Method of brazing cemented carbide to steel and brazed assembly

Abstract

The present application relates to a kind of hard alloy and steel brazing method and brazing assembly, wherein the brazing method includes: providing brazing material, the brazing material is by 5~15% of Co, 0~10% of Fe, 0~5% of Mn, 3~8% of Si, 5~15% of Cu and the alloy foil of balance Ni, with the atomic fraction, melting temperature interval is 1100~1300 ℃;Providing hard alloy structure and steel structure, the brazing material is placed between the hard alloy structure and the steel structure of the surface to be welded, obtains the welding piece;Resistance brazing is carried out to the welding piece, obtains brazing assembly.The brazing material of the present application has good wetting to hard alloy and steel, and the strength of the welded joint is high, especially the high temperature strength is high, so that brazing assembly can be served in the working condition of bearing larger load, in addition, the method of resistance brazing is used in the present application, and the required equipment and process are simple, and welding efficiency is high, suitable for mass production.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous material joining technology, and in particular to a resistance brazing method and brazing assembly for cemented carbide and steel. Background Technology

[0002] Cemented carbide possesses a range of excellent properties, including high strength, high hardness, and superior wear resistance, making it widely used in the manufacture of cutting and impact tools such as machine tool tips and drill bits, as well as corrosion-resistant tools. However, it is often difficult to simultaneously achieve both hardness and toughness in cemented carbide, and its manufacturing process limits its size, coupled with its high cost. Therefore, in actual production, cemented carbide is usually welded to high-toughness, high-strength steel to create tools or devices with excellent overall performance. However, cemented carbide and steel differ significantly in physical properties such as melting point, coefficient of thermal expansion, and specific heat capacity. This difference leads to significant residual stress at the weld interface during welding, causing deformation, cracks, and other defects in the weld joint. This not only reduces the joint strength but also easily leads to the formation of a brittle η phase at the weld interface, significantly weakening the mechanical properties of the weld joint. Therefore, achieving a reliable connection between cemented carbide and steel has become a critical technical problem that urgently needs to be solved.

[0003] In recent years, there have been some research reports both domestically and internationally on the joining of cemented carbide and steel. Based on existing reports, the main method for joining cemented carbide and steel is brazing, such as vacuum brazing, electron beam brazing, and laser brazing. The brazing materials involved are mainly Ag-Cu eutectic brazing filler metals and Cu-based brazing filler metals, such as Ag-Cu, Ag-Cu-Ti, Ag-Cu-in-Ti, Cu-Mn-Ni, and Cu-Ni-Al. Although welded joints with good mechanical properties can be obtained by selecting appropriate brazing materials and brazing processes, current brazing processes and the resulting welded joints still have the following problems: ① The low melting point of existing brazing materials limits the service temperature of the welded joints; ② Brazing materials are generally soft metals, resulting in low strength of the welded joints, which cannot be used in conditions subject to large loads; ③ Brazing generally requires overall heating of the workpieces to be welded, which leads to microcracks in the cemented carbide, affecting the performance of the base material and the joint; ④ The heating and holding times during brazing are long, resulting in low production efficiency. In addition, excessively high brazing temperatures can easily cause severe oxidation of the surface layer, reducing the joint strength, and excessively long holding times can easily generate the η phase, making the brazed joint embrittled.

[0004] In view of the problems existing in the connection between cemented carbide and steel, there is an urgent need to research and develop a new connection method to meet the requirements for welding efficiency, weld joint performance, and especially high-temperature performance. Summary of the Invention

[0005] To overcome the problems existing in related technologies, embodiments of the present invention provide a brazing method for cemented carbide and steel, which can effectively improve the performance of the welded joint in the brazed assembly, especially the high-temperature performance, and has high welding efficiency, making it suitable for automated industrial production.

