Cobalt-based alloy powder and matrix high-temperature resistant strengthening method

Abstract

The present invention discloses a cobalt-based alloy powder and a method for strengthening a substrate to achieve high-temperature resistance, relating to the field of strengthening technology. Specifically, a cobalt-based alloy powder is disclosed: comprising: 0.9%-1.2% Ni, 0.9%-1.2% Si, 0.9%-1.0% Mn, 30.4%-31.2% Cr, 3.9%-4.4% W, 0.9%-1.3% C, 1%-1.2% B, with the balance being Co. Also disclosed is a strengthening method, comprising cladding cobalt-based alloy powder A onto the substrate to form a transition layer; and cladding the cobalt-based alloy powder onto the transition layer to form a high-temperature-resistant layer. Cobalt-based alloy powder is combined with laser cladding to strengthen the base, which strengthens the substrate to improve the base's high temperature resistance, wear resistance, and corrosion resistance. In addition, the metal elements such as Co, Cr, W, and Ni contained in this cobalt-based alloy powder can generate various carbides during the laser cladding process, becoming a strengthening layer of the laser cladding layer, effectively improving the hardness, and then a higher hardness strengthening layer can be obtained compared to conventional cobalt-based alloy powder.

Description

Technical Field

[0001] The present invention relates to the technical field of substrate surface strengthening, and in particular to a cobalt-based alloy powder and a substrate high-temperature resistant strengthening method. Background Art

[0002] Cobalt-based alloy powder is a powder material made by pulverizing cobalt alloy castings. It has excellent high-temperature oxidation, creep, and wear properties. Cobalt-based alloy powder is widely used in aerospace, petroleum, refining, chemical, and other fields, for example, on substrates that work in high-temperature conditions such as gun breech blocks. However, although the existing cobalt-based alloy powder can improve the substrate's high-temperature resistance, wear resistance, corrosion resistance, and oxidation resistance compared to previous ones, there is still room for improvement in these properties. Therefore, how to further improve the performance of cobalt-based alloy powder, and thus improve the performance of the substrate, remains a constant goal in the field of substrate surface strengthening technology. Summary of the Invention

[0003] The present invention aims to provide a cobalt-based alloy powder and a method for strengthening a substrate at high temperatures, thereby resolving the technical problem of low heat resistance, wear resistance, and corrosion resistance of existing substrates. To enhance these properties, the present invention provides a novel cobalt-based alloy powder, in conjunction with laser cladding for substrate strengthening. This powder, combined with the properties of laser cladding, significantly enhances the substrate's heat resistance, wear resistance, and corrosion resistance.

[0004] The technical solution adopted in the present invention is as follows:

[0005] In the first aspect, the present application provides a cobalt-based alloy powder, wherein the substrate needs to withstand high temperature. This cobalt-based alloy powder is used in laser cladding strengthening operations. Calculated by weight percentage, the cobalt-based alloy powder includes: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co.

[0006] Furthermore, the particle size of the cobalt-based alloy powder is 75-150 μm.

[0007] In a second aspect, the present application provides a method for strengthening a substrate at high temperature, the method comprising:

[0008] Cladding cobalt-based alloy powder A onto the substrate to form a transition layer;

[0009] The cobalt-based alloy powder mentioned above is melt-coated on the transition layer to form a high-temperature resistant layer.

[0010] Furthermore, the cobalt-based alloy powder A contains Stellite 6 and TC4, and the weight ratio of Stellite 6 to TC4 is 3:1 to 6:1.

[0011] Furthermore, the weight ratio of Stellite 6 to TC4 is 4:1.

[0012] Furthermore, the Stellite 6 and TC4 are mixed evenly, dried, and then used for cladding the transition layer.

[0013] Furthermore, in terms of weight percentage, the Stellite 6 contains Ni 0.98%, Si 0.98%, Fe 2.06%, Mn 0.97%, Cr 28.08%, Mo≤0.10%, W 4.45%, C 0.91%, S 0.0015%, P≤0.005%, and the balance is Co.

[0014] Furthermore, the TC4 powder contains, by weight percentage: Fe≤0.30%, C≤0.10%, N≤0.05%, H≤0.015%, O≤0.20%, Al5.5%-6.8%, V3.5%-4.5%, and the balance is Ti.

[0015] Furthermore, the thickness of the transition layer is 0.2 to 0.4 mm.

