A copper-based alloy for hard metal brazing and a method of manufacturing and use thereof

Abstract

The application provides a copper-based alloy for brazing of hard alloy and a preparation method and application thereof, and relates to the technical field of brazing. Specifically, the copper-based alloy comprises the following elements in percentage by weight: Zn 25-40%, Mn 1-10%, Si 0.1-2%, Co 0.1-2%, Cr 0.1-1%, Zr 0.01-0.5%, Nb 0.01-0.5%, and the balance of Cu. Meanwhile, the application provides a specific preparation process of the copper-based alloy. By optimizing the relative content of zinc and manganese elements, and by adding silicon, cobalt, chromium, zirconium and niobium elements to refine the alloy structure, the copper-based alloy has good mechanical strength, welding performance and wetting performance when brazing hard alloy workpieces, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of brazing technology, and more specifically, to a copper-based alloy for brazing cemented carbide, a method for preparing the copper-based alloy, and applications of the copper-based alloy. Background Technology

[0002] Hard alloys are alloy materials made from hard compounds of refractory metals and binder metals through powder metallurgy. They are known as "industrial teeth" due to their high strength, high hardness, high wear resistance, low coefficient of linear expansion, and good red hardness, and are widely used in the petroleum industry, aerospace, geological exploration, and machinery manufacturing. Joining hard alloys to steel can fully utilize their high hardness and high strength-toughness characteristics, further expanding the application areas of hard alloys.

[0003] Currently, the main welding methods for joining cemented carbide to steel include brazing, diffusion welding, arc welding, resistance welding, and friction welding. Among these, brazing is widely used due to its low cost and simple process. The quality of the brazed joint depends on the properties of the filler metal. The most commonly used filler metals are silver-based, copper-based, and nickel-based. However, silver-based filler metals are expensive and have a low melting point, which limits the service temperature of the workpiece. Although nickel-based filler metals have a high melting temperature, they can soften the steel base material during welding. Copper-based filler metals, on the other hand, have a moderate melting point, excellent plasticity, toughness, and wettability, and are therefore widely used.

[0004] Currently, the copper brazing filler metal commonly used to join cemented carbide and steel is L105. This filler metal contains 4 wt.% Mn, 38 wt.% Zn, and the balance copper. However, its strength and wettability are poor, leading to fractures at the brazed joint during later service life. Therefore, developing copper brazing filler metals with higher joint strength and wettability is of great significance for improving the connection performance between cemented carbide and steel substrates.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The first objective of this invention is to provide a copper-based alloy for cemented carbide brazing, which addresses the shortcomings of existing copper-based alloy solders in cemented carbide brazing, such as insufficient joint strength or wettability.

[0007] The second objective of this invention is to provide a method for preparing the copper-based alloy for cemented carbide brazing, which is simple, easy to implement, and suitable for mass production.

[0008] A third objective of this invention is to provide an application of the copper-based alloy described above for cemented carbide brazing, particularly its application in the welding of cemented carbide and steel workpieces.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] A copper-based alloy for cemented carbide brazing, comprising the following elemental composition by weight percentage:

[0011] Zn 25%–40%, Mn 1%–10%, Si 0.1%–2%, Co 0.1%–2%, Cr 0.1%–1%, Zr 0.01%–0.5%, Nb 0.01%–0.5%, and the balance Cu.

[0012] The method for preparing the copper-based alloy for cemented carbide brazing is characterized by comprising the following steps:

[0013] Step 1: Prepare the raw material components according to the weight ratio; the raw material components include Cu, Mn, CuSi, CuCo, CuCr, CuZr and CuNb;

[0014] Step 2: Mix all raw material components except Zn and perform the first melting to obtain the first molten liquid;

[0015] Step 3: When the first melt cools down to solidify, add Zn and perform a second melting process to obtain the second melt;

[0016] Step 4: After the second molten liquid has melted completely, it is heated and stirred, and then air-cooled to room temperature to obtain a copper-based alloy.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) By formulating the elemental composition of the copper-based brazing alloy, the present invention enhances the feasibility of the smelting process by optimizing the relative content of zinc and manganese, enabling more precise control of the alloy composition during the smelting process, and improving the wettability of the alloy. On the other hand, by adding silicon, the melting temperature of the copper alloy is regulated, improving the brazing filler performance. At the same time, the addition of silicon, cobalt, chromium, zirconium and niobium refines the alloy structure, increases the alloy strength, inhibits the loss of Co in the cemented carbide binder phase, and enhances the welding effect.

