Corrosion-resistant overlay welding layer for inner wall of nuclear power pressure vessel and preparation method

Abstract

A corrosion-resistant overlay welding layer for an inner wall of a nuclear power pressure vessel and a preparation method. In the corrosion-resistant overlay welding layer for an inner wall of a nuclear power pressure vessel, components of the overlay welding layer are calculated to be at the following proportions by percentage by mass: 0.01-0.02% of C, 2.69-3.61% of Mn, 2.04-3.59% of Si, 20.22-23.18% of Cr, and 5.20-5.80% of Ni, the balance being Fe. According to a preparation method for and use of a senary alloy, a gradient material of the overlay welding layer is synthesized by using laser direct energy deposition or plasma spraying, effectively mitigating the differences in thermal expansion coefficients, melting points, and elastic moduli between interfaces. Moreover, the level of residual stress between interfaces can be reduced during preparation of the material, preventing a low-melting point phase and a brittle phase from precipitation. Thus, manufacturing requirements can be met, and a high-strength bonding interface can be manufactured.

Description

A corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel and a preparation method thereof Technical Field

[0001] The invention relates to a surfacing layer and a preparation method thereof, and in particular to a corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel and a preparation method thereof. Background Art

[0002] Against the backdrop of today's increasingly severe energy situation, nuclear power energy has highlighted its importance. First, nuclear power energy is a low-carbon clean energy that does not produce atmospheric pollutants and greenhouse gases, and helps to address climate change issues. Secondly, nuclear power energy has high energy density, can stably supply large-scale electricity, reduce dependence on fossil fuels, and ensure energy security. In addition, nuclear power has advantages in terms of basic power load, can stabilize the operation of the power grid, and reduce the impact of energy fluctuations on the social economy. Nuclear power safety issues have always been the focus of public attention, and strict safety measures and regulatory mechanisms must be adopted. Nuclear power regulators, reactor pressure vessels, etc., as important components of nuclear power plants, play a key role in maintaining the pressure of the reactor's primary coolant system in nuclear reactors. Therefore, the design, manufacture and maintenance of main equipment such as reactor pressure vessels and regulators must meet extremely high safety standards and strict technical requirements. Elements such as Co, Mo, Nb are activating elements, such as cobalt. 59 Co is excited by the environment and forms radioactive isotopes 60 Co. Nuclear power materials containing elements like cobalt generate alloy debris during service and operation due to wear and corrosion. These alloy debris, due to the activation of elements like Co, Mo, and Nb in the irradiated environment, become radiation "hotspots." These problems must be addressed to prevent environmental pollution. Furthermore, the high barrier to entry and cost of nuclear power technology are also limiting factors.

[0003] In summary, nuclear power plays a crucial role in meeting energy demand, reducing carbon emissions, and ensuring energy security. Going forward, we must continue to strengthen nuclear power technology research and development, improve safety, and address nuclear pollution issues to achieve the sustainable development of nuclear energy within a clean energy system.

[0004] The shell of a large nuclear power plant pressure vessel consists of a composite structure consisting of a base material and an inner weld overlay, ensuring excellent structural strength and corrosion resistance. The base material is typically high-strength alloy steel, while the weld overlay is typically a corrosion-resistant alloy. However, due to the significant difference in physical properties between the two materials, high levels of weld stress are generated during weld overlay. When designing and researching weld overlay materials for nuclear power pressure vessels, considerations must be not only to extend service life while reducing costs, but also to improve the safety of nuclear power operations. Therefore, there is an urgent need to find a new alloy system and process to address the shortcomings of traditional processes.

[0005] Summary of the Invention

[0006] In view of the defects of the prior art, the present invention provides a corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel and a preparation method thereof.

[0007] The present invention is achieved as follows: a corrosion-resistant cladding layer for the inner wall of a nuclear power pressure vessel, wherein the components of the cladding layer are calculated as follows according to mass percentage:

[0008] As described above, a corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel, wherein the surfacing layer includes n layers, and when the total thickness of the surfacing layer is fixed, the thickness of each layer is one nth of the total thickness, n=1 or 2 or 3 or 4 or 5.

