Constant-temperature corrosion control device and control method for aluminum alloy intergranular corrosion

Abstract

The invention provides a constant-temperature corrosion control device and a constant-temperature corrosion control method for aluminum alloy intergranular corrosion. The constant-temperature corrosion control device comprises a test box unit and a corrosion unit, the test box unit comprises a test box and a test box bracket; the corrosion unit comprises a vessel, a sample, a clamp, a string / belt and a vessel cover; an intergranular corrosion solution is contained in the vessel, the vessel is arranged in the test box, a sample is clamped on the surface of the sample through a clamp, the clamp penetrates through the vessel cover through a thin rope / belt and is connected to a test box support, and the test box support is located at the top end of the test box and can meet parallel tests of three or more sample products. Under the condition that the sample is not damaged, the temperature of the intergranular corrosion solution is controlled according to the heat conduction and heat convection principle of the test box, and the accurate control problem of the corrosion temperature in the aluminum alloy intergranular corrosion method is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallographic analysis, and in particular to a constant temperature corrosion control device and a control method for intergranular corrosion of an aluminum alloy. Background Art

[0002] The aluminum alloy intergranular corrosion test is a corrosion test that accelerates the intergranular corrosion rate by enhancing the cathode depolarization effect of the sample. The sample is immersed for a certain period of time to observe the corrosion state and depth at the aluminum alloy grain boundary. The test includes sample pretreatment, corrosion, reprocessing, inlaying, grinding, polishing, analysis and other links. The aluminum alloy intergranular corrosion test is much less than the stainless steel intergranular corrosion test in the metallographic test. According to GB / T 7998-2023 "Evaluation Method for Intergranular Corrosion Sensitivity of Aluminum Alloys", 2xxx, 6xxx, and 7xxx series are evaluated using the corrosion depth method.

[0003] After sample preparation and pretreatment, the sample is usually placed directly in a beaker to immerse the contact vessel. The liquid flow is restricted, which can easily cause uneven corrosion. It is usually necessary to drill holes in the sample before corrosion. If the hole is close to the observation surface, it may aggravate the corrosion on one side.

[0004] At present, there are no special equipment and devices for intergranular corrosion of aluminum alloys. The conduction thermostat required by the standard is usually a water bath or an electric furnace, which is required to reach a relatively stable corrosion temperature of 30℃±3℃. Due to the lack of necessary thermostat control equipment, the corrosion temperature cannot be fully guaranteed, which in turn affects the observation of corrosion status and depth. In addition, water baths and electric furnaces are usually small. Due to the ratio of the test liquid volume to the area of ​​the sample immersion surface and the accumulation of corrosion products, materials of different grades cannot be tested in the same water bath or electric furnace, and simultaneous testing of multiple materials and multiple stations cannot be achieved in one test. Summary of the invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a constant temperature corrosion control device and control method for intergranular corrosion of aluminum alloys.

[0006] According to the present invention, a constant temperature corrosion control device for aluminum alloy intergranular corrosion includes: a test box unit and a corrosion unit;

[0007] The test box unit includes a test box 6 and a test box bracket 5;

[0008] The corrosion unit comprises a vessel 1, a sample 2, a fixture 3, a string / belt 4 and a vessel cover 7;

[0009] The vessel 1 is filled with an intergranular corrosion solution and placed in a test box 6. The sample 2 is clamped on the surface of the sample 2 by a clamp 3. The clamp 3 is connected to the test box bracket 5 through a thin rope / belt 4 passing through the vessel cover 7. The test box bracket 5 is located at the top of the test box 6 and can meet the needs of parallel testing of 3 or more sample products.

[0010] Preferably, the test chamber unit has a temperature control function, the temperature settings include 30°C and 35°C, the temperature variation is ±2°C, and it also has a time setting function.

[0011] Preferably, the vessel 1 comprises a glass beaker and a polytetrafluoroethylene beaker;

[0012] The vessel container is 100 to 200 mL.

