Copper-based alloy, copper-based brazing filler metal and short-process preparation method and application of copper-based alloy and copper-based brazing filler metal

Abstract

The invention relates to a copper-based alloy, copper-based brazing filler metal and a short-process preparation method and application of the copper-based alloy and the copper-based brazing filler metal, belongs to the technical field of cutting pick brazing, and solves the problem that excellent brazing performance and mechanical performance of existing copper-based brazing filler metal cannot be achieved at the same time. The copper-based alloy comprises the following components in percentage by mass: 25%-40% of Zn, 2%-10% of Ni, 2%-6% of Mn, 0.1%-0.5% of Fe, 0.1%-0.3% of Si, 0.05%-0.1% of rare earth elements and the balance of Cu and inevitable trace impurities. The copper-based brazing filler metal comprises the copper-based alloy.

Description

Technical Field

[0001] This invention relates to the field of brazing technology for cutting teeth, and in particular to a copper-based alloy, a copper-based brazing filler metal, and their short-process preparation method and application. Background Technology

[0002] Cutting teeth are key wear components of engineering machinery used in coal mining, tunneling, and other applications. Their performance and service life directly affect the overall operational efficiency of the equipment. Cutting teeth are typically constructed by brazing alloy steel teeth and carbide tips together. The quality of the brazing is one of the core factors determining the performance of the cutting teeth, and the selection of the brazing filler metal is crucial.

[0003] Currently, copper-based brazing filler metals are widely used in cutting tool brazing due to their good strength, wettability, and economy. Traditional copper-based brazing filler metals (such as ordinary brass filler metals) suffer from insufficient strength and poor wear resistance, making them unsuitable for the demands of high-intensity mining operations. Furthermore, traditional filler metals are often produced using a long process of casting, rolling, and punching. This process is complex, energy-intensive, and prone to defects such as cracks and edge breakage when producing thin and brittle filler metal foils, resulting in low yield and high costs.

[0004] Therefore, there is an urgent need in this field to develop a copper-based brazing filler metal that combines excellent brazing performance and mechanical properties, along with an efficient and short-process preparation method, to address the shortcomings of existing technologies. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a copper-based alloy, a copper-based brazing filler metal and its short-process preparation method and application, which can at least solve one of the following technical problems: (1) the excellent brazing performance and mechanical properties of existing copper-based brazing filler metals cannot be obtained at the same time; (2) the existing process for preparing sheet brazing filler metals is long, complicated and energy-intensive.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] The present invention provides a copper-based alloy comprising, by mass percentage: Zn, 25%-40%, Ni, 2%-10%, Mn, 2%-6%, Fe, 0.1%-0.5%, Si, 0.1%-0.3%, rare earth elements, 0.05%-0.1%, with the balance being Cu and unavoidable trace impurities.

[0008] Optionally, the copper-based alloy comprises, by weight percentage: Zn, 28%-35%, Ni, 3%-8%, Mn, 2%-6%, Fe, 0.1%-0.5%, Si, 0.1%-0.3%, rare earth elements, 0.05%-0.1%, with the balance being Cu and unavoidable trace impurities.

[0009] The present invention provides a copper-based brazing filler metal, comprising the aforementioned copper-based alloy.

[0010] Optionally, the copper-based brazing filler metal is in sheet form with a thickness of 1-2.5 mm.

[0011] Optionally, the copper-based brazing filler metal is in the form of a disc with a diameter of 10-25 mm.

[0012] This invention provides a method for preparing the above-mentioned copper-based solder, comprising the following steps:

[0013] Step 1: Melt the above copper-based alloy to obtain an alloy melt;

[0014] Step 2: The alloy melt is introduced into the intermediate ladle;

[0015] Step 3: Casting to obtain sheet-like copper-based brazing filler metal.

[0016] Optionally, in step 1, the melting temperature is 800-1200℃.

[0017] Optionally, in step 3, the casting includes: pouring the alloy melt into the gap between the first cooling roller and the second cooling roller through a nozzle at the bottom of the tundish to obtain sheet-like brazing filler metal.

[0018] Optionally, the outer surface of the first cooling roller is provided with a grooved area, and the grooved area is provided with multiple grooves, and the second cooling roller is a flat roller.

[0019] The present invention provides an application of the above-mentioned copper-based brazing filler metal in brazing of cutting teeth, comprising: brazing an alloy steel tooth body and a cemented carbide tooth tip with the above-mentioned copper-based brazing filler metal to obtain a cutting tooth.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] The brazing filler metal boasts an excellent composition design: through the synergistic effect of Zn, Ni, and Mn, the shear strength of the brazed joint is significantly improved while ensuring a suitable melting point (the shear strength of brazed joints welded with ordinary brass filler metal is around 200 MPa, while the shear strength of brazed joints welded with the filler metal of this invention is ≥300 MPa, for example, 300-338 MPa). It is a copper-based filler metal that combines excellent brazing performance and mechanical properties. Strict control of Fe and Si content reduces the formation of brittle phases and improves the workability of the filler metal.

[0022] Advanced and efficient manufacturing process: Employing vacuum twin-roll rapid quenching technology, the traditional multiple processes of smelting, casting, hot rolling, cold rolling, annealing, and punching are simplified into a single step, achieving "short-process" production and significantly reducing energy consumption and production costs. Specifically, energy consumption is reduced by approximately 70%, for example, 68%-72%. Production costs are reduced by approximately 50%, for example, 49%-53%.