[0006] According to a first aspect of the present invention, a brazing method for cemented carbide and steel is provided, the brazing method comprising the following steps:

[0007] Provide brazing material, in atomic fraction, the brazing material is an alloy foil composed of 5~15% Co, 0~10% Fe, 0~5% Mn, 3~8% Si, 5~15% Cu and balance Ni, with a melting temperature range of 1100~1300℃;

[0008] A cemented carbide structural component and a steel structural component are provided. The brazing material is placed between the surfaces of the cemented carbide structural component and the steel structural component to be welded, thereby obtaining a component to be welded.

[0009] The workpiece to be welded is subjected to resistance brazing to obtain a brazed assembly.

[0010] In one embodiment, the brazing material, by atomic fraction, is an alloy foil consisting of 6-10% Co, 3-8% Fe, 1-3% Mn, 4-7% Si, 6-10% Cu, and the balance Ni.

[0011] In one embodiment, the brazing material is an alloy foil with a thickness of 0.05~0.5mm.

[0012] In one embodiment, the cemented carbide structural component is selected from one of tungsten carbide structural components, TiC-Ni cemented carbide structural components, TaC-NbC cemented carbide structural components, and TiC-TiN-TiCN cemented carbide structural components.

[0013] In one embodiment, the steel structural component is selected from one of 42CrMo steel structural components, No. 45 steel structural components, Q235 structural components, and Q345 structural components.

[0014] In one embodiment, the cemented carbide structural component is a cemented carbide drill bit, and the steel structural component is a steel drill rod.

[0015] In one embodiment, during the resistance brazing step, the preheating current density is 10~30 A / mm. 2 The welding current density is 30~50A / mm. 2 The electrode pressure is 50~100N in the pre-pressure stage, the welding pressure is 100~300N, the holding pressure is 100~300N, the welding time is 200~500ms, and the entire welding process is protected by argon or reducing gas.

[0016] In one embodiment, during the resistance brazing step, the preheating current density differs from the welding current density by 10~20 A / mm. 2 And / or, the welding pressure and holding pressure are the same.

[0017] According to a second aspect of the present invention, a brazing assembly obtained by the brazing method of cemented carbide and steel is provided, the brazing assembly comprising a cemented carbide structural component and a steel structural component, wherein the cemented carbide structural component and the steel structural component are connected by a welded joint.

[0018] In one embodiment, the brazing assembly includes a carbide drill bit and a steel drill rod, which are connected by a welded joint.

[0019] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: The brazing material of the present invention is a high-temperature resistant Ni-based material with a melting point between 1100 and 1300°C. At the same time, the brazing material contains elements such as Si to improve fluidity, thereby making the brazing material have good wettability to both cemented carbide and steel, good weld joint formability, and high weld joint strength, especially high-temperature strength, which enables the brazed assembly to be used in working conditions that bear large loads.

[0020] In addition, the present invention uses resistance brazing, which does not require overall heating of the workpiece, and the required equipment and process are simple. It can complete the welding of cemented carbide and steel in a few seconds, with high welding efficiency, and is suitable for mass automated production.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Detailed Implementation

[0022] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0024] the term

[0025] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0026] In this application, the selection range involving "and / or", "or / and", and "and / or" includes any one of two or more related listed items, as well as any and all combinations of the related listed items, wherein any and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items.

[0027] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more or more.

[0028] In this application, numerical intervals (i.e. numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the above-mentioned numerical intervals are considered continuous, and include the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as every value between the two numerical endpoints.

[0029] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0030] The present invention provides a brazing method for cemented carbide and steel, the brazing method comprising the following steps:

[0031] S1, providing brazing material, in atomic fraction, the brazing material is an alloy foil composed of 5~15% Co, 0~10% Fe, 0~5% Mn, 3~8% Si, 5~15% Cu and balance Ni, with a melting temperature range of 1100~1300℃.

[0032] S2, providing a cemented carbide structural component and a steel structural component, placing the brazing material between the surfaces to be welded of the cemented carbide structural component and the steel structural component to obtain a component to be welded;

[0033] S3, resistance brazing is performed on the workpiece to be welded to obtain a brazed assembly.

