Hard alloy and steel brazing method and brazing assembly

Abstract

The invention relates to a hard alloy and steel brazing method and a brazing assembly.The brazing method comprises the steps that a brazing material is provided, the brazing material is an alloy foil composed of, by atomic fraction, 5%-15% of Co, 0%-10% of Fe, 0%-5% of Mn, 3%-8% of Si, 5%-15% of Cu and the balance Ni, and the melting temperature interval ranges from 1100 DEG C to 1300 DEG C; a hard alloy structural part and a steel structural part are provided, the brazing material is placed between the to-be-welded faces of the hard alloy structural part and the steel structural part, and a to-be-welded part is obtained; and resistance brazing is conducted on the to-be-welded part, and a brazed assembly is obtained. The brazing material has good wettability to hard alloy and steel, a welding joint is good in formability, high in strength and particularly high in high-temperature strength, a brazing assembly can serve for the working condition of bearing a large load, in addition, a resistance brazing method is adopted, needed equipment and the needed process are simple, the welding efficiency is high, and the method is suitable for large-scale production. The method is suitable for large-scale automatic production.

Description

Technical Field

[0001] The invention relates to the technical field of heterogeneous material connection, and in particular to a resistance brazing method for hard alloy and steel and a brazing assembly. Background Art

[0002] Cemented carbide has a series of excellent properties such as high strength, high hardness, and excellent wear resistance. It is widely used in the manufacture of cutting and impact tools such as machine tool heads and drill bits, as well as corrosion-resistant tools. Since cemented carbide often cannot take into account both hardness and toughness at the same time, and its preparation process limits the size, coupled with high cost, in actual production, cemented carbide is usually welded with high-toughness, high-strength steel to form tools or devices with excellent comprehensive performance. However, there are large differences between cemented carbide and steel in physical properties such as melting point, expansion coefficient, and specific heat capacity, which makes it easy for the welding interface to produce large residual stress during the welding process, which in turn causes deformation, cracks and other defects in the welded joint, which not only reduces the joint strength, but also easily forms a brittle η phase at the welding interface, greatly weakening the mechanical properties of the welded joint. Therefore, achieving reliable connection between cemented carbide and steel has become a key technical problem that needs to be solved urgently.

[0003] In recent years, there have been some research reports on the connection between cemented carbide and steel at home and abroad. According to existing reports, the main method for connecting cemented carbide and steel is brazing, such as vacuum brazing, electron beam brazing, laser brazing, etc. The brazing materials involved are mainly Ag-Cu eutectic brazing and Cu-based brazing, such as Ag-Cu, Ag-Cu-Ti, Ag-Cu-in-Ti, Cu-Mn-Ni, Cu-Ni-Al, etc. Although welding joints with good mechanical properties can be obtained by selecting suitable brazing materials and choosing appropriate brazing processes, the current brazing processes and the obtained welding joints still have the following problems: ① Due to the low melting point of existing brazing materials, the service temperature of the welding joint is limited; ② Brazing materials are generally soft metals, and the strength of the obtained welding joints is not high, and they cannot be used in working conditions with large loads; ③ During brazing, it is generally necessary to heat the workpiece as a whole, which causes microcracks in the cemented carbide and affects the performance of the parent material and the joint; ④ The heating and holding time during the brazing process is long, and the production efficiency is low. In addition, when the brazing temperature is too high, it is easy to cause severe oxidation of the surface layer, reducing the strength of the joint. When the holding time is too long, it is easy to produce η phase to make the brazed joint embrittled.

[0004] In view of the above-mentioned problems existing in the connection between cemented carbide and steel, it is urgent to research and develop a new connection method to meet the requirements of welding efficiency, welding joint performance, especially high temperature performance. Summary of the invention

[0005] In order to overcome the problems existing in the related art, an embodiment of the present invention provides a method for brazing cemented carbide and steel, which can effectively improve the performance of the welded joints in the brazing assembly, especially the high temperature performance, and has high welding efficiency and is suitable for automated industrial production.

