CN115127886A - Internal stress testing method for aluminum alloy sheet - Google Patents
Internal stress testing method for aluminum alloy sheet Download PDFInfo
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- CN115127886A CN115127886A CN202210716206.9A CN202210716206A CN115127886A CN 115127886 A CN115127886 A CN 115127886A CN 202210716206 A CN202210716206 A CN 202210716206A CN 115127886 A CN115127886 A CN 115127886A
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Abstract
The invention relates to the field of stress testing of aluminum alloy materials, in particular to an internal stress testing method of an aluminum alloy sheet. The method carries out the evaluation of the internal stress by measuring the bending value of the sheet, can accurately reflect the size of the internal stress value of the sheet, is convenient for visually carrying out the transverse comparison of the internal stress size between the aluminum alloy sheets, and thus evaluates the quality of the aluminum alloy sheets.
Description
Technical Field
The invention relates to the field of stress testing of aluminum alloy materials, in particular to an internal stress testing method of an aluminum alloy sheet.
Background
The aluminum alloy plate has various excellent performances of easy processing and forming, small density, high corrosion resistance, low thermal expansion coefficient, high specific strength, outstanding strain capacity and the like, thereby being widely applied to the fields of aerospace, navigation, road traffic, building industry, advanced weapons and the like.
Internal stress refers to the stress remaining in the elastic material after the external load is removed, and is characterized by forming a balanced force system in the object, i.e. observing the static condition. Internal stress is an inherent stress generally existing in an aluminum alloy sheet and is generated due to uneven volume change of a macroscopic or microscopic structure inside the material. The rolling deformation condition of the aluminum alloy sheet is symmetrical to the neutral plane, and the deformation of the part which is far away from the neutral plane and close to the roller is more serious, so the internal stress distribution situation has the following characteristics: the internal stress of the sheet varies only with the thickness of the sheet and is uniformly distributed in any plane parallel to the median plane of the sheet, and is symmetrically distributed along the median plane of the sheet, parallel to the median plane of the sheet.
The existence of the internal stress has important influence on the strength, fatigue property and surface strength of the part, and can also cause the size deviation of the part and the harmful influence such as deformation in the using process. Therefore, the research on the internal stress is of great significance in the aspects of controlling the processing deformation and ensuring the strength and the surface quality of the part.
At present, the traditional residual stress measurement method can be divided into a mechanical release measurement method and a nondestructive measurement method. The mechanical relaxation method is a method in which a part having internal stress is separated or cut from a member to relax the stress, and the residual internal stress is obtained by measuring the change in strain, and this method requires a certain degree of damage to the workpiece, is more difficult to handle for a thin plate, and introduces new residual stress, and mainly includes a drilling method, a ring core method, a division slitting method, and the like. The delamination method needs to remove the material layer by layer, and the residual stress value is measured by combining other testing methods, so that the measured value is inaccurate due to stress release caused in the process of removing the material. The nondestructive measurement method, i.e., the physical detection method, includes mainly an X-ray diffraction method, a neutron diffraction method, a scanning electron-acoustic microscopy method, an electron speckle interferometry, an ultrasonic method, a magnetic method, and the like. These methods are not harmful to the measured object, but require expensive equipment, among them, the X-ray method and the neutron diffraction method cannot accurately measure the internal stress of the thin plate with serious texture and the detection range is shallow, and the magnetic method is only suitable for the material with ferromagnetism.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention provides an internal stress testing method for an aluminum alloy sheet, which can accurately evaluate the internal stress of the aluminum alloy sheet. The method selects the rectangular plate when measuring the residual stress, when a part of material parallel to a neutral plane is removed, the original stress balance state is destroyed, the test piece is subjected to redistribution and bending deformation of the internal stress, and the internal stress of the thin plate is evaluated by measuring the warping value of the aluminum alloy thin plate, thereby completing the invention.
In order to achieve the above purpose, the invention provides the following technical scheme:
a method for internal stress testing of an aluminum alloy sheet, comprising the steps of:
step 1): preparing a rectangular aluminum alloy test piece, wherein the length direction x of the test piece is parallel to the rolling direction, one surface formed in the length direction x and the width direction y of the test piece is marked as a front surface, and the other surface opposite to the front surface is a negative surface;
step 2): coating protective glue on the other five surfaces of the test piece in the step 1) except the negative side;
step 3): preparing an alkaline corrosion solution;
step 4): soaking the test piece coated with the protective adhesive in the step 2) in the alkaline corrosion solution in the step 3) for chemical corrosion, so that the thickness of the test piece is reduced to half of the original thickness;
step 5): carrying out post-treatment on the thinned test piece in the step 4);
step 6): and measuring the warpage value of the test piece after the post-treatment in the step 5).
