Metallographic corrosion method of high-temperature alloy and high-temperature alloy

Abstract

The invention provides a metallographic corrosion method of a high-temperature alloy and the high-temperature alloy, and relates to the technical field of metallographic detection. The metallographic corrosion method of the high-temperature alloy comprises the following steps: machining the high-temperature alloy to form a microscopic structure observation plane on the high-temperature alloy; the microscopic structure observation plane is ground on a metallographic phase pre-grinding machine, and the ground microscopic structure observation plane is placed on a polishing machine to be subjected to mechanical polishing; etching the mechanically polished microscopic structure observation plane by using an etchant solution to obtain a microscopic structure observation plane to be observed; wherein the ratio of HCl to HNO3 to H2O2 in the etchant solution is (2-3): 1: 1. The metallographic corrosion time of the high-temperature alloy can be shortened.

Description

Technical Field

[0001] The present disclosure relates to the technical field of metallographic detection, and in particular to a metallographic corrosion method for a high-temperature alloy and the high-temperature alloy. Background Art

[0002] One of the important characteristics of high-temperature alloys is their corrosion resistance, which results in a long etching process of metallographic corrosion solution in metallographic testing. This high time cost will result in low metallographic testing efficiency.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a metallographic corrosion method for a high-temperature alloy and a high-temperature alloy, thereby overcoming the problem of long metallographic corrosion time in metallographic detection of high-temperature alloys at least to a certain extent.

[0005] According to a first aspect of the present disclosure, a metallographic corrosion method for a high-temperature alloy is provided, comprising: mechanically processing the high-temperature alloy to form a microstructure observation plane on the high-temperature alloy; grinding the microstructure observation plane on a metallographic pre-grinder, and placing the ground microstructure observation plane on a polishing machine for mechanical polishing; and etching the mechanically polished microstructure observation plane with a corrosion solution to obtain a microstructure observation plane to be observed; wherein the ratio of the corrosion solution is HCl:HNO3:H2O2=(2-3):1:1.

[0006] Optionally, grinding the microstructure observation plane on the metallographic pre-grinding machine includes: grinding the microstructure observation plane on the metallographic pre-grinding machine using metallographic water-abrasive papers of different mesh sizes; wherein the grinding direction is rotated 90° each time the metallographic water-abrasive paper is replaced.

[0007] Optionally, using metallographic water-jet sandpapers of different mesh sizes to grind the microstructure observation plane includes: using 120#, 800# and 1200# metallographic water-jet sandpapers to grind the microstructure observation plane in sequence.

[0008] Optionally, during the mechanical polishing process, the polishing machine used is a diamond spray polishing agent with a particle size of 5 μm to 2.5 μm, and the polishing cloth is a metallographic velvet polishing cloth.

[0009] Optionally, etching the mechanically polished microstructure observation plane with the corrosive solution includes: for high-temperature alloys, immersing the mechanically polished microstructure observation plane into the corrosive solution in an inverted suspension manner.

[0010] Optionally, the microstructure observation plane after mechanical polishing is immersed in a corrosion solution with an immersion depth of less than 2 mm.

[0011] Optionally, the corrosion time is 3s to 5s.

[0012] Optionally, the metallographic corrosion method of the high-temperature alloy further includes: in the process of generating the corrosion solution, the configuration order is to add HCl, HNO3, and H2O2 in sequence.

[0013] Optionally, HCl and HNO3 are analytical grade reagents.

[0014] According to a second aspect of the present disclosure, a high-temperature alloy is provided, comprising a microstructure observation plane prepared by any of the above-mentioned metallographic corrosion methods for the high-temperature alloy.

[0015] In the exemplary embodiments of the present disclosure, a 1:1 ratio of HCl:HNO₃:H₂O₂ is used for etching. This allows for extremely rapid etching, resulting in a clear and uniform microstructure. This significantly reduces the difficulty and cost of etching high-temperature alloys and improves the efficiency of metallographic testing. Furthermore, this solution requires no specialized equipment, is simple to operate, and can be applied to metallographic testing of various types of high-temperature alloys, demonstrating its universal applicability.

[0016] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0018] Figure 1 A flow chart schematically illustrates a method for metallographic corrosion of a high-temperature alloy according to an exemplary embodiment of the present disclosure.

[0019] Figure 2 The microstructure of the N06625 high-temperature alloy of Example 1 of the present disclosure is schematically shown.