[0034] In the brazing method of the present invention, the brazing material is a high-temperature resistant Ni-based material with a melting point between 1100 and 1300°C. At the same time, the brazing material contains elements such as Si to improve fluidity, thereby giving the brazing material good wettability to both cemented carbide and steel, good weld joint formability, and high weld joint strength, especially high-temperature strength, which enables the brazed assembly to be used in conditions that bear large loads.

[0035] To further improve the welding effect and increase the strength of the welded joint, especially the high-temperature strength, the brazing material is preferably an alloy foil composed of 6-10% Co, 3-8% Fe, 1-3% Mn, 4-7% Si, 6-10% Cu and the balance Ni.

[0036] Preferably, the brazing material is an alloy foil with a thickness of 0.05~0.5mm, and the specific thickness can be selected as needed.

[0037] Preferably, the preparation method of the brazing material includes: weighing each metal raw material in proportion, vacuum induction melting into an alloy ingot, rolling it into an alloy foil with a thickness of 0.05~0.5mm, and then processing it into an alloy foil with a size slightly smaller than the welding surface by stamping, wire cutting and other methods.

[0038] The brazing method of the present invention can weld any cemented carbide structural component and steel structural component to form a brazed assembly. Preferably, the cemented carbide structural component is selected from one of tungsten carbide structural components, TiC-Ni cemented carbide structural components, TaC-NbC cemented carbide structural components, and TiC-TiN-TiCN cemented carbide structural components, and the steel structural component is selected from one of 42CrMo steel structural components, No. 45 steel structural components, Q235 structural components, and Q345 structural components.

[0039] In one embodiment, the carbide structural component is a carbide drill bit, and the steel structural component is a steel drill rod. The brazed assembly composed of the carbide drill bit and the steel drill rod can be used as a cutting and impact tool in machine tools and other fields. In particular, the brazed assembly obtained by the brazing method of the present invention has high high-temperature strength and can be used in working conditions that bear large loads.

[0040] It is understandable that, before brazing, it is preferable to pretreat the surfaces of the cemented carbide structural components and steel structural components to be brazed, as well as the brazing material, to remove surface impurities and oxide films, thereby achieving better welding results. Preferably, the pretreatment steps include: first, pickling or polishing with 240-600 grit sandpaper, then immersing in alcohol and repeatedly cleaning with an ultrasonic cleaner 2-3 times, followed by drying in a vacuum drying oven at a temperature of 30-50°C for 10-30 minutes.

[0041] Because the brazing material of this invention has a high melting temperature range, vacuum brazing or other methods would damage the welded components. Therefore, this invention uses resistance brazing, which does not require overall heating of the workpiece. The required equipment and process are simple, and the welding of cemented carbide and steel can be completed in a few seconds. It has high welding efficiency and is suitable for mass automated production.

[0042] Preferably, in the resistance brazing step, the preheating current density is 10~30 A / mm.2 The welding current density is 30~50A / mm. 2 The electrode pressure is 50~100N in the pre-pressure stage, the welding pressure is 100~300N, the holding pressure is 100~300N, the welding time is 200~500ms, and the entire welding process is protected by argon or reducing gas.

[0043] Furthermore, in the resistance brazing process, the preheating current density differs from the welding current density by 10~20 A / mm. 2 And / or, having the same welding pressure and holding pressure can better ensure the welding effect.

[0044] The brazed assembly obtained by the brazing method of cemented carbide and steel provided by the present invention includes a cemented carbide structural component and a steel structural component, wherein the cemented carbide structural component and the steel structural component are connected by a welded joint.

[0045] Wherein, when the carbide structural component is selected from carbide drill bits and the steel structural component is selected from steel drill rods, the brazing assembly includes carbide drill bits and steel drill rods, and the carbide drill bits and the steel drill rods are connected by a welded joint.