[0019] (2) The present invention provides a method for preparing copper-based brazing alloys. By planning the specific steps of melting and heating and the zinc addition points, the volatilization of zinc is greatly reduced, and a more uniformly melted and diffused metal melt can be obtained.

[0020] (3) When the copper-based brazing alloy provided by the present invention is used for brazing of cemented carbide, especially when brazing cemented carbide and steel workpieces, it can achieve higher wetting performance and joint strength. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 Tensile strength-displacement value comparison curves for Example 2 and Comparative Example 2 are provided;

[0023] Figure 2 A comparison curve of shear strength-displacement curves for Q235 steel-YG8 cemented carbide using Example 2 and Comparative Example 2 is provided.

[0024] Figure 3 A schematic diagram of the melting characteristics of the alloys of Example 2 and Comparative Example 2 is provided;

[0025] Figure 4 Light microscopic tissue comparison images of Example 2 are provided;

[0026] Figure 5 Comparative images of tissue under light microscopy are provided for Example 2;

[0027] Figure 6 Electron micrographs of tissue comparison from Example 2 are provided;

[0028] Figure 7 Electron micrographs of the tissues in Comparative Example 2 are provided;

[0029] Figure 8 An electron microscope scanning elemental distribution map of Example 2 is provided;

[0030] Figure 9 An EDS layered diagram of Example 2 is provided. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0032] A copper-based alloy for cemented carbide brazing comprises the following elemental composition by weight percentage: Zn 25%–40%, Mn 1%–10%, Si 0.1%–2%, Co 0.1%–2%, Cr 0.1%–1%, Zr 0.01%–0.5%, Nb 0.01%–0.5%, and the balance Cu.

[0033] In a preferred embodiment, the copper-based alloy comprises the following elemental composition by weight percentage: Cu 55%–65%, Zn 28%–36%, Mn 2%–7%, Si 0.3%–1.5%, Co 0.2%–1.3%, Cr 0.1%–0.8%, Zr 0.05%–0.4%, and Nb 0.05%–0.5%.

[0034] As an optional implementation, the weight percentage of each element in the copper-based alloy can be expressed as the following point values, or any real value within the numerical range formed by the following point values: Cu: 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%; Zn: 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%; Mn: 2%, 3%, 4%, 5%, 6%, 7%; Si: 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%. %, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%; Co: 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%; Cr: 0.1%, 0.2%, 0.3% , 0.4%, 0.5%, 0.6%, 0.7%, 0.8%; Zr: 0.05%, 0.1%, 0.2%, 0.3%, 0.35%, 0.4%; Nb: 0.05%, 0.1%, 0.2%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%.

[0035] In the copper-based brazing alloy of the present invention, the relative contents of Zn and Mn are optimized. Compared with commercially available conventional copper-based brazing alloys, the present invention reduces the proportion of Zn and increases the content of Mn, avoiding the difficulty in controlling the alloy composition caused by the low boiling point and easy volatility of high Zn content. In addition, the high Mn content can simultaneously improve the high-temperature strength of the alloy, reduce the melting point of the alloy, thereby reducing the residual stress of the workpiece after welding steel and cemented carbide, while improving wettability, without deteriorating the plasticity of the brazing alloy, and secondary deoxidation and other advantageous characteristics.

[0036] Adding trace amounts of Si to the copper-based brazing alloy of the present invention can reduce the melting temperature of the copper alloy, improve the brazing filler performance, enhance oxidation resistance, and inhibit the volatilization of Zn and Mn elements to a certain extent.

[0037] The copper-based brazing alloy of this invention incorporates trace amounts of high-melting-point elements such as Co, Cr, Zr, and Nb, which refine the alloy microstructure, improve the strength of the alloy and the brazing seam, further extend the service life of the workpiece, and reduce usage costs. Furthermore, during the brazing of cemented carbide and steel, the Co in the brazing alloy can mitigate the loss of the binder phase Co in the cemented carbide.

[0038] In the copper-based brazing alloy of the present invention, by adding trace amounts of Nb, Cr2Nb, Ni2Si, NbNi3 and other particles will precipitate during the solidification process of the alloy. On the one hand, the precipitated compound particles have good high-temperature stability so that the alloy has good high-temperature performance. On the other hand, the precipitated compound particles can act as nucleation particles in the solidification process, thereby refining the grains and improving the strength of the alloy.

