A macrography method for low flow line corrosion of nickel-based wrought superalloy forgings

Abstract

The application provides a low-magnification flow line corrosion method for a nickel-based wrought superalloy forge piece, which has high corrosion efficiency, a simple operation process and clear display of flow line details. The nickel-based wrought superalloy is forged between a recrystallization temperature and a superheat temperature of the corresponding material, or is subjected to heat treatment again after forging, a corrosion solution obtained by mixing analytical pure phosphoric acid and water at a proportion of 1:5-10 in volume is used as an electrolyte, a low-magnification sample of the nickel-based wrought superalloy to be subjected to corrosion detection after treatment is used as an anode, an inert metal or a carbon plate is used as a cathode, and direct current stabilized power is used for electrolytic corrosion.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nickel-based wrought superalloy forging technology, in particular to a low-magnification flow line corrosion method for nickel-based wrought superalloy forgings. BACKGROUND

[0002] Metal flow lines are a kind of low-magnification structure formed by the linear and continuous distribution of inclusions, carbides and other precipitates along the deformation direction during forging. This low-magnification structure has obvious directionality, so the mechanical properties also have obvious directionality. The tensile strength is high along the flow line direction, and the shear strength is high perpendicular to the flow line direction. Reasonable flow line distribution can make the mechanical properties of the product better. On the contrary, if there are major defects such as turbulence, chaotic flow, and flow-through, it will seriously affect the mechanical properties and final performance of the product.

[0003] As can be seen from the above, flow lines are an important means to characterize the rationality of metal product forging process, and have become an important detection item in low-magnification structure detection.

[0004] Nickel-based wrought superalloy is a kind of nickel-based superalloy. Due to its excellent mechanical properties and performance, it is widely used in high-end manufacturing industries such as aerospace, energy power, and ships. However, the high degree of alloying of nickel-based wrought superalloy leads to difficulty in deformation, so high-temperature forging is usually used. In addition, the product geometry is complex, and the deformation is extremely uneven, so flow line detection is extremely important. Nickel-based superalloy low-magnification flow line detection is usually detected simultaneously with other low-magnification structure items. According to the arrangement of product production process, some products are detected in the forged state, and some products are detected in the heat-treated state of solid solution + aging.

[0005] Nickel-based superalloy low-magnification structure is usually detected after chemical corrosion. Two kinds of chemical corrosion solutions are commonly used. One is copper sulfate + sulfuric acid + hydrochloric acid solution, and the other is hydrochloric acid + hydrofluoric acid + water + high-iron chloride solution. When using the above two solutions to corrode the low-magnification flow lines of nickel-based superalloy, under normal sample surface roughness conditions, the flow line structure cannot be basically displayed. For GH4169 (foreign brand IN718) material, after the sample surface is polished with 80 mesh, 180 mesh, 400 mesh, 800 mesh, 1200 mesh, and 2000 mesh metallographic sandpaper in turn, and then corroded with the above two corrosion solutions, slight flow line structure can be seen, and sometimes additional interference structure will be generated, which will seriously interfere with the judgment of low-magnification flow line detection. This method not only consumes a lot of time in the sample preparation process, but also has unstable corrosion effect. Even if the above-mentioned metallographic sandpaper is used to polish GH4413, GH4133B, GH4698 and other coarse-grained nickel-based wrought superalloys, the flow line structure still cannot be displayed, which seriously affects the flow line structure detection. SUMMARY

[0006] In order to solve the problem that the traditional method cannot obtain the clear macro flow line structure of the nickel-based wrought superalloy forge piece, the application provides a nickel-based wrought superalloy forge piece macro flow line etching method, which has high etching efficiency, simple operation process and clear flow line structure detail display.

[0007] The technical scheme is as follows: a nickel-based wrought superalloy forge piece macro flow line etching method, characterized in that: after the nickel-based wrought superalloy is forged between the recrystallization temperature and the overheating temperature of the corresponding material or after the nickel-based wrought superalloy is forged and then heat treated again, the etching solution obtained by mixing the analytically pure phosphoric acid and water in a proportion of 1:5-10 by volume is used as the electrolyte, the nickel-based wrought superalloy macro sample to be etched and detected after treatment is used as the anode, the inert metal or the carbon plate is used as the cathode, and the direct current stabilized power supply is used for electrolytic etching.