[0046] This invention utilizes a brazing material with a melting point between 1100 and 1300°C and good fluidity for resistance brazing. This results in welded joints with good formability and high strength, especially high-temperature strength, enabling brazed components to operate under heavy loads. Furthermore, the required equipment and processes are simple, the welding efficiency is high, and it is suitable for mass automated production.

[0047] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are available from publicly available commercial sources. Example 1

[0048] This embodiment describes a resistance brazing method for a cemented carbide drill bit and a steel drill rod. The cemented carbide drill bit is a tungsten carbide (WC) drill bit with a diameter of φ8mm. The steel drill rod is a 42CrMo high-strength alloy structural steel with a tensile strength ≥1080 MPa, yield strength ≥930 MPa, elongation ≥12%, impact energy ≥63J, and hardness ≤217HB, and a diameter of φ7.5mm. The brazing material, by atomic fraction, is an alloy foil composed of 5% Co, 5% Fe, 3% Mn, 5% Si, 10% Cu, and the balance Ni, with a melting point of 1280℃ and a foil thickness of 0.3mm.

[0049] The specific brazing process in this embodiment includes the following steps:

[0050] Grind the surfaces of the carbide drill bit and the 42CrMo steel drill rod to be welded with 240-600 grit sandpaper to remove surface impurities and oxide film. Then, put the ground carbide drill bit and 42CrMo steel drill rod into alcohol and clean them repeatedly with an ultrasonic cleaner 3 times. After cleaning, put them in a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0051] Similarly, first polish the brazing material with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the polished brazing material into alcohol and clean it repeatedly with an ultrasonic cleaner 3 times. After cleaning, put it into a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0052] Then, the prepared brazing material is pre-placed between the carbide drill bit and the 42CrMo steel drill rod to be welded, ensuring the coaxiality and radial angle of the drill rod and the drill bit, to obtain the workpiece to be welded.

[0053] Finally, the workpieces are subjected to resistance brazing using a resistance welding machine to obtain a brazed assembly. The preheating current density is 20 A / mm². 2 The welding current density is 30A / mm². 2 The electrode pressure pre-compression stage is 100N, the welding pressure is 150N, the holding pressure is 150N, the welding time is 300ms, and the entire welding process is protected by argon gas.

[0054] The welded joint obtained in this embodiment was subjected to room temperature and high temperature shear strength tests using a special fixture on an electronic universal testing machine. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 350 MPa, the maximum service temperature of the welded joint is 1100℃, and the shear strength of the welded joint at 900℃ is 210 MPa. Example 2

[0055] This embodiment describes a resistance brazing method for a cemented carbide drill bit and a steel drill rod. The cemented carbide drill bit is a tungsten carbide (WC) drill bit with a diameter of φ8mm. The steel drill rod is a 42CrMo high-strength alloy structural steel with a tensile strength ≥1080 MPa, yield strength ≥930 MPa, elongation ≥12%, impact energy ≥63J, and hardness ≤217HB, and a diameter of φ7.5mm. The brazing material, by atomic fraction, is an alloy foil composed of 6% Co, 5% Fe, 3% Mn, 5% Si, 8% Cu, and the balance Ni, with a melting point of 1287℃ and a foil thickness of 0.2mm.

[0056] The specific brazing process in this embodiment includes the following steps:

[0057] Grind the surfaces of the carbide drill bit and the 42CrMo steel drill rod to be welded with 240-600 grit sandpaper to remove surface impurities and oxide film. Then, put the ground carbide drill bit and 42CrMo steel drill rod into alcohol and clean them repeatedly with an ultrasonic cleaner 3 times. After cleaning, put them in a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0058] Similarly, first polish the brazing material with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the polished brazing material into alcohol and clean it repeatedly with an ultrasonic cleaner 3 times. After cleaning, put it into a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0059] Then, the prepared brazing material is pre-placed between the carbide drill bit and the 42CrMo steel drill rod to be welded, ensuring the coaxiality and radial angle of the drill rod and the drill bit, to obtain the workpiece to be welded.