[0009] As described above, a corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel, wherein the total thickness of the surfacing layer is H=3 mm.

[0010] The corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel as described above, wherein the particle size of the surfacing layer alloy powder is 100-350 meshes, and the surfacing layer is in block or film form.

[0011] As described above, a corrosion-resistant cladding layer for the inner wall of a nuclear power pressure vessel, wherein when n=1, the components of the cladding layer are calculated in the following proportions according to mass percentage: carbon 0.015%, manganese 3.15%, silicon 2.07%, chromium 21.70%, nickel 5.50%, and the rest is iron.

[0012] As described above, a corrosion-resistant cladding layer for the inner wall of a nuclear power pressure vessel, wherein when n=2, the components of the cladding layer are calculated in the following proportions according to mass percentage: the first layer comprises 0.015% carbon, 3.15% manganese, 2.07% silicon, 21.70% chromium, 5.50% nickel, and the remainder is iron; the second layer comprises 0.02% carbon, 3.55% manganese, 3.47% silicon, 21.60% chromium, 5.50% nickel, and the remainder is iron.

[0013] A method for preparing a corrosion-resistant cladding layer on the inner wall of a nuclear power pressure vessel, comprising the following steps:

[0014] Step 1: Ingredients

[0015] Prepare sufficient quantities of ingredients according to the number of layers and proportion requirements;

[0016] Step 2: Melting

[0017] Add the prepared metal iron, metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace, heat it with electricity to melt it, adjust the composition before the furnace and take it out of the furnace after it meets the requirements. The furnace temperature is controlled at 1450℃~1500℃;

[0018] Step 3: Vacuum air atomization

[0019] The alloy solution is atomized in a vacuum gas atomization device in step 2 to obtain alloy powder, wherein the atomization medium is argon, the atomization pressure is 2-10 MPa, and the furnace temperature is maintained at 1450° C. to 1500° C. during atomization;

[0020] Step 4: Drying

[0021] Drying the alloy powder obtained by atomization in step 3;

[0022] Step 5: Screening

[0023] The alloy powder obtained by drying in step 4 is screened by a screening machine. The particle size of the powder is 100 mesh to 350 mesh. The solid solution powder within the above particle size range is screened out as the finished powder for later use.

[0024] The alloy powder in step five is sent to laser direct energy deposition or plasma spraying to obtain a block-shaped or thin-film-shaped alloy as a surfacing layer.

[0025] A method for preparing a corrosion-resistant cladding layer on the inner wall of a nuclear power pressure vessel as described above, wherein:

[0026] During the smelting process of step 2, the pre-mixed metal manganese, metal chromium and metal nickel ingredients are first added to the medium frequency induction furnace for smelting, and then the remaining ingredients are added as supplementary materials to the molten alloy solution. When adding the supplementary materials, the temperature in the medium frequency induction furnace is controlled at 1500°C to 1550°C.

[0027] A method for preparing a corrosion-resistant cladding layer on the inner wall of a nuclear power pressure vessel as described above, wherein:

[0028] In the step 4, a far-infrared drying machine is used, and the drying temperature is 200° C. to 250° C. After drying for 1 hour, the temperature is naturally lowered to room temperature.

[0029] The present invention has the following significant advantages: a preparation method and application of a hexavalent alloy using laser direct energy deposition or plasma spraying to synthesize a gradient material for the weld overlay layer effectively mitigates differences in thermal expansion coefficient, melting point, elastic modulus, and other characteristics between interfaces. This method also reduces residual stress levels between interfaces during material preparation, preventing the precipitation of low-melting-point phases and hard-brittle phases, thereby meeting manufacturing requirements and producing a high-strength bond interface. This component material exhibits high interface strength and hardness, and is widely applicable in the bonding of nuclear power components. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is an electron microscope image of the hexavalent alloy powder;