[0023] High product performance and high yield: Rapid solidification technology refines the alloy microstructure and reduces component segregation, resulting in uniform solder composition and stable performance. Simultaneously, this net-finish forming process avoids cracks and damage that may occur during subsequent processing, making it particularly suitable for producing difficult-to-machine, thin, and brittle sheet solders, significantly improving the yield. Specifically, the yield is 85%-90%.

[0024] High flexibility: By designing a cooling roller with grooves, sheet brazing materials of different specifications and sizes can be flexibly and directly prepared to meet the brazing requirements of different types of cutting teeth.

[0025] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1 This is a schematic diagram of the cooling roller and nozzle of the present invention.

[0028] Figure 2 This is a schematic diagram showing the relative position of the cooling roller and the nozzle after the cooling roller of the present invention rotates;

[0029] Figure 3 This is a schematic diagram of the structure of the first cooling roller of the present invention having grooves on its surface;

[0030] Figure 4 This is a schematic diagram of the structure of the first cooling roller of the present invention, which has a slightly grooved groove.

[0031] Figure 5 The OM diagram of the tooth body prepared in Example 1 of the present invention is shown.

[0032] Figure 6 SEM image of the tooth body prepared in Example 1 of the present invention;

[0033] Figure 7 This is a physical image of the cutting teeth prepared in Example 1 of the present invention.

[0034] Figure label:

[0035] 1-First cooling roller; 2-Second cooling roller; 3-Nozzle; α-Slight degree. Detailed Implementation

[0036] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and, together with the embodiments, serve to illustrate the principles of the invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the methods described are conventional methods. Unless otherwise specified, the raw materials are all available from commercially available sources.

[0037] Cutting teeth are key wear parts of engineering machinery used in coal mining, tunneling, and other applications. They are typically constructed by brazing an alloy steel tooth body and a cemented carbide tip. The quality of the brazing is one of the core factors determining the performance of the cutting teeth, and the selection of the brazing filler metal is crucial. Copper-based brazing filler metals are widely used in cutting tooth brazing due to their good strength, wettability, and economy. In one aspect, this invention provides a copper-based alloy, whose chemical composition, by mass percentage, includes Zn 25%-40%, Ni 2%-10%, Mn 2%-6%, Fe 0.1%-0.5%, Si 0.1%-0.3%, rare earth elements 0.05%-0.1%, and the balance being Cu and unavoidable trace impurities.

[0038] The rare earth element is at least one of La and Ce.

[0039] The following details the function and dosage selection of the components contained in this invention:

[0040] Cu: As the matrix of the solder, it provides the main metallic properties. Pure copper has a high melting point (1083℃), but by adding other elements, the melting point can be lowered to form alloys suitable for brazing.

[0041] Zn: The addition of Zn can form a low-melting eutectic with Cu, enabling the solder to operate at lower temperatures and improving its ability to fill gaps. Therefore, this invention limits the Zn content to 25%-40%.

[0042] Ni: The addition of Ni can strengthen the matrix through solid solution treatment, especially improving high-temperature strength, and enhancing the stability of the brazing seam under harsh environments (such as wear and corrosion). Therefore, this invention limits the Ni content to 2% to 10%.

[0043] Mn: The addition of Mn can reduce oxides during brazing, improving the fluidity and wettability of the brazing filler metal. Therefore, this invention limits the Mn content to 2% to 6%.

[0044] Fe: The addition of Fe inhibits Cu grain growth and improves the strength and toughness of the brazing seam. However, the amount added needs to be controlled; too much will reduce plasticity and may form a brittle phase. Therefore, this invention limits the Fe content to 0.1%-0.5%.

[0045] Si: The addition of Si can effectively reduce oxides on the surface of the solder and the base material, improving wettability; however, excessive Si will also increase brittleness. Therefore, this invention limits the Si content to 0.1%-0.3%.

[0046] Rare earth elements: The rare earth element is at least one of La and Ce. The addition of rare earth elements can purify the solder melt, reduce the segregation of harmful impurities at grain boundaries, and reduce the oxide film on the surface of the base metal during brazing, significantly improving the wettability and spreading ability of the solder to the base metal. Therefore, this invention limits the content of rare earth elements to 0.05%-0.1%.

[0047] The copper-based alloy described above is prepared by the following method: weigh each component according to the above proportions, and melt them under vacuum or protective atmosphere at a temperature of 800-1200°C to obtain the copper-based alloy.

[0048] Secondly, the present invention also provides a copper-based brazing filler metal for brazing cutting teeth, comprising the aforementioned copper-based alloy.

[0049] To further improve the overall performance of the copper-based solder, the composition of the copper-based solder, by mass percentage, can be: Zn, 28%-35%, Ni, 3%-8%, Mn, 2%-6%, Fe, 0.1%-0.5%, Si, 0.1%-0.3%, rare earth elements, 0.05%-0.1%, with the balance being Cu and unavoidable trace impurities.

[0050] This invention significantly improves the strength, toughness, and wear resistance of brazed joints by leveraging the synergistic effect of Zn, Ni, and Mn, while ensuring a suitable melting point for the brazing filler metal. Strict control of Fe and Si content reduces the formation of brittle phases and improves the machinability of the brazing filler metal.

[0051] The copper-based brazing filler metal of the present invention is in sheet form with a thickness of 1-2.5 mm, for example, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2 mm, 2.2 mm, 2.4 mm, 2.5 mm.

[0052] In one specific embodiment, the solder is in the shape of a disc with a diameter of 10-25 mm, for example, 10 mm, 12 mm, 14 mm, 15 mm, 17 mm, 19 mm, 20 mm, 22 mm, 24 mm, or 25 mm.