[0006] According to a first aspect of an embodiment of the present invention, a method for brazing cemented carbide and steel is provided, the brazing method comprising the following steps: A brazing material is provided, wherein 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 the balance Ni in terms of atomic fraction, and the melting temperature range is 1100-1300° C.; Providing a hard alloy structural part and a steel structural part, placing the brazing material between the surfaces to be welded of the hard alloy structural part and the steel structural part, to obtain a part to be welded; The parts to be welded are subjected to resistance brazing to obtain a brazing assembly.

[0007] In one embodiment, 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 the balance Ni, calculated by atomic fraction.

[0008] In one embodiment, the brazing material is an alloy foil with a thickness of 0.05-0.5 mm.

[0009] In one embodiment, the cemented carbide structural component is selected from one of a tungsten carbide structural component, a TiC-Ni cemented carbide structural component, a TaC-NbC cemented carbide structural component, and a TiC-TiN-TiCN cemented carbide structural component.

[0010] In one embodiment, the steel structural member is selected from one of 42CrMo steel structural members, No. 45 steel structural members, Q235 structural members, and Q345 structural members.

[0011] In one embodiment, the cemented carbide structural component is a cemented carbide drill bit, and the steel structural component is a steel drill rod.

[0012] In one embodiment, during the resistance brazing step, the preheating current density is 10-30 A / mm 2 , welding current density is 30~50A / mm 2 The electrode pressure in the pre-pressing stage is 50~100N, the welding pressure is 100~300N, the holding pressure is 100~300N, the welding time is 200~500ms, and argon or reducing gas protection is used throughout the welding process.

[0013] In one embodiment, in 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 the holding pressure are the same.

[0014] According to a second aspect of an embodiment of the present invention, a brazing assembly obtained by the brazing method of cemented carbide and steel is provided, wherein the brazing assembly comprises a cemented carbide structural member and a steel structural member, wherein the cemented carbide structural member and the steel structural member are connected via a welding joint.

[0015] In one embodiment, the brazing assembly comprises a cemented carbide drill bit and a steel drill rod, wherein the cemented carbide drill bit and the steel drill rod are connected via a welding joint.

[0016] The technical solution 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 that improve fluidity, so that the brazing material has good wettability to both cemented carbide and steel, the welded joint has good formability, the welded joint has high strength, especially high-temperature strength, thereby enabling the brazing assembly to serve in working conditions with large loads.

[0017] In addition, the present invention adopts resistance brazing, which does not require the overall heating of the workpiece to be welded, and the required equipment and process are simple. The welding of cemented carbide and steel can be completed within a few seconds, the welding efficiency is high, and it is suitable for large-scale automated production.

[0018] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. DETAILED DESCRIPTION

[0019] The present application will be further described in detail below in conjunction with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0021] the term Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings: In the present application, the selection scope involving "and / or", "or / and", and "and / or" includes any one of two or more related listed items, and also includes any and all combinations of the related listed items, and the any and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items.

[0022] In the present application, "plurality", "multiple", "multiple times", "plurality", etc., unless otherwise specified, refer to a number greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0023] In the present application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the optional numerical distribution within the above numerical interval is deemed to be continuous and includes the two numerical endpoints of the numerical range (i.e., the minimum value and the maximum value), and every numerical value between the two numerical endpoints.

[0024] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0025] The present invention provides a method for brazing cemented carbide and steel, the brazing method comprising the following steps: S1, providing a brazing material, wherein 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 the balance Ni, in terms of atomic fraction, and has a melting temperature range of 1100-1300° C.; S2, providing a cemented carbide structural part and a steel structural part, placing the brazing material between the surfaces to be welded of the cemented carbide structural part and the steel structural part, to obtain a part to be welded; S3, performing resistance brazing on the parts to be welded to obtain a brazed assembly.

[0026] 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 that improve fluidity, so that the brazing material has good wettability to both cemented carbide and steel, the welded joint has good formability, and the welded joint has high strength, especially high-temperature strength, so that the brazing assembly can serve in working conditions with large loads.