[0016] Furthermore, the thickness of the high temperature resistant layer is 0.3 to 0.7 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the proportional relationships of the various components in the drawings of this specification do not represent the proportional relationships in actual material selection and design, and are merely schematic diagrams of structures or positions, among which:

[0018] Figure 1 is a metallographic diagram of the transition layer laser cladding onto a substrate according to the present invention;

[0019] Figure 2 This is a metallographic diagram of the high temperature resistant laser cladding onto the transition layer of the present invention;

[0020] Figure 3 This is a hardness test report of the strengthening layer after strengthening by the present invention;

[0021] Figure 4 This is a dry rubber wheel abrasive wear test report. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0023] Some substrates requiring surface strengthening typically utilize conventional cobalt-based alloy powders to enhance their surface properties, such as high-temperature resistance, wear resistance, corrosion resistance, and oxidation resistance. The substrate can be any object requiring strengthening, such as a gun breech block, which is typically constructed from a titanium alloy, referred to as a titanium alloy breech block. Titanium alloys are highly chemically active and readily react strongly with ambient gases such as oxygen, nitrogen, hydrogen, carbon monoxide, carbon dioxide, water vapor, and ammonia. Therefore, conventional cobalt-based alloy powders are currently primarily used to enhance the surface properties of such substrates, improving their high-temperature resistance, wear resistance, corrosion resistance, and oxidation resistance, thereby achieving superior performance. While there is always room for further improvement in substrate surface properties, the higher the performance improvement, the greater the challenge. Therefore, further enhancing these beneficial properties of conventional cobalt-based alloy powders presents a significant challenge for those skilled in the art. This requires not only time and effort in research and development, but also outstanding innovation.

[0024] Based on this, the inventors of this application conducted in-depth research on substrates that need to be strengthened, such as the breech block, and found that factors affecting the deviation of the projectile trajectory, in addition to the conventional consideration of the breech block processing accuracy, also need to consider the changes in the surface quality of the ejection track for transporting the projectile after the explosion of the gunpowder. Although conventional cobalt-based alloy powders are used for surface strengthening on such substrates, their compatibility with such severe working conditions is still insufficient. Specifically, during the explosion of gunpowder, the instantaneous high temperature of the breech block can reach over 1000°C. This means that even after the breech block has been strengthened, some areas of the flame outlet and its upper and lower surfaces will still be burned, thereby reducing the surface quality of the breech block and causing the projectile trajectory to seriously deviate from the normal trajectory.

[0025] At the same time, the inventors also found that after the conventional cobalt-based alloy powder is used to strengthen the matrix, the matrix still needs to be machined, which increases the time cost required for matrix strengthening.

[0026] The inventors have discovered that existing matrix strengthening methods have many problems. Common strengthening methods currently include ion implantation, plasma spraying, vapor deposition, chemical plating, welding, etc. Among the aforementioned methods, the biggest disadvantages of other methods except welding are:

[0027] 1) Although the surface of new parts can be strengthened to a certain extent, the high-temperature resistant layer formed is extremely thin;

[0028] 2) The thin strengthening layer cannot work for a long time in its harsh working environment, making its working effect unstable;

[0029] 3) The bonding strength between the formed strengthening layer and the substrate is low, and peeling occurs.

[0030] Conventional welding reinforcement is to build up a layer of reinforcement alloy on the surface, which has the following disadvantages:

[0031] 1) The heat affected zone is large and the bonding strength is low;

[0032] 2) The thickness of the cladding layer is large, the processing allowance is large, and the welding material waste is large;

[0033] 3) The heat output is large, especially when targeting titanium alloy substrates. The closer to the titanium alloy substrate, the more serious the dilution of the strengthening alloy;

[0034] 4) After strengthening, the strengthening layer needs to be machined, which not only increases the strengthening time cost, but also thins the strengthening layer. If the retained amount of the strengthening layer is too small, the heat resistance, hardness and wear resistance will be weakened, which is not conducive to the use of the breech block;

[0035] 5) In order to prevent the occurrence of welding cracks, welding needs to be preheated to about 400°C, which increases the strengthening time cost;

[0036] 6) The welding heat input is large, the wall of the breech block parts is thin, and it is easy to deform;

[0037] 7) Preheating requires a lot of electricity.

[0038] In light of the above circumstances and after in-depth research, the inventors have developed a specially formulated cobalt-based alloy powder. Compared to existing cobalt-based alloy powders, this powder offers numerous improvements in substrate surface strengthening performance. This, in turn, enhances the performance stability and service life of substrates reinforced with this alloy powder under specialized operating conditions, thus contributing to the smooth development of related technologies. Furthermore, by integrating this new matrix strengthening technology, it eliminates machining and improves strengthening efficiency, representing a significant advancement in matrix strengthening.