[0060] Finally, the workpieces are subjected to resistance brazing using a resistance welding machine to obtain a brazed assembly. The preheating current density is 20 A / mm². 2 The welding current density is 40A / mm². 2 The electrode pressure pre-compression stage is 100N, the welding pressure is 150N, the holding pressure is 150N, the welding time is 300ms, and the entire welding process is protected by argon gas.

[0061] The welded joint obtained in this embodiment was subjected to room temperature and high temperature shear strength tests using a special fixture on an electronic universal testing machine. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 310 MPa, the maximum service temperature of the welded joint is 1100℃, and the shear strength of the welded joint at 900℃ is 180 MPa. Example 3

[0062] This embodiment describes a resistance brazing method for a cemented carbide drill bit and a steel drill rod. The cemented carbide drill bit is a tungsten carbide (WC) drill bit with a diameter of φ8mm. The steel drill rod is a 42CrMo high-strength alloy structural steel with a tensile strength ≥1080 MPa, yield strength ≥930 MPa, elongation ≥12%, impact energy ≥63J, and hardness ≤217HB, and a diameter of φ9.5mm. The brazing material, by atomic fraction, is an alloy foil composed of 10% Co, 4% Fe, 3% Mn, 6% Si, 6% Cu, and the balance Ni, with a melting point of 1267℃ and a foil thickness of 0.3mm.

[0063] The specific brazing process in this embodiment includes the following steps:

[0064] Grind the surfaces of the carbide drill bit and the 42CrMo steel drill rod to be welded with 240-600 grit sandpaper to remove surface impurities and oxide film. Then, put the ground carbide drill bit and 42CrMo steel drill rod into alcohol and clean them repeatedly with an ultrasonic cleaner 3 times. After cleaning, put them in a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0065] Similarly, first polish the brazing material with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the polished brazing material into alcohol and clean it repeatedly with an ultrasonic cleaner 3 times. After cleaning, put it into a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0066] Then, the prepared brazing material is pre-placed between the carbide drill bit and the 42CrMo steel drill rod to be welded, ensuring the coaxiality and radial angle of the drill rod and the drill bit, to obtain the workpiece to be welded.

[0067] Finally, the workpieces are subjected to resistance brazing using a resistance welding machine to obtain a brazed assembly. The preheating current density is 25 A / mm². 2 The welding current density is 30A / mm². 2 The electrode pressure pre-compression stage is 100N, the welding pressure is 150N, the holding pressure is 150N, the welding time is 300ms, and the entire welding process is protected by argon gas.

[0068] The welded joint obtained in this embodiment was subjected to room temperature and high temperature shear strength tests using a special fixture on an electronic universal testing machine. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 290 MPa, the maximum service temperature of the welded joint is 1200℃, and the shear strength of the welded joint at 900℃ is 172 MPa. Example 4

[0069] This embodiment describes a resistance brazing method for a cemented carbide drill bit and a steel drill rod. The cemented carbide drill bit is a tungsten carbide (WC) drill bit with a diameter of φ8mm. The steel drill rod is made of No. 45 steel with a tensile strength ≥600 MPa, a yield strength ≥355 MPa, an elongation ≥16%, and a diameter of φ7.5mm. The brazing material, by atomic fraction, is an alloy foil composed of 15% Co, 10% Fe, 0% Mn, 8% Si, 5% Cu, and the balance Ni, with a melting point of 1240℃ and a foil thickness of 0.3mm.

