W-reinforced copper-based welding wire for cavitation resistance of water turbine, preparation method and surfacing method

Abstract

The invention relates to the technical field of metal materials, and discloses a W-reinforced copper-based welding wire for cavitation resistance of a water turbine, a preparation method and a surfacing method.The welding wire comprises powder and a welding skin used for wrapping the powder, the powder comprises, by mass, 35.0%-40.0% of Sn powder, 10%-15% of Al powder, 6.0%-8.0% of Ni powder, 30.0%-40.0% of W powder and the balance Cu powder, and the sum of the mass percent of the components is 100%. The preparation method comprises the following steps: mixing the powder, ball-milling, wrapping with a T2 red copper belt, and drawing. According to the welding wire, the Rockwell hardness of a surfacing layer is 30-40 HRC and the cavitation resistance of the surfacing layer is more than three times that of a 0Cr13Ni5Mo base material through the synergistic effect of a W additional hard phase and a Cu-Al and Cu-Sn in-situ synthesis hard phase in cooperation with a low-heat-input CMT process.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a W-reinforced copper-based welding wire for water turbine anti-cavitation, a preparation method and a surfacing method. Background Art

[0002] Hydropower units play an irreplaceable role in the peak and frequency regulation of power systems with their fast start and stop, excellent load regulation capabilities and dynamic response characteristics. However, frequent participation in grid frequency regulation has caused hydropower units to be in a state of poor stability for a long time, accelerating the generation of cracks in turbines and threatening the durability and safety of hydropower units. Specifically, they are as follows: First, the challenge of non-steady-state operation: the proportion of low-load and no-load operation time has increased significantly, resulting in the intensification of hydraulic pulsation of flow-through components and a significant increase in the frequency of guide vane mechanism movements. Second, the damage mechanism of key components: the cavitation damage of the runner shows an accelerating trend, and the risk of crack initiation and expansion increases. These flow-through components work underwater for a long time, suffering from cavitation, sediment wear, corrosion and other damage. In addition, the narrow pit and poor maintenance conditions make the research and development and application of repair and protection materials particularly critical. However, existing anti-cavitation materials often have problems such as poor welding performance and easy generation of pores during the repair process, which increases the difficulty and cost of repair.

[0003] 0Cr13Ni5Mo is an ultra-low carbon martensitic stainless steel. With its high strength, high toughness, excellent corrosion resistance and good welding performance, it has become an ideal material for turbine runners. However, due to the easy occurrence of cavitation during the operation of turbine runners, the turbine runner material 0Cr13Ni5Mo is difficult to resist the high-speed cutting of cavitation microjets, and microcracks are easily generated to accelerate local corrosion. In view of the shortcomings of 0Cr13Ni5Mo material in resisting high-speed cavitation microjets and inhibiting the initiation of microcracks, it is urgent to develop special repair and strengthening materials that match its performance to improve its ability to resist cavitation damage and extend its service life.

[0004] Chinese patent CN119733990A discloses a cavitation-resistant martensitic welding wire for a turbine runner and a preparation method thereof. This technology studies the matching cladding welding materials for the frequent cavitation failure of the turbine runner material 0Cr13Ni5Mo, and develops a cavitation-resistant martensitic welding wire. Although the cavitation-resistant martensitic welding wire can improve the wear resistance of the turbine runner material through the martensitic structure, the martensitic structure is easily decomposed or phase-changed at high temperatures, resulting in a decrease in performance, affecting its cavitation resistance, and in complex working conditions such as sand-containing water flow, the wear resistance of the turbine runner material is easily reduced due to changes in the structure, thereby reducing the service life of the hydropower unit. Summary of the invention

[0005] The object of the present invention is to solve the problem that the material of the water turbine runner, 0Cr13Ni5Mo, in the prior art is prone to cavitation, resulting in a decline in wear resistance and service life. The present invention provides a W-reinforced copper-based welding wire for water turbine cavitation resistance, a preparation method and a surfacing method, so as to obtain a cladding layer with excellent cavitation resistance, improve the service life of the hydropower unit, and ensure the safety performance of the hydropower unit under the peak shaving condition.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a W-reinforced copper-based welding wire for water turbine cavitation resistance, including a powder and a welding skin for wrapping the powder. In terms of mass percentage, the raw materials of the powder include: 35.0% - 40.0% of Sn powder, 10% - 15% of Al powder, 6.0% - 8.0% of Ni powder, 30.0% - 40.0% of W powder, and the rest is Cu powder.