[0027] In order to further improve the welding effect and improve the strength of the welded joint, especially the high temperature strength, preferably, 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 the remainder Ni.

[0028] Preferably, the brazing material is an alloy foil with a thickness of 0.05-0.5 mm, and the specific thickness can be selected as needed.

[0029] Preferably, the preparation method of the brazing material comprises: weighing each metal raw material in proportion, vacuum induction melting into an alloy ingot, and rolling it into an alloy foil with a thickness of 0.05-0.5 mm, and then processing it into an alloy foil with a size slightly smaller than the welding surface by stamping, wire cutting and other methods.

[0030] The brazing method of the present invention can weld any cemented carbide structural parts and steel structural parts to form a brazing assembly. Preferably, the cemented carbide structural parts are selected from one of tungsten carbide structural parts, TiC-Ni cemented carbide structural parts, TaC-NbC cemented carbide structural parts, and TiC-TiN-TiCN cemented carbide structural parts, and the steel structural parts are selected from one of 42CrMo steel structural parts, No. 45 steel structural parts, Q235 structural parts, and Q345 structural parts.

[0031] In one embodiment, the cemented carbide structural component is a cemented carbide drill bit, and the steel structural component is a steel drill rod. The brazed assembly composed of the cemented carbide drill bit and the steel drill rod can be used as a cutting 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 serve in working conditions with large loads.

[0032] It is understood that before brazing, it is preferred to pre-treat the surface to be welded of the carbide structural part, the surface to be welded of the steel structural part and the brazing material to remove surface debris and oxide film, so as to obtain a better welding effect. Preferably, the pre-treatment step includes: firstly pickling or polishing with 240-600 mesh sandpaper, then putting it in alcohol, repeatedly cleaning it with an ultrasonic cleaner 2-3 times, and then putting it in a vacuum drying oven for drying after cleaning, the drying temperature is 30-50°C, and the drying time is 10-30min.

[0033] Since the melting temperature range of the brazing material of the present invention is relatively high, the welding components will be damaged if vacuum brazing or other methods are used. Therefore, the present invention adopts the resistance brazing method, which does not require the overall heating of the workpiece to be welded, and the required equipment and process are simple. The welding of cemented carbide and steel can be completed within a few seconds, the welding efficiency is high, and it is suitable for large-scale automated production.

[0034] Preferably, in the resistance brazing step, the preheating current density is 10-30 A / mm2 , welding current density is 30~50A / mm 2 The electrode pressure in the pre-pressing stage is 50~100N, the welding pressure is 100~300N, the holding pressure is 100~300N, the welding time is 200~500ms, and argon or reducing gas protection is used throughout the welding process.

[0035] Furthermore, in 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 the holding pressure are the same, which can better ensure the welding effect.

[0036] The brazing assembly obtained by the brazing method of cemented carbide and steel provided by the present invention comprises a cemented carbide structural part and a steel structural part, wherein the cemented carbide structural part and the steel structural part are connected via a welding joint.

[0037] Wherein, when the cemented carbide structural component is selected from a cemented carbide drill bit and the steel structural component is selected from a steel drill rod, the brazing assembly comprises a cemented carbide drill bit and a steel drill rod, and the cemented carbide drill bit and the steel drill rod are connected via a welding joint.

[0038] The present invention adopts a brazing material with a melting point between 1100 and 1300° C. and good fluidity for resistance brazing, so that not only the obtained welded joint has good formability and high strength, especially high high-temperature strength, so that the brazed assembly can serve in working conditions with large loads, but also the required equipment and process are simple, the welding efficiency is high, and it is suitable for large-scale automated production.