[0039] The method for preparing the copper-based alloy for cemented carbide brazing includes the following steps:

[0040] Step 1: Prepare the raw material components according to the weight ratio; the raw material components include Cu, Mn, CuSi, CuCo, CuCr, CuZr, and CuNb; Step 2: Mix all raw material components except Zn and perform a first smelting to obtain a first melt; Step 3: When the first melt cools down to solidify, add Zn and perform a second smelting to obtain a second melt; Step 4: After the second melt is completely melted, perform heating and stirring treatment, and then air cool to room temperature to obtain a copper-based alloy.

[0041] In a preferred embodiment, the purity of the raw material components (Cu, Zn, Mn, CuSi, CuCo, CuCr, CuZr and CuNb) used in this invention is independently ≥99.999%; the raw material components can take any form, such as metal particles, metal blocks, metal ingots, metal powder, metal wires, metal sheets, etc., and this invention does not limit them.

[0042] In a preferred embodiment, Si, Co, Cr, Zr, and Nb are all added in the form of intermediate alloys in this invention to avoid element segregation of the added trace elements and element burn-off caused by excessively high melting temperature and long melting time. When making the weight ratio of Cu, it is necessary to calculate the mass of Cu in each intermediate alloy and then calculate the mass of the additional Cu element.

[0043] In a preferred embodiment, in step two, the temperature of the first melting is 1000℃~1350℃, and the melting time is 8min~12min; in an optional embodiment, the temperature of the first melting includes, but is not limited to, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350 (℃), and the melting time includes, but is not limited to, 8, 9, 10, 11, 12 (min).

[0044] In a preferred embodiment, in step three, the temperature of the second melting is 500℃~700℃, and the time of the second melting is 2min~5min; in an optional embodiment, the temperature of the second melting includes but is not limited to 500, 520, 550, 580, 600, 620, 640, 680, 700 (℃), and the time of the second melting includes but is not limited to 2, 2.5, 3, 3.5, 4, 4.5, 5 (min).

[0045] In a preferred embodiment, both the first melting and the second melting are carried out under air-isolated conditions to avoid oxidation of elements at high temperatures and thus prevent burn-off.

[0046] The air isolation is achieved by at least one of feature (a) or (b): (a) a surface covering agent is applied to the surface of the raw material components, the surface covering agent comprising charcoal and / or dehydrated borax; (b) the first melting is carried out in an inert gas atmosphere; wherein the inert gas in feature (b) includes, but is not limited to, nitrogen, helium, neon, and argon.

[0047] In a preferred embodiment, one or more of the first melting, the second melting, and the heating process are carried out by induction heating.

[0048] In a preferred embodiment, in step four, the heating process includes heating the second molten liquid to 850°C to 950°C; in an optional embodiment, the temperature of the heating process includes, but is not limited to, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, and 950°C.

[0049] In a preferred embodiment, in step four, the stirred molten metal is allowed to stand for 30 to 120 seconds, then poured into a preheated container, and subsequently air-cooled; the preheating temperature is 400°C to 600°C. Standing allows gases in the melt to escape and impurities to float to the surface, preventing defects such as bubbles or inclusions from forming in the ingot. The preheating can be performed in a resistance furnace, and the preheated container typically refers to a mold used for pouring the molten metal.

[0050] In a preferred embodiment, in step four, the heating process and the stirring process can be carried out simultaneously, that is, the heating process is carried out while the stirring is performed by a graphite rod.

[0051] Example 1

[0052] This embodiment provides a copper-based brazing alloy comprising the following elemental composition by weight percentage: Zn 28%, Mn 2%, Si 0.3%, Co 0.2%, Cr 0.1%, Zr 0.05%, Nb 0.05%, with the balance being Cu.

[0053] The copper-based brazing alloy provided in this embodiment is prepared by the following method and steps:

[0054] 1) Select the following components, all of which have a purity of 99.999%: copper ingots, electrolytic manganese sheets, zinc ingots, CuSi, CuCo, CuCr, CuZr and CuNb, and formulate the raw materials according to the above weight percentages.

[0055] 2) Place copper ingots, electrolytic manganese sheets, CuSi, CuCo, CuCr, CuZr and CuNb into a high-purity graphite crucible, and cover the surface with dehydrated borax as a covering agent; use induction melting to melt the materials at a temperature of 1200℃ for 10 minutes, and continuously introduce argon gas into the crucible during the melting process.

[0056] 3) After the metal in the crucible has melted completely, gradually lower the temperature until the alloy solidifies. Then add zinc ingots and cover with sufficient dehydrated borax. Control the melting temperature to 600℃ until the two are completely miscible.

