastable β phase in the titanium alloy core to transform into a fine α+β dual-phase structure; finally, it is naturally cooled to room temperature to eliminate residual stress.

[0026] In addition, this cooling method can further promote the precipitation of strengthening phases in the binder phase cobalt and nickel or maintain the metastable structure, thereby further improving the strength and toughness of the matrix.

[0027] Optionally, in the vacuum sintering step, the vacuum degree is 10. -3 ~10 -5 Pa, during the degreasing and pre-sintering stages, argon gas is introduced for protection.

[0028] By adopting the above technical solution, this vacuum level can reduce the residual oxygen partial pressure inside the furnace to 10. -6 Below Pa, argon gas is introduced, which not only protects the titanium alloy core from oxidation and further avoids performance failure caused by material oxidation and embrittlement, but also protects the tungsten carbide in the outer shell from decarburization, preventing the formation of the η-brittle phase. Argon gas is introduced during degreasing to accelerate the discharge of the decomposition products of the forming agent and avoid the increase of residual carbon content affecting the liquid phase sintering temperature.

[0029] Optionally, in the brazing assembly step, the melting point of the copper-based brazing filler metal is 890-930°C, the brazing temperature is 30-50°C higher than the melting point of the copper-based brazing filler metal, and the temperature is maintained for 10-20 seconds after brazing.

[0030] By employing the above technical solution, a brazing temperature higher than the melting point of the brazing filler metal is used. This temperature range is lower than the phase transformation point of the titanium alloy core of the composite alloy head and lower than the eutectic temperature of the tungsten carbide and cobalt in the outer shell. This ensures that the microstructure inside the alloy head does not undergo remelting or grain growth. The short holding time enables instantaneous heating and completion, allowing the copper-based brazing filler metal to fully fill the gaps, forming a dense brazing seam, while also limiting the thickness of the interfacial reaction layer and preventing the large-scale diffusion of iron elements from the cutting tooth body to the alloy head.

[0031] In summary, this application includes at least one of the following beneficial technical effects: 1. Tungsten carbide is used to provide wear resistance and compressive hardness, while cobalt fills the gaps between particles to ensure the overall density and structural toughness of the outer shell. The tungsten carbide particles doped in the internal core uniformly disperse and strengthen the titanium alloy matrix, compensating for the strength of the lightweight titanium alloy matrix. At the same time, nickel, cobalt, and molybdenum are dissolved in the titanium matrix to refine the alloy grains and produce a solid solution strengthening effect, giving the core a better buffering and energy absorption effect, further improving its strength.

[0032] 2. By employing an integrated molding process combining powder metallurgy pressing and secondary pressing with powder filling, the interfacial gaps between the separate structures are eliminated. Titanium carbide and tantalum carbide are dissolved in the tungsten carbide lattice to form composite carbides, inhibiting abnormal grain growth and refining the grain structure; chromium carbide is added to improve strength and tortuosity.

[0033] 3. By employing degreasing, pre-sintering, and high-temperature sintering, cracking and the formation of brittle phases caused by binder volatilization are prevented; at the same time, high-temperature sintering at a temperature slightly lower than conventional temperatures avoids grain coarsening of the titanium alloy core; during the cooling stage, residual stress is better eliminated; and argon gas is introduced during vacuum sintering to reduce the oxygen partial pressure in the furnace to an extremely low level, preventing oxidative embrittlement of the titanium alloy core and decarburization of tungsten carbide.

[0034] 4. By using copper-based brazing filler metal, heating and heat preservation are carried out in a temperature range that is higher than the melting point of the filler metal but lower than the phase transformation point of the matrix, ensuring the formation of a dense brazing seam while limiting the thickness of the interface reaction layer. Attached Figure Description

[0035] Figure 1 This is the cross-sectional structure of the cutting tooth in Embodiment 1 of this application.

[0036] Reference numerals: 1. Bottom cylindrical outer shell; 2. Titanium alloy core; 3. Cutting tooth body. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments.

[0038] Unless otherwise specified, the experimental methods used in the embodiments of this application are conventional methods, and the materials used are commercially available unless otherwise specified.

[0039] Example 1: This example discloses a cutting tooth and its preparation method.