[0039] The present invention is further described below in conjunction with specific embodiments, wherein the methods described are conventional methods unless otherwise specified, and the raw materials described can be obtained from public commercial channels unless otherwise specified. Example 1

[0040] The present embodiment is a resistance brazing method for a cemented carbide drill bit and a steel drill rod, wherein the cemented carbide drill bit involved is a tungsten carbide (WC) drill bit with a diameter of φ8 mm; the steel drill rod involved is a 42CrMo high-strength alloy structural steel with a tensile strength ≥1080 MPa, a yield strength ≥930 MPa, an elongation ≥12%, an impact energy ≥63 J, a hardness ≤217 HB, and a diameter of φ7.5 mm; in terms of atomic fraction, the brazing material involved is an alloy foil composed of 5% Co, 5% Fe, 3% Mn, 5% Si, 10% Cu and the remainder Ni, with a melting point of 1280°C and a foil thickness of 0.3 mm.

[0041] The specific brazing process of this embodiment includes the following steps: The surfaces to be welded of the carbide drill bit and the 42CrMo steel drill rod were polished with 240-600 mesh sandpaper to remove surface debris and oxide film. Then the polished carbide drill bit and the 42CrMo steel drill rod were placed in alcohol and cleaned repeatedly for 3 times with an ultrasonic cleaner. After cleaning, they were placed in a vacuum drying oven for drying at a temperature of 30°C and a drying time of 10 min.

[0042] Similarly, first grind the brazing material with 240-600 mesh sandpaper to remove surface debris and oxide film, then put the polished brazing material into alcohol, and clean it repeatedly 3 times with an ultrasonic cleaner. After cleaning, put it into a vacuum drying oven for drying. The drying temperature is 30°C and the drying time is 10 minutes.

[0043] Then, the prepared brazing material is pre-placed between the carbide drill bit and the surface to be welded of the 42CrMo steel drill rod to ensure the coaxiality and radial angle of the drill rod and the drill bit to obtain the welded part.

[0044] Finally, the resistance brazing of the workpieces to be welded is performed by resistance welding equipment to obtain a brazed assembly. The preheating current density is 20 A / mm 2 , welding current density is 30A / mm 2 The electrode pressure in the pre-pressing stage is 100N, the welding pressure is 150N, the holding pressure is 150N, the welding time is 300ms, and argon gas protection is used throughout the welding process.

[0045] The room temperature and high temperature shear strength tests were performed on the welded joint obtained in this embodiment using a special fixture on an electronic universal testing machine, with a loading rate of 0.5 mm / min. The maximum load output when the workpiece was sheared was recorded, and the joint shear strength was converted according to the maximum load. The average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 350 MPa, the maximum service temperature of the welded joint was 1100°C, and the shear strength of the welded joint at 900°C was 210 MPa. Example 2

[0046] The present embodiment is a resistance brazing method for a cemented carbide drill bit and a steel drill rod, wherein the cemented carbide drill bit involved is a tungsten carbide (WC) drill bit with a diameter of φ8 mm; the steel drill rod involved is a 42CrMo high-strength alloy structural steel with a tensile strength ≥1080 MPa, a yield strength ≥930 MPa, an elongation ≥12%, an impact energy ≥63 J, a hardness ≤217 HB, and a diameter of φ7.5 mm; in terms of atomic fraction, the brazing material involved is an alloy foil composed of 6% Co, 5% Fe, 3% Mn, 5% Si, 8% Cu and the remainder Ni, with a melting point of 1287°C and a foil thickness of 0.2 mm.

[0047] The specific brazing process of this embodiment includes the following steps: The surfaces to be welded of the carbide drill bit and the 42CrMo steel drill rod were polished with 240-600 mesh sandpaper to remove surface debris and oxide film. Then the polished carbide drill bit and the 42CrMo steel drill rod were placed in alcohol and cleaned repeatedly for 3 times with an ultrasonic cleaner. After cleaning, they were placed in a vacuum drying oven for drying at a temperature of 30°C and a drying time of 10 min.

[0048] Similarly, first grind the brazing material with 240-600 mesh sandpaper to remove surface debris and oxide film, then put the polished brazing material into alcohol, and clean it repeatedly 3 times with an ultrasonic cleaner. After cleaning, put it into a vacuum drying oven for drying. The drying temperature is 30°C and the drying time is 10 minutes.