[0013] Preferably, the string / ribbon comprises polypropylene rope or other non-metallic ribbon.

[0014] Preferably, the vessel cover has a hole at the center of the cover, and the diameter of the hole is less than 5 mm;

[0015] The vessel cover comprises a cover made of polytetrafluoroethylene or a plastic film.

[0016] Preferably, the material of the clamp 3 is engineering material, including non-metallic material;

[0017] The clamp 3 has holes.

[0018] Preferably, the isothermal corrosion control device for intergranular corrosion of aluminum alloy can be arranged in a multi-array manner to achieve multi-station testing of multiple batches of samples.

[0019] According to a control method of a constant temperature corrosion control device for intergranular corrosion of an aluminum alloy provided by the present invention, the control method adopts the constant temperature corrosion control device for intergranular corrosion of an aluminum alloy, and comprises:

[0020] Step S1: setting the temperature of the test chamber to a predetermined temperature;

[0021] Step S2: placing an intergranular corrosion solution in a container and placing the container in the test box for constant temperature heating for a predetermined time;

[0022] Step S3: pre-treating the intergranular corrosion sample and clamping the non-viewing side of the sample with a clamp;

[0023] Step S4: Pass one end of the string / belt through the hole of the clamp and fix it, and pass the other end through the vessel cover and wrap it around the test box bracket and fix it;

[0024] Step S5: the sample is placed in a container and completely immersed in the intergranular corrosion solution, with the clamping surface being lower than the solution by a certain distance;

[0025] Step S6: The surface of the vessel is covered with a vessel cover, and the test box is set to perform corrosion test according to the material type.

[0026] Preferably, the predetermined time in step S2 is 5 minutes;

[0027] In step S3, the fixture clamps the non-observation surface of the sample, and the clamping depth is no more than 2 mm;

[0028] In step S5, the distance is 25 mm, and the sample is suspended in the middle of the solution, and the sides and bottom are not allowed to touch the container.

[0029] Preferably, the material types in step S6 include 2xxx, 6xxx, 7xxx series aluminum alloys and 5xxx series aluminum alloys, and the set corrosion times are 6 hours and 24 hours, respectively.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention realizes temperature control of the intergranular corrosion solution by heat conduction and heat convection principle of the test box without destroying the sample, thereby solving the problem of accurate control of corrosion temperature in the intergranular corrosion method of aluminum alloy.

[0032] 2. The present invention realizes the clamping method on the non-observation surface with a simple device, providing a more accurate corrosion environment. The temperature difference during the test changes by only ±0.2°C. The simple device realizes a more reliable corrosion process and meets the standard requirements. At the same time, a more typical continuous distributed intergranular corrosion phenomenon is observed.

[0033] 3. The large-space test box of the present invention can form a multi-array corrosion system to realize multi-station testing of multiple batches of samples, better serve the intergranular corrosion test, and realize and obtain more accurate corrosion status and corrosion depth.

[0034] 4. The present invention can be used as a test method for the corrosion depth method of intergranular corrosion test. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0036] Figure 1 It is a structural schematic diagram of the constant temperature corrosion control device for intergranular corrosion of aluminum alloy according to the present invention;

[0037] Figure 2 This is an overall diagram of the multiple stations of the constant temperature corrosion control device for intergranular corrosion of aluminum alloys of the present invention.

[0038] Reference numerals: 1. vessel; 2. sample; 3. fixture; 4. string / belt; 5. test chamber support; 6. test chamber; 7. vessel cover. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0040] The present invention includes a test box and a beaker containing an intergranular corrosion solution, which is placed in the box for constant temperature control; the sample is clamped on the sample surface with an engineering material clamp, so that it does not react with the solution; a polypropylene rope is passed through the hole of the clamp and then hung on the low-temperature test box bracket, and a hanging height is reserved; the sample is immersed in the intergranular corrosion solution. After 6 or 24 hours of corrosion, the sample is taken out and rinsed with an ultrasonic cleaner and dried naturally. After grinding and polishing, a sample that meets the test standard requirements can be obtained and inspected under a microscope at 100 to 500 times.