[0057] 4) After the solution is completely dissolved, raise the temperature to 900°C and stir evenly with a stone mill rod; after standing for 1 minute, pour it into a graphite crucible preheated to 500°C and air cool to room temperature to obtain the copper-based alloy of this embodiment.

[0058] Example 2

[0059] This embodiment provides a copper-based brazing alloy comprising the following elemental composition by weight percentage: Zn 32.5%, Mn 5%, Si 1%, Co 0.8%, Cr 0.5%, Zr 0.2%, Nb 0.2%, with the balance being Cu.

[0060] The preparation method of the copper-based brazing alloy provided in this embodiment is exactly the same as that in Embodiment 1.

[0061] Example 3

[0062] This embodiment provides a copper-based brazing alloy comprising the following elemental composition by weight percentage: Zn 33.5%, Mn 4.2%, Si 0.8%, Co 1.0%, Cr 0.4%, Zr 0.25%, Nb 0.3%, with the balance being Cu.

[0063] The preparation method of the copper-based brazing alloy provided in this embodiment is exactly the same as that in Embodiment 1.

[0064] Example 4

[0065] This embodiment provides a copper-based brazing alloy comprising the following elemental composition by weight percentage: Zn 36%, Mn 7%, Si 1.5%, Co 1.3%, Cr 0.8%, Zr 0.4%, Nb 0.5%, with the balance being Cu.

[0066] The preparation method of the copper-based brazing alloy provided in this embodiment is exactly the same as that in Embodiment 1.

[0067] Example 5

[0068] This is basically the same as Example 2, except for the preparation method:

[0069] In step 2), the melting temperature is 1000℃ and the melting time is 12 minutes.

[0070] The melting temperature in step 3) is 500℃;

[0071] In step 4), the temperature is raised to 850°C.

[0072] Example 6

[0073] This is basically the same as Example 2, except for the preparation method:

[0074] In step 2), the melting temperature is 1350℃ and the melting time is 8 minutes.

[0075] The melting temperature in step 3) is 700℃;

[0076] In step 4), the temperature is raised to 950°C.

[0077] Comparative Example 1

[0078] This comparative example provides a copper-based brazing alloy comprising the following elemental composition by weight percentage: Zn 36%, Mn 7%, Co 1.3%, Cr 0.8%, Zr 0.4%, with the balance being Cu.

[0079] The preparation method of the copper-based brazing alloy provided in this comparative example is exactly the same as that in Example 1.

[0080] Comparative Example 2

[0081] Commercially available copper-based alloy, grade L105.

[0082] Experimental Example 1

[0083] The tensile strength of the alloy was tested using a universal testing machine, and the experimental results are shown in Table 1 (five tests were conducted independently, and the average value was calculated as the tensile strength value). It can be found that the shear strength of the alloy of the present invention is 1.2 times that of Comparative Example 2.

[0084] Simultaneously, the tensile strength-displacement value comparison curves of Example 2 and Comparative Example 2 were tested, such as... Figure 1 As shown.

[0085] Table 1

[0086] 1 2 3 4 5 Tensile strength / MPa Example 1 415.3 396.5 401.4 428.5 434.9 415.3 Example 2 457.9 448.3 454.7 442.6 465.8 453.9 Example 3 422.4 453.8 457.2 439.9 452.8 445.2 Example 4 418.3 432.3 469.4 431.2 420.1 434.3 Example 5 458.5 431.9 429.7 448.1 466.8 447 Example 6 432.8 452.3 427.1 428.7 436.8 435.54 Comparative Example 1 398.9 384.3 389.6 395.2 408.9 395.4 Comparative Example 2 365.1 379.4 372.9 378.5 360.9 371.4

[0087] Experimental Example 2

[0088] Using the copper-based alloys obtained in Example 2 and Comparative Example 2 as brazing filler metals, welding experiments were conducted on Q235 steel-YG8 cemented carbide via induction brazing. The flux used was paste-like QJ308 flux, and the weld was followed by water quenching. The shear strength of the joint was tested using a universal testing machine (five independent tests were performed, and the average value was calculated as the shear strength value). The experimental results are shown in Table 2. It can be found that the shear strength of the alloy prepared by this invention is 28% higher than that of the traditional 105 alloy when applied.

[0089] Simultaneously, the shear strength-displacement curves of Q235 steel-YG8 cemented carbide in Example 2 and Comparative Example 2 were compared, as shown in the figure. Figure 2 As shown.