[0053] Specifically, the microstructure of the aforementioned copper-based solder is a rapidly solidified fine-grained structure. Specifically, the grain size is 1-3 μm.

[0054] Thirdly, the present invention also provides a method for preparing the aforementioned copper-based brazing filler metal. This method employs vacuum twin-roll rapid quenching technology, the core of which lies in rapidly solidifying molten metal into shape, achieving a short process and a clean final shape. The method includes the following steps:

[0055] Step 1: Melt the above copper-based alloy under vacuum or a protective atmosphere to obtain a homogeneous alloy melt.

[0056] Step 2: Pour the alloy melt into a preheated tundish;

[0057] Step 3: The alloy melt is poured into the gap between a pair of relatively rotating cooling rollers through the nozzle at the bottom of the tundish. The alloy melt is rapidly cooled and solidified by the rapidly rotating cooling rollers as it passes through the gap, resulting in sheet-like brazing filler metal.

[0058] In step 1, the melting temperature is 800-1200℃, for example, 800℃, 900℃, 1000℃, 1100℃, 1200℃.

[0059] In step 2, the preheating temperature is 800-950℃, for example, 800℃, 850℃, 900℃, 950℃.

[0060] In step 3, the rotational speed of the cooling roller is 2-5 m / s, for example, 2 m / s, 3 m / s, 4 m / s, 5 m / s. The roller gap is 0.02-0.15 mm, for example, 0.02 mm, 0.04 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm.

[0061] The diameter of the sheet solder obtained in step 3 is 10-25mm, for example, 10mm, 12mm, 14mm, 15mm, 17mm, 19mm, 20mm, 22mm, 24mm, 25mm. The thickness is 1-2.5mm, for example, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.7mm, 1.9mm, 2mm, 2.2mm, 2.4mm, 2.5mm.

[0062] The cooling roller is made of a material with high thermal conductivity, such as pure copper or copper alloy.

[0063] The cooling roller is a dual-roller assembly, comprising a first cooling roller and a second cooling roller. The outer surface of the first cooling roller has a grooved area, within which multiple grooves are arranged at intervals. The second cooling roller is a flat roller. This invention, through the engagement of the grooves and the flat roller, can directly produce sheet-like brazing filler metals of different sizes and thicknesses.

[0064] Specifically, such as Figure 1 and Figure 3 As shown, along the axial direction of the first cooling roller, the outer surface of the first cooling roller is provided with more than two groove areas. The grooves in the same groove area have the same size, while the grooves in different groove areas have different sizes. By moving the intermediate tundish and nozzle to the corresponding size area, sheet-shaped brazing filler metal of different specifications and sizes can be solidified to meet the brazing requirements of different types of cutting teeth.

[0065] In a preferred embodiment, such as Figure 4 As shown, the groove has a slight angle, with the opening of the groove being larger than the bottom, and the size of the groove gradually decreasing from the opening to the bottom. This slight angle facilitates the detachment of the sheet solder from the groove after solidification. Exemplarily, the angle α is 1°-2°, for example, 1°, 1.2°, 1.3°, 1.5°, 1.7°, 1.8°, 1.9°, or 2°.

[0066] In one specific embodiment, the cross-section of the groove is circular, and the diameter of the groove is 10-25mm, for example, 10mm, 12mm, 14mm, 15mm, 17mm, 19mm, 20mm, 22mm, 24mm, 25mm.

[0067] The depth of the groove is 1-2.5mm, for example, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.7mm, 1.9mm, 2mm, 2.2mm, 2.4mm, 2.5mm.

[0068] In addition, the inner walls of the first and second cooling rollers can be designed with single or multiple spiral grooves to increase the system's cooling capacity.

[0069] The present invention also provides a vacuum rapid quenching apparatus, comprising a melting furnace, a tundish, a nozzle, a brazing filler metal collection device, and the aforementioned cooling roller. The tundish is connected to the melting furnace, the nozzle is connected to the tundish, and the brazing filler metal collection device is located below the cooling roller.

[0070] The present invention also provides the application of the above-mentioned copper-based brazing filler metal in brazing of cutting teeth, including: using the above-mentioned copper-based brazing filler metal to braze an alloy steel tooth body and a cemented carbide tooth tip to obtain a cutting tooth.

[0071] Specifically, the chemical composition of the alloy steel tooth body, by mass percentage, is as follows: C 0.28%–0.32%, Si 0.50%–1.20%, Al 0.50%–1.00%, Mn 2.80%–3.50%, Cr 0.15%–1.50%, Mo 0.15%–0.25%, Nb 0.01–0.03%, Ti 0.01–0.025%, N≤0.005%, P≤0.02%, S≤0.005%, with the remainder being Fe and unavoidable impurities.

[0072] The reasons for limiting the steel composition of the vacuum brazed high-strength and high-toughness bainitic tooth body and its preparation method in this invention will be explained. Hereinafter, only the mass percentage of the composition is expressed as %.

[0073] Carbon (C) is a key solid solution strengthening element in high-strength and high-toughness bainitic steel, directly affecting the hardness, strength, and hardenability of the bainitic phase. Carbon atoms can significantly improve the strength of steel and promote the stabilization of retained austenite during the bainitic transformation, thereby enhancing the toughness and impact resistance of the material. However, excessively high carbon content increases the brittleness of the bainitic structure, reducing impact toughness and weldability. Therefore, considering the requirements for strength, toughness, brazing adaptability, and wear resistance, this invention controls the carbon content to 0.28%–0.32%, for example, 0.28%, 0.29%, 0.30%, 0.31%, and 0.32%.