[0031] Figure 2 is a scanning electron microscope photograph of the connection between 16MnD5 steel and the cladding layer;

[0032] Figure 3 shows the thermophysical properties of the six-element alloy at different temperatures;

[0033] FIG4 is a diagram showing the friction and wear test results of the product of Example 3;

[0034] FIG5 is a diagram showing the friction and wear test results of the product of Example 4. DETAILED DESCRIPTION

[0035] A corrosion-resistant cladding layer for the inner wall of a nuclear power pressure vessel, wherein the various components of the cladding layer are calculated as follows according to mass percentage:

[0036] Effect of Cr element: Improves corrosion resistance and strength;

[0037] Effect of Mn element: Improve the strength of the cladding layer;

[0038] Effect of Si element: Improve the processability and strength of the cladding layer material;

[0039] Effect of Ni element: Improve corrosion resistance;

[0040] The weld overlay layer can be in powder form, which can be used as a deposition interface bonding material. The hexameric alloy of this composition is used to form a gradient material during the additive deposition process, which can effectively alleviate the differences in the thermal expansion coefficient, melting point, elastic modulus, etc. of the interface, and can reduce the residual stress level at the interface during the additive deposition process to meet nuclear-grade manufacturing requirements.

[0041] The cladding layer is within this range and needs to be selected based on the number of cladding layers required in actual conditions. The total thickness of the cladding layer is H = 3 mm. When cladding is performed in layers, the thickness of a single layer is S mm. The number of layers is n, H = n*S, where n is less than or equal to 5.

[0042] The surfacing layer is in powder form, and the particle size of the surfacing layer alloy powder is 100 meshes to 350 meshes.

[0043] The cladding layer is in block or film form.

[0044] The surfacing layers are all obtained by laser direct energy deposition or plasma spraying.

[0045] A method for preparing the above-mentioned nuclear power pressure vessel overlay layer comprises the following steps:

[0046] Step 1: Ingredients

[0047] Arrange metallic iron, metallic manganese, metallic chromium, metallic nickel and silicon according to target composition;

[0048] The target component configuration is configured according to the following ratio:

[0049] Step 2: Melting

[0050] Add the prepared metal iron, metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace, heat it with electricity to melt it, adjust the composition before the furnace and take it out of the furnace after it meets the requirements. The furnace temperature is controlled at 1450℃~1500℃;

[0051] The pre-furnace composition adjustment in this step refers to the adjustment of the alloy composition in the vacuum air atomization furnace during the preparation and smelting process. The adjustment is based on the composition range. During the smelting process, the proportion of materials added is determined, but there is burn-off, so additional materials need to be added based on the test results. The composition test mentioned here refers to the detection of the alloy composition in the vacuum air atomization furnace using the detection method in the prior art.

[0052] Step 3: Vacuum air atomization

[0053] The alloy solution is atomized in a vacuum gas atomization device in step 2 to obtain alloy powder, wherein the atomization medium is argon, the atomization pressure is 2-10 MPa, and the furnace temperature is maintained at 1450° C. to 1500° C. during atomization;

[0054] Step 4: Drying

[0055] Drying the alloy powder obtained by atomization in step 3;

[0056] In this step, a far-infrared dryer is used at a drying temperature of 200°C to 250°C. After drying for 1 hour, the temperature is naturally lowered to room temperature.

[0057] Step 5: Screening

[0058] The alloy powder obtained by drying in step 4 is screened by a screening machine. The particle size of the powder is 100 mesh to 350 mesh. The solid solution powder within the above particle size range is screened out and used as the finished product powder.

[0059] The alloy powder in step five is sent to laser direct energy deposition or plasma spraying to obtain a block-shaped or thin-film-shaped alloy as a surfacing layer.

[0060] During the smelting process of step 2, the pre-mixed metal manganese, metal chromium and metal nickel ingredients are first added to the medium frequency induction furnace for smelting, and then the remaining ingredients are added as supplementary materials to the molten alloy solution. When adding supplementary materials, the temperature in the medium frequency induction furnace is controlled at 1500℃~1550℃.