According to an embodiment of the invention, in step 1), the rectangular aluminum alloy test piece has an aspect ratio of 3:1 to 6:1, such as 3:1, 4:1, 5:1 or 6:1, a length in a range of 90mm to 120mm, such as 90mm, 100mm, 110mm or 120mm, and a thickness in a range of 1.0mm to 4.0mm, such as 1.0mm, 2.0mm, 3.0mm or 4.0 mm.
According to an embodiment of the present invention, in the step 1), the rectangular aluminum alloy test piece is obtained by performing solution heat treatment, and then leveling and reducing internal stress by using a stretching process.
According to an embodiment of the present invention, in the step 1), the rectangular aluminum alloy test piece is preferably a rectangular aluminum alloy test piece which is subjected to pretreatment such as cleaning and decontamination.
According to the embodiment of the invention, in the step 2), the protection glue is coated uniformly and completely on the front surface of the test piece and four surfaces of the test piece in the thickness direction z by using a soft brush, and the natural air drying time is 24-48 h.
According to an embodiment of the present invention, in the step 2), the thickness of the protective glue is 0.2mm to 0.3 mm.
According to an embodiment of the present invention, in the step 2), the protective adhesive is a protective adhesive known in the art and capable of preventing the aluminum alloy from being corroded by the alkaline corrosion solution, and is exemplarily selected from HX-150 protective adhesives.
According to an embodiment of the present invention, in the step 3), the alkaline etching solution comprises sodium hydroxide: 200-300 g/L, benzotriazole and derivatives thereof: 5-20 g/L; the alkaline corrosion solution can realize the rapid thinning treatment of the aluminum alloy test piece, so that the aluminum alloy test piece can finish the uneven distribution of stress as soon as possible to generate uniform deformation, and the test accuracy of the warpage value is further improved.
According to an embodiment of the present invention, in the step 3), the alkaline etching solution preferably comprises sodium hydroxide: 200-300 g/L (such as 200g/L, 210g/L, 220g/L, 230g/L, 240g/L, 250g/L, 260g/L, 270g/L, 280g/L, 290g/L or 300g/L), benzotriazole and its derivatives: 5-20 g/L (e.g., 5g/L, 6g/L, 7g/L, 8g/L, 9g/L, 10g/L, 11g/L, 12g/L, 13g/L, 14g/L, 15g/L, 16g/L, 17g/L, 18g/L, 19g/L, or 20 g/L).
According to an embodiment of the invention, in the step 3), the temperature of the alkaline etching solution is 80-90 ℃.
According to an embodiment of the present invention, the step 4) specifically includes: vertically soaking the test piece obtained in the step 1) in an alkaline corrosion solution, recording the residual thickness of the thin plate every 5min of soaking, shortening the time of each measurement to 1-3 min when the thickness approaches 1/2 until the thickness reaches 1/2, and recording the total corrosion time t; the test piece coated with the protective adhesive in the step 2) is corroded to 1/2 the thickness of the total thickness of the test piece according to the corrosion speed, and the corrosion speed of the test piece coated with the protective adhesive in the step 2) is 2 t.
According to the embodiment of the invention, in the step 4), the test piece is placed in the solution vertically (perpendicular to the ground).
According to the embodiment of the invention, in the step 5), the post-treatment comprises the steps of removing the protective glue and brightening, wherein the deformation of the test piece after the protective glue is removed is further increased, which is beneficial to obtaining a more accurate warping value of the test piece, so as to increase the accuracy of the internal stress testing method of the aluminum alloy sheet. In addition, the aluminum alloy generates black ash after contacting with the alkaline corrosive solution, so the surface is dirty and is not beneficial to subsequent tests.
The light extraction is performed for 30-60 s in a 500mL/L nitric acid (w ═ 65%) light extraction solution at room temperature of 25 +/-5 ℃ for example until the surface of the test piece is bright.
According to an embodiment of the present invention, in the step 6), the warpage value measurement method is: the test piece is placed on a plane with the convex surface facing upward, the width direction y of the test piece is parallel to the plane and is attached to the plane, and the highest distance from the highest point of the convex surface to the plane is measured, that is, the warpage value, for example, refer to fig. 2.