[0049] Then, the prepared brazing material is pre-placed between the carbide drill bit and the surface to be welded of the 42CrMo steel drill rod to ensure the coaxiality and radial angle of the drill rod and the drill bit to obtain the welded part.

[0050] Finally, the resistance brazing of the workpieces to be welded is performed by resistance welding equipment to obtain a brazed assembly. The preheating current density is 20 A / mm 2 , welding current density is 40A / mm 2 The electrode pressure in the pre-pressing stage is 100N, the welding pressure is 150N, the holding pressure is 150N, the welding time is 300ms, and argon gas protection is used throughout the welding process.

[0051] The room temperature and high temperature shear strength tests were performed on the welded joint obtained in this embodiment using a special fixture on an electronic universal testing machine, with a loading rate of 0.5 mm / min. The maximum load output when the workpiece was sheared was recorded, and the joint shear strength was converted according to the maximum load. The average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 310 MPa, the maximum service temperature of the welded joint was 1100°C, and the shear strength of the welded joint at 900°C was 180 MPa. Example 3

[0052] The present embodiment is a resistance brazing method for a cemented carbide drill bit and a steel drill rod, wherein the cemented carbide drill bit involved is a tungsten carbide (WC) drill bit with a diameter of φ8 mm; the steel drill rod involved is a 42CrMo high-strength alloy structural steel with a tensile strength ≥1080 MPa, a yield strength ≥930 MPa, an elongation ≥12%, an impact energy ≥63 J, a hardness ≤217 HB, and a diameter of φ9.5 mm; in terms of atomic fraction, the brazing material involved is an alloy foil composed of 10% Co, 4% Fe, 3% Mn, 6% Si, 6% Cu and the remainder Ni, with a melting point of 1267°C and a foil thickness of 0.3 mm.

[0053] The specific brazing process of this embodiment includes the following steps: The surfaces to be welded of the carbide drill bit and the 42CrMo steel drill rod were polished with 240-600 mesh sandpaper to remove surface debris and oxide film. Then the polished carbide drill bit and the 42CrMo steel drill rod were placed in alcohol and cleaned repeatedly for 3 times with an ultrasonic cleaner. After cleaning, they were placed in a vacuum drying oven for drying at a temperature of 30°C and a drying time of 10 min.

[0054] Similarly, first grind the brazing material with 240-600 mesh sandpaper to remove surface debris and oxide film, then put the polished brazing material into alcohol, and clean it repeatedly 3 times with an ultrasonic cleaner. After cleaning, put it into a vacuum drying oven for drying. The drying temperature is 30°C and the drying time is 10 minutes.

[0055] Then, the prepared brazing material is pre-placed between the carbide drill bit and the surface to be welded of the 42CrMo steel drill rod to ensure the coaxiality and radial angle of the drill rod and the drill bit to obtain the welded part.

[0056] Finally, the resistance brazing of the workpieces to be welded is performed by resistance welding equipment to obtain a brazed assembly. The preheating current density is 25A / mm 2 , welding current density is 30A / mm 2 The electrode pressure in the pre-pressing stage is 100N, the welding pressure is 150N, the holding pressure is 150N, the welding time is 300ms, and argon gas protection is used throughout the welding process.

[0057] The room temperature and high temperature shear strength tests were performed on the welded joint obtained in this embodiment using a special fixture on an electronic universal testing machine, with a loading rate of 0.5 mm / min. The maximum load output when the workpiece was sheared was recorded, and the joint shear strength was converted according to the maximum load. The average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 290 MPa, the maximum service temperature of the welded joint was 1200°C, and the shear strength of the welded joint at 900°C was 172 MPa. Example 4

[0058] The present embodiment is a resistance brazing method for a cemented carbide drill bit and a steel drill rod, wherein the cemented carbide drill bit involved is a tungsten carbide (WC) drill bit with a diameter of φ8 mm; the steel drill rod involved is No. 45 steel, with a tensile strength ≥600 MPa, a yield strength ≥355 MPa, an elongation ≥16%, and a diameter of φ7.5 mm; in terms of atomic fraction, the brazing material involved is an alloy foil composed of 15% Co, 10% Fe, 0% Mn, 8% Si, 5% Cu and the remainder Ni, with a melting point of 1240°C and a foil thickness of 0.3 mm.