[0008] Further features are as follows:

[0009] The voltage of electrolysis is 10V-15V, and the electrolysis time is 5min-8min;

[0010] The surface of the nickel-based wrought superalloy macro sample of the anode to be etched is processed by the grinding wheel of the grinding machine before etching;

[0011] The nickel-based wrought superalloy macro sample of the anode is in the forged state or the heat treated state;

[0012] After electrolytic etching, the sample is taken out, washed in flowing water, and then the surface of the sample is blown dry before naked eye observation.

[0013] The application has the following beneficial effects: the application uses the phosphoric acid solution as the electrolyte, uses the nickel-based wrought superalloy macro sample to be detected as the anode, uses the inert metal as the cathode, and uses the direct current stabilized power supply for electrolytic etching to obtain the macro flow line structure, the application can complete the etching of the flow line structure in a short time, the etched flow line structure can be clearly observed by naked eye, the traditional chemical etching method has the problems of long etching time, unstable etching effect, difficult etching of the macro flow line structure, inability to take photos, and interference with the flow line structure detection. Compared with the traditional metal flow line etching method, the etching efficiency of the application is improved by several times to dozens of times or more, the working intensity is significantly reduced, and the application is not affected by the sample state of the macro sample, can clearly display the flow line structure of the nickel-based wrought superalloy regardless of the forged state or the heat treated state, and is convenient for the detection personnel and the technical personnel to accurately judge whether the flow line of the nickel-based wrought superalloy meets the product technical standard or the process design. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a local longitudinal macro flow line measurement graph of the IN718 material forge piece (heat treated state) in the embodiment 1 of the application;

[0015] Figure 2 Figure 2 is a flow line measurement diagram of a local longitudinal low-power sample of the IN718 material forge piece (hot treatment state) in the embodiment 2 of the present application;

[0016] Figure 3 Figure 2 is a flow line measurement diagram of a local longitudinal low-power sample of the IN718 material forge piece (hot treatment state) in the embodiment 2 of the present application;

[0017] Figure 4 Figure 2 is a flow line measurement diagram of a local longitudinal low-power sample of the IN718 material forge piece (hot treatment state) in the embodiment 2 of the present application;

[0018] Figure 5 Figure 2 is a flow line measurement diagram of a local longitudinal low-power sample of the IN718 material forge piece (hot treatment state) in the embodiment 2 of the present application;

[0019] Figure 6 Figure 2 is a flow line measurement diagram of a local longitudinal low-power sample of the IN718 material forge piece (hot treatment state) in the embodiment 2 of the present application;

[0020] Figure 7 Figure 2 is a flow line measurement diagram of a local longitudinal low-power sample of the IN718 material forge piece (hot treatment state) in the embodiment 2 of the present application. DETAILED DESCRIPTION

[0021] A low-power flow line corrosion method for a nickel-based wrought superalloy forge piece, after the nickel-based wrought superalloy is forged between the recrystallization temperature and the overheating temperature of the corresponding material (i.e. in a forged state) or after the nickel-based wrought superalloy is forged and then heat treated again (i.e. in a hot treatment state), the grains will undergo dynamic recovery and dynamic recrystallization during the forging process, forming equiaxed grains. At this time, the grains have no directionality, and it is difficult to show the flow lines by corroding the grain boundaries. If the nickel-based wrought superalloy is heat treated after forging, the grains will recrystallize again, and equiaxed grains will also be produced. Under this condition, first, a grinding machine with a 40-mesh or higher mesh abrasive wheel is used to process the surface to be corroded of the nickel-based wrought superalloy low-power sample. Then, an electrolyte obtained by mixing analytical pure phosphoric acid and water at a volume ratio of 1:5-10 is used as the electrolyte. The nickel-based wrought superalloy low-power sample (in a forged state or in a hot treatment state) to be detected is used as the anode, and an inert metal (stainless steel plate, nickel-based superalloy plate, lead plate) or carbon plate is used as the cathode. A direct current stabilized power supply is used for electrolytic corrosion. The voltage for electrolysis is 10-15 V, and the electrolysis time is 5-8 min. After electrolytic corrosion, the sample is taken out, washed in flowing water, and dried. The flow line structure can be observed by naked eye after the surface of the sample is dried.