According to an embodiment of the present invention, in the step 6), the warpage value is measured specifically by: and measuring the length L of the bent test piece along the x direction, measuring the vertical distances from the L/2 position of the test piece and the horizontal planes at 5 positions which are 1mm and 2mm away from the L/2 position and are positioned at the 1/2 position of the test piece width to the test piece by using a vernier caliper, and taking the maximum value as the warpage value of the test piece.
According to the embodiment of the invention, the thickness measurement mode of the test piece is specifically as follows: 5 points of the test piece in the length direction x are averagely selected at the position of the width 1/2 of the test piece, and the thickness of the 5 points is measured by a vernier caliper to obtain the average value as the thickness of the test piece.
According to the embodiment of the invention, at least three samples of each type of aluminum alloy sheet sample are taken for carrying out the above steps, and the average value of the warpage values of the three samples is taken as the warpage value of the sample for internal stress evaluation.
According to an embodiment of the invention, the testing method comprises the following steps:
the method comprises the following steps: preparing an internal stress test piece, which specifically comprises: taking a rectangular aluminum alloy sheet without obvious defects as an internal stress test piece, wherein the length-width ratio is 3: 1-6: 1, the length range is 90-120 mm, the thickness range is 1.0-4.0 mm, cleaning the test piece, firstly lightly rubbing the front and back surfaces of the test piece with clean wiping cloth in flowing water at the flow rate of 0.5m/s for 30-60 s respectively to remove obvious stains, then wiping the test piece with a degreasing cotton ball dipped with alcohol, carrying out 20kHz ultrasonic oscillation in a mixed solution of acetone and water at the volume ratio of 1:2 for 5-10 min, then taking out, sequentially washing the test piece with alcohol and deionized water, and blowing the test piece by using a blowing cylinder, wherein the air speed is 20-40 m/s;
step two: coating a protective adhesive at a corresponding position on the test piece in the step one, and specifically comprises the following steps: stirring the protective glue for 1min at a speed of 120r/min by using a stirring rod, uniformly coating the protective glue with the thickness of 0.2-0.3 mm on the front surface of the test piece and four surfaces of the test piece in the thickness direction z by using a soft brush, and naturally drying the protective glue for 24-48 h until the protective glue is completely combined with the surface of the plate;
step three: preparing an alkaline etching solution, which specifically comprises the following steps: the alkaline corrosion solution comprises the following components in percentage by weight: sodium hydroxide: 200-300 g/L, benzotriazole and derivatives thereof: 5-20 g/L; the temperature of the solution is 80-90 ℃; weighing the experimental materials on a balance, putting the materials into a beaker, slowly adding deionized water and stirring the materials to prepare a uniform solution, and heating and preserving heat in a constant-temperature water bath box; the volume of the adopted container is more than 1L, and the height is more than the length of the test piece, so that the test piece can be completely soaked in the solution;
step four: vertically soaking the test piece treated in the step two in an alkaline corrosion solution to be corroded to a certain thickness, and specifically comprising the following steps: performing a pre-test to determine the corrosion speed of the test piece, soaking the test piece which is not coated with the protective adhesive and is obtained in the step one in the alkaline corrosion solution obtained in the step three for 5min to record the residual thickness of the thin plate, shortening the time of each measurement to 1-3 min when the thickness approaches 1/2 until the thickness reaches 1/2, and recording the total corrosion time t; corroding the thin plate to 1/2 with the thickness being equal to the total thickness of the test piece according to the corrosion speed, wherein the corrosion time of the test piece coated with the protective adhesive obtained in the step two is 2 t;
step five: and D, carrying out post-treatment on the test piece treated in the step four, and specifically comprising the following steps of: taking out 1/2 test pieces corroded to the total thickness of the test pieces, washing the test pieces in flowing water at the flow rate of 0.5m/s, stripping off protective glue by hands, then, polishing the test pieces in 500mL/L nitric acid (w is 65%) at the room temperature of 25 +/-5 ℃ for 30-60 s until the surfaces of the test pieces are bright, washing the test pieces cleanly by the flowing water at the flow rate of 0.5m/s, and then, drying the test pieces by a blowing cylinder at the air speed of 20-40 m/s;
step six: measuring the warpage value of the test piece processed in the fifth step, and specifically comprising the following steps: and D, placing the sample obtained in the fifth step on a horizontal plane in a convex upward mode, wherein the width direction y of the sample is parallel to the plane and is attached to the plane. And measuring the vertical distance from the horizontal plane to the highest point of the convex surface as the warping value of the test piece.