[0007] The present invention is further improved in that the powder particle size of the powder is all 100 - 200 mesh.

[0008] The present invention is further improved in that the welding skin is a T2 copper strip with a thickness of 0.4 mm and a width of 10 mm.

[0009] The present invention is further improved in that the filling rate of the powder in the welding skin is controlled at 30% - 35%.

[0010] In the second aspect, the present invention also provides a preparation method of a W-reinforced copper-based welding wire for water turbine cavitation resistance, including the following steps: Step 1, respectively weigh the following raw materials in terms of mass percentage: 35.0% - 40.0% of Sn powder, 10% - 15% of Al powder, 6.0% - 8.0% of Ni powder, 30.0% - 40.0% of W powder, and the rest is Cu powder; Step 2, heat-treat the raw materials weighed in Step 1, then dry and mix them to obtain a powder; Step 3, wrap the powder prepared in Step 2 in the welding skin and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4, after the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, so that the diameter of the finally obtained welding wire is 1.2 mm, and a W-reinforced copper-based welding wire for water turbine cavitation resistance is prepared.

[0011] The present invention is further improved in that in Step 2, the temperature of the heat treatment is 100 - 150 °C, and the heat treatment holding time is 1 - 2 h.

[0012] A further improvement of the present invention lies in that, in step 2, the mixing time is 1 to 2 hours.

[0013] A further improvement of the present invention lies in that, in step 3, the welding skin is a T2 copper strip with a thickness of 0.4 mm and a width of 10 mm.

[0014] A further improvement of the present invention lies in that, in step 3, the filling rate of the powder in the welding skin is controlled at 30% to 35%.

[0015] In a third aspect, the present invention also provides a surfacing method, which uses the CMT process to perform surfacing on the above-mentioned W-reinforced copper-based wire for water turbine cavitation resistance; The process parameters of the surfacing are as follows: The welding current is 150 to 200 A, the welding voltage is 20 to 25 V, the surfacing layer thickness is 2.0 to 2.5 mm, the swing width is 5 to 10 mm, the overlap amount is 2 to 5 mm, the surfacing layer is 1 layer, and the shielding gas is pure argon.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a W-reinforced copper-based wire for water turbine cavitation resistance. The wire uses Cu as the matrix of the surfacing layer and is combined with hard W reinforcement particles, resulting in a surfacing layer with good toughness and high hardness, ensuring its excellent cavitation resistance. In addition to W as the strengthening phase, there are also various nano-sized Cu-Al and Cu-Sn strengthening phases in-situ formed by Cu, Al, and Sn. These strengthening phases are dispersedly distributed in the Cu matrix, further improving the strengthening effect of the surfacing layer and solving the contradiction between the coarsening of hard phases and the embrittlement of the matrix in traditional surfacing. In addition, Ni element is added to the wire. Ni can not only promote the formation of a dense oxide film on the surface of the Cu-based surfacing layer through alloying, but also improve the strength of the Cu matrix and enhance the ability to resist the impact of cavitation microjets. The W-reinforced copper-based wire for water turbine cavitation resistance of the present invention has a simple composition, is convenient to process, has a wide promotion prospect, and is especially suitable for harsh environments such as hydroelectric runners that require both cavitation resistance and impact resistance.

[0017] The present invention also provides a preparation method of a W-reinforced copper-based wire for water turbine cavitation resistance. By heating, drying, and mixing the raw materials to obtain a powder, then wrapping the powder in a welding skin, and then through a multi-pass drawing process with gradually decreasing die apertures to precisely control the wire diameter, finally obtaining a W-reinforced copper-based wire for water turbine cavitation resistance with high weld strength and strong cavitation resistance, meeting the increasingly harsh working conditions requirements of hydropower units.

[0018] The present invention also provides a surfacing method. By using a W-reinforced copper-based wire for water turbine cavitation resistance and selecting the CMT process with low heat input for surfacing, the in-situ synthesis of nanoscale Cu-Sn strengthening phases is ensured. At the same time, during the welding process, the heat input is precisely controlled to promote the reaction of Cu with Sn and Cu with Al to generate hard phases at the nanoscale, significantly improving the hardness and cavitation resistance of the surfacing layer. In addition, by reducing the heat-affected zone, excessive melting of W is reduced, and the generation of brittle phases is avoided, thereby optimizing the strength-toughness balance of the surfacing layer. While ensuring high hardness, good toughness and crack resistance are maintained, which is applicable to the repair and strengthening of cavitation-resistant components with high working condition requirements. Description of the Drawings

[0019] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way. Additionally, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention.

