Additive manufacturing method for corrosion-resistant and wear-resistant heavy metal impeller

Abstract

The invention discloses a corrosion and wear resistant heavy metal impeller additive manufacturing method, and belongs to the technical field of impeller additive manufacturing. The invention discloses an additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller. The additive manufacturing method comprises the following steps that A, an impeller hub blank is obtained; b, iron-based tungsten carbide alloy powder is obtained; c, the alloy powder is subjected to additive manufacturing on the impeller hub through the 3D printing technology to form impeller blades, and impeller finish machining is conducted; and D, the whole impeller part blank is subjected to heat treatment, and performance detection is conducted. According to the method, iron-based tungsten carbide alloy powder mixed with different tungsten carbide powder proportions is adopted in different blade size ranges, the blade is manufactured through 3D printing additive manufacturing, the hardness of the blade is gradually increased from the blade root to the blade tip, the corrosion and wear resistance of the blade in the high-temperature and high-speed lead-bismuth alloy environment can be improved, and the service life of an impeller is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of impeller additive manufacturing, and specifically relates to a method for additive manufacturing of a corrosion-resistant and wear-resistant heavy metal impeller. Background Art

[0002] The lead-bismuth fast reactor (BBR) is a hot research topic for fourth-generation nuclear energy systems. It uses a high-temperature liquid lead-bismuth alloy (typically a eutectic) to cool the reactor core. With its advantages of high safety, high fuel utilization, and long refueling cycles, BBRs hold great promise for application in a wide range of fields, including small- and medium-sized power grids, urban heating, offshore floating nuclear power plants, and ship propulsion. The impeller of the lead-bismuth main pump, which drives the lead-bismuth alloy medium, operates in a high-temperature, high-velocity, high-density, and highly corrosive environment for extended periods of time. Therefore, the impeller must exhibit excellent resistance to high temperatures and corrosion wear.

[0003] In the lead-bismuth main pump, the lead-bismuth alloy medium exhibits high temperature, high density, and high corrosion properties, significantly different from common pump working media. The Cr and Ni elements in 304 and 316 stainless steel are easily corroded by the high-temperature lead-bismuth alloy. The impeller is the core flow-through component of the lead-bismuth main pump. Velocities and pressures increase closer to the blade tips, exacerbating damage to the 304 and 316 stainless steel materials. Therefore, the blades, especially at the blade tips, need to be hardened to enhance wear resistance. As the drive device for the lead-bismuth fast reactor coolant, the lead-bismuth main pump requires a long operating life. Therefore, impellers made from common materials such as 304 and 316 stainless steel are unsuitable for operation in lead-bismuth main pumps.

[0004] In the existing lead-bismuth main pump, the pump material is destroyed too quickly in the high-temperature, high-speed, high-density and highly corrosive lead-bismuth alloy working medium. For example, in the patent with application number 202011489040.9, the guide bearing with a low rotational linear speed has a lifespan of only more than 5 years after adopting the said high-wear-resistant and high-temperature resistant hard alloy. This material has poor corrosion and wear resistance in the high-temperature and high-speed alloy environment and a short service life. Summary of the Invention

[0005] In order to solve the problem in the prior art that common pump impeller materials are destroyed too quickly in high-temperature, high-speed, high-density and highly corrosive lead-bismuth alloy working media, the present invention provides a corrosion-resistant and wear-resistant heavy metal impeller additive manufacturing method. Iron-based tungsten carbide alloy powder mixed with different proportions of tungsten carbide powder is used within different blade size ranges. Blades are manufactured through 3D printing additive manufacturing, so that the hardness of the blades gradually increases from the root to the tip, which is beneficial to improving the corrosion and wear resistance of the blades in a high-temperature and high-speed lead-bismuth alloy environment and extending the service life of the impeller.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A method for additively manufacturing a corrosion-resistant and wear-resistant heavy metal impeller comprises the following steps: A. Obtain the impeller hub blank; B. Obtaining iron-based tungsten carbide alloy powder; C. Use 3D printing technology to additively manufacture iron-based tungsten carbide alloy powder into impeller blades on the impeller hub, and then perform impeller finishing. D. Heat treat the entire impeller blank and conduct performance testing.

[0007] Preferably, the step A comprises the following specific steps: A1. forging an impeller hub blank; A2. Perform proper heat treatment on the impeller hub blank; A3. Process the inner cavity of the impeller hub; A4. Perform wheel hub surface finishing.

[0008] Preferably, in step B, the iron-based tungsten carbide alloy powder is formed by uniformly mixing Fe90-2 powder and spherical cast tungsten carbide powder.

[0009] Preferably, the blending ratio of tungsten carbide powder in the iron-based tungsten carbide alloy powder is 1% to 9%.