Compared with the prior art, the invention has the beneficial effects that:
compared with a damage detection method, the method has the advantages that the damage and yield of the material caused by mechanical damage can be avoided, the measurement effect is not influenced, the thickness of the test piece is removed in a corrosion mode relative to a mechanical damage mode, the control is easy, and the method can be applied to the measurement of the internal stress of the thin plate. The nondestructive testing method has no damage to the tested piece, but has higher cost, expensive required equipment and difficult accurate measurement on the thin plate with complex texture, and the method has simple and convenient operation, requires less required experimental equipment and can accurately evaluate the internal stress of the aluminum alloy thin material without expensive large-scale equipment. In addition, other methods have complex calculation processes, are dedicated to measuring the value of the internal stress of the alloy, and cannot be intuitively compared. The method can accurately reflect the magnitude of the internal stress value of the sheet by measuring the buckling value of the bend of the sheet, and is convenient for visually carrying out transverse comparison of the magnitude of the internal stress between the aluminum alloy sheets, thereby evaluating the quality of the aluminum alloy sheets.
In addition, the testing method provided by the invention simulates the deformation of an aviation aluminum alloy sheet part subjected to weight reduction treatment by adopting single-side chemical milling, can be combined with the practical engineering application, and the tested internal stress level of the aluminum alloy sheet can be used for measuring the precision of the part after chemical milling, predicting the deformation, providing a basis for setting forming parameters, and simultaneously measuring the internal stress level of the aluminum alloy sheet and screening a material with small deformation for application.
Drawings
Fig. 1 is a schematic view of the position of the protective paste application.
FIG. 2 is a diagram showing the warpage value of the test piece after corrosion.
FIG. 3 is a schematic diagram showing the warp value of the test piece after corrosion in example 1.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
Example 1:
(1) taking a rectangular 2024 aluminum alloy sheet as an internal stress test piece, wherein the length-width ratio is 6:1, the length is 120mm, the thickness is 1.24mm, a surface formed in the length direction x and the width direction y of the test piece is marked as a front surface, the opposite surface of the front surface is marked as a back surface, and the length direction x of the test piece is parallel to the rolling direction. Cleaning the test piece, firstly rubbing the front and back surfaces of the test piece with clean wiping cloth in 0.5m/s flowing water for 30s respectively to remove obvious stains, then wiping the test piece with absorbent cotton balls dipped with alcohol, carrying out ultrasonic vibration at 20kHz for 5min in a mixed solution of acetone and water with the volume ratio of 1:2, then taking out the test piece, washing the test piece with alcohol and deionized water in sequence, and drying the test piece with a blowing cylinder at the air speed of 20 m/s.
(2) Stirring the mixture by using a stirring rod at a rotating speed of 120r/min for 1min to uniformly stir the HX-150 protective adhesive, then uniformly and completely coating the HX-150 protective adhesive on the periphery of the front surface and the thickness direction z of the test piece in the step (1) by using a soft brush, and naturally air-drying the coated protective adhesive for 24h, wherein the thickness of the coated protective adhesive is 0.2mm, as shown in figure 1, until the protective adhesive is completely combined with the surface of the plate.
(3) Preparing an alkaline corrosion solution in a beaker, firstly weighing 210g of sodium hydroxide, benzotriazole: 10g/L, placing the experimental materials in a beaker, slowly adding a small amount of deionized water, stirring to completely dissolve the experimental materials, and then slowly adding deionized water to 1L while stirring. And (4) putting the stabilized uniform corrosion solution into a constant-temperature water bath box for heating and preserving heat to 85 ℃.
(4) Vertically soaking the test piece treated in the step (1) in the solution prepared in the step (3) for corrosion, firstly, performing a pre-test to determine the corrosion speed of the test piece, recording the residual thickness of the thin plate of the test piece treated in the step (1) in the corrosion solution prepared in the step (3) every 5min, and shortening the time of each measurement to 2min when the thickness is close to 1/2 to obtain the residual thickness 1/2 of the test piece after 18min of corrosion. And (3) taking the test piece treated in the step (2) for one-time corrosion for 36min (the corrosion thickness is 0.62 mm).
(5) And (3) carrying out post-treatment on the test piece treated in the step (4), taking out the test piece corroded to 1/2 of the total thickness of the test piece, washing the test piece in flowing water with the flow rate of 0.5m/s, stripping the protective glue coated on the test piece by hands, brightening the surface of the test piece for 35s by using 500mL/L nitric acid (w is 65%) at the room temperature of 25 +/-5 ℃, washing the test piece cleanly by using the flowing water with the flow rate of 0.5m/s, and drying the test piece by using a blowing cylinder at the air speed of 20 m/s.