[0040] 1. A cutting tooth, see attached document. Figure 1 The device includes a cutting tooth body 3 and a composite alloy head; the composite alloy head includes a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 is composed of 76 parts by mass of hard phase and 24 parts of cobalt; the hard phase includes tungsten carbide. The titanium alloy core 2 is composed of the following components by mass: 52 parts titanium, 22 parts nickel, 12 parts cobalt, 5 parts molybdenum, and 16 parts tungsten carbide.

[0041] 2. A method for preparing a cutting tooth, comprising the following steps: 1) Raw material pretreatment: The hard phase and metal powder were washed with 10% dilute hydrochloric acid to remove impurities; the bottom cylindrical shell 1 powder and titanium alloy core 2 powder were taken by mass and separately prepared and ball-milled separately, with anhydrous ethanol as the ball milling medium, the ball-to-material ratio was set at 8:1, the speed was 40 r / min, and the ball milling was continued for 48 h; after ball milling, the powder was vacuum dried at 70℃, and then sieved through a 200 mesh sieve. Finally, 2wt% of paraffin wax was added to the bottom cylindrical shell 1 powder and titanium alloy core 2 powder respectively, and stirred evenly for later use.

[0042] 2) Preparation of the bottom cylindrical shell 1 preform: The pretreated bottom cylindrical shell 1 powder (tungsten carbide and cobalt mixed powder) is placed into the hardened mold, and a unidirectional pressure of 350 MPa is applied to the powder through the mold for 15 seconds to obtain the bottom cylindrical shell 1 preform; 3) Press molding: Place the bottom cylindrical shell 1 blank into the mold, fill the cavity of the bottom cylindrical shell 1 blank with pretreated titanium alloy core 2 powder, perform secondary pressing molding, press pressure 350MPa, hold pressure for 15s, slowly demold to obtain an integral pressed blank. 4) Vacuum sintering: The integral pressed blank is placed in a vacuum sintering furnace for sintering. After sintering, the heating is turned off, and the blank is allowed to cool naturally to room temperature to obtain a composite alloy head. The vacuum degree is 10 throughout the entire vacuum sintering process. -4 Pa; The sintering method is as follows: Degreasing: Heat to 500℃ at a heating rate of 4℃ / min and hold for 45min; Pre-sintering: Continue heating to 950℃ and hold for 30 minutes; High-temperature sintering: Continue heating to 1380℃ and hold for 135 minutes; During the degreasing and pre-sintering stages, argon gas is introduced for protection; during the high-temperature sintering stage, the argon gas is turned off. 5) Brazing assembly: Using copper-based brazing filler metal, the composite alloy head is welded to the cutting tooth body 3 through a cutting tooth brazing process to obtain the cutting tooth; a clamp is used to fix the composite alloy head and the cutting tooth body 3 to ensure coaxiality and uniform gap, with the gap controlled at 0.12±0.02mm; the melting point of the copper-based brazing filler metal used is 910℃, and the brazing temperature is set to 950℃ (40℃ higher than the melting point of the copper-based brazing filler metal), and the temperature is maintained for 15s after brazing.

[0043] Among them, the copper-based brazing filler metal can be selected from copper-zinc-manganese brazing filler metal, copper-tin-phosphorus brazing filler metal, and copper-nickel-manganese brazing filler metal. In this embodiment, copper-nickel-manganese brazing filler metal is selected; the cutting tooth body 3 is made of 42CrMo alloy steel, which is a common wear-resistant cutting tooth matrix material in the industry.

[0044] 3. The following indicators shall be tested on the manufactured cutting teeth: shear strength, tooth surface hardness, and impact toughness. The test standard shall be: MT / T 246-2006 "Cutting Teeth for Mining Machinery"; Shear strength of brazed joint (MPa): reflects the shear bearing capacity of the brazed interface between the composite alloy head and the cutting tooth body 3; Tooth surface hardness (HRC): assesses the ability of the tooth surface to resist wear and deformation. The higher the hardness, the better the wear resistance and the better it can cope with frictional loss under harsh working conditions. Impact toughness (J / cm) 2 ): Reflects the ability of the cutting teeth to resist impact loads and suppress crack initiation and propagation.

[0045] 4. The manufactured cutting teeth can be applied to complex and alternating impact mining conditions such as coal mining machines and tunneling machines mining pure coal seams and coal interbedded with gangue.

[0046] Example 2: This example discloses a cutting tooth and its preparation method.