[0041] Embodiment 1

[0042] According to the invention, a constant temperature corrosion control device for aluminum alloy intergranular corrosion is provided, such as Figure 1 As shown, it includes a test box unit and a corrosion unit. The test box unit includes a test box 6 and a test box bracket 5, and the corrosion unit includes a vessel 1, a sample 2, a fixture 3, a string / belt 4 and a vessel cover 7. The vessel 1 is filled with an intergranular corrosion solution and is placed in the test box 6. The sample 2 is clamped on the surface of the sample 2 by the fixture 3. The fixture 3 is connected to the test box bracket 5 through the vessel cover 7 by a string / belt 4. The test box bracket 5 is located at the top of the test box 6, which can meet the parallel testing of 3 or more sample products.

[0043] The test chamber unit has a temperature control function, the temperature settings include 30°C and 35°C, the temperature change is ±2°C, and it also has a time setting function.

[0044] The vessel 1 includes a glass beaker and a polytetrafluoroethylene beaker, and the vessel container is 100-200 mL. The thin rope / belt includes a polypropylene rope or other non-metallic ribbon. The lid of the vessel is punched in the center, and the hole diameter is less than 5 mm. The material includes polytetrafluoroethylene material and plastic film. The clamp 3 is an engineering material, such as a non-metallic material with holes.

[0045] In addition, if Figure 2As shown, the constant temperature corrosion control device for intergranular corrosion of aluminum alloy can be arranged in a multi-array manner to realize multi-station testing of multiple batches of samples, better serve the intergranular corrosion test, and realize and obtain more accurate corrosion status and corrosion depth.

[0046] Embodiment 2

[0047] A control method of a constant temperature corrosion control device for aluminum alloy intergranular corrosion provided by the present invention comprises:

[0048] Step S1: Set the temperature of the test box to a predetermined temperature, such as 30°C.

[0049] Step S2: The intergranular corrosion solution is placed in a container and placed in the test box for constant temperature heating for a predetermined time, such as 5 minutes, to ensure that the temperature of the intergranular corrosion solution meets the standard requirements.

[0050] Step S3: After pre-treating the intergranular corrosion sample, clamp the non-observation side of the sample with a clamp. Specifically, after pre-treating the intergranular corrosion sample with a size of 40 mm×25 mm, clamp the non-observation side of the sample with a small engineering material clamp, and the clamping depth should not be greater than 2 mm to obtain a more comprehensive corrosion surface.

[0051] Step S4: Pass one end of the string / belt through the hole of the clamp and fix it, and pass the other end through the cover of the vessel, wrap it around the test box bracket and fix it. Pass one end of the polypropylene rope through the hole of the clamp and tie a knot to fix it. Pass the other end through the cover of the vessel, wrap it around the test box bracket and tie a knot to fix it.

[0052] Step S5: The sample is placed in a container and completely immersed in the intergranular corrosion solution, with the clamping surface being lower than the solution by a distance of 25 mm. The sample is suspended in the middle of the solution, and the sides and bottom are not allowed to touch the container.

[0053] Step S6: The surface of the vessel is covered with a vessel cover, and the test box is set to perform corrosion test for a certain time according to the material type. The corrosion time for 2xxx, 6xxx, and 7xxx series aluminum alloys is 6 hours, and the corrosion time for 5xxx series aluminum alloys is 24 hours.