[0070] The specific brazing process in this embodiment includes the following steps:

[0071] Grind the surfaces of the carbide drill bit and the 45# steel drill rod to be welded with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the ground carbide drill bit and the 45# steel drill rod into alcohol and clean them repeatedly with an ultrasonic cleaner 3 times. After cleaning, put them in a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0072] Similarly, first polish the brazing material with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the polished brazing material into alcohol and clean it repeatedly with an ultrasonic cleaner 3 times. After cleaning, put it into a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0073] Then, the prepared brazing material is placed between the carbide drill bit and the 45# steel drill rod to be welded, ensuring the coaxiality and radial angle of the drill rod and the drill bit, to obtain the part to be welded.

[0074] Finally, the workpieces are subjected to resistance brazing using a resistance welding machine to obtain a brazed assembly. The preheating current density is 15 A / mm². 2 The welding current density is 35A / mm². 2 The electrode pressure pre-compression stage is 100N, the welding pressure is 130N, the holding pressure is 130N, the welding time is 200ms, and the entire welding process is protected by argon gas.

[0075] The welded joint obtained in this embodiment was subjected to room temperature and high temperature shear strength tests using a special fixture on an electronic universal testing machine. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 313 MPa, the maximum service temperature of the welded joint is 1150℃, and the shear strength of the welded joint at 900℃ is 198 MPa. Example 5

[0076] This embodiment describes a resistance brazing method for a cemented carbide drill bit and a steel drill rod. The cemented carbide drill bit is a tungsten carbide (WC) drill bit with a diameter of φ8mm. The steel drill rod is made of No. 45 steel with a tensile strength ≥600 MPa, a yield strength ≥355 MPa, an elongation ≥16%, and a diameter of φ7.5mm. The brazing material, by atomic fraction, is an alloy foil composed of 15% Co, 10% Fe, 0% Mn, 8% Si, 15% Cu, and the balance Ni, with a melting point of 1186℃ and a foil thickness of 0.3mm.

[0077] The specific brazing process in this embodiment includes the following steps:

[0078] Grind the surfaces of the carbide drill bit and the 45# steel drill rod to be welded with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the ground carbide drill bit and the 45# steel drill rod into alcohol and clean them repeatedly with an ultrasonic cleaner 3 times. After cleaning, put them in a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0079] Similarly, first polish the brazing material with 240~600 grit sandpaper to remove surface impurities and oxide film. Then, put the polished brazing material into alcohol and clean it repeatedly with an ultrasonic cleaner 3 times. After cleaning, put it into a vacuum drying oven to dry for later use. The drying temperature is 30℃ and the drying time is 10 minutes.

[0080] Then, the prepared brazing material is placed between the carbide drill bit and the 45# steel drill rod to be welded, ensuring the coaxiality and radial angle of the drill rod and the drill bit, to obtain the part to be welded.

[0081] Finally, the workpieces are subjected to resistance brazing using a resistance welding machine to obtain a brazed assembly. The preheating current density is 20 A / mm². 2 The welding current density is 50A / mm². 2 The electrode pressure pre-compression stage is 100N, the welding pressure is 120N, the holding pressure is 120N, the welding time is 200ms, and the entire welding process is protected by argon gas.

[0082] The welded joint obtained in this embodiment was subjected to room temperature and high temperature shear strength tests using a special fixture on an electronic universal testing machine. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 245 MPa, the maximum service temperature of the welded joint is 1000℃, and the shear strength of the welded joint at 900℃ is 139 MPa.

[0083] Comparative Example 1

[0084] The only difference between Comparative Example 1 and Example 1 is that, in terms of atomic fraction, the brazing material involved is an alloy foil composed of 5% Co, 5% Fe, 3% Mn, 1% Si, 10% Cu and the balance Ni, with a melting point of 1352°C and a foil thickness of 0.3 mm.

[0085] The welded joint obtained in this comparative example was subjected to room temperature and high temperature shear strength tests on an electronic universal testing machine using a special fixture. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 64 MPa, the maximum service temperature of the welded joint is 1100℃, and the shear strength of the welded joint at 900℃ is 35 MPa.