[0020] Figure 3 The microstructure of the N06625 high-temperature alloy according to Example 2 of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0021] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present disclosure will be more comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or that other methods, processes, steps, etc. may be employed. In other cases, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0022] In addition, the accompanying drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. Identical reference numerals in the drawings represent identical or similar parts, and thus their repeated descriptions will be omitted. The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all steps. For example, some steps may be decomposed, while others may be combined or partially combined. Therefore, the actual order of execution may vary depending on the actual situation.

[0023] The embodiments of the present disclosure use N06625 alloy as an example to illustrate the metallographic corrosion scheme of the high-temperature alloy of the present disclosure. However, the scheme of the present disclosure is not limited to the type of high-temperature alloy. For example, the scheme can also be applied to the metallographic corrosion process of high-temperature alloy materials that are originally difficult to corrode, such as cobalt-based high-temperature alloys.

[0024] N06625 alloy (internationally known as Inconel 625) is a solid-solution-strengthened, nickel-based wrought-temperature superalloy developed by International Nickel Company (INCO) in the 1960s. Its exceptional comprehensive performance has made it an indispensable key material in modern industry. In high-end applications such as aircraft engines, deep-sea equipment, and nuclear reactors, N06625, thanks to its unique chemical composition (a nickel matrix supplemented with key elements such as chromium, molybdenum, and niobium), achieves adaptability to extreme environments, resolving the industry's pain point of material failure under high-temperature and highly corrosive conditions.

[0025] Grain size, referring to the size of crystal grains within a crystal, is a crucial physical property parameter in superalloys. It is a key factor in determining a superalloy's high-temperature mechanical properties, durability, and reliability. Precisely controlling superalloy grain size is crucial for balancing the triad of strength, ductility, and high-temperature stability. Grain size grading is an effective means of controlling superalloy grain size, enabling more optimized and controllable superalloy manufacturing processes.

[0026] At present, due to the extremely strong corrosion resistance of N06625, it usually requires a long time of etching in the metallographic corrosion solution, and the corrosion effect of the microstructure is often not ideal, which affects the grain size rating results.

[0027] To address, or at least alleviate, the long metallographic corrosion time of high-temperature alloys, the disclosed embodiments provide a novel metallographic corrosion solution for high-temperature alloys. This solution enables rapid, accurate, and uniform visualization of microstructure, significantly reducing time and improving the accuracy of high-temperature alloy grain size grading results. It addresses the challenges of high-temperature alloys being difficult to corrode, exhibiting poor corrosion results, and undergoing a complex and lengthy corrosion process.

[0028] Figure 1 The flowchart of the metallographic corrosion method of the high temperature alloy according to the exemplary embodiment of the present disclosure is schematically shown. Figure 1 The metallographic corrosion method of the high-temperature alloy according to the embodiment of the present disclosure comprises the following steps:

[0029] S12. Machining the high-temperature alloy to form a microstructure observation plane on the high-temperature alloy.

[0030] The embodiments of the present disclosure do not limit the machining process. In addition, the microstructure observation plane is the basis of metallographic detection, and the present disclosure does not limit it either.

[0031] S14. Grind the microstructure observation plane on a metallographic pre-grinder, and place the ground microstructure observation plane on a polishing machine for mechanical polishing.

[0032] According to some embodiments of the present disclosure, the microstructure observation plane is ground using different mesh sizes of metallographic water-reinforced sandpaper on a metallographic pre-grinding machine. Each time the metallographic water-reinforced sandpaper is changed, the grinding direction is rotated 90 degrees to ensure that the previous grinding marks are completely eliminated. For example, the microstructure observation plane is ground using 120#, 800#, and 1200# metallographic water-reinforced sandpaper in sequence.

[0033] After grinding, wash away the sand particles on the microstructure observation surface.

[0034] During the mechanical polishing process, the polisher used is a diamond spray polisher with a particle size of 5μm to 2.5μm, and the polishing cloth is a metallographic velvet polishing cloth. After the polishing process, care should be taken to ensure that no liquid droplets remain on the microstructure observation surface after mechanical polishing, and it must not be rinsed with water and must be kept smooth and dry.

[0035] According to some embodiments of the present disclosure, mechanical polishing is performed until the surface of the microstructure observation plane is smooth and bright, free of scratches and drag.

[0036] S16. Etching the mechanically polished microstructure observation plane using a corrosive solution to obtain a microstructure observation plane to be observed.

[0037] In an exemplary embodiment of the present disclosure, the etching solution may have a ratio of HCl:HNO3:H2O2 = (2-3):1:1. That is, the ratio of HCl, HNO3, and H2O2 in the etching solution ranges from 2:1:1 to 3:1:1, all by weight. HCl and HNO3 may be analytical grade reagents, and the concentration of H2O2 may be 25% to 35%, for example, 30%.