[0047] 1. A cutting tooth, comprising a cutting tooth body 3 and a composite alloy head; the composite alloy head comprising a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprising, by mass, 84 parts of hard phase and 16 parts of cobalt; the hard phase comprising tungsten carbide; The titanium alloy core 2 is composed of the following components by mass: 55 parts titanium, 18 parts nickel, 9 parts cobalt, 7 parts molybdenum, and 4 parts tungsten carbide.

[0048] Everything else is exactly the same as in Example 1.

[0049] Example 3: This example discloses a cutting tooth and its preparation method.

[0050] 1. A cutting tooth, comprising a cutting tooth body 3 and a composite alloy head; the composite alloy head comprising a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprising, by mass, 80 parts of a hard phase and 20 parts of cobalt; the hard phase comprising tungsten carbide; The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 20 parts nickel, 10.5 parts cobalt, 6 parts molybdenum, and 10 parts tungsten carbide.

[0051] Everything else is exactly the same as in Example 1.

[0052] The cutting teeth prepared in Examples 1-3 were tested respectively, and the test results are shown in Table 1: Table 1

[0053] Comparing the data from Examples 1-3, it can be seen that in Example 1, the bottom cylindrical shell 1 has a relatively high cobalt content and sufficient binder phase, resulting in better plasticity and the best impact toughness among the three examples. In Example 2, the bottom cylindrical shell 1 has the highest proportion of hard phase and an increased content of tungsten carbide hard phase, resulting in the best surface hardness among the three examples. However, the cobalt binder phase is insufficient, and the tungsten carbide content in the titanium alloy core 2 is also relatively low, leading to a slight decrease in interfacial bonding strength and toughness. In Example 3, the proportions are relatively balanced, resulting in the highest shear strength among the three examples, while the hardness and impact toughness are at an intermediate level. Overall, all three examples can meet the application requirements of cutting teeth.

[0054] Example 4: This example discloses a cutting tooth and its preparation method.

[0055] In this embodiment, the hard phase also includes 5 parts of titanium carbide and 3 parts of tantalum carbide; 1. A cutting tooth, comprising a cutting tooth body 3 and a composite alloy head; the composite alloy head comprising a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprises, by mass, 80 parts of hard phase and 20 parts of cobalt; the hard phase is: 72 parts of tungsten carbide, 5 parts of titanium carbide, and 3 parts of tantalum carbide. The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 20 parts nickel, 10.5 parts cobalt, 6 parts molybdenum, and 10 parts tungsten carbide.

[0056] 2. In a method for preparing a cutting tooth, the bottom cylindrical shell 1 powder in the raw material pretreatment stage includes tungsten carbide, titanium carbide, tantalum carbide and cobalt. Other pretreatment process parameters and process details for preparing the bottom cylindrical shell 1 blank are the same as in Example 3. Everything else is the same as in Example 3.

[0057] Example 5: This example discloses a cutting tooth and its preparation method.

[0058] In this embodiment, the hard phase also includes 1 part of chromium carbide; 1. A cutting tooth, comprising a cutting tooth body 3 and a composite alloy head; the composite alloy head comprising a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprises, by mass, 80 parts of hard phase and 20 parts of cobalt; the hard phase is: 71 parts of tungsten carbide, 5 parts of titanium carbide, 3 parts of tantalum carbide, and 1 part of chromium carbide. The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 20 parts nickel, 10.5 parts cobalt, 6 parts molybdenum, and 10 parts tungsten carbide.

[0059] 2. In a method for preparing a cutting tooth, the bottom cylindrical shell 1 powder in the raw material pretreatment stage includes tungsten carbide, titanium carbide, tantalum carbide, chromium carbide and cobalt. Other pretreatment process parameters and process details for preparing the bottom cylindrical shell 1 blank are the same as in Example 4. Everything else is the same as in Example 4.

[0060] Example 6: This example discloses a cutting tooth and its preparation method.