[0061] The third object of the present invention is to provide an application of the alloy.

[0062] To achieve the above object, the technical solution adopted by the present invention is: application of the above alloy in nuclear power pressure vessel equipment, wherein the alloy forms a surfacing layer on the inner wall.

[0063] Due to the application of the above-mentioned technical solution, the present invention has the following advantages over the prior art: The present invention provides a method for preparing and applying a hexavalent alloy, employing laser direct energy deposition or plasma spraying to synthesize a gradient material for the weld overlay layer. This effectively mitigates differences in thermal expansion coefficient, melting point, elastic modulus, and other characteristics between interfaces. It also reduces residual stress levels between interfaces during material preparation, preventing the precipitation of low-melting-point phases and hard-brittle phases, thereby meeting manufacturing requirements and producing a high-strength bond interface. This component material exhibits high interface strength and hardness, making it widely applicable in the bonding of nuclear power components.

[0064] The thermophysical performance parameters of the hexavalent alloy at different temperatures are shown in FIG3 .

[0065] Several specific examples are given below.

[0066] Example 1

[0067] This embodiment is a single-layer cladding layer, and the ingredients are prepared according to the following ratio, which is calculated in percentage by weight: 0.015% carbon, 3.15% manganese, 2.07% silicon, 21.70% chromium, 5.50% nickel, and the rest is iron.

[0068] Add the prepared metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace and heat them to melt. The temperature in the medium frequency induction furnace is controlled at about 1520℃. After the composition is adjusted before the furnace and qualified, take it out of the furnace. The temperature is 1460℃.

[0069] The alloy melt is atomized to prepare alloy powder. The atomization medium is argon gas and the atomization pressure is 4MPa. The atomized alloy powder is dried in a far infrared dryer at a drying temperature of 210℃. Then the powder is sieved by a powder sieving machine to obtain a particle size range of 100 ～ The 350-mesh powder is used as the finished powder. This finished powder is directly used as a powdered hexavalent alloy as an interface bonding material for laser additive manufacturing.

[0070] Using 16MnD5 steel as a substrate, the hexametallic alloy was clad on it using a laser cladding method with a power of 1400W, resulting in a connection material with a surfacing layer made using laser additive manufacturing. Specifically, the Fe-C-Si-Cr-Ni-Mn hexametallic alloy was used as the surfacing layer to obtain a gradient material.

[0071] The gradient materials obtained from the above different usage conditions were subjected to Vickers hardness tests. The test duration was 10s and the test force was 200g. The test results are as follows:

[0072] Vickers hardness test results

[0073] The above Vickers hardness test results show that the hardness of the gradient materials obtained under different usage conditions is relatively large, indicating that the gradient material obtained by the surfacing layer composed of the hexavalent alloy can obtain a higher hardness close to that of 16MnD5 steel, making the application of the combined materials more extensive.

[0074] Example 2

[0075] This embodiment comprises two overlay layers, each prepared according to the following ratios: in weight percentage, the first layer comprises 0.015% carbon, 3.15% manganese, 2.07% silicon, 21.70% chromium, 5.50% nickel, and the remainder iron. The second layer comprises 0.02% carbon, 3.55% manganese, 3.47% silicon, 21.60% chromium, 5.50% nickel, and the remainder iron.

[0076] Add the prepared metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace and heat them to melt. The temperature in the medium frequency induction furnace is controlled at about 1520℃. After the composition is adjusted before the furnace and qualified, take it out of the furnace. The temperature is 1460℃.

[0077] The alloy melt is atomized to prepare alloy powder. The atomization medium is argon gas and the atomization pressure is 4MPa. The atomized alloy powder is dried in a far infrared dryer at a drying temperature of 210℃. Then the powder is sieved by a powder sieving machine to obtain a particle size range of 100 ～ The 350-mesh powder is used as the finished powder. This finished powder is directly used as a powdered hexavalent alloy as an interface bonding material for laser additive manufacturing.