[0020] Figure 1 It is a schematic diagram of the metallographic structure of the surfacing layer after surfacing with a W-reinforced copper-based wire for water turbine cavitation resistance prepared in Example 2 on a 0Cr13Ni5Mo base material. Figure 2 It is a schematic diagram of the cavitation damage on the surface of the surfacing layer after a 6-hour cavitation test on the surfacing layer obtained by surfacing with a W-reinforced copper-based wire for water turbine cavitation resistance prepared in Example 2 on a 0Cr13Ni5Mo base material. Figure 3 It is a schematic diagram of the cavitation damage on the surface of a 0Cr13Ni5Mo base material after a 6-hour cavitation test. Detailed Embodiments

[0021] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0022] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0023] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0024] In this text, unless otherwise specified, the terms "include", "comprise", "contain", "have" or similar terms cover the meanings of "consist of" and "consist essentially of". For example, "A includes a" covers the meanings of "A includes a and others" and "A only includes a".

[0025] In this text, for the sake of concise description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0026] The present invention provides a W-reinforced copper-based welding wire for anti-cavitation of hydraulic turbines, which includes welding powder and a welding skin for wrapping the welding powder. By mass percentage, the raw materials of the welding powder include: 35.0% - 40.0% of Sn powder, 10% - 15% of Al powder, 6.0% - 8.0% of Ni powder, 30.0% - 40.0% of W powder, and the rest is Cu powder.

[0027] The powder particle size of the welding powder is all 100 - 200 mesh.

[0028] The welding skin is a T2 copper strip with a thickness of 0.4 mm and a width of 10 mm.

[0029] The filling rate of the welding powder in the welding skin is controlled at 30% - 35%.

[0030] The functions and roles of the main alloy components in the welding wire of the present invention are as follows: In the welding wire, Cu is used as the substrate of the surfacing layer, and Sn and Al strengthening phases are added. Among them, the Cu-based alloy has a high elastic modulus and good anti-damping performance. When there is a cavitation impact, it can effectively absorb the vibration energy caused by the bubble collapse and reduce the damage to the surface of the surfacing layer. Secondly, the Cu-based alloy has good corrosion resistance. Part of the reason for cavitation damage is the combined action of chemical corrosion. Therefore, using the Cu-based alloy can promote the formation of a surface passivation film. Cu can in-situ generate a variety of nano-sized Cu-Al hard phases and Cu-Sn hard phases with Al and Sn. These hard phases are dispersedly distributed in the Cu matrix, which can improve the hardness of the matrix without damaging the toughness of the matrix.

[0031] Ni element is added to the welding wire: The addition of Ni element can promote the formation of a dense oxide film (NiO) on the surface of the Cu-based surfacing layer through alloying, thereby effectively resisting cavitation damage; Ni is dissolved in Cu, effectively improving the strength of the Cu matrix and further enhancing the ability to resist the impact of cavitation micro-jet. In addition, Ni atoms can hinder the movement of dislocations, reduce the initiation of surface fatigue cracks; Ni can also inhibit the growth of Cu grains and reduce the cavitation-sensitive area at the grain boundaries.

[0032] Adding element W to the welding wire: The melting point of W is 3422 °C, which is much higher than that of Cu (1083 °C). Combined with the CMT cold metal transfer process, most of the W exists as elemental W in the Cu-based weld seam, forming a natural hard phase and improving the cavitation resistance of the surfacing layer. At the same time, a small amount of W will diffuse and react with the Cu matrix or Ni element under the action of the arc to form W-Cu or W-Ni dispersed particles, such as WCu4 and W2Ni3, with a hardness of 1200-1800 HV, effectively resisting the impact of cavitation micro-jet and abrasive wear.