[0039] The following combination Figure 1 、 Figure 2 The present invention is described in detail.

[0040] Figure 1 This is a metallographic diagram of the transition layer laser cladding onto a substrate according to the present invention, wherein the upper portion of the diagram is the transition layer and the lower portion is the substrate;

[0041] Figure 2 This is a metallographic diagram of the high-temperature resistant laser cladding onto the transition layer of the present invention. The upper part of the diagram is the strengthening layer, and the lower part of the diagram is the transition layer. Figure 3This is a hardness test report of the strengthening layer after strengthening by the present invention; Figure 4 It is a report on dry rubber wheel abrasive wear experiment; the new cobalt-based material in the two reports is the cobalt-based alloy powder designed for this application.

[0042] According to some embodiments of the present application, a cobalt-based alloy powder is provided. This cobalt-based alloy powder is used in laser cladding to strengthen a substrate, and the substrate needs to withstand high temperatures. The cobalt-based alloy powder comprises, by weight percentage: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co.

[0043] In the cobalt-based alloy powder designed in this embodiment of the present application, all components are suitable for bases under high-temperature working conditions and will not damage the surface quality of the base at high temperatures of the base, such as 1000°C. They will only enhance the surface quality of the base, thereby improving the high-temperature resistance, wear resistance, and corrosion resistance of the base. At the same time, the above components have good oxidation resistance and high hardness, which are beneficial to the transportation and storage of the base and will not be oxidized or damaged due to contact with air. The laser cladding process is a rapid heating and cooling process, and the toughness of each material in the above components is good, and there is no welding brittleness problem. In addition, the metal elements such as Co, Cr, W, and Ni contained in this cobalt-based alloy powder can generate a variety of carbides during the laser cladding process, becoming a strengthening layer of the laser cladding layer, effectively improving the hardness, and then a strengthening layer with higher hardness can be obtained compared with conventional cobalt-based alloy powder.

[0044] And, most importantly, this cobalt-based alloy powder is combined with laser cladding to strengthen the base. After strengthening the base, the surface roughness is low and it can be put into use directly without the need for subsequent machining. After using this formula to strengthen the base, it can be used directly, which improves the efficiency of base strengthening and facilitates subsequent maintenance of the base.

[0045] According to some embodiments of the present application, a cobalt-based alloy powder is provided for laser cladding strengthening of a titanium alloy breech block, where the substrate must withstand high temperatures. The cobalt-based alloy powder comprises, by weight, 0.9%-1.2% Ni, 0.9%-1.2% Si, 0.9%-1.0% Mn, 30.4%-31.2% Cr, 3.9%-4.4% W, 0.9%-1.3% C, 1%-1.2% B, with the balance being Co. Metal elements such as Co, Cr, W, and Ni have a higher hardness than Tc4 (titanium alloy) itself.

[0046] According to some embodiments of the present application, the particle size of the cobalt-based alloy powder is 75-150 μm.

[0047] According to some embodiments of the present application, the cobalt-based alloy powder includes, by weight percentage: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co, and its particle size is 75μm.

[0048] According to some embodiments of the present application, the cobalt-based alloy powder includes, by weight percentage: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co, and its particle size is 100 μm.

[0049] According to some embodiments of the present application, the cobalt-based alloy powder includes, by weight percentage: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co, and its particle size is 150 μm.

[0050] According to some embodiments of the present application, the present application provides a method for strengthening a substrate at high temperature, the method comprising:

[0051] Cladding cobalt-based alloy powder A onto the substrate to form a transition layer;

[0052] cladding cobalt-based alloy powder onto the transition layer to form a high-temperature resistant layer;

[0053] Calculated by weight percentage, the cobalt-based alloy powder includes: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co.

[0054] The laser cladding method forms a transition layer and a strengthening layer, and combined with the cobalt-based alloy powder designed in this application, it can form a strengthening layer with better high-temperature resistance, wear resistance and corrosion resistance on the surface of the base under high-temperature conditions, and there is no need to machine the formed strengthening layer. It can be put into use directly, which improves the surface properties of the base, facilitates its long-term stable operation under high-temperature conditions, and can also improve the strengthening efficiency and reduce the time cost required for strengthening.