[0078] The hexa-element alloy was clad onto a 16MnD5 steel substrate using a laser cladding method at 1400W. Component 1 was clad first, followed by component 2. This laser additive manufacturing method yielded a weld-surfaced connection material. Specifically, the Fe-C-Si-Cr-Ni-Mn hexa-element alloy served as the weld-surface layer, resulting in a gradient material.

[0079] The gradient materials obtained from the above different usage conditions were subjected to Vickers hardness tests. The test duration was 10s and the test force was 200g. The test results are as follows:

[0080] Vickers hardness test results

[0081] The above Vickers hardness test results show that the hardness of the gradient materials obtained under different usage conditions is relatively large, indicating that the gradient material obtained by the surfacing layer composed of the hexavalent alloy can obtain a higher hardness close to 16MnD5, making the application of the combined materials more extensive.

[0082] Example 3

[0083] This embodiment is a single-layer cladding layer, and the ingredients are prepared according to the following ratio, which is calculated in percentage by weight: 0.015% carbon, 3.15% manganese, 2.07% silicon, 21.70% chromium, 5.50% nickel, and the rest is iron.

[0084] Add the prepared metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace and heat them to melt. The temperature in the medium frequency induction furnace is controlled at about 1520℃. After the composition is adjusted before the furnace and qualified, take it out of the furnace. The temperature is 1460℃.

[0085] The substrate is 16MnD5 steel. Before plasma spraying, the surface of the substrate is cleaned of oil and other impurities. The plasma spraying parameters are a current of 450A and a voltage of 60V. During the spraying process, the distance between the nozzle and the sample is 110mm, and the powder feeding rate is 25g / min. Before plasma spraying, the equipment needs to be heated and the wire and material powder used inside are transported to a high-temperature area by the heating source, where they are heated, melted, or softened. Subsequently, under the action of an external compressed air flow or the jet of the heat source itself, the softened alloy is atomized into fine molten droplets and moved forward. The fine molten droplets are then accelerated to form a particle stream, and the flying speed in the medium gradually decreases, and then adheres to the surface of the substrate.

[0086] The connection material for the surfacing layer is obtained by plasma spraying, that is, a gradient material is obtained by using Fe-C-Si-Cr-Ni-Mn hexa-alloy as the surfacing layer.

[0087] The surfacing layer under the above process was subjected to friction and wear tests, and the test results are shown in FIG4 . The upper curve represents the friction coefficient measured by the friction and wear test, and the lower curve represents the friction force measured by the friction and wear test.

[0088] Example 4

[0089] This embodiment is a two-layer gradient composition cladding layer, and the ingredients are prepared according to the following ratios. In terms of weight percentage, the first layer composition is carbon 0.015%, manganese 3.15%, silicon 2.07%, chromium 21.70%, nickel 5.50%, and the balance is iron. The second layer composition is carbon 0.02%, manganese 3.55%, silicon 3.47%, chromium 21.60%, nickel 5.50%, and the balance is iron.

[0090] Add the prepared metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace and heat them to melt. The temperature in the medium frequency induction furnace is controlled at about 1520℃. After the composition is adjusted before the furnace and qualified, take it out of the furnace. The temperature is 1460℃.

[0091] The substrate is 16MnD5 steel. Before plasma spraying, the surface of the substrate is cleaned of oil and other impurities. The plasma spraying parameters are a current of 450A and a voltage of 60V. During the spraying process, the distance between the nozzle and the sample is 110mm, and the powder feeding rate is 25g / min. Before plasma spraying, the equipment needs to be heated and the wire and material powder used inside are transported to a high-temperature area for heating, melting or softening. Then, under the action of an external compressed air flow or the jet of the heat source itself, the softened alloy is atomized into fine molten droplets and moves forward. The fine molten droplets are then accelerated to form a particle flow, and the flying speed in the medium gradually decreases, and then adheres to the surface of the substrate. The two components are sprayed one layer each.