[0033] The present invention also provides a preparation method of a W-reinforced copper-based welding wire for water turbine cavitation resistance, comprising the following steps: Step 1: Weigh the following raw materials by mass percentage: 35.0%-40.0% of Sn powder, 10%-15% of Al powder, 6.0%-8.0% of Ni powder, 30.0%-40.0% of W powder, and the rest is Cu powder; Step 2: Heat-treat the raw materials weighed in Step 1. The heat-treatment temperature is 100-150 °C, and the heat-treatment holding time is 1-2 h. Then, remove the crystal water in the raw materials by drying, and mix the dried raw materials for 1-2 h to obtain the powder; Step 3: Remove the grease on the surface of the welding skin, and wrap the powder prepared in Step 2 in the welding skin through a flux-cored wire drawing device to perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; In Step 3, the welding skin is a T2 copper strip with a thickness of 0.4 mm and a width of 10 mm. The filling rate of the powder in the welding skin is controlled at 30%-35%; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, so that the diameter of the finally obtained welding wire is 1.2 mm, and a W-reinforced copper-based welding wire for water turbine cavitation resistance is prepared.

[0034] The present invention also provides a surfacing method, using the CMT process to perform surfacing on the above-mentioned W-reinforced copper-based welding wire for water turbine cavitation resistance; The process parameters of the surfacing are as follows: The welding current is 150-200 A, the welding voltage is 20-25 V, the surfacing layer thickness is 2.0-2.5 mm, the swing width is 5-10 mm, the overlap amount is 2-5 mm, surfacing is performed in one layer, and the shielding gas is pure argon.

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0036] Conventional instrument and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0037] All the following embodiments of the present invention are carried out by CMT surfacing on the 0Cr13Ni5Mo base material.

[0038] Example 1 This embodiment provides a preparation method of a W-reinforced copper-based welding wire for anti-cavitation of hydraulic turbines, including the following steps: Step 1: Weigh the following raw materials by mass percentage, where Sn powder is 35.0%, Al powder is 10%, Ni powder is 6.0%, W powder is 30.0%, and the rest is Cu powder; Step 2: Place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 100°C, and the heat treatment holding time is 1 h. Then, remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 1 h to obtain the powder; Step 3: Use alcohol to remove the grease on the surface of the T2 copper strip. Wrap the powder prepared in Step 2 in the T2 copper strip through a flux-cored wire drawing device, and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a welding wire with a diameter of 1.2 mm is obtained; Step 5: After the wire drawing of the welding wire is completed, wind it on a wire reel by a wire winding machine, and finally seal it in a vacuum packaging bag of the welding wire for standby.

[0039] Use the W-reinforced copper-based welding wire for anti-cavitation of hydraulic turbines prepared in Example 1 to perform CMT surfacing on the surface of the 0Cr13Ni5Mo substrate. The welding current is 150 A, the welding voltage is 20 V, the surfacing layer thickness is 2.0 mm, the swing width is 5 mm, the overlap amount is 2 mm, and one layer is surfaced. The shielding gas is pure argon.

[0040] After testing: (1) The Rockwell hardness of the surfacing layer is 30 HRC; (2) After 6 hours of cavitation test on the surfacing layer, the weight loss is 0.12 mg. After the same time of cavitation test on the base material 0Cr13Ni5Mo, the weight loss is 0.58 mg. Therefore, the cavitation resistance of the surfacing layer is 4.8 times that of the base material.

[0041] Example 2 This example provides a preparation method of a W-reinforced copper-based welding wire for anti-cavitation of hydraulic turbines, including the following steps: Step 1: Weigh the following raw materials by mass percentage, where Sn powder is 40.0%, Al powder is 15%, Ni powder is 8.0%, W powder is 40.0%, and the rest is Cu powder; Step 2: Place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 150 °C, and the heat treatment holding time is 2 h. Then, remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 2 h to obtain the powder; Step 3: Use alcohol to remove the grease on the surface of the T2 copper strip. Wrap the powder prepared in Step 2 in the T2 copper strip through a flux-cored wire drawing device, and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a welding wire with a diameter of 1.2 mm is obtained; Step 5: After the wire drawing of the welding wire is completed, wind it on a wire spool by a wire winding machine, and finally seal it in a vacuum packaging bag of the welding wire for standby.

[0042] Use the W-reinforced copper-based welding wire for anti-cavitation of hydraulic turbines prepared in Example 2 to perform CMT surfacing on the surface of the 0Cr13Ni5Mo substrate. The welding current is 200 A, the welding voltage is 25 V, the surfacing layer thickness is 2.5 mm, the swing width is 10 mm, the overlap amount is 5 mm, and one layer of surfacing is performed. The shielding gas is pure argon.