[0055] Laser cladding involves rapidly heating and melting metal with a laser, followed by rapid cooling. This rapid cooling promotes grain refinement and improves the hardness of the cladding layer. The protective argon atmosphere during laser cladding, combined with the deoxidizing and slag-forming properties of elements like boron and silicon, effectively reduces the likelihood of defects such as porosity and slag inclusions in the cladding layer. These two elements also harden and strengthen the cladding layer, improving its processability.

[0056] According to some embodiments of the present application, the cobalt-based alloy powder A contains Stellite 6 and TC4, and the weight ratio of Stellite 6 to TC4 is 3:1 to 6:1.

[0057] According to some embodiments of the present application, the weight ratio of Stellite 6 to TC4 is 4:1. This cobalt-based alloy powder A has the following advantages:

[0058] 1) Cobalt-based alloy powder A has good plasticity. Due to the presence of 20% TC4 alloy, the plasticity of the transition layer formed by cladding is increased, the stress of the cladding layer is reduced to the maximum extent, and the substrate and cladding layer do not need to be preheated and will not produce cracks;

[0059] 2) The bonding strength between the transition layer and the substrate is increased, which can effectively prevent the peeling of the substrate and the cobalt-based alloy layer under the action of welding stress.

[0060] According to some embodiments of the present application, the Stellite 6 and TC4 are mixed evenly, dried, and then used to clad the transition layer.

[0061] According to some embodiments of the present application, the Stellite 6 contains, by weight percentage, Ni 0.98%, Si 0.98%, Fe 2.06%, Mn 0.97%, Cr 28.08%, Mo≤0.10%, W 4.45%, C 0.91%, S 0.0015%, P≤0.005%, and the balance is Co.

[0062] According to some embodiments of the present application, the TC4 powder contains, by weight percentage: Fe≤0.30%, C≤0.10%, N≤0.05%, H≤0.015%, O≤0.20%, Al5.5%~6.8%, V3.5%~4.5%, and the balance is Ti.

[0063] According to some embodiments of the present application, the thickness of the transition layer is 0.2 to 0.4 mm.

[0064] According to some embodiments of the present application, the thickness of the high temperature resistant layer is 0.3 to 0.7 mm.

[0065] According to some embodiments of the present application, the present application provides a method for strengthening a substrate at high temperature, the method comprising:

[0066] Pretreatment: clean the oxides and dirt on the surface of the substrate;

[0067] Preparation of transition layer powder: 80% by weight of Stellite 6 and 20% by weight of TC4 titanium alloy powder are mixed evenly and dried to obtain cobalt-based high-temperature alloy powder;

[0068] Laser cladding transition layer: The transition layer powder is clad onto the substrate with a thickness of 0.3 mm as the transition layer;

[0069] The laser cladding process parameters for the transition layer are as follows: semiconductor fiber coupled laser, Gaussian distribution 2mm spot, 30mm / s scanning speed, powder feed rate 10.6g / min, 2300W laser power, overlap 53%. The metallographic photograph of the transition layer is as follows: Figure 1 As shown;

[0070] Preparation of high temperature resistant layer powder: by weight percentage, Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co. The above ingredients are mixed evenly and dried to obtain the cobalt-based high temperature alloy powder designed in this application;

[0071] Laser cladding of the high-temperature resistant layer: The high-temperature resistant layer powder is clad onto the transition layer, and a 0.5 mm high-temperature resistant layer is clad on the transition layer surface. The powder material used for the high-temperature resistant layer is the cobalt-based alloy powder designed in this application. The cobalt-based alloy powder designed in this application can effectively increase the surface hardness of the substrate, enhancing its surface wear resistance and high-temperature resistance. This can effectively improve the substrate's safety in harsh working environments characterized by transient high temperatures, oxidation, wear and collision, and strong corrosion, reducing major safety hazards and increasing the substrate's precision and performance.

[0072] The laser cladding process parameters of the high temperature resistant layer are as follows: semiconductor fiber coupled laser, Gaussian distribution 2mm spot, 28mm / s scanning speed, powder feeding rate 14.28g / min, 2500W laser power, overlap amount 53%, and the metallographic photos are as follows: Figure 2 shown.