[0010] Compared with 304 and 316 stainless steel materials, the Cr and Ni content in iron-based tungsten carbide materials is lower, which can weaken the corrosion effect of lead-bismuth alloys, and the addition of tungsten carbide components can improve the wear resistance of the material.

[0011] Preferably, in step C, the impeller blades are divided into six size ranges from the inside to the outside in the radial direction: 0% to 10%, 10% to 20%, 20% to 40%, 40% to 60%, 60% to 80% and 80% to 100%.

[0012] Preferably, the impeller blades are made of iron-based tungsten carbide alloy powder with tungsten carbide powder blending ratios of 1%, 2%, 3%, 5%, 7% and 9% respectively from the inside to the outside in radial direction.

[0013] As the linear velocity and pressure on the blade surface gradually increase radially from the inside to the outside, the wear and damage caused by the lead-bismuth alloy on the blade surface becomes more and more serious. Therefore, the use of iron-based tungsten carbide alloy powder with a high tungsten carbide powder blending ratio to manufacture the blade in the high-speed and high-pressure area of ​​the blade is beneficial to increase the hardness of this area, improve wear resistance, and extend service life.

[0014] At the same time, gradually increasing the material hardness from the root to the tip can reduce the risk of cracking caused by the decrease in material toughness. Controlling the proportion of tungsten carbide powder between 1% and 9% can not only increase the hardness of the iron-based tungsten carbide alloy, but also reduce the risk of material cracking.

[0015] Preferably, in step C, the blade root is rounded, the leading edge and the trailing edge of the blade are rounded and thinned, and the blade surface is fine-machined.

[0016] Preferably, in step C, the surface roughness of the blade is not higher than Ra3.2.

[0017] Preferably, in step D, the performance test includes performing flaw detection on the machined impeller parts and testing the hardness of the blades within different size ranges using an RT test method.

[0018] A corrosion-resistant and wear-resistant heavy metal impeller is prepared by the above preparation method.

[0019] Therefore, the present invention has the following beneficial effects: (1) In the iron-based tungsten carbide alloy powder used in the present invention, the blending ratio of tungsten carbide powder is between 1% and 9%, which can increase the hardness of the material and reduce the risk of material cracking during processing and use.

[0020] (2) Using an alloy powder blended with Fe90-2 powder and spherical cast tungsten carbide powder to manufacture blades can reduce the corrosion effect of high-temperature lead-bismuth alloy on the blades and improve the corrosion resistance of the blades. Blending tungsten carbide powder with Fe90-2 powder can increase the material hardness, thereby improving the wear resistance of the blades.

[0021] (3) The impeller blades are divided into different size ranges according to the surface linear velocity and pressure variation patterns, and iron-based tungsten carbide alloy powders with different tungsten carbide powder ratios are used for additive manufacturing within the blades of different size ranges. As the tungsten carbide powder mixing ratio increases, the material hardness gradually increases. Therefore, the present invention can gradually increase the blade hardness from the root to the tip of the blade in the radial direction, so that the parts of the blade with higher speed and pressure have higher hardness, obtain better wear resistance, slow down the blade damage rate, and extend the service life of the impeller. By gradually increasing the blade hardness from the inside to the outside in the radial direction, the risk of blade cracking caused by the decrease in material toughness due to the high tungsten carbide powder content can be reduced.

[0022] (4) Compared with casting, forging, and turning processes, the use of 3D printing additive manufacturing technology to manufacture blades can save materials and reduce waste. For pump blades with distorted geometric shapes, 3D printing additive manufacturing technology has higher precision and can reduce the difficulty of subsequent processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the radial size range of the blades described in the embodiment. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and embodiments, so as to clearly describe and illustrate the objectives, technical solutions and advantages of the present invention.

[0025] Overall embodiment A method for additively manufacturing a corrosion-resistant and wear-resistant heavy metal impeller comprises the following steps: A. Obtain the impeller hub blank; B. Obtaining iron-based tungsten carbide alloy powder; C. Use 3D printing technology to additively manufacture alloy powder into impeller blades on the impeller hub and perform impeller finishing; D. Heat treat the entire impeller blank and conduct performance testing.

[0026] Preferably, the step A comprises the following specific steps: A1. Forging the impeller hub blank; A2. Perform proper heat treatment on the impeller hub blank; A3. Process the inner cavity of the impeller hub; A4. Perform wheel hub surface finishing.

[0027] As a specific implementation, in step B, the iron-based tungsten carbide alloy powder is formed by uniformly mixing Fe90-2 powder and spherical cast tungsten carbide powder.

[0028] As a specific implementation manner, the blending ratio of tungsten carbide powder in the iron-based tungsten carbide alloy powder is 1% to 9%.

[0029] As a specific embodiment, in step C, the impeller blades are divided into six size ranges from the inside to the outside along the radial direction: 0% to 10%, 10% to 20%, 20% to 40%, 40% to 60%, 60% to 80% and 80% to 100%. Figure 1 shown.