(6) And (4) placing the sample obtained in the step (5) on a plane in a convex upward manner, wherein the width direction y of the sample is parallel to the plane and is attached to the plane. The maximum distance from the highest point of the convex surface to the plane is measured according to the warpage value schematic diagram of fig. 2, the length L of the bent test piece along the x direction is measured, the vertical distances from the horizontal plane of the test piece at L/2 and at 5 positions which are 1mm and 2mm away from the L/2 and are located at the position of 1/2 of the test piece width to the test piece are measured by using a vernier caliper, the maximum value is taken as the warpage value of the test piece, and the warpage value is obtained to be 2.85mm, as shown in fig. 3.
Examples 2 to 3 and comparative examples 1 to 4
The other operations are the same as example 1, except that: the aluminum alloy thin plates have different thicknesses (only different thicknesses and completely same composition) and different compositions of the alkaline etching solution, and are specifically shown in the following table 1:
TABLE 1 thickness of sheet, composition of alkaline etching solution and warpage value of examples 1 to 3 and comparative examples 1 to 4
The results of the examples and the comparative examples show that the aluminum alloy sheet is subjected to chemical corrosion, the 1/2 thickness of the sheet is removed, the sheet is bent, and the degree of bending (warpage value) of the sheet can indicate the magnitude of the internal stress. In conclusion, the invention provides a simple and convenient internal stress assessment method, solves the problem that the internal stress assessment of the aluminum alloy sheet is difficult to carry out, can accurately and transversely compare the quality of the aluminum alloy sheet without complex calculation, and has important reference value in the aspects of the internal stress assessment and comparison of the aluminum alloy sheet.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. The internal stress testing method of the aluminum alloy sheet is characterized by comprising the following steps of:
step 1): preparing a rectangular aluminum alloy test piece, wherein the length direction x of the test piece is parallel to the rolling direction, one surface formed in the length direction x and the width direction y of the test piece is marked as a positive surface, and the other surface opposite to the positive surface is a negative surface;
step 2): coating protective glue on the other five surfaces of the test piece in the step 1) except the negative side;
step 3): preparing an alkaline corrosion solution;
step 4): soaking the test piece coated with the protective adhesive in the step 2) in the alkaline corrosion solution in the step 3) for chemical corrosion, so that the thickness of the test piece is reduced to half of the original thickness;
step 5): carrying out post-treatment on the thinned test piece in the step 4);
step 6): and measuring the warpage value of the test piece after the post-treatment in the step 5).
2. The internal stress test method of the aluminum alloy sheet according to claim 1, wherein in the step 1), the length-width ratio of the rectangular aluminum alloy test piece is 3:1 to 6:1, the length range is 90mm to 120mm, and the thickness range is 1.0mm to 4.0 mm.
3. The method for testing the internal stress of the aluminum alloy sheet as recited in claim 1, wherein in the step 1), the rectangular aluminum alloy test piece is obtained by performing solution heat treatment, and then flattening and reducing the internal stress by using a stretching process.
4. The internal stress test method of the aluminum alloy sheet according to claim 1, wherein in the step 2), the thickness of the protective glue is 0.2mm to 0.3 mm.
5. The internal stress test method of the aluminum alloy sheet according to claim 1, wherein in the step 3), the alkaline etching solution comprises the following components: 200-300 g/L, benzotriazole and derivatives thereof: 5 to 20 g/L.
6. The internal stress testing method of the aluminum alloy sheet according to claim 1, wherein the step 4) specifically comprises the following steps: vertically soaking the test piece obtained in the step 1) in an alkaline corrosion solution, recording the residual thickness of the thin plate every 5min of soaking, shortening the time of each measurement to 1-3 min when the thickness approaches 1/2 until the thickness reaches 1/2, and recording the total corrosion time t; the test piece coated with the protective adhesive in the step 2) is corroded to 1/2 the thickness of the total thickness of the test piece according to the corrosion speed, and the corrosion speed of the test piece coated with the protective adhesive in the step 2) is 2 t.
7. The internal stress testing method of the aluminum alloy sheet according to claim 1, wherein in the step 5), the post-treatment comprises the steps of removing the protective glue and the light extraction.