[0043] After testing: (1) The Rockwell hardness of the surfacing layer is 40 HRC; (2) After 6 hours of cavitation test on the surfacing layer, the weight loss is 0.10 mg. After the same time of cavitation test on the base material 0Cr13Ni5Mo, the weight loss is 0.58 mg. Therefore, the cavitation resistance of the surfacing layer is 5.8 times that of the base material.

[0044] Figure 1The schematic diagram of the metallographic structure of the surfacing layer after surfacing with a W-reinforced copper-based welding wire for water turbine cavitation resistance prepared in Example 2 on a 0Cr13Ni5Mo base metal. It can be seen from the figure that the surfacing layer is mainly composed of α-Cu, and there are W particles and in-situ reaction hard phases of Cu-Sn and Cu-Al in the surfacing layer.

[0045] Figure 2 The surface cavitation damage diagram of the surfacing layer after 6 hours of cavitation test after surfacing with a W-reinforced copper-based welding wire for water turbine cavitation resistance prepared in Example 2 on a 0Cr13Ni5Mo base metal; Figure 3 The schematic diagram of the surface cavitation damage of the 0Cr13Ni5Mo base metal after 6 hours of cavitation test. From Figure 2 and Figure 3 it can be seen that the cavitation pits on the surface of the surfacing layer formed by the welding wire of the present invention are significantly fewer than those on the surface of the 0Cr13Ni5Mo base metal.

[0046] Example 3 This example provides a preparation method of a W-reinforced copper-based welding wire for water turbine cavitation resistance, including the following steps: Step 1, weigh the following raw materials by mass percentage, wherein 37.0% is Sn powder, 13% is Al powder, 7.0% is Ni powder, 35.0% is W powder, and the rest is Cu powder; Step 2, place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 130 °C, and the heat treatment holding time is 1.5 h. Then, remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 1.5 h to obtain powder; Step 3, use alcohol to remove the grease on the surface of the T2 copper strip, and wrap the powder prepared in Step 2 in the T2 copper strip through a flux-cored wire drawing device for the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4, after the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a welding wire with a diameter of 1.2 mm is obtained; Step 5, after the welding wire drawing is completed, wind it on a welding wire reel by a wire winding machine, and finally seal it in a welding wire vacuum packaging bag for standby.

[0047] CMT surfacing is carried out on the surface of a 0Cr13Ni5Mo substrate with the W-reinforced copper-based welding wire for water turbine cavitation resistance prepared in Example 3. The welding current is 180 A, the welding voltage is 23 V, the surfacing layer thickness is 2.3 mm, the swing width is 8 mm, the overlap amount is 4 mm, and 1 layer of surfacing is carried out. The shielding gas is pure argon.

[0048] After testing: (1)The Rockwell hardness of the surfacing layer is between 30 and 40 HRC; (2)After a 6-hour cavitation test, the weight loss of the surfacing layer is 0.13 mg. For the base material 0Cr13Ni5Mo after the same cavitation test for the same time, the weight loss is 0.58 mg. Therefore, the cavitation resistance of the surfacing layer is 4.4 times that of the base material.

[0049] Example 4 This example provides a method for preparing a W-reinforced copper-based wire for water turbine cavitation resistance, including the following steps: Step 1: Weigh the following raw materials by mass percentage. Among them, Sn powder is 36.0%, Al powder is 12%, Ni powder is 6.5%, W powder is 36.0%, and the rest is Cu powder; Step 2: Place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 120 °C, and the heat treatment holding time is 1.2 h. Then, remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 1.2 h to obtain powder; Step 3: Use alcohol to remove the grease on the surface of the T2 copper strip. Wrap the powder prepared in Step 2 in the T2 copper strip through a flux-cored wire drawing device, and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a wire with a diameter of 1.2 mm is obtained; Step 5: After the wire drawing is completed, wind the wire around a wire reel by a wire winding machine, and finally seal it in a wire vacuum packaging bag for use.

[0050] The W-reinforced copper-based wire for water turbine cavitation resistance prepared in Example 4 is used for CMT surfacing on the surface of the 0Cr13Ni5Mo substrate. The welding current is 160 A, the welding voltage is 22 V, the surfacing layer thickness is 2.2 mm, the swing width is 6 mm, the overlap amount is 2.5 mm, and one layer is surfaced. The shielding gas is pure argon.