[0059] The specific brazing process of this embodiment includes the following steps: The surfaces to be welded of the carbide drill bit and the No. 45 steel drill rod were polished with 240-600 mesh sandpaper to remove surface debris and oxide film. Then the polished carbide drill bit and the No. 45 steel drill rod were placed in alcohol and cleaned repeatedly 3 times with an ultrasonic cleaner. After cleaning, they were placed in a vacuum drying oven for drying at a temperature of 30°C and a drying time of 10 min.

[0060] Similarly, first grind the brazing material with 240-600 mesh sandpaper to remove surface debris and oxide film, then put the polished brazing material into alcohol, and clean it repeatedly 3 times with an ultrasonic cleaner. After cleaning, put it into a vacuum drying oven for drying. The drying temperature is 30°C and the drying time is 10 minutes.

[0061] Then, the prepared brazing material is pre-placed between the carbide drill bit and the surface to be welded of the 45# steel drill rod, the coaxiality and radial angle of the drill rod and the drill bit are ensured, and the welded part is obtained.

[0062] Finally, the resistance brazing of the workpieces to be welded is performed by resistance welding equipment to obtain a brazed assembly. The preheating current density is 15 A / mm 2 , welding current density is 35A / mm 2 The electrode pressure in the pre-pressing stage is 100N, the welding pressure is 130N, the holding pressure is 130N, the welding time is 200ms, and argon gas protection is used throughout the welding process.

[0063] The room temperature and high temperature shear strength tests were performed on the welded joint obtained in this embodiment using a special fixture on an electronic universal testing machine, with a loading rate of 0.5 mm / min. The maximum load output when the workpiece was sheared was recorded, and the joint shear strength was converted according to the maximum load. The average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 313 MPa, the maximum service temperature of the welded joint was 1150°C, and the shear strength of the welded joint at 900°C was 198 MPa. Example 5

[0064] The present embodiment is a resistance brazing method for a cemented carbide drill bit and a steel drill rod, wherein the cemented carbide drill bit involved is a tungsten carbide (WC) drill bit with a diameter of φ8 mm; the steel drill rod involved is No. 45 steel, with a tensile strength ≥600 MPa, a yield strength ≥355 MPa, an elongation ≥16%, and a diameter of φ7.5 mm; in terms of atomic fraction, the brazing material involved is an alloy foil composed of 15% Co, 10% Fe, 0% Mn, 8% Si, 15% Cu and the remainder Ni, with a melting point of 1186°C and a foil thickness of 0.3 mm.

[0065] The specific brazing process of this embodiment includes the following steps: The surfaces to be welded of the carbide drill bit and the No. 45 steel drill rod were polished with 240-600 mesh sandpaper to remove surface debris and oxide film. Then the polished carbide drill bit and the No. 45 steel drill rod were placed in alcohol and cleaned repeatedly 3 times with an ultrasonic cleaner. After cleaning, they were placed in a vacuum drying oven for drying at a temperature of 30°C and a drying time of 10 min.

[0066] Similarly, first grind the brazing material with 240-600 mesh sandpaper to remove surface debris and oxide film, then put the polished brazing material into alcohol, and clean it repeatedly 3 times with an ultrasonic cleaner. After cleaning, put it into a vacuum drying oven for drying. The drying temperature is 30°C and the drying time is 10 minutes.

[0067] Then, the prepared brazing material is pre-placed between the carbide drill bit and the surface to be welded of the 45# steel drill rod, the coaxiality and radial angle of the drill rod and the drill bit are ensured, and the welded part is obtained.