[0074] Silicon (Si): Exists in steel in solid solution form, effectively inhibiting cementite precipitation during bainite transformation, promoting the formation of fine bainitic ferrite laths, and optimizing the strength-toughness balance of the material. It also enhances the tempering resistance of steel, delays high-temperature softening, and strengthens the stability of cutting teeth under heavy-load impact and friction-wear conditions. Therefore, considering the overall strengthening effect, toughness, and brazing adaptability, this invention sets the Si content to 0.50%–1.20%, for example, 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.00%, 1.10%, and 1.20%.

[0075] Aluminum (Al): Exists in steel in solid solution form, which can regulate the bainitic phase transformation kinetics, increase the bainitic transformation rate, optimize production process efficiency, and, together with silicon, inhibit cementite precipitation. Aluminum can form AlN precipitates with nitrogen, improving steel cleanliness and optimizing material toughness. Therefore, considering oxidation resistance, grain refinement effect, and process adaptability, this invention controls the Al content at 0.50%–1.00%.

[0076] Manganese (Mn) is a key hardenability element in high-strength and high-toughness bainitic steel. It is inexpensive and provides excellent hardenability. It significantly improves austenite stability, lowers the bainite transformation temperature, and promotes the formation of fine lath bainite, thereby enhancing the strength and toughness of the steel. It effectively inhibits ferrite precipitation in high-temperature regions, increases the bainite transformation ratio during continuous cooling, and ensures the uniformity of microstructure in large-section workpieces. Therefore, considering hardenability, phase transformation control, and microstructure uniformity, this invention limits the Mn content to 2.80%–3.50%, for example, 2.80%, 2.90%, 3.00%, 3.10%, 3.20%, 3.30%, 3.40%, and 3.50%.

[0077] Chromium (Cr): As an important hardenability element in high-strength and high-toughness bainitic steel, it can significantly improve the hardenability of steel, refine the size of bainite lath bundles, and enhance tempering resistance, thereby improving the high-temperature strength and wear resistance of the steel. Considering the balance between hardenability, microstructure refinement, corrosion resistance, and processing performance, this invention limits the Cr content to 0.15%–1.50%, for example, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 1.0%, 1.05%, 1.1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, and 1.5%.

[0078] Molybdenum (Mo): As a key microalloying element in bainitic steel, Mo can significantly improve hardenability and delay high-temperature phase transformation; it also refines the bainitic lath structure through the solute dragging effect, enhancing dislocation strengthening. Therefore, considering hardenability control, microstructure refinement, and economy, this invention optimizes the Mo content to 0.15%–0.25%, for example, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, and 0.25%.

[0079] Niobium (Nb) is a microalloying carbonitride forming element. During rolling, it can suppress recrystallization and refine the original austenite grains. Simultaneously, deformation-induced precipitation of nanoscale Nb(C,N) pins dislocations and grain boundaries, increasing the bainite nucleation density and refining the bainite lath bundle size. Therefore, considering grain refinement, precipitation strengthening, and process adaptability, the niobium content in this invention ranges from 0.01% to 0.03%, for example, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.022%, 0.024%, 0.026%, 0.028%, and 0.3%.

[0080] Titanium (Ti): A microalloying carbonitride forming element. The solid solubility of nitrides formed by Ti combining with N is lower than that of Nb, enabling the formation of titanium nitride at high temperatures. This refines austenite grains. However, excessive titanium content leads to the precipitation and significant coarsening of TiN in the liquid phase, negatively impacting the hot working performance of the gear teeth. Therefore, considering all factors, the titanium content in this invention ranges from 0.01% to 0.025%, for example, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.020%, 0.022%, 0.024%, and 0.025%.

[0081] Phosphorus (P): It is a harmful element in bainitic steel, and the phosphorus content in this invention does not exceed 0.02%.

[0082] Sulfur (S): It is a harmful element in bainitic steel. The sulfur content in this invention does not exceed 0.005%.

[0083] The high-strength and high-toughness bainitic tooth body of this invention has low cost. It adopts a medium-carbon Mn-Cr-Si / Al main element alloy design, combined with a small amount of Mo element and Nb and Ti composite microalloying, without the need to introduce expensive alloying elements, and the tooth body steel has good economic efficiency.

[0084] Specifically, the chemical composition of the cutting tooth body also satisfies the following conditions: 3.0% ≤ Mn + Cr ≤ 4.5%, for example, Mn + Cr is 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.5%; 1.0% ≤ Si + Al ≤ 2.0%, for example, Si + Al is 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%; and 0.025% ≤ Nb + Ti ≤ 0.055%, for example, Nb + Ti is 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%.

[0085] The high-strength and tough tooth steel alloy composition of this invention has good compatibility with the vacuum brazing process. The 3.0% ≤ Mn + Cr ≤ 4.5% composition can ensure the stability of supercooled austenite and avoid the formation of ferrite or pearlite during cooling, resulting in a microstructure with a bainite content of over 90%. The 1.0% ≤ Si + Al ≤ 2.0% composition can suppress the precipitation of cementite, avoid the precipitation of carbides during the slow cooling stage, and improve the carbon atom utilization efficiency. The 0.025% ≤ Nb + Ti ≤ 0.055% composition can refine the original austenite grains, avoid coarse austenite grains during the brazing heating process, and further improve the hardness and toughness of the cutting teeth.