[0051] After testing: (1)The Rockwell hardness of the surfacing layer is 35 HRC; (2)After a 6-hour cavitation test, the weight loss of the surfacing layer is 0.15 mg. For the base material 0Cr13Ni5Mo after the same cavitation test for the same time, the weight loss is 0.58 mg. Therefore, the cavitation resistance of the surfacing layer is 3.8 times that of the base material.

[0052] Example 5 This example provides a method for preparing a W-reinforced copper-based wire for water turbine cavitation resistance, including the following steps: Step 1: Weigh the following raw materials by mass percentage, where the Sn powder is 39.0%, the Al powder is 14%, the Ni powder is 7.5%, the W powder is 39%, and the rest is Cu powder; Step 2: Place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 290 °C, and the heat treatment holding time is 1.8 h. Then, remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 1.8 h to obtain the powder; Step 3: Use alcohol to remove the grease on the surface of the T2 copper strip. Wrap the powder prepared in Step 2 in the T2 copper strip through a flux-cored wire drawing equipment, and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a wire with a diameter of 1.2 mm is obtained; Step 5: After the wire drawing is completed, wind the wire on a wire spool through a wire winding machine, and finally seal it in a vacuum packaging bag for the wire for standby.

[0053] The W-reinforced copper-based wire for water turbine cavitation resistance prepared in Example 5 is used for CMT surfacing on the surface of the 0Cr13Ni5Mo substrate. The welding current is 190 A, the welding voltage is 24 V, the surfacing layer thickness is 2.4 mm, the swing width is 9 mm, the overlap amount is 4.5 mm, and one layer is surfaced. The shielding gas is pure argon.

[0054] After testing: (1) The Rockwell hardness of the surfacing layer is 36 HRC; (2) After a 6-hour cavitation test on the surfacing layer, its weight loss is 0.114 mg. After the same time cavitation test on the base material 0Cr13Ni5Mo, its weight loss is 0.58 mg. Therefore, the cavitation resistance of the surfacing layer is 5.1 times that of the base material.

[0055] Example 6 This example provides a preparation method of a W-reinforced copper-based wire for water turbine cavitation resistance, including the following steps: Step 1: Weigh the following raw materials by mass percentage, where the Sn powder is 35.5%, the Al powder is 11%, the Ni powder is 6.2%, the W powder is 31.5%, and the rest is Cu powder; Step 2: Place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 115 °C, and the heat treatment holding time is 1.85 h. Then, remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 1.85 h to obtain the powder; Step 3: Use alcohol to remove the grease on the surface of the T2 copper strip. Wrap the powder prepared in Step 2 with the flux-cored wire drawing equipment inside the T2 copper strip, and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a wire with a diameter of 1.2 mm is obtained; Step 5: After the wire drawing is completed, wind it on a wire spool by a wire winding machine, and finally seal it in a wire vacuum packaging bag for standby.

[0056] Use the W-reinforced copper-based wire for anti-cavitation of hydraulic turbines prepared in Example 6 to perform CMT surfacing on the surface of the 0Cr13Ni5Mo matrix. The welding current is 155 A, the welding voltage is 20.5 V, the surfacing layer thickness is 2.45 mm, the oscillation width is 5.5 mm, the overlap amount is 2.1 mm, and one layer is surfaced. The shielding gas is pure argon.

[0057] After testing: (1) The Rockwell hardness of the surfacing layer is 35.5 HRC; (2) After a 6-hour cavitation test on the surfacing layer, its weight loss is 0.135 mg. After the same cavitation test on the base material 0Cr13Ni5Mo, its weight loss is 0.58 mg. Therefore, the anti-cavitation ability of the surfacing layer is 4.3 times that of the base material.

[0058] Example 7 This example provides a preparation method of a W-reinforced copper-based wire for anti-cavitation of hydraulic turbines, including the following steps: Step 1: Weigh the following raw materials by mass percentage. Among them, Sn powder is 38.6%, Al powder is 13.4%, Ni powder is 7.9%, W powder is 38.40%, and the rest is Cu powder; Step 2: Place the raw materials weighed in Step 1 in a vacuum heating furnace for heat treatment. The heat treatment temperature is 150 °C, and the heat treatment holding time is 2 h. Then remove the crystal water in the raw materials by drying, and place the dried raw materials in a powder mixer for sufficient mixing. The mixing time is 2 h to obtain the powder; Step 3: Use alcohol to remove the grease on the surface of the T2 copper strip. Wrap the powder prepared in Step 2 with the flux-cored wire drawing equipment inside the T2 copper strip, and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4: After the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, and finally a wire with a diameter of 1.2 mm is obtained; Step 5: After the wire drawing of the welding wire is completed, it is wound around a welding wire reel by a wire winding machine and finally sealed in a vacuum packaging bag of the welding wire for standby.