[0030] As a specific embodiment, the impeller blades are manufactured radially from the inside out using iron-based tungsten carbide alloy powder with tungsten carbide powder blending ratios of 1%, 2%, 3%, 5%, 7% and 9% respectively.

[0031] As a specific implementation, in step C, the blade root is rounded, the leading edge and the trailing edge of the blade are rounded and thinned, and the blade surface is fine-machined.

[0032] As a specific implementation, in step C, the surface roughness of the blade is not higher than Ra3.2.

[0033] As a specific implementation, in step D, the performance test includes performing flaw detection on the machined impeller parts using an RT test method, and testing the hardness of blades within different size ranges.

[0034] As a specific embodiment, a corrosion-resistant and wear-resistant heavy metal impeller is prepared by the above-mentioned preparation method.

[0035] Example 1 The present invention provides a method for additive manufacturing of corrosion- and wear-resistant heavy metal impellers. Based on 3D printing additive manufacturing technology, the impellers are manufactured using iron-based tungsten carbide alloy powder mixed with different proportions of tungsten carbide powder within different blade size ranges, thereby achieving a gradual increase in blade hardness from the inside to the outside in the radial direction. This can improve the corrosion resistance and wear resistance of the blades to high-temperature and high-speed lead-bismuth alloys, thereby extending the service life of the impeller.

[0036] The specific steps include: A. Using 316 stainless steel, we forge an impeller hub blank close to the design dimensions. Heat-treat the hub blank to eliminate internal stress and defects, improving mechanical properties such as hardness and toughness. Based on the hub blank, we use CNC technology to machine the hub cavity to the design dimensions for mounting bearings and other parts. Surface finishing is performed on the hub to meet surface roughness and other requirements. B. Purchase Fe90-2 powder and spherical cast tungsten carbide powder according to the composition requirements, and evenly blend the two powders to obtain iron-based tungsten carbide alloy powders with tungsten carbide powder ratios of 1%, 2%, 3%, 5%, 7% and 9% respectively; Compared with 304 and 316 stainless steel materials, the Cr and Ni content in iron-based tungsten carbide materials is lower, which can weaken the corrosion effect of lead-bismuth alloys, and the addition of tungsten carbide components can improve the wear resistance of the material.

[0037] C. Figure 1 As shown in the figure, the blades are divided into six size ranges along the radial direction: 0-10%, 10-20%, 20-40%, 40-60%, 60-80%, and 80-100%. Within these six blade size ranges, iron-based tungsten carbide alloy powders with tungsten carbide powder blending ratios of 1%, 2%, 3%, 5%, 7%, and 9% are used, respectively, to additively manufacture the alloy powder into blades using 3D printing technology; When the tungsten carbide powder blending ratio is 0% and 5%, the HRC hardness of the processed material can reach 55 and 60 respectively. As the tungsten carbide powder blending ratio increases, the material hardness gradually increases. Therefore, using the alloy powder prepared according to the above tungsten carbide powder blending ratio to process the impeller blades can gradually increase the blade hardness along the radial direction.

[0038] As the linear velocity and pressure on the blade surface gradually increase radially from the inside to the outside, the wear and damage caused by the lead-bismuth alloy on the blade surface becomes more and more serious. Therefore, the use of iron-based tungsten carbide alloy powder with a high tungsten carbide powder blending ratio to manufacture the blade in the high-speed and high-pressure area of ​​the blade is beneficial to increase the hardness of this area, improve wear resistance, and extend service life.

[0039] At the same time, gradually increasing the material hardness from the root to the tip can reduce the risk of cracking caused by the decrease in material toughness. Controlling the proportion of tungsten carbide powder between 1% and 9% can not only increase the hardness of the iron-based tungsten carbide alloy, but also reduce the risk of material cracking.

[0040] D. After completing the 3D printing of the blade, the blade root fillet is processed according to the use requirements, the leading and trailing edges of the blade are rounded and thinned, and the blade surface is polished to improve the smoothness and enhance the flow performance of the blade; E. After finishing the blades, heat treat the impeller parts to eliminate the adverse effects such as internal stress generated during the 3D printing process; F. Use RT testing methods to inspect impeller parts, focusing on the blade roots and the intersections of different blade sizes to avoid material defects caused by processing and heat treatment that may affect the normal use of parts. Check whether the hardness of blades within different size ranges meets the use requirements.

[0041] The impeller manufactured using the above method was installed on a corresponding lead-bismuth main pump for operational testing. The impeller tip surface had an HRC hardness of over 60. In a high-temperature lead-bismuth alloy medium, the impeller achieved a linear velocity of approximately 8 m / s. After 3000 hours of continuous, stable operation, the blade tip wear was approximately 30 μm, with a wear rate of 86.4 μm / year. Based on the allowable blade tip wear of 500 μm for the lead-bismuth main pump, the impeller's operational lifespan can exceed five years, meeting the design service life requirements.