[0073] According to some embodiments provided in this application, the substrate is strengthened according to the implementation method of this application to obtain Figure 3Hardness test report, based on this report, the hardness comparison before and after strengthening can be known. At the same time, the hardness of the alloy after the matrix is ​​strengthened by the cobalt-based alloy powder currently available on the market is 36-45hrc. According to the test results of this embodiment, it can be seen that the hardness of the alloy after the matrix is ​​strengthened by the estimated alloy powder designed in this application is 49.1-51.5hrc. The solution in this application not only achieves a significant improvement in hardness, but also reduces the distribution range of its hardness. Compared with a large range of hardness distribution, it can effectively improve the overall hardness and wear resistance of the cladding layer. During use, the wear amount at low hardness points will not be greater than that at high hardness points, resulting in unevenness in the cladding strengthening layer.

[0074] according to Figure 3 and Figure 4 It can be seen from the two experimental reports that the solution designed in this application has greatly improved both hardness and wear resistance compared with existing strengthening materials and strengthening methods.

[0075] The present invention strengthens the base, significantly improving the safety of related equipment, enhancing the operational efficiency of related teams, and increasing the performance of the base. For example, when the base is a titanium alloy breech block, it can increase the trajectory accuracy of the artillery. A transition layer is used to bond the wear-resistant layer to the base. Based on the self-fluxing alloy bonding to the base material and the metallurgical bonding of the self-fluxing alloy to the wear-resistant layer, the bonding between the two is enhanced, thereby improving the stability of the wear-resistant layer. Due to the use of the transition layer, the outermost layer can be made of a special cobalt-based alloy powder with high hardness, high wear resistance, and high temperature resistance as the high-temperature resistant layer without cracking. The transition layer also stably bonds the high-temperature resistant layer, preventing the wear-resistant layer from flaking. Compared to ion implantation, plasma spraying, vapor deposition, electroless plating, etc., the method provided in this embodiment produces a thicker high-temperature resistant layer produced by cladding, can operate in harsh working environments, avoids frequent replacement and safety accidents, and improves the operational efficiency of the related teams. For example, when the breech block is used as the base, it can improve the training and operational efficiency of the troops.

[0076] Laser cladding also reduces heat input, making the breechblock less susceptible to deformation than existing strengthening methods. Laser cladding offers high efficiency and high heat resistance, is simple to operate, and is easily replicated, allowing for streamlined mass production, improving strengthening efficiency and reducing time costs. Preheating the strengthening layer on the substrate is not required, effectively reducing energy consumption.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for strengthening a matrix at high temperature, characterized in that: include: Cladding cobalt-based alloy powder A onto the substrate to form a transition layer; cladding cobalt-based alloy powder onto the transition layer to form a high-temperature resistant layer; The cobalt-based alloy powder comprises: Ni 0.9%-1.2%, Si 0.9%-1.2%, Mn 0.9%-1.0%, Cr 30.4%-31.2%, W 3.9%-4.4%, C 0.9%-1.3%, B 1%-1.2%, and the balance is Co; The cobalt-based alloy powder A comprises Stellite 6 and TC4, and the weight ratio of Stellite 6 to TC4 is 3:1 to 6:1; The Stellite 6 comprises Ni 0.98%, Si 0.98%, Fe 2.06%, Mn 0.97%, Cr 28.08%, Mo ≤0.10%, W 4.45%, C 0.91%, S 0.0015%, P ≤0.005%, and the balance is Co; The TC4 powder contains: Fe≤0.30%, C≤0.10%, N≤0.05%, H≤0.015%, O≤0.20%, Al5.5%-6.8%, V3.5%-4.5%, and the balance is Ti.

2. The method for strengthening the matrix at high temperature resistance according to claim 1, characterized in that: The particle size of the cobalt-based alloy powder is 75-150 μm.

3. The method for strengthening the matrix at high temperature resistance according to claim 1, characterized in that: The cobalt-based alloy powder A comprises Stellite 6 and TC4, and the weight ratio of Stellite 6 to TC4 is 3:1 to 6:

1.

4. The method for strengthening the matrix at high temperature resistance according to claim 3, characterized in that: The weight ratio of Stellite 6 to TC4 is 4:

1.

5. The method for strengthening the matrix at high temperature resistance according to claim 3, characterized in that: The Stellite 6 and TC4 are mixed evenly, dried, and then used for cladding the transition layer.

6. The method for strengthening a matrix at high temperature resistance according to any one of claims 1 to 5, characterized in that: The thickness of the transition layer is 0.2-0.4 mm.

7. The method for strengthening a matrix at high temperature resistance according to any one of claims 1 to 5, characterized in that: The thickness of the high temperature resistant layer is 0.3-0.7 mm.

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