[0092] The connection material for the surfacing layer is obtained by plasma spraying, that is, a gradient material is obtained by using Fe-C-Si-Cr-Ni-Mn hexa-alloy as the surfacing layer.

[0093] The surfacing layer under the above process was subjected to friction and wear tests, and the test results are shown in FIG5 . The upper curve represents the friction coefficient measured by the friction and wear test, and the lower curve represents the friction force measured by the friction and wear test.

[0094] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel, characterized in that: The components of the cladding layer are calculated as follows according to mass percentage: C 0.01-0.02% Mn 2.69-3.61% Si 2.04-3.59% Cr 20.22-23.18% Ni 5.20-5.80% Fe balance.

2. The corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel according to claim 1, characterized in that: The cladding layer includes n layers. When the total thickness of the cladding layer is fixed, the thickness of each layer is one nth of the total thickness, and n is less than or equal to 5.

3. A corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel according to claim 2, characterized in that: The total thickness of the cladding layer is H = 3 mm.

4. A corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel according to claim 3, characterized in that: The particle size of the alloy powder of the surfacing layer is 100 meshes to 350 meshes, and the surfacing layer is in the form of a block or a film.

5. A corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel according to claim 4, characterized in that: When n=1, the components of the cladding layer are calculated as follows according to mass percentage: carbon 0.015%, manganese 3.15%, silicon 2.07%, chromium 21.70%, nickel 5.50%, and the rest is iron.

6. A corrosion-resistant surfacing layer for the inner wall of a nuclear power pressure vessel as claimed in claim 5, characterized in that: When n=2, the components of the cladding layer are calculated in the following proportions according to mass percentage: the first layer consists of 0.015% carbon, 3.15% manganese, 2.07% silicon, 21.70% chromium, 5.50% nickel, and the rest is iron; the second layer consists of 0.02% carbon, 3.55% manganese, 3.47% silicon, 21.60% chromium, 5.50% nickel, and the rest is iron.

7. A method for preparing a corrosion-resistant surfacing layer on the inner wall of a nuclear power pressure vessel, characterized in that, The steps include: Step 1: Ingredients Prepare sufficient quantities of ingredients according to the number of layers and proportion requirements; Step 2: Melting Add the prepared metal iron, metal manganese, metal chromium, metal nickel and silicon into the medium frequency induction furnace, heat it with electricity to melt it, adjust the composition in front of the furnace and take it out of the furnace after it is qualified, and the temperature out of the furnace is controlled at 1450℃~1500℃; Step 3: Vacuum air atomization The alloy solution is atomized in a vacuum gas atomization device in step 2 to obtain alloy powder, wherein the atomization medium is argon gas, the atomization pressure is 2-10 MPa, and the furnace temperature is maintained at 1450° C. to 1500° C. during atomization; Step 4: Drying Drying the alloy powder obtained by atomization in step 3; Step 5: Screening The alloy powder obtained by drying in step 4 is screened by a screening machine, and the particle size of the powder is 100 mesh to 350 mesh. The solid solution powder within the above particle size range is screened out as the finished product powder for standby use. The alloy powder in step five is sent to laser direct energy deposition or plasma spraying to obtain a block-shaped or film-shaped alloy as a surfacing layer.

8. A method for preparing a corrosion-resistant cladding layer on the inner wall of a nuclear power pressure vessel according to claim 7, characterized in that: During the smelting process of step 2, the pre-prepared metal manganese, metal chromium and metal nickel ingredients are first added to the medium frequency induction furnace for smelting, and then the remaining ingredients are added to the molten alloy solution as supplementary materials. When adding the supplementary materials, the temperature in the medium frequency induction furnace is controlled at 1500°C to 1550°C.

9. A method for preparing a corrosion-resistant cladding layer for the inner wall of a nuclear power pressure vessel according to claim 8, characterized in that: In the step 4, a far-infrared drying machine is used, and the drying temperature is 200° C. to 250° C. After drying for 1 hour, the temperature is naturally lowered to room temperature.

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