[0086] This invention, through rational composition design and strict control of process parameters, produces tooth bodies with high strength and high toughness. The combined use of Mn and Cr elements ensures the stability of supercooled austenite, inhibits ferrite formation, and promotes bainite transformation in the low-temperature phase region, thereby refining the bainite lath width. The combined use of Si and Al elements inhibits cementite precipitation during bainite transformation and improves the stability of retained austenite. The combined use of Nb and Ti elements inhibits grain coarsening during the brazing heating and holding stages, while simultaneously dispersing microalloyed carbides. The combined use of these alloying elements helps to obtain a high proportion of bainite microstructure, improving the strength and toughness of the vacuum brazed tooth body.

[0087] Specifically, the microstructure of the cutting tooth body includes bainite, and the volume percentage of bainite is ≥90%.

[0088] Preferably, the microstructure of the tooth body further includes martensite / austenite islands (martensite + retained austenite) and microalloyed carbides, without proeutectoid ferrite.

[0089] Another specific embodiment of the present invention discloses a method for preparing the above-mentioned cutting tooth body, comprising the following steps:

[0090] Step 1: Prepare the raw materials according to the composition of the cutting tooth body, and obtain the casting billet through smelting and casting;

[0091] Step 2: Homogenize the cast billet;

[0092] Step 3: After descaling the homogenized billet, roll it to obtain a round bar;

[0093] Step 4: Forge and machine the round bar to obtain the cutting tooth body.

[0094] Specifically, in step 1, the smelting includes converter smelting, LF refining, RH or VD degassing, electromagnetic stirring treatment, and casting to obtain a billet.

[0095] Specifically, in step 2, the homogenization treatment temperature is 1180-1250℃, for example, 1180℃, 1190℃, 1200℃, 1210℃, 1220℃, 1230℃, 1240℃, 1250℃, and the holding time is 2-5h, for example, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h.

[0096] It should be noted that in order to reduce elemental segregation in the tooth body and to take into account the grain coarsening caused by the high-temperature melting of titanium nitride particles, the homogenization temperature is controlled at 1180-1250℃. At the same time, the high Si and Al content in the tooth body leads to poor thermal conductivity, which easily causes cracking and incomplete burning. Therefore, the billet should be in the furnace for no less than 2-5 hours before continuous rolling.

[0097] Specifically, in step 3, the initial rolling temperature is 1080–1150℃, for example, 1080℃, 1090℃, 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, or 1150℃, and the final rolling temperature is 860–930℃, for example, 860℃, 870℃, 880℃, 890℃, 900℃, 910℃, 920℃, or 930℃.

[0098] It should be noted that if the final rolling temperature is too high, the hot-rolled austenite grains will be coarser, and the refining effect of titanium and niobium precipitates on the austenite grains during the hot rolling stage will be insignificant; if the final rolling temperature is too low, vanadium carbide particles will precipitate and coarsen prematurely, weakening the precipitation strengthening effect.

[0099] Specifically, in step 3, the diameter of the round bar is 28 to 45 mm, for example, 28 mm, 30 mm, 32 mm, 34 mm, 36 mm, 38 mm, 40 mm, 42 mm, 44 mm, or 45 mm.

[0100] Specifically, in step 4, the holding temperature for forging is 950-1000℃, for example, 950℃, 960℃, 970℃, 980℃, 990℃, or 1000℃, and the final forging temperature is 820-860℃, for example, 820℃, 830℃, 840℃, 850℃, or 860℃, and the compression ratio is ≥8, for example, 8, 9, 10, 11, 12, 13, or 14.

[0101] It should be noted that excessively high forging holding temperatures can lead to excessive austenite grain growth, while the re-dissolution of titanium and niobium carbonitrides weakens the subsequent precipitation strengthening effect. Conversely, excessively low holding temperatures significantly increase the resistance to hot deformation, making microcracks more likely and resulting in insufficient dynamic recrystallization, thus affecting the uniformity of the microstructure. When the compression ratio is insufficient, dendritic segregation and shrinkage cavities in the steel bar microstructure are difficult to break up completely, affecting the consistency of the steel bar's mechanical properties. However, excessively high compression ratios will significantly increase the equipment load and may lead to excessive core temperature rise, causing abnormal local grain growth.

[0102] Another specific embodiment of the present invention discloses a cutting tooth made from the above-described cutting tooth body.

[0103] Another specific embodiment of the present invention discloses a method for preparing a cutting tooth, comprising the following steps: placing the tooth body, brazing material and flux in a vacuum brazing setup, heating to the brazing temperature and holding at that temperature, and furnace cooling to room temperature to obtain the cutting tooth.

[0104] Specifically, the brazing temperature is 890–970℃, for example, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, and the holding time is 2–30 min, for example, 2 min, 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min.

[0105] It should be noted that excessively high brazing temperatures can lead to coarsening of the tooth grains, excessive spread and loss of the brazing filler metal, and even localized erosion. Conversely, excessively low temperatures result in insufficient fluidity of the brazing filler metal, making it difficult to achieve proper wetting and gap filling, thus reducing joint strength. Insufficient holding time leads to inadequate brazing filler metal diffusion and poor interfacial metallurgical bonding; excessive holding time can easily lead to the formation of brittle intermetallic compounds and increase the risk of grain growth.

[0106] Specifically, the furnace cooling rate is 0.3℃ / s to 3℃ / s above 500℃, for example, 0.3℃ / s, 0.5℃ / s, 0.7℃ / s, 0.9℃ / s, 1.1℃ / s, 1.3℃ / s, 1.5℃ / s, 1.7℃ / s, 1.9℃ / s, 2.1℃ / s, 2.3℃ / s, 2.5℃ / s, 2.7℃ / s, 2.9℃ / s, and 3℃ / s. The cooling rate is 0.01℃ / s to 0.3℃ / s between 500℃ and 200℃, for example, 0.01℃ / s, 0.05℃ / s, 0.10℃ / s, 0.15℃ / s, 0.2℃ / s, 0.25℃ / s, and 0.3℃ / s.