[0059] The W-reinforced copper-based welding wire for hydraulic turbine cavitation resistance prepared in Example 7 is used for CMT surfacing on the surface of a 0Cr13Ni5Mo substrate. The welding current is 188 A, the welding voltage is 24.3 V, the surfacing layer thickness is 2.37 mm, the oscillation width is 6.3 mm, the overlap amount is 4.7 mm, and one layer is surfaced. The shielding gas is pure argon.

[0060] After testing: (1) The Rockwell hardness of the surfacing layer is 33.3 HRC; (2) After a 6-hour cavitation test of the surfacing layer, the weight loss is 0.103 mg. After the same time cavitation test of the base material 0Cr13Ni5Mo, the weight loss is 0.58 mg. Therefore, the cavitation resistance of the surfacing layer is 5.6 times that of the base material.

[0061] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A W-reinforced copper-based welding wire for cavitation resistance of water turbines, characterized in that, It includes powder and a welding skin for wrapping the powder. By mass percentage, the raw materials of the powder include: 35.0% - 40.0% of Sn powder, 10% - 15% of Al powder, 6.0% - 8.0% of Ni powder, 30.0% - 40.0% of W powder, and the balance is Cu powder.

2. The W-reinforced copper-based welding wire for cavitation resistance of a water turbine according to claim 1, characterized in that, The powder size of the powder is 100 - 200 mesh.

3. A W-reinforced copper-based welding wire for cavitation resistance of a water turbine, characterized in that, The welding skin is a T2 copper strip with a thickness of 0.4 mm and a width of 10 mm.

4. A W-reinforced copper-based welding wire for anti-cavitation of a water turbine according to claim 1, characterized in that, The filling rate of the powder in the welding skin is controlled at 30% - 35%.

5. A preparation method of a W-reinforced copper-based welding wire for cavitation resistance of a water turbine as described in claim 1, characterized in that, It includes the following steps: Step 1, respectively weigh the following raw materials by mass percentage: 35.0% - 40.0% of Sn powder, 10% - 15% of Al powder, 6.0% - 8.0% of Ni powder, 30.0% - 40.0% of W powder, and the balance is Cu powder; Step 2, heat-treat the raw materials weighed in Step 1, then dry and mix them to obtain the powder; Step 3, wrap the powder prepared in Step 2 in the welding skin and perform the first drawing process. The aperture of the drawing die used in the first drawing process is 2.6 mm; Step 4, after the first drawing process is completed, set several drawing processes in sequence. The aperture of the drawing die corresponding to each drawing process decreases in sequence, so that the diameter of the finally obtained welding wire is 1.2 mm, and a W-reinforced copper-based welding wire for water turbine anti-cavitation is prepared.

6. The preparation method of a W-reinforced copper-based welding wire for cavitation resistance of a water turbine according to claim 5, characterized in that, In Step 2, the temperature of the heat treatment is 100 - 150 °C, and the heat preservation time of the heat treatment is 1 - 2 h.

7. The preparation method of a W-reinforced copper-based welding wire for anti-cavitation of a water turbine according to claim 5, characterized in that In Step 2, the mixing time is 1 - 2 h.

8. The preparation method of a W-reinforced copper-based welding wire for cavitation resistance of a water turbine according to claim 5, characterized in that, In Step 3, the welding skin is a T2 copper strip with a thickness of 0.4 mm and a width of 10 mm.

9. The preparation method of a W-reinforced copper-based welding wire for cavitation resistance of a water turbine according to claim 5, characterized in that, In Step 3, the filling rate of the powder in the welding skin is controlled at 30% - 35%.

10. A surfacing method, characterized in that, Use the CMT process to build up weld on the W-reinforced copper-based welding wire for water turbine anti-cavitation as described in any one of Claims 1 to 4; The process parameters of the build-up welding are as follows: The welding current is 150 - 200 A, the welding voltage is 20 - 25 V, the thickness of the build-up welding layer is 2.0 - 2.5 mm, the swing width is 5 - 10 mm, the overlap amount is 2 - 5 mm, the build-up welding layer is 1 layer, and the shielding gas is pure argon.

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