[0086] Comparative Example 2

[0087] The only difference between Comparative Example 2 and Example 1 is that, in terms of atomic fraction, the brazing material involved is an alloy foil composed of 20% Co, 5% Fe, 3% Mn, 5% Si, 10% Cu and the balance Ni, with a melting point of 1332°C and a foil thickness of 0.3 mm.

[0088] The welded joint obtained in this comparative example was subjected to room temperature and high temperature shear strength tests on an electronic universal testing machine using a special fixture. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 79 MPa, the maximum service temperature of the welded joint is 1100℃, and the shear strength of the welded joint at 900℃ is 54 MPa.

[0089] Comparative Example 3

[0090] The only difference between Comparative Example 3 and Example 1 is that, in terms of atomic fraction, the brazing material involved is an alloy foil composed of 5% Co, 5% Fe, 3% Mn, 5% Si, 2% Cu and the balance Ni, with a melting point of 1372°C and a foil thickness of 0.3 mm.

[0091] The welded joint obtained in this comparative example was subjected to room temperature and high temperature shear strength tests on an electronic universal testing machine using a special fixture. The loading rate was 0.5 mm / min, and the maximum load output when the workpiece broke was recorded. The shear strength of the joint was calculated based on the maximum load, and the average value of 5 samples was taken as the final result. The results are as follows: the room temperature shear strength of the welded joint is 62 MPa, the maximum service temperature of the welded joint is 1100℃, and the shear strength of the welded joint at 900℃ is 37 MPa.

[0092] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

Claims

1. A method for brazing cemented carbide to steel, characterized in that, The brazing method includes the following steps: Provide brazing material, in atomic fraction, the brazing material is an alloy foil composed of 6~10% Co, 3~8% Fe, 1~3% Mn, 4~7% Si, 6~10% Cu and balance Ni, with a melting temperature range of 1100~1300℃; A cemented carbide structural component and a steel structural component are provided. The brazing material is placed between the surfaces of the cemented carbide structural component and the steel structural component to be welded, thereby obtaining a component to be welded. The workpieces to be welded are subjected to resistance brazing to obtain a brazed assembly. In the resistance brazing process, the preheating current density is 10~30 A / mm. 2 The welding current density is 30~50A / mm. 2 The electrode pressure is 50~100N in the pre-pressure stage, the welding pressure is 100~300N, the holding pressure is 100~300N, the welding time is 200~500ms, and the entire welding process is protected by argon or reducing gas.

2. The brazing method between cemented carbide and steel according to claim 1, characterized in that, The brazing material is an alloy foil with a thickness of 0.05~0.5mm.

3. The brazing method between cemented carbide and steel according to claim 1, characterized in that, The cemented carbide structural component is selected from one of the following: tungsten carbide structural components, WC-Co cemented carbide structural components, TiC-Ni cemented carbide structural components, TaC-NbC cemented carbide structural components, and TiC-TiN-TiCN cemented carbide structural components.

4. The brazing method between cemented carbide and steel according to claim 1, characterized in that, The steel structural components are selected from one of the following: 42CrMo steel structural components, No. 45 steel structural components, Q235 structural components, and Q345 structural components.

5. The brazing method between cemented carbide and steel according to claim 1, characterized in that, The cemented carbide structural component is a cemented carbide drill bit, and the steel structural component is a steel drill rod.

6. The brazing method between cemented carbide and steel according to claim 1, characterized in that, In the resistance brazing process, the preheating current density differs from the welding current density by 10~20 A / mm. 2 And / or, the welding pressure and holding pressure are the same.

7. A brazed assembly obtained by the brazing method of cemented carbide and steel as described in any one of claims 1-6, characterized in that, The brazing assembly includes a cemented carbide structural component and a steel structural component, which are connected by a welded joint.

8. The brazing assembly according to claim 7, characterized in that, The brazing assembly includes a carbide drill bit and a steel drill rod, which are connected by a welded joint.