[0107] This invention employs a furnace cooling process that combines rapid cooling above 500°C with slow cooling. Rapid cooling above 500°C ensures efficient production of bainitic gear teeth. Slow cooling between 500°C and 200°C guarantees the full transformation of bainite, resulting in a microstructure with a bainite content exceeding 90%. Simultaneously, it reduces the cooling rate requirements above 500°C, preventing damage to vacuum brazing equipment due to excessive cooling. Below 200°C, the bainite transformation is complete, and there are no restrictions on the cooling rate.

[0108] In step 5, the brazing of the tooth body uses either resistance heating or induction heating. Resistance heating allows for precise temperature control and is suitable for uniform heating of complex-shaped teeth; induction heating has the advantages of rapid heating and a narrow heat-affected zone, making it suitable for localized heating of the tooth tip and helping to reduce the loss of matrix microstructure properties.

[0109] The high-strength and tough bainitic tooth body provided by this invention has superior overall performance. Compared with traditional tooth bodies, it has better strength and toughness under vacuum brazing conditions, room temperature impact energy AKU2≥40J, hardness≥42HRC, which can improve the service life and reliability of cutting teeth.

[0110] 1. This invention, through rational composition design, produces tooth bodies with high strength and high toughness. The combined use of Mn and Cr elements ensures the stability of supercooled austenite, inhibits ferrite formation, and promotes bainite transformation in the low-temperature phase region, thereby refining the bainite lath width. The combined use of Si and Al elements inhibits cementite precipitation during bainite transformation, improving the stability of retained austenite. The combined use of Nb and Ti elements inhibits grain coarsening during the brazing heating and holding stages, while simultaneously dispersing microalloyed carbides. The combined use of these alloying elements helps to obtain a high proportion of bainite microstructure, enhancing the strength and toughness of the vacuum brazed tooth body.

[0111] 2. The high-strength and tough tooth steel alloy composition of the present invention has good compatibility with the vacuum brazing process. 3.0%≤Mn+Cr≤4.5% can ensure the stability of supercooled austenite and avoid the formation of ferrite or pearlite during the cooling process, resulting in a microstructure with a bainite content of over 90%. 1.0%≤Si+Al≤2.0% can suppress the precipitation of cementite, avoid the precipitation of carbides during the slow cooling stage, and improve the carbon atom utilization efficiency. 0.025%≤Nb+Ti≤0.055% can refine the original austenite grains, avoid coarse austenite grains during the brazing heating process, and further improve the hardness and toughness of the cutting teeth.

[0112] 3. The high-strength and tough bainitic tooth body provided by this invention has better overall performance. Compared with traditional tooth bodies, it has better strength and toughness under vacuum brazing conditions, room temperature impact energy AKU2≥40J, hardness≥42HRC, which can improve the service life and reliability of cutting teeth.

[0113] The following specific embodiments will be used to describe the present invention in detail.

[0114] Example 1

[0115] The copper-based solder is prepared with the following composition (by mass percentage): Zn 34%, Ni 5.5%, Mn 4%, Fe 0.2%, Si 0.1%, Ce 0.09%, and the balance being Cu.

[0116] The groove on the surface of the cooling copper roller has a diameter of 10mm, a depth of 1.5mm, and a groove angle of 1°.

[0117] The above raw materials are melted in a vacuum induction furnace (melting temperature 800℃) to obtain a pure melt.

[0118] The melt is transferred to a preheated (preheating temperature 800°C) tundish.

[0119] Adjust the rotation speed (2 m / s) and roll gap (0.02 mm) of the first and second cooling rollers, and turn on the forced cooling water system.

[0120] The melt is injected into the gap between the two rollers through nozzle 2 and is instantly cooled and solidified to form a sheet of brazing filler metal with a diameter of about 10 mm and a thickness of about 1.5 mm.

[0121] The collected sheet-like brazing filler metal has a smooth surface, uniform composition, and no cracks. The yield is shown in Table 1.

[0122] Example 2

[0123] The copper-based solder is prepared with the following composition (by mass percentage): Zn 30%, Ni 5%, Mn 3.5%, Fe 0.2%, Si 0.2%, Ce 0.07%, and the balance being Cu.

[0124] The surface of the cooling copper roller has a groove diameter of 12mm, a groove depth of 2mm, and a groove angle of 2°.

[0125] The above raw materials are melted in a vacuum induction furnace (melting temperature 1200℃) to obtain a pure melt.

[0126] The melt is transferred to a preheated (preheating temperature 950°C) tundish.

[0127] Adjust the rotation speed (2 m / s) and roll gap (0.15 mm) of the first and second cooling rollers, and turn on the forced cooling water system.

[0128] The melt is injected into the gap between the two rollers through nozzle 2 and is instantly cooled and solidified to form a sheet-like brazing filler metal with a diameter of about 12 mm and a thickness of about 2 mm.

[0129] The collected sheet-like brazing filler metal has a smooth surface, uniform composition, and no cracks. The yield is shown in Table 1.

[0130] Example 3

[0131] The copper-based solder is prepared with the following composition (by mass percentage): Zn 30%, Ni 5%, Mn 3.5%, Fe 0.2%, Si 0.2%, La 0.05%, and the balance being Cu.

[0132] The cooling copper roller has a groove diameter of 12mm, a groove depth of 2mm, and a groove angle of 1.5°.