[0042] Comparative Example 1 A method for additive manufacturing of a heavy metal impeller, comprising the following steps: A. Using 316 stainless steel, an impeller hub blank close to the design size is obtained through forging. The hub blank is heat treated to eliminate internal stress and internal defects and improve the mechanical properties of the hub, such as hardness and toughness. Based on the hub blank, the hub cavity is machined according to the design size using CNC technology to install other parts such as bearings. The required hub is surface-finished to meet the use requirements such as surface roughness. B. The blades are divided into six size ranges along the radial direction: 0-10%, 10%-20%, 20%-40%, 40%-60%, 60%-80% and 80%-100%. C. 316 stainless steel welding wire is manufactured into blades on the impeller hub using 3D printing technology. D. The blade root fillet is machined according to the use requirements, the leading and trailing edges of the blades are rounded and thinned, and the blade surface is polished to improve smoothness and enhance the flow performance of the blades. E. Use RT testing method to test impeller parts, focus on flaw detection of blade roots and junctions of blades with different size ranges, and test whether the hardness of blades with different size ranges meets the use requirements.

[0043] The difference between this comparative example and Example 1 is that only 316 stainless steel material is used.

[0044] The impeller manufactured using the above method was installed on a corresponding lead-bismuth main pump for operational testing. The impeller tip surface had an HRC hardness of approximately 30. In a high-temperature lead-bismuth alloy medium, the impeller achieved a linear velocity of approximately 8 m / s. After 1000 hours of continuous, stable operation, the blade tip wear reached 200 μm, with a wear rate of 1728 μm / year. Based on the allowable blade tip wear of 500 μm for the lead-bismuth main pump, the impeller's operational life is only 0.29 years, which is short.

[0045] In summary, the additive manufacturing method of a corrosion-resistant heavy metal impeller of the present invention adopts iron-based tungsten carbide alloy powder mixed with different proportions of tungsten carbide powder for additive manufacturing, so that the hardness of the blade gradually increases radially from the root to the tip, so that the parts of the blade with higher speed and pressure have higher hardness, obtain better wear resistance, slow down the blade damage rate, and extend the service life of the impeller.

[0046] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and optimizations within the spirit and principles of the present invention shall be deemed to be within the scope of protection of the present invention. The scope of protection claimed by the present invention shall be subject to the content of the claims.

Claims

1. A method for additive manufacturing of a corrosion-resistant and wear-resistant heavy metal impeller, characterized in that: The following steps are involved: A. Obtain the impeller hub blank; B. Obtaining iron-based tungsten carbide alloy powder; C. Use 3D printing technology to additively manufacture iron-based tungsten carbide alloy powder into impeller blades on the impeller hub, and then perform impeller finishing. D. Heat treat the entire impeller blank and conduct performance testing.

2. The additive manufacturing method for a corrosion-resistant heavy metal impeller according to claim 1, characterized in that: The step A comprises the following specific steps: A1. Forging the impeller hub blank; A2. Heat treatment of the impeller hub blank; A3. Process the inner cavity of the impeller hub; A4. Perform wheel hub surface finishing.

3. The additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller according to claim 1, characterized in that: In step B, the iron-based tungsten carbide alloy powder is prepared by uniformly mixing Fe90-2 powder and spherical cast tungsten carbide powder.

4. The additive manufacturing method for a corrosion-resistant heavy metal impeller according to claim 1 or 3, characterized in that: The blending ratio of tungsten carbide powder to the iron-based tungsten carbide alloy powder is 1% to 9%.

5. The additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller according to claim 1, characterized in that: In step C, the impeller blades are divided into six size ranges from the inside to the outside in the radial direction: 0% to 10%, 10% to 20%, 20% to 40%, 40% to 60%, 60% to 80% and 80% to 100%.

6. The additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller according to claim 5, characterized in that: The impeller blades are manufactured from iron-based tungsten carbide alloy powder with tungsten carbide powder mixing ratios of 1%, 2%, 3%, 5%, 7% and 9% respectively from the inside to the outside in radial direction.

7. The additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller according to claim 1, characterized in that: In step C, the blade root is rounded, the leading edge and the trailing edge of the blade are rounded and thinned, and the blade surface is fine-machined.

8. The additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller according to claim 1, characterized in that: In step C, the surface roughness of the blade is not higher than Ra3.

2.

9. The additive manufacturing method for a corrosion-resistant and wear-resistant heavy metal impeller according to claim 1, characterized in that: In step D, the performance test includes performing flaw detection on the machined impeller parts using an RT test method, and testing the hardness of blades within different size ranges.

10. A corrosion-resistant heavy metal impeller, characterized in that: The impeller is prepared by the preparation method according to any one of claims 1 to 9.

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