[0054] Specifically. The operation method of the device of the present invention is specifically described as follows: open the test box and set the temperature to 30°C. Put 150mL of intergranular corrosion solution (57gNaCl in 990mL water + 10mL30% H2O2) into a 200mL glass beaker and place it in a low-temperature test box for constant temperature heating for 5 to 10 minutes. After pretreatment, the intergranular corrosion specimen with a size of 40mm×25mm is clamped with a clamp to clamp the observation surface of the plate perpendicular to the rolling direction of the plate. In order to obtain a comprehensive corrosion surface, the clamping depth should not be greater than 2mm. Pass one end of the polypropylene rope through the hole of the clamp and tie it to fix it. The other end passes through the polytetrafluoroethylene cover, is wrapped around the test box bracket, and is tied to fix it. The sample is completely immersed in the intergranular corrosion solution, and the clamping surface is 25mm below the liquid level. The sample is suspended in the middle of the solution, and any surface does not touch the container. Cover the lid and set the corrosion time for the test box. The temperature deviation of the low-temperature test box should be less than ±1°C, and it has a time display function. The fixture with holes is of engineering material, which can be non-metallic such as plastic. The string / belt used for fixing can be polypropylene rope or other non-metallic ribbon. The vessel cover can be made of polytetrafluoroethylene, with a hole punched in the center of the cover, and the hole diameter is less than 5mm.

[0055] Furthermore, the apparatus and test method of the present invention are illustrated by way of example. It is assumed that the test sample is a 2219 plate, and GB / T 7998-2023 “Evaluation Method for Intergranular Corrosion Sensitivity of Aluminum Alloys” is used to carry out an intergranular corrosion test of a 2xxx series aluminum alloy.

[0056] The samples were processed into three intergranular corrosion samples with a size of 40 mm × 25 mm × 6 mm along the rolling direction, and the thickness of 6 mm was the original thickness of the material. The samples were pretreated in a solution containing 100 g / L sodium hydroxide for 15 minutes.

[0057] Sample 2 was subjected to intergranular corrosion in the apparatus described above. Figure 1 As shown, the sample is clamped at 1mm with a fixture 3 and fixed to the test box bracket 5 with a polypropylene rope 4. The sample is completely immersed in a beaker 1 filled with 150mL of analytical pure corrosion solution (57gNaCl in 990mL laboratory secondary water + 10mL30% H2O2), covered with a vessel cover 7, and corroded for 6 hours in a relatively closed corrosion environment. The temperature control range of the test box 6 is 29.9℃ to 30.2℃.

[0058] The corroded samples were cleaned with an ultrasonic cleaner for at least 5 times until the corrosion products were removed, and cut with a cutting machine at least 5 mm away from the observation surface. After grinding and polishing, the intergranular corrosion results were evaluated under a metallographic microscope and a confocal microscope at a magnification of 200. The typical and continuously distributed intergranular corrosion depth was 0.17 mm, which was standard level 4 intergranular corrosion.

[0059] Similarly, assuming that the test specimen is 2024 plate, GB / T 7998-2023 “Evaluation Method for Intergranular Corrosion Sensitivity of Aluminum Alloys” is used to carry out intergranular corrosion test of 2xxx series aluminum alloys.

[0060] The samples were processed into 3 intergranular corrosion samples with a size of 40 mm × 25 mm × 0.5 mm along the rolling direction, and the thickness of 0.5 mm was the original thickness of the material. The samples were pretreated in a solution containing 100 g / L sodium hydroxide for 15 minutes. The remaining steps were the same as in implementation 1. After microscopic evaluation, there was no intergranular corrosion.

[0061] From the above analysis, it can be seen that the test box corrosion device of this embodiment is convenient for conducting intergranular corrosion of aluminum alloys, and realizes synchronous testing of multiple batches and multiple station samples.

[0062] In summary, the present invention has a simple structure and an obvious effect during the experiment, and realizes the inspection and measurement of the state and depth of intergranular corrosion of aluminum alloys. While overcoming the lack of test equipment, a practical and efficient corrosion method is realized. For those skilled in the art, the experimental object of the present invention can be subjected to various changes and variations. All approved changes, equivalent substitutions, improvements, etc. made within the spirit and original site of the present invention are included in the protection of the present invention.