[0133] The above raw materials are melted in a vacuum induction furnace (melting temperature 1200℃) to obtain a pure melt.

[0134] The melt is transferred to a preheated (preheating temperature 900°C) tundish.

[0135] Adjust the rotational speed (2.5 m / s) and roller gap (0.03 mm) of the first and second cooling rollers, and turn on the forced cooling water system.

[0136] The melt is injected into the gap between the two rollers through nozzle 2 and is instantly cooled and solidified to form a sheet-like brazing filler metal with a diameter of about 12 mm and a thickness of about 2 mm.

[0137] The collected sheet-like brazing filler metal has a smooth surface, uniform composition, and no cracks. The yield is shown in Table 1.

[0138] Example 4

[0139] The copper-based solder is prepared with the following composition (by mass percentage): Zn 30%, Ni 5%, Mn 3.5%, Fe 0.2%, Si 0.2%, Ce 0.1%, and the balance being Cu.

[0140] The groove on the surface of the cooling copper roller has a diameter of 12mm, a depth of 2mm, and a groove angle of 1.8°.

[0141] The above raw materials are melted in a vacuum induction furnace (melting temperature 1200℃) to obtain a pure melt.

[0142] The melt is transferred to a preheated (preheating temperature 900°C) tundish.

[0143] Adjust the rotation speed (4 m / s) and roll gap (0.1 mm) of the first and second cooling rollers, and turn on the forced cooling water system.

[0144] The melt is injected into the gap between the two rollers through nozzle 2 and is instantly cooled and solidified to form a sheet-like brazing filler metal with a diameter of about 12 mm and a thickness of about 2 mm.

[0145] The collected sheet-like brazing filler metal has a smooth surface, uniform composition, and no cracks. The yield is shown in Table 1.

[0146] Example 5

[0147] The copper-based brazing filler metal is prepared with the following composition (by mass percentage): Zn 30%, Ni 5%, Mn 3.5%, Fe 0.2%, Si 0.2%, La 0.1%, and the balance being Cu.

[0148] The cooling copper roller has a groove diameter of 15mm, a groove depth of 2mm, and a groove angle of 1.5°.

[0149] The above raw materials are melted in a vacuum induction furnace (melting temperature 1200℃) to obtain a pure melt.

[0150] The melt is transferred to a preheated (preheating temperature 900°C) tundish.

[0151] Adjust the rotational speed (4 m / s) and roll gap (0.05 mm) of the first and second cooling rollers, and turn on the forced cooling water system.

[0152] The melt is injected into the gap between the two rollers through nozzle 2 and is instantly cooled and solidified to form a sheet-like brazing filler metal with a diameter of about 15 mm and a thickness of about 2 mm.

[0153] The collected sheet-like brazing filler metal has a smooth surface, uniform composition, and no cracks. The yield is shown in Table 1.

[0154] The advantages of precise control over the composition and process parameters of the high-strength and high-toughness bainitic tooth profile for vacuum brazing of the present invention are demonstrated below using specific preparation examples and comparative examples. The chemical composition of the tooth profiles in the preparation examples and comparative examples is shown in Table 2, the specific process parameters are shown in Table 3, and the mechanical properties of the bainitic cutting tooth profiles obtained during the preparation process are shown in Table 4.

[0155] Preparation Example

[0156] The raw materials are smelted in a converter, refined by LF refining, degassed by RH, electromagnetically stirred, and continuously cast into 280mm×280mm square billets. These billets are then cut into 8000mm long billets, rolled, and heated to 1180–1250℃, held for 2–5 hours, and descaled. After exiting the furnace, they are hot-rolled into steel bars with a diameter of 28–45mm. The initial rolling temperature is 1080–1150℃, and the final rolling temperature is 860–930℃. After hot rolling, the bars are air-cooled. The prepared round steel bars undergo pretreatment such as pickling to remove surface oxide scale. They are then hot-forged, with a forging holding temperature of 950–1000℃ and a final forging temperature of 820–860℃. The compression ratio is ≥8:1. Finally, the bars are machined to obtain the cutter teeth of the target dimensions.

[0157] Finally, the tooth body, cemented carbide head (YG8 tungsten steel), copper-based brazing filler and borax flux are assembled and placed in a vacuum brazing equipment. The equipment is heated to 890-970℃ for brazing, held for 2-30 minutes, and then furnace cooled to room temperature to obtain a high-strength and tough vacuum brazed cutting tooth. The cooling rate above 500℃ is 0.3℃ / s to 3℃ / s, and the cooling rate between 500-200℃ is 0.01℃ / s to 0.3℃ / s.

[0158] Comparative Example

[0159] The preparation method of the comparative example is similar to that of the preparation example. The specific chemical composition of the tooth body is shown in Table 2. The process parameters in the preparation method are shown in Table 3. The mechanical properties of the cutting teeth prepared in the comparative example and the preparation example are shown in Table 4.

[0160] Table 2. Chemical composition (%) of the steel used for tooth bodies in the preparation examples and comparative examples, with the balance being iron and unavoidable impurities.