[0061] In this embodiment, in a method for preparing a cutting tooth, during the pressing and molding step: a transition layer is provided between the bottom cylindrical shell 1 and the titanium alloy core 2; the powder of the transition layer includes, by mass parts: 35 parts cobalt, 25 parts nickel, and 40 parts tungsten carbide; wherein, the radial thickness ratio of the bottom cylindrical shell 1, the transition layer, and the titanium alloy core 2 is 2:0.6:6. The specific pressing and molding steps are as follows: The bottom cylindrical shell 1 blank is placed in the mold. First, the uniformly mixed transition layer powder is evenly and symmetrically spread in the inner cavity of the bottom cylindrical shell 1 blank. After the spreading is completed, it is lightly pre-compressed and compacted under a pre-compression pressure of 50MPa for 3s. Then, titanium alloy core 2 mixed powder is filled on top of the compacted transition layer powder, and then a second pressing is performed. The pressing pressure is 350MPa, the pressure is held for 15s, and the mold is slowly demolded to obtain an integral pressed blank. The transition layer powder uses the same pretreatment method and ball milling process parameters as the bottom cylindrical shell 1 and titanium alloy core 2 powders in Example 3.

[0062] Everything else is the same as in Example 5.

[0063] Example 7: This example discloses a cutting tooth and its preparation method.

[0064] In this embodiment, in a method for preparing a cutting tooth, the cooling method in the vacuum sintering step is as follows: First, the temperature is reduced to 900±5℃ at a cooling rate of 1.8℃ / min; then to 550±10℃ at a cooling rate of 2.8℃ / min; then to 300±20℃ at a cooling rate of 5℃ / min; finally, the furnace is allowed to cool naturally to room temperature. Specifically: 4) Vacuum sintering: The integral compact is placed in a vacuum sintering furnace for sintering. After sintering, the heating is turned off, and the temperature is first reduced to 900±5℃ at a cooling rate of 1.8℃ / min; then reduced to 550±10℃ at a cooling rate of 2.8℃ / min; then reduced to 300±20℃ at a cooling rate of 5℃ / min; finally, it is allowed to cool naturally to room temperature in the furnace to obtain the composite alloy head; the vacuum degree is 10 throughout the entire vacuum sintering process. -4 Pa; Everything else is the same as in Example 6.

[0065] Comparative Example 1: This comparative example discloses a cutting tooth and its preparation method.

[0066] In this comparative example, a cutting tooth includes a cutting tooth body 3 and an alloy head; the alloy head is composed of 90 parts by mass of tungsten carbide and 10 parts of cobalt; all other components are the same as in Example 3.

[0067] Comparative Example 2: This comparative example discloses a cutting tooth and its preparation method.

[0068] In this comparative example, iron powder replaces cobalt in the powder composition of the bottom cylindrical shell 1. A cutting tooth includes a cutting tooth body 3 and a composite alloy head; the composite alloy head includes a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprises, by mass, 80 parts of hard phase and 20 parts of iron powder; the hard phase includes tungsten carbide. The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 20 parts nickel, 10.5 parts cobalt, 6 parts molybdenum, and 10 parts tungsten carbide.

[0069] In a method for preparing cutting teeth, 1) raw material pretreatment: all powders except iron powder are subjected to a dilute hydrochloric acid pickling step, and the remaining pretreatment processes are the same as in Example 3; Everything else is the same as in Example 3.

[0070] Comparative Example 3: This comparative example discloses a cutting tooth and its preparation method.

[0071] In this comparative example, iron powder replaces tungsten carbide and cobalt in the powder composition of the bottom cylindrical shell 1. A cutting tooth includes a cutting tooth body 3 and a composite alloy head; the composite alloy head includes a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 is composed of 100 parts of iron powder. The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 20 parts nickel, 10.5 parts cobalt, 6 parts molybdenum, and 10 parts tungsten carbide.

[0072] In a method for preparing cutting teeth, 1) raw material pretreatment: all powders except iron powder are subjected to a dilute hydrochloric acid pickling step, and the remaining pretreatment processes are the same as in Example 3; Everything else is the same as in Example 3.

[0073] Comparative Example 4: This comparative example discloses a cutting tooth and its preparation method.

[0074] In this comparative example, the titanium alloy core 2 powder does not contain molybdenum; A cutting tooth includes a cutting tooth body 3 and a composite alloy head; the composite alloy head includes a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprises, by mass, 80 parts of hard phase and 20 parts of cobalt; the hard phase includes tungsten carbide. The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 20 parts nickel, 10.5 parts cobalt, and 10 parts tungsten carbide; all other components are the same as in Example 3.

[0075] Comparative Example 5: This comparative example discloses a cutting tooth and its preparation method.