[0038] It should be noted that in the process of generating the corrosion solution, the configuration order is to add HCl, HNO3, and H2O2 in sequence, and the microstructure observation plane is immersed immediately after the addition of H2O2.

[0039] For this high-temperature alloy, the microstructure observation plane after mechanical polishing can be immersed in the corrosion solution by an inverted suspension method.

[0040] According to some embodiments of the present disclosure, the microstructure observation plane can be controlled to be in contact with the liquid surface of the corrosion solution.

[0041] According to other embodiments of the present disclosure, the immersion depth of the mechanically polished microstructure observation plane in the etching solution can be controlled to less than 2 mm. Otherwise, the etching effect will be affected. Experiments have found that compared to immersing the entire high-temperature alloy in the etching solution, the inverted suspension and flat immersion scheme in these embodiments can significantly increase the corrosion rate of the microstructure observation plane.

[0042] In this case, the etching time is 3 to 5 seconds to obtain a microstructure observation plane to be observed.

[0043] Thus, the microstructure observation plane to be observed can be placed under a metallographic microscope, and the microstructure can be observed using a wide-field observation method.

[0044] On the one hand, conventional etching solutions for high-temperature alloys have the problem of being unable to etch out microstructures, or even if they do, the etching time is too long, and the etching effect is unstable. Unlike other metallographic etching solutions that require several minutes or even more than ten minutes for the metallographic etching process, the etching solution of the disclosed embodiment can etch out microstructures at an extremely fast speed, and the microstructure morphology is clear and uniform, greatly reducing the difficulty and investment cost of etching high-temperature alloys.

[0045] Furthermore, the disclosed embodiments not only clearly visualize the grain structure of N06625 superalloy, but can also be used for metallographic corrosion of difficult-to-corrode superalloy materials, such as cobalt-based superalloys. This makes grain size assessment more accurate and eliminates the need for specialized equipment, making it suitable for widespread application.

[0046] On the other hand, the embodiment of the present disclosure is suitable for large-scale laboratory testing, and its fast corrosion time, simple corrosion solution ratio, and easy-to-operate corrosion method all help to improve detection efficiency.

[0047] The metallographic corrosion scheme of the high-temperature alloy disclosed in the present invention is described below through examples.

[0048] Example 1

[0049] First, a microstructure observation plane was machined from a sample of N06625 superalloy. This plane was then ground on a metallographic pre-grinder, and the sand on the plane was rinsed away. The grinding process involved sequentially grinding with 120#, 800#, and 1200# grit metallographic water-jet sandpaper. Each time the metallographic water-jet sandpaper was changed, the grinding direction was rotated 90° to ensure that any traces of the previous grinding were completely removed.

[0050] Next, the microstructure observation plane obtained above was placed on a polishing machine for mechanical polishing until the surface was smooth, shiny, and free of scratches and drag. The polishing agents used for mechanical polishing were diamond spray polishing agents with particle sizes of 5μm and 2.5μm, respectively. A metallographic velvet polishing cloth was used. After the polishing process, the surface of the microstructure observation plane was smooth and dry, free of residual droplets.

[0051] Subsequently, immerse the mechanically polished microstructure observation surface in a corrosive solution for etching. The corrosive solution ratio is HCl:HNO3:H2O2 = 3:1:1. HCl, HNO3, and H2O2 are added in this order. Immediately after adding H2O2, the polished microstructure observation surface should be inverted and suspended above the metallographic corrosive solution surface for etching, ensuring that the microstructure observation surface is in contact with the metallographic corrosive solution surface. The etching time is 3 seconds.

[0052] Then, the etched microstructure observation plane is placed under a metallographic microscope, and the metallographic microstructure is observed using a wide-field observation method.

[0053] Figure 2 The microstructure of the N06625 high temperature alloy of Example 1 of the present disclosure is schematically shown. Figure 2It can be seen that the corrosion effect on the microstructure of the high-temperature alloy is uniform and the grain boundary details are clearly visible.

[0054] Example 2

[0055] First, a microstructure observation plane was machined from a sample of N06625 superalloy. This plane was then ground on a metallographic pre-grinder, and the sand on the plane was rinsed away. The grinding process involved sequentially grinding with 120#, 800#, and 1200# grit metallographic water-jet sandpaper. Each time the metallographic water-jet sandpaper was changed, the grinding direction was rotated 90° to ensure that any traces of the previous grinding were completely removed.