[0068] Finally, the resistance brazing of the workpieces to be welded is performed by resistance welding equipment to obtain a brazed assembly. The preheating current density is 20 A / mm 2 , welding current density is 50A / mm 2 The electrode pressure in the pre-pressing stage is 100N, the welding pressure is 120N, the holding pressure is 120N, the welding time is 200ms, and argon gas protection is used throughout the welding process.

[0069] The room temperature and high temperature shear strength tests were performed on the welded joint obtained in this embodiment using a special fixture on an electronic universal testing machine, with a loading rate of 0.5 mm / min. The maximum load output when the workpiece was sheared was recorded, and the joint shear strength was converted according to the maximum load. The average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 245 MPa, the maximum service temperature of the welded joint was 1000°C, and the shear strength of the welded joint at 900°C was 139 MPa.

[0070] Comparative Example 1 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.

[0071] The room temperature and high temperature shear strength tests were carried out on the welded joints obtained in this comparative example 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 was sheared was recorded. The joint shear strength was converted according to the maximum load, and the average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 64 MPa, the maximum service temperature of the welded joint was 1100°C, and the shear strength of the welded joint at 900°C was 35 MPa.

[0072] Comparative Example 2 The 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.

[0073] The room temperature and high temperature shear strength tests were carried out on the welded joints obtained in this comparative example 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 was sheared was recorded. The joint shear strength was converted according to the maximum load, and the average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 79 MPa, the maximum service temperature of the welded joint was 1100°C, and the shear strength of the welded joint at 900°C was 54 MPa.

[0074] Comparative Example 3 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.

[0075] The room temperature and high temperature shear strength tests were carried out on the welded joints obtained in this comparative example 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 was sheared was recorded. The joint shear strength was converted according to the maximum load, and the average value of 5 samples was taken as the final result. The results were: the room temperature shear strength of the welded joint was 62 MPa, the maximum service temperature of the welded joint was 1100°C, and the shear strength of the welded joint at 900°C was 37 MPa.

[0076] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the disclosure disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The description and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

Claims

1. A method for brazing cemented carbide and steel, characterized in that: The brazing method comprises the following steps: A brazing material is provided, wherein 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 the balance Ni in terms of atomic fraction, and the melting temperature range is 1100-1300° C.; Providing a hard alloy structural part and a steel structural part, placing the brazing material between the surfaces to be welded of the hard alloy structural part and the steel structural part, to obtain a part to be welded; The parts to be welded are subjected to resistance brazing to obtain a brazing assembly.

2. The method for brazing cemented carbide and steel according to claim 1, characterized in that: 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 the balance Ni in terms of atomic fraction.

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

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

5. The method for brazing cemented carbide and steel according to claim 1, characterized in that: The steel structural parts are selected from one of 42CrMo steel structural parts, No. 45 steel structural parts, Q235 structural parts, and Q345 structural parts.

6. The method for brazing cemented carbide and steel according to claim 1, characterized in that: The hard alloy structural part is a hard alloy drill bit, and the steel structural part is a steel drill rod.

7. The method for brazing cemented carbide and steel according to any one of claims 1 to 6, characterized in that: In the resistance brazing step, the preheating current density is 10~30A / mm 2 , welding current density is 30~50A / mm 2 The electrode pressure in the pre-pressing stage is 50~100N, the welding pressure is 100~300N, the holding pressure is 100~300N, the welding time is 200~500ms, and argon or reducing gas protection is used throughout the welding process.

8. The method for brazing cemented carbide and steel according to claim 7, characterized in that: In the resistance brazing process, the preheating current density and welding current density differ by 10~20 A / mm 2 , and / or, the welding pressure and the holding pressure are the same.

9. A brazed assembly obtained by the brazing method of cemented carbide and steel as claimed in any one of claims 1 to 8, characterized in that: The brazing assembly comprises a cemented carbide structural component and a steel structural component, and the cemented carbide structural component and the steel structural component are connected via a welding joint.

10. The brazing assembly according to claim 9, characterized in that: The brazing assembly comprises a carbide drill bit and a steel drill rod, and the carbide drill bit and the steel drill rod are connected via a welding joint.