[0076] In this comparative example, the titanium alloy core 2 powder does not contain nickel; A cutting tooth includes a cutting tooth body 3 and a composite alloy head; the composite alloy head includes a bottom cylindrical shell 1 and a titanium alloy core 2; the bottom cylindrical shell 1 comprises, by mass, 80 parts of hard phase and 20 parts of cobalt; the hard phase includes tungsten carbide. The titanium alloy core 2 is composed of the following components by mass: 53.5 parts titanium, 10.5 parts cobalt, 6 parts molybdenum, and 10 parts tungsten carbide; all other components are the same as in Example 3.

[0077] The cutting teeth prepared in Examples 4-7 and Comparative Examples 1-5 were tested respectively, and the test results are shown in Table 2: Table 2

[0078] By comparing Example 4 with Example 3, it can be seen that Example 4 added titanium carbide and tantalum carbide to the hard phase of the bottom cylindrical shell 1. The two carbides can suppress the abnormal growth of tungsten carbide grains during high-temperature sintering and achieve grain refinement. The grain refinement further improves the surface hardness of the alloy and the shear strength of the brazing interface. The fine grains can disperse impact stress and hinder crack propagation. Therefore, the three indicators of shear strength, tooth surface hardness and impact toughness have all increased.

[0079] By comparing Example 5 with Example 4, it can be seen that Example 5 adds chromium carbide to the hard phase of the bottom cylindrical shell 1. Chromium carbide can form a dense oxide protective layer on the alloy surface, enhance wear resistance and oxidation resistance, and further improve surface hardness, resulting in a slight improvement in various performance indicators.

[0080] By comparing Example 6 with Example 5, it can be seen that Example 6 adds a transition layer of cobalt, nickel and tungsten carbide between the bottom cylindrical shell 1 and the titanium alloy core 2, so that the transition layer has the hard phase of the bottom cylindrical shell 1 and the intermediate components of the titanium alloy core 2, eliminating the abrupt change that may occur when the two dissimilar materials are directly bonded, thereby reducing the residual internal stress at the interface and improving the metallurgical bonding strength at the interface; at the same time, it also reduces the difficulty of interlaminar crack initiation, thus improving the shear strength and impact toughness.

[0081] By comparing Example 7 with Example 6, it can be seen that Example 7 replaces the natural cooling with a different temperature cooling method. This cooling method can release the internal residual tensile stress caused by the difference in thermal expansion coefficients of the bottom cylindrical shell 1, transition layer, and titanium alloy core 2 during the sintering process, and reduce the occurrence rate of microcracks and porosity inside the alloy; thereby improving the shear strength and impact toughness of the alloy.

[0082] By comparing Comparative Example 1 and Example 3, it can be seen that the comparative example uses a conventional tungsten carbide-cobalt cemented carbide integral alloy head, which has a higher proportion of tungsten carbide and higher shear strength, but lacks toughening alloying elements such as titanium, nickel, and molybdenum; the single cemented carbide has slightly higher brittleness and slightly lower impact toughness.

[0083] By comparing Comparative Example 2 and Example 3, it can be seen that the outer shell bonding phase of Comparative Example 2 uses iron powder to replace cobalt metal. The wettability of iron with tungsten carbide is much lower than that of cobalt, which may lead to an increase in the porosity and defects inside the shell after sintering, thus resulting in a decrease in the density of the shell. At the same time, the metallurgical compatibility between iron and the inner titanium alloy core 2 is slightly poor, and gaps are easily generated at the interlayer bonding interface. The hardness of the wear-resistant layer of the shell, the interfacial shear strength, and the overall impact toughness all decrease.

[0084] By comparing Comparative Example 3 with Example 3, it can be seen that the bottom cylindrical shell 1 of Comparative Example 3 does not use tungsten carbide hard phase, but only pure iron powder. Without the support of a high-hardness and wear-resistant hard phase, the shell loses its wear resistance. The pure iron matrix has low strength and hardness, and all three mechanical performance indicators are the lowest among all groups, which does not meet the actual application requirements.

[0085] By comparing Comparative Example 4 with Example 3, it can be seen that in Comparative Example 4, molybdenum was removed from the titanium alloy core 2. Molybdenum is the main grain refining element. After the removal of molybdenum, the core has coarse grains. The coarse grain structure is prone to stress concentration points, and cracks are prone to rapid propagation along the coarse grain boundaries. The core's toughness and load-bearing capacity decrease, resulting in a decrease in overall shear strength, hardness, and impact toughness.