[0161] Group C Mn Si Cr Al Mo Ti Nb N P S Preparation Example 1 0.32 3.12 1.04 1.05 0.62 0.21 0.02 0.017 0.0022 0.012 0.0029 Preparation Example 2 0.28 2.81 1.06 0.17 1.21 0.17 0.025 0.017 0.0012 0.019 0.0025 Preparation Example 3 0.28 3.31 0.54 1.05 1.25 0.02 0.02 0.015 0.0033 0.010 0.0012 Preparation Example 4 0.29 2.87 1.14 1.45 0.86 0.15 0.02 0.019 0.0021 0.012 0.0035 Preparation Example 5 0.32 2.90 0.95 1.06 0.96 0.11 0.02 0.023 0.0037 0.020 0.0017 Comparative Example 1 0.37 5.26 1.10 0.56 0.02 0.05 0.02 0.012 0.0022 0.011 0.0025 Comparative Example 2 0.28 1.53 0.50 1.04 1.10 0.25 0.02 0.002 0.0037 0.017 0.0032 Comparative Example 3 0.41 2.14 0.46 0.73 0.51 0.07 0.015 0.021 0.0012 0.009 0.0035 Comparative Example 4 0.45 3.03 1.10 0.87 0.35 0.51 0.01 0.001 0.0025 0.014 0.0022 Comparative Example 5 0.17 3.11 1.42 1.10 0.77 0.03 0.02 0.021 0.0022 0.012 0.0015 Comparative Example 6 0.32 3.12 1.04 1.05 0.62 0.21 0.02 0.017 0.0022 0.012 0.0029

[0162] Table 3. Process parameters during the preparation of the preparation examples and comparative examples.

[0163]

[0164]

[0165] Table 4 Mechanical properties of the tooth body in the cutting teeth prepared by vacuum brazing in the preparation examples and comparative examples.

[0166]

[0167]

[0168] According to Table 4, the microstructure of the tooth body prepared by the present invention has a bainite volume fraction of ≥91%, preferably 91-97%, and also includes martensite + retained austenite with a volume fraction of ≤9%, preferably 3-9%, a hardness of ≥42.5HRC, preferably 42.5-45.8HRC, and a room temperature impact energy AKU2 ≥42J, preferably 42-85J.

[0169] The OM diagram of the tooth body prepared in Example 1 of this invention is as follows: Figure 5 As shown, the SEM image is as follows: Figure 6 As shown, according to Figure 5 and Figure 6 It can be seen that the microstructure of the tooth body of the present invention is mainly bainite. A physical image of the cutting tooth prepared in Preparation Example 1 is shown below. Figure 7 As shown.

[0170] Application examples

[0171] Alloy steel tooth bodies (prepared in Preparation Example 1) and cemented carbide tooth tips (YG8 tungsten steel) were brazed using the brazing filler metals of Examples 1-5, respectively. The shear strength of the brazed joints was tested. Comparative Example 7 used conventional brass brazing filler metal to braze alloy steel tooth bodies and cemented carbide tooth tips. The shear strength of the brazed joints was tested. The results are listed in Table 1.

[0172] Table 1 Shear strength of brazed joints

[0173]

[0174] As can be seen from Table 1, after brazing the alloy steel tooth body and the cemented carbide tooth tip with the brazing filler metal of Examples 1-5, the shear strength of the brazed joint is 300-338 MPa, which is much higher than the shear strength of the brazed joint after brazing the alloy steel tooth body and the cemented carbide tooth tip with the existing ordinary brass filler metal (199 MPa). It is a copper-based filler metal with both excellent brazing performance and mechanical properties.

[0175] As can be seen from Table 1, the yield of the brazing filler metal prepared by the method of the present invention is 85%-90%, which is significantly higher than the yield of the existing long process of casting + rolling + punching (around 75%).

[0176] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A copper-based alloy, characterized in that, The composition by mass percentage includes: Zn, 25%-40%, Ni, 2%-10%, Mn, 2%-6%, Fe, 0.1%-0.5%, Si, 0.1%-0.3%, rare earth elements, 0.05%-0.1%, with the balance being Cu and unavoidable trace impurities.

2. The copper-based alloy according to claim 1, characterized in that, The copper-based alloy comprises, by mass percentage: Zn, 28%-35%, Ni, 3%-8%, Mn, 2%-6%, Fe, 0.1%-0.5%, Si, 0.1%-0.3%, rare earth elements, 0.05%-0.1%, with the balance being Cu and unavoidable trace impurities.

3. A copper-based brazing filler metal, characterized in that, Including the copper-based alloy as described in claim 1 or 2.

4. The copper-based brazing filler metal according to claim 3, characterized in that, The copper-based brazing filler metal is in sheet form with a thickness of 1-2.5 mm.

5. The copper-based brazing filler metal according to claim 4, characterized in that, The copper-based brazing filler metal is in the shape of a disc with a diameter of 10-25 mm.

6. A method for preparing a copper-based solder according to any one of claims 3-5, characterized in that, Includes the following steps: Step 1: Melt the copper-based alloy as described in claim 1 or 2 to obtain an alloy melt; Step 2: The alloy melt is introduced into the intermediate ladle; Step 3: Casting to obtain sheet-like copper-based brazing filler metal.

7. The preparation method according to claim 6, characterized in that, In step 1, the melting temperature is 800-1200℃.

8. The preparation method according to claim 6 or 7, characterized in that, In step 3, the casting process includes: pouring the alloy melt into the gap between the first and second cooling rollers through the nozzle at the bottom of the tundish to obtain sheet-like brazing filler metal.

9. The preparation method according to claim 8, characterized in that, The outer surface of the first cooling roller has a grooved area, and multiple grooves are provided in the grooved area. The second cooling roller is a flat roller.

10. The application of the copper-based brazing filler metal according to any one of claims 3-5 in brazing cutting teeth, comprising: The alloy steel tooth body and the cemented carbide tooth tip are brazed using the copper-based brazing filler metal described in any one of claims 3-5 to obtain a cutting tooth.

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