[0063] The method of the present invention overcomes the shortcomings of existing detection technology without destroying the sample, and provides a corrosion test system suitable for aluminum alloy intergranular corrosion test, which uses a test box for constant temperature control to achieve corrosion and clamping integration. It solves the problem of accurate control of corrosion temperature in the aluminum alloy intergranular corrosion method, solves the problem of insufficient corrosion on each surface, and can realize multi-station tests of multiple batches of samples, better serve the intergranular corrosion test, and achieve and obtain more accurate corrosion status and corrosion depth. It is suitable as a test method means for the corrosion depth method of intergranular corrosion test.

[0064] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0065] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A constant temperature corrosion control device for intergranular corrosion of aluminum alloy, characterized in that: include: Includes test chamber unit and corrosion unit; The test chamber unit comprises a test chamber (6) and a test chamber support (5); The corrosion unit comprises a vessel (1), a sample (2), a fixture (3), a string / belt (4) and a vessel cover (7); The vessel (1) is filled with an intergranular corrosion solution and is placed in a test box (6). The sample (2) is clamped on the surface of the sample (2) by a clamp (3). The clamp (3) is connected to the test box bracket (5) through a thin rope / belt (4) passing through the vessel cover (7). The test box bracket (5) is located at the top of the test box (6) and can meet the needs of parallel testing of 3 or more sample products.

2. The isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 1, characterized in that: The test chamber unit has a temperature control function, the temperature settings include 30°C and 35°C, the temperature change is ±2°C, and it also has a time setting function.

3. The isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 1, characterized in that: The vessel (1) comprises a glass beaker and a polytetrafluoroethylene beaker; The vessel container is 100 to 200 mL.

4. The isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 1, characterized in that: The string / ribbon may include polypropylene string or other non-metallic ribbon.

5. The isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 1, characterized in that: The lid of the vessel has a hole at the center, and the diameter of the hole is less than 5 mm; The vessel cover comprises a cover made of polytetrafluoroethylene or a plastic film.

6. The isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 1, characterized in that: The material of the clamp (3) is engineering material, including non-metallic material; The clamp (3) has holes.

7. The isothermal corrosion control device for aluminum alloy intergranular corrosion according to any one of claims 1 to 6, characterized in that: The constant temperature corrosion control device for intergranular corrosion of aluminum alloy can be arranged in a multi-array manner to achieve multi-station testing of multiple batches of samples.

8. A control method for a constant temperature corrosion control device for intergranular corrosion of aluminum alloys, characterized in that: The isothermal corrosion control device for intergranular corrosion of aluminum alloys according to any one of claims 1 to 6 and the control method include: Step S1: setting the temperature of the test chamber to a predetermined temperature; Step S2: placing an intergranular corrosion solution in a container and placing the container in the test box for constant temperature heating for a predetermined time; Step S3: pre-treating the intergranular corrosion sample and clamping the non-viewing side of the sample with a clamp; Step S4: Pass one end of the string / belt through the hole of the clamp and fix it, and pass the other end through the vessel cover and wrap it around the test box bracket and fix it; Step S5: the sample is placed in a container and completely immersed in the intergranular corrosion solution, with the clamping surface being lower than the solution by a certain distance; Step S6: The surface of the vessel is covered with a vessel cover, and the test box sets the time according to the material type to conduct the corrosion test.

9. The control method of the isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 8, characterized in that: The predetermined time in step S2 is 5 minutes; In step S3, the fixture clamps the non-observation surface of the sample, and the clamping depth is no more than 2 mm; In step S5, the distance is 25 mm, and the sample is suspended in the middle of the solution, and the sides and bottom are not allowed to touch the container.

10. The control method of the isothermal corrosion control device for aluminum alloy intergranular corrosion according to claim 8, characterized in that: The material types in step S6 include 2xxx, 6xxx, 7xxx series aluminum alloys and 5xxx series aluminum alloys, and the set corrosion times are 6 hours and 24 hours respectively.

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