8. The internal stress test method of an aluminum alloy sheet according to claim 1, wherein in the step 6), the warpage value is determined by: the test piece is placed on a plane with the convex surface facing upwards, the width direction y of the test piece is parallel to the plane and is attached to the plane, and the maximum distance from the highest point of the convex surface to the plane is measured, namely the warping value.
9. The internal stress testing method of the aluminum alloy sheet according to claim 8, wherein in the step 6), the warpage value is measured by: and measuring the length L of the bent test piece along the x direction, measuring the vertical distances from the L/2 position of the test piece and the horizontal planes which are 1mm and 2mm away from the L/2 position and are positioned at 5 positions of the test piece width 1/2 to the test piece by using a vernier caliper, and taking the maximum value as the warpage value of the test piece.
10. The internal stress testing method of an aluminum alloy sheet according to claim 1, comprising the steps of:
the method comprises the following steps: preparing an internal stress test piece, which specifically comprises: taking a rectangular aluminum alloy sheet without obvious defects as an internal stress test piece, wherein the length-width ratio is 3: 1-6: 1, the length range is 90-120 mm, the thickness range is 1.0-4.0 mm, cleaning the test piece, firstly lightly rubbing the front and back surfaces of the test piece with clean wiping cloth in flowing water at the flow rate of 0.5m/s for 30-60 s respectively to remove obvious stains, then wiping the test piece with a degreasing cotton ball dipped with alcohol, carrying out 20kHz ultrasonic oscillation in a mixed solution of acetone and water at the volume ratio of 1:2 for 5-10 min, then taking out, sequentially washing the test piece with alcohol and deionized water, and blowing the test piece by using a blowing cylinder, wherein the air speed is 20-40 m/s;
step two: coating a protective adhesive at a corresponding position on the test piece in the first step, specifically comprising: stirring the protective glue by a stirring rod at 120r/min for 1min, uniformly stirring the protective glue, uniformly coating the protective glue with the thickness of 0.2-0.3 mm on the front surface of the test piece and four surfaces of the test piece in the thickness direction z by using a soft brush, and naturally air-drying the protective glue for 24-48 h until the protective glue is completely combined with the surface of the plate;
step three: preparing an alkaline etching solution, which specifically comprises the following steps: the alkaline corrosion solution comprises the following components in percentage by weight: sodium hydroxide: 200-300 g/L, benzotriazole and derivatives thereof: 5-20 g/L; the temperature of the solution is 80-90 ℃; weighing the experimental materials on a balance, putting the materials into a beaker, slowly adding deionized water and stirring the materials to prepare a uniform solution, and heating and preserving heat in a constant-temperature water bath box; the volume of the adopted container is more than 1L, and the height is more than the length of the test piece, so that the test piece can be completely soaked in the solution;
step four: vertically soaking the test piece treated in the step two in an alkaline corrosion solution to be corroded to a certain thickness, and specifically comprising the following steps: performing a pre-test to determine the corrosion speed of the test piece, soaking the test piece which is not coated with the protective adhesive and is obtained in the step one in the alkaline corrosion solution obtained in the step three for 5min to record the residual thickness of the thin plate, shortening the time of each measurement to 1-3 min when the thickness approaches 1/2 until the thickness reaches 1/2, and recording the total corrosion time t; corroding the thin plate to 1/2 with the thickness being the total thickness of the test piece according to the corrosion speed, wherein the corrosion time of the test piece coated with the protective adhesive obtained in the step two is 2 t;
step five: and D, carrying out post-treatment on the test piece treated in the step four, and specifically comprising the following steps of: taking out 1/2 test pieces corroded to the total thickness of the test pieces, washing the test pieces in flowing water with the flow rate of 0.5m/s, removing protective glue by hands, then, brightening the test pieces by 500mL/L nitric acid (w is 65%) in brightening solution at the room temperature of 25 +/-5 ℃ for 30-60 s until the surfaces of the test pieces are bright, washing the test pieces by the flowing water with the flow rate of 0.5m/s, and then, drying the test pieces by a blowing cylinder at the wind speed of 20 m/s-40 m/s;
step six: measuring the warpage value of the test piece processed in the fifth step, and specifically comprising the following steps: and D, placing the sample obtained in the fifth step on a horizontal plane with the convex surface upward, enabling the width direction y of the sample to be parallel to the plane and attached to the plane, and measuring the vertical distance from the horizontal plane to the highest point of the convex surface to be the warping value of the test piece.
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| CN (1) | CN115127886A (en) |
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2022
- 2022-06-22 CN CN202210716206.9A patent/CN115127886A/en active Pending
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