[0090] Table 2

[0091] 1 2 3 4 5 Shear strength / MPa Example 2 389 401 378 382 395 389 Comparative Example 2 306 298 289 305 317 303

[0092] Experimental Example 3

[0093] The melting characteristics of the alloys in Example 2 and Comparative Example 2 were tested using a STA449F3 thermal analyzer at a heating rate of 10℃ / min. It was found that the endothermic peak in Example 2 shifted to the left compared to Comparative Example 2. The initial melting temperature was 857.84℃, a decrease of 22.26℃ compared to Comparative Example 2, the peak temperature decreased by 17.41℃, and the final melting temperature decreased by 18.02℃, which is beneficial for improving the alloy's flow properties, as shown in Table 3 below. Meanwhile... Figure 3 A schematic diagram of the melting characteristics of the alloys in Example 2 and Comparative Example 2 is provided.

[0094] Table 3

[0095]

[0096]

[0097] In addition, the present invention also provides a series of microscopic test images of Embodiment 2 and Comparative Example 2; Figure 4 and Figure 5 Light microscopic tissue comparison images of Example 2 and Comparative Example 2 are provided respectively. Figure 6 and Figure 7 Electron micrographs of tissues from Example 2 and Comparative Example 2 are provided respectively. Figure 8 The electron microscopy scanning elemental distribution map of Example 2 is provided. Figure 9 EDS layered images of Example 2 are provided. It can be seen from the above image information that: compared with the comparative example, the metallographic structure obtained in the example is significantly refined. Grain refinement can significantly improve the strength of the alloy and also bring about a toughening effect; the main manifestations include, but are not limited to: (1) grain refinement increases the total area of ​​grain boundaries per unit volume and reduces the harmful effect of grain boundary segregation; (2) it reduces the stress concentration on grain boundaries that collide with slip surfaces; (3) grain refinement makes the non-uniform deformation caused by strain anisotropy more uniform and has the effect of strain dispersion, etc.

[0098] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A copper-based alloy for brazing cemented carbide, characterized in that, The copper-based alloy is composed of the following elemental components by weight percentage: Zn 25%~40%, Mn 1%~10%, Si 0.1%~1.5%, Co 0.1%~2%, Cr 0.1%~0.8%, Zr 0.01%~0.5%, Nb 0.01%~0.5%, and the balance Cu.

2. The copper-based alloy for cemented carbide brazing according to claim 1, characterized in that, The copper-based alloy is composed of the following elemental components by weight percentage: Cu 55%~65%, Zn 28%~36%, Mn 2%~7%, Si 0.3%~1.5%, Co 0.2%~1.3%, Cr 0.1%~0.8%, Zr0.05%~0.4% and Nb 0.05%~0.5%.

3. The method for preparing a copper-based alloy for cemented carbide brazing as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Prepare the raw material components according to the weight ratio; the raw material components include Cu, Mn, CuSi, CuCo, CuCr, CuZr and CuNb; Step 2: Mix all raw material components except Zn and perform the first melting to obtain the first molten liquid; Step 3: When the first melt cools down to solidify, add Zn and perform a second melting process to obtain the second melt; Step 4: After the second molten liquid has melted completely, it is heated and stirred, and then air-cooled to room temperature to obtain a copper-based alloy.

4. The method for preparing a copper-based alloy for cemented carbide brazing according to claim 3, characterized in that, In step two, the temperature of the first melting is 1000℃~1350℃, and the melting time is 8min~12min.

5. The method for preparing a copper-based alloy for cemented carbide brazing according to claim 3, characterized in that, In step three, the temperature of the second melting is 500℃~700℃, and the time of the second melting is 2min~5min.

6. The method for preparing a copper-based alloy for cemented carbide brazing according to claim 3, characterized in that, Both the first and second melting processes were carried out under conditions of air isolation.

7. The method for preparing a copper-based alloy for cemented carbide brazing according to claim 6, characterized in that... The air isolation is achieved through at least one of feature (a) or (b): (a) A surface covering agent is applied to the surface of the raw material components, said surface covering agent comprising charcoal and / or dehydrated borax; (b) The first melting is carried out in an inert gas atmosphere.

8. The method for preparing a copper-based alloy for cemented carbide brazing according to claim 3, characterized in that, In step four, the heating process includes heating the second molten liquid to 850°C~950°C.

9. The method for preparing a copper-based alloy for cemented carbide brazing according to claim 3, characterized in that, In step four, the stirred melt is allowed to stand for 30s to 120s, then poured into a preheated container and air-cooled. The preheating temperature is 400℃~600℃.

10. The application of the copper-based alloy for cemented carbide brazing as described in claim 1 or 2 in cemented carbide brazing.

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