[0022] The effects are described below in conjunction with the embodiments:

[0023] Embodiment 1

[0024] In this embodiment, the flow line corrosion is performed on a local longitudinal low-power sample of an IN718 material forge piece (in a hot treatment state).

[0025] The tools used in this embodiment are DC stabilized power supply, measuring cup, beaker, glass rod, lead plate, etc.

[0026] The specific steps of the nickel-based wrought superalloy streamline corrosion method of this embodiment are as follows:

[0027] 1) The longitudinal low-power sample observation surface of the IN718 material forge piece (heat treated state) to be corroded for detection is polished by using a grinding machine with a 40-mesh grinding wheel;

[0028] 2) In a beaker, 98% analytical pure phosphoric acid and water are mixed in a ratio of 1:10 (volume ratio) to obtain a clear electrolytic corrosion solution, which is stirred uniformly with a glass rod;

[0029] 3) The corrosion solution is placed in an electrolytic container, and a lead plate is used as the cathode, and the local longitudinal low-power sample of the IN718 material forge piece (heat treated state) to be corroded is used as the anode, and electrolysis is carried out at a voltage of 10V for 8min;

[0030] 4) The IN718 material forge piece (heat treated state) with electrolytic corrosion is taken out, washed with running water, and the sample surface is blown dry.

[0031] 5) The local longitudinal streamline of the IN718 material forge piece (heat treated state) with electrolytic corrosion is observed with the naked eye to observe whether the metal streamline meets the specification requirements, and a photograph is taken for record.

[0032] The local longitudinal low-power streamline requirements of the IN718 material forge piece (heat treated state) are that the streamline of the forge piece should basically follow the contour, and no flow or vortex is allowed.

[0033] Figure 1 The streamline morphology of the local longitudinal low-power sample of the IN718 material forge piece (heat treated state) after electrolytic corrosion can be seen from the figure: the streamline basically follows the contour of the forge piece, and no flow or vortex is seen, meeting the specification requirements.

[0034] The steps of the conventional chemical corrosion of the local longitudinal low-power sample of the IN718 material forge piece (heat treated state) are as follows: 1) analytical pure hydrochloric acid 150ml, analytical pure hydrofluoric acid 30ml, water 100ml, and high-iron chloride 50g are mixed to obtain a corrosion solution;

[0035] 2) The low-power sample is polished;

[0036] 3) After cleaning the sample, it is immersed in the above-prepared corrosion solution for 20 minutes;

[0037] 4) The sample is taken out and the surface corrosion products are washed with running water;

[0038] 5) The sample surface is observed and photographed.

[0039] Figure 2 The streamline effect of the IN718 material forging (heat treated state) after the conventional chemical corrosion of the local longitudinal macroscopic sample can be seen from the figure, and there is no trace of any streamline. Therefore, the streamline of the material cannot be observed by naked eye after the conventional chemical treatment.

[0040] Example 2

[0041] In this example, the streamline corrosion is performed on the IN718 material forging (forged state) local longitudinal macroscopic sample.

[0042] The tools used in this example are DC stabilized power supply, measuring cup, beaker, glass rod, lead plate, etc.

[0043] The specific steps of the streamline corrosion method of the nickel-based wrought high-temperature alloy in this example are as follows:

[0044] 1) The IN718 material forging (forged state) local longitudinal macroscopic sample observation surface to be corroded and detected is polished using a grinder with a 40-mesh grinding wheel;

[0045] 2) In the beaker, 98% analytical pure phosphoric acid and water are mixed in a ratio of 1:5 (volume ratio) to obtain a clear electrolytic corrosion solution, which is stirred uniformly with a glass rod;

[0046] 3) The corrosion solution is placed in an electrolytic container, and a lead plate is used as the cathode, and the IN718 material forging (forged state) local longitudinal macroscopic sample to be corroded is used as the anode. Electrolysis is carried out at a voltage of 15V for 5min;

[0047] 4) The IN718 material forging (forged state) local longitudinal macroscopic sample after electrolytic corrosion is removed and washed in flowing water, and the sample surface is blown dry.

[0048] 5) The electrolytically corroded IN718 material forging (forged state) local longitudinal streamline is observed by naked eye to observe whether the metal streamline meets the specification requirements, and a photograph is taken for record.

[0049] The requirements for the IN718 material forging (forged state) local longitudinal macroscopic streamline are that the streamline of the forging should basically follow the contour, and no through-flow or vortex is allowed.