[0056] Next, the microstructure observation plane obtained above was placed on a polishing machine for mechanical polishing until the surface was smooth, shiny, and free of scratches and drag. The polishing agents used for mechanical polishing were diamond spray polishing agents with particle sizes of 5μm and 2.5μm, respectively. A metallographic velvet polishing cloth was used. After the polishing process, the surface of the microstructure observation plane was smooth and dry, free of residual droplets.

[0057] Subsequently, immerse the mechanically polished microstructure observation surface in a corrosive solution for etching. The corrosive solution ratio is HCl:HNO3:H2O2 = 3:1:1. HCl, HNO3, and H2O2 are added in that order. Immediately after adding H2O2, the polished microstructure observation surface should be inverted and suspended above the metallographic corrosive solution surface for etching, ensuring that the microstructure observation surface is in direct contact with the metallographic corrosive solution surface. The etching time is 5 seconds.

[0058] Then, the etched microstructure observation plane is placed under a metallographic microscope, and the metallographic microstructure is observed using a wide-field observation method.

[0059] Figure 3 The microstructure of the N06625 high temperature alloy of Example 2 of the present disclosure is schematically shown. Figure 3 It can be seen that the microstructure corrosion effect of the high temperature alloy is uniform, compared with Figure 2 , the grain boundary details are slightly thickened and more clearly visible.

[0060] Furthermore, an embodiment of the present disclosure also provides a high-temperature alloy, which includes a microstructure observation plane, and the microstructure observation plane is prepared using the metallographic corrosion method of the above-mentioned high-temperature alloy.

[0061] It should be noted that although the steps of the method of the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all steps must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0062] Furthermore, the above-mentioned figures are merely illustrative of the processes included in the methods according to exemplary embodiments of the present disclosure and are not intended to be limiting. It is readily understood that the processes illustrated in the above-mentioned figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0063] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing what is disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the claims.

[0064] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A metallographic corrosion method for high-temperature alloys, characterized in that: include: Mechanically processing the high-temperature alloy to form a microstructure observation plane on the high-temperature alloy; The microstructure observation plane is ground on a metallographic pre-grinding machine, and the ground microstructure observation plane is placed on a polishing machine for mechanical polishing; Using a corrosive solution to etch the mechanically polished microstructure observation plane to obtain a microstructure observation plane to be observed; Wherein, the ratio of the corrosion solution is HCl:HNO3:H2O2=(2-3):1:

1.

2. The metallographic corrosion method of a high-temperature alloy according to claim 1, characterized in that: Grinding of the microstructure observation plane on the metallographic pre-grinding machine includes: On the metallographic pre-grinding machine, the microstructure observation plane was ground using metallographic water-sandpaper of different mesh sizes. Each time the metallographic water sandpaper is replaced, the grinding direction is rotated 90°.

3. The metallographic corrosion method of a high-temperature alloy according to claim 2, characterized in that: The microstructure observation plane is ground using metallographic water sandpaper of different mesh sizes, including: The microstructure observation plane was ground using 120#, 800# and 1200# metallographic water sandpaper in sequence.

4. The metallographic corrosion method of a high-temperature alloy according to claim 1, characterized in that: During the mechanical polishing process, the polishing machine used is a diamond spray polishing agent with a particle size of 5μm to 2.5μm, and the polishing cloth is a metallographic velvet polishing cloth.

5. The metallographic corrosion method of a high-temperature alloy according to claim 1, characterized in that: Etching the mechanically polished microstructure observation plane using a corrosive solution includes: For the high-temperature alloy, an inverted suspension method is used to immerse the mechanically polished microstructure observation plane into a corrosion solution.

6. The metallographic corrosion method of a high-temperature alloy according to claim 5, characterized in that: The mechanically polished microstructure observation plane is immersed in the corrosion solution with an immersion depth of less than 2 mm.

7. The metallographic corrosion method for a high-temperature alloy according to claim 5 or 6, characterized in that: The corrosion time is 3s to 5s.

8. The metallographic corrosion method of a high-temperature alloy according to claim 1, characterized in that: The metallographic corrosion method of the high-temperature alloy further comprises: In the process of generating the corrosion solution, the configuration order is to add HCl, HNO3, and H2O2 in sequence.

9. The metallographic corrosion method for a high-temperature alloy according to claim 1 or 8, characterized in that: HCl and HNO3 were analytical grade reagents.

10. A high temperature alloy, characterized in that: The high-temperature alloy includes a microstructure observation plane prepared by the metallographic corrosion method of the high-temperature alloy according to any one of claims 1 to 9.

Images