[0086] By comparing Comparative Example 5 with Example 3, it can be seen that in Comparative Example 5, nickel was removed from the titanium alloy core 2. Nickel has the effect of plastic toughening, which can improve the plastic deformation ability of the titanium matrix and improve the metallurgical bonding ability between the core and the cobalt-based shell. After the loss of nickel, the plasticity of the core is reduced and the interlayer bonding force may be weakened.

[0087] Meanwhile, the cutting teeth prepared in Examples 3-7 were tested for the following indicators, according to MT / T246-2006. The test results are shown in Table 3: Table 3

[0088] As can be seen from Table 3, all the tested indicators meet the standard of MT / T 246-2006.

[0089] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A pick, comprising: It includes a cutting tooth body (3) and a composite alloy head; the composite alloy head includes a bottom cylindrical shell (1) and a titanium alloy core (2); the bottom cylindrical shell (1) is composed of 76 to 84 parts by mass of hard phase and 16 to 24 parts of cobalt; the hard phase includes tungsten carbide; The titanium alloy core (2) comprises the following components by mass: 52-55 parts titanium, 18-22 parts nickel, 9-12 parts cobalt, 5-7 parts molybdenum, and 4-16 parts tungsten carbide.

2. The pick of claim 1 wherein, The hard phase also includes 3-8 parts of titanium carbide and 1-4 parts of tantalum carbide.

3. A pick according to claim 2, wherein, The hard phase also includes 0.5 to 2 parts of chromium carbide.

4. A method of manufacturing a pick according to any one of claims 1 to 3, characterized in that, Includes the following steps: Preparation of the bottom cylindrical shell (1) blank: The bottom cylindrical shell (1) blank was formed by powder metallurgy process; Press molding: The bottom cylindrical shell (1) blank is placed into the mold, and titanium alloy core (2) powder is filled into the inner cavity of the bottom cylindrical shell (1) blank. Secondary pressing molding is performed to obtain an integral pressed blank. Vacuum sintering: The integral pressed blank is placed in a vacuum sintering furnace for sintering and cooling to obtain a composite alloy head; Brazing assembly: Using copper-based brazing filler metal, the composite alloy head is welded to the cutting tooth body (3) through a cutting tooth brazing process to obtain the cutting tooth.

5. The method of claim 4, wherein the pick is formed by, In the compression molding step, the pressure of the secondary compression is 100-600 MPa, and the holding time is 5-30 seconds.

6. The method of claim 4, wherein the pick is formed by, In the pressing and molding step, a transition layer is provided between the bottom cylindrical shell (1) and the titanium alloy core (2); The powder of the transition layer includes, by mass parts: 30-40 parts cobalt, 20-30 parts nickel, and 30-50 parts tungsten carbide; wherein, the radial thickness ratio of the bottom cylindrical shell (1), the transition layer and the titanium alloy core (2) is 1-3:0.2-1:3-8.

7. The method of claim 6, wherein the pick is formed by, In the vacuum sintering step, the sintering method is as follows: Degreasing: Heat to 400-600℃ at a heating rate of 3-5℃ / min, and hold for 30-60 minutes; Pre-sintering: Continue heating to 900-1000℃ and hold for 20-40 minutes; High-temperature sintering: Continue heating to 1350-1400℃ and hold for 120-150 minutes.

8. The method of claim 7, wherein the pick is formed by, In the vacuum sintering step, the cooling method is as follows: First, the temperature is reduced to 900±5℃ at a cooling rate of 1.5~2.0℃ / min; then it is reduced to 550±10℃ at a cooling rate of 2.5~3℃ / min; then it is reduced to 300±20℃ at a cooling rate of 4~5℃ / min; finally, it is allowed to cool naturally to room temperature with the furnace.

9. The method of claim 7 wherein the pick is formed by, In the vacuum sintering step, the vacuum degree is 10 -3 ~ 10 -5 Pa, and argon gas is introduced for protection during the debinding and pre-sintering stages.

10. The method of manufacturing a pick according to any one of claims 4-9, characterized in that, In the brazing assembly step, the melting point of the copper-based brazing filler metal is 890-930℃, the brazing temperature is 30-50℃ higher than the melting point of the copper-based brazing filler metal, and the temperature is maintained for 10-20 seconds after brazing.

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