[0050] Figure 3 The streamline morphology of the IN718 material forging (forged state) local longitudinal macroscopic sample after electrolytic corrosion can be seen from the figure: the streamline basically follows the contour of the forging, but there is a very obvious strain band in the middle of the forging, so the forging does not meet the specification requirements can be found by naked eye.

[0051] The steps of conventional chemical corrosion for the local longitudinal macroscopic sample of IN718 material forging (forged state) are as follows: 1) 150ml of analytical pure hydrochloric acid, 30ml of analytical pure hydrofluoric acid, 100ml of water and 50g of high iron chloride are mixed to obtain a corrosion solution;

[0052] 2) The macroscopic sample is polished;

[0053] 3) After the sample is cleaned, it is immersed in the above-prepared corrosion solution for 20 minutes;

[0054] 4) The sample is taken out and the surface corrosion products are washed with flowing water;

[0055] 5) The sample surface is observed and photographed.

[0056] Figure 4 The streamline effect of the local longitudinal macroscopic sample of IN718 material forging (forged state) after conventional chemical corrosion can be seen from the figure, and there is no trace of streamline and no obvious strain band trace, so the conventional chemical method cannot directly show the streamline of the material.

[0057] From Examples 1 and 2, it can be concluded that using a simple corrosion solution and an electrolytic corrosion method can easily corrode the low-magnification streamline structure of the nickel-based wrought high-temperature alloy forging, accurately determine whether the streamline meets the specification requirements, verify the rationality of the forging process, and the operation is simple, the cost is low, and it can be used for scientific research testing or industrial production detection.

[0058] Example 3

[0059] The difference between this scheme and Example 1 is that the corrosion solution of this scheme is obtained by mixing hydrofluoric acid and water, and the streamline morphology of the local longitudinal macroscopic sample of IN718 material forging (heat treated state) after electrolytic corrosion obtained after treatment is as shown in Figure 5 The lines corroded are all interference structures, not normal streamline structures, so they cannot be used for streamline observation.

[0060] Example 4

[0061] The difference between this scheme and Example 1 is that the corrosion solution of this scheme is obtained by mixing hydrofluoric acid and water, and the streamline morphology of the local longitudinal macroscopic sample of IN718 material forging (heat treated state) after electrolytic corrosion obtained after treatment is as shown in Figure 6 It can be seen that the corrosion surface is full of holes and no streamline structure is seen, so it cannot be used for streamline observation.

[0062] Example 5

[0063] The difference between this scheme and Example 2 is that the corrosion solution of this scheme is obtained by mixing oxalic acid and water, and the streamline morphology of the local longitudinal macroscopic sample of IN718 material forging (forged state) after electrolytic corrosion obtained after treatment is as shown inFigure 7 As shown by comparison Figure 3 and Figure 7 Especially, comparing A with a, B with b, and C with c, it can be found that the scheme is difficult to remove the corrosion product, which causes uneven and discontinuous display of the streamline, and affects the judgment of the streamline organization.

[0064] The above merely provides the preferred embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A macro etch method for nickel-based wrought superalloy forgings, characterized by: The nickel-based wrought superalloy is subjected to forging treatment between the recrystallization temperature and the overheating temperature of the corresponding material or is subjected to heat treatment again after the forging treatment, and then is subjected to electrolytic corrosion by using a corrosion solution obtained by mixing analytical pure phosphoric acid with water at a volume ratio of 1:5-10 as an electrolyte, using a nickel-based wrought superalloy macroscopic sample to be subjected to corrosion detection after treatment as an anode, and using an inert metal or a carbon plate as a cathode, and adopting a direct-current stabilized power supply. The voltage of the electrolysis is 10V-15V, and the electrolysis time is 5min-8min; the nickel-based wrought superalloy macroscopic sample of the anode is in a forged state or a heat-treated state.

2. The method for low-magnification flow line corrosion of nickel-based deformed high-temperature alloy forgings according to claim 1, characterized in that: The surface of the nickel-based wrought superalloy macroscopic sample of the anode to be subjected to corrosion is subjected to grinding wheel processing treatment by using a grinding machine before corrosion.

3. The method according to any one of claims 1-2, characterized in that: After the electrolytic corrosion, the sample is taken out, washed in flowing water, and then observed by naked eyes after the surface of the sample is blown dry.

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