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

Abstract

The application provides an aluminum alloy intergranular corrosion constant-temperature corrosion control device and control method, which comprises a test box unit and a corrosion unit; the test box unit comprises a test box and a test box support; the corrosion unit comprises a vessel, a sample, a clamp, a thin rope / belt and a vessel cover; the vessel is filled with an intergranular corrosion solution and is placed in the test box; the sample is clamped on the sample surface by the clamp; the clamp is connected to the test box support through the thin rope / belt and the vessel cover; the test box support is located at the top end of the test box and can satisfy parallel test of three or more sample products. The application realizes temperature control of the intergranular corrosion solution by heat conduction and heat convection principles of the test box without damaging the sample, and solves the problem of accurate control of corrosion temperature in the aluminum alloy intergranular corrosion method.

Description

TECHNICAL FIELD

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

[0002] Aluminum alloy intergranular corrosion test is a kind of corrosion test that accelerates the intergranular corrosion rate by enhancing the cathode depolarization effect, and observes the corrosion state and depth of the aluminum alloy grain boundary after soaking for a certain period of time. The test includes sample pretreatment, corrosion, reprocessing, inlaying, grinding, polishing, and analysis. 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 "Aluminum Alloy Intergranular Corrosion Sensitivity Evaluation Method", 2xxx, 6xxx, and 7xxx series are evaluated by corrosion depth method.

[0003] After the sample is prepared and pretreated, it is generally placed in a beaker to immerse the container, and the liquid flow is limited, which can cause uneven corrosion. Usually, holes need to be punched on the sample before corrosion, and the hole position may exacerbate the corrosion of one side if it is close to the observation surface.

[0004] At present, there is no special equipment and device for aluminum alloy intergranular corrosion. The standard required conductive constant temperature device is usually a water bath or an electric furnace, which requires a relatively stable corrosion temperature of 30℃±3℃. Due to the lack of necessary constant temperature control equipment, the corrosion temperature cannot be completely guaranteed, which affects the observation of corrosion state and depth. Moreover, the water bath and electric furnace are usually small, and the ratio of the volume of the test liquid to the area of the sample immersed surface and the accumulation of corrosion products affect that different grades of materials cannot be tested in the same water bath or electric furnace, and multiple materials and multiple stations cannot be tested simultaneously in one test. SUMMARY

[0005] In view of the defects in the prior art, the present application aims to provide a constant-temperature corrosion control device and control method for intergranular corrosion of aluminum alloy.

[0006] According to the present application, a constant-temperature corrosion control device for intergranular corrosion of aluminum alloy is provided, which comprises: a test box unit and a corrosion unit.

[0007] The test box unit comprises a test box 6 and a test box support 5.

[0008] The corrosion unit comprises a container 1, a sample 2, a clamp 3, a thin rope / belt 4, and a container cover 7.

[0009] The vessel 1 is filled with intergranular corrosion solution and placed in the test box 6, the sample 2 is clamped on the surface of the sample 2 by the clamp 3, the clamp 3 is connected to the test box support 5 through the thin rope / belt 4, the test box support 5 is located at the top end of the test box 6, and the parallel test of three or more sample products can be met.

[0010] Preferably, the test box unit has a temperature control function, the temperature setting includes 30℃ and 35℃, the temperature change is ±2℃, and the time setting function is also provided.

[0011] Preferably, the vessel 1 includes a glass beaker and a polytetrafluoroethylene beaker.

[0012] The capacity of the vessel is 100-200 mL.

[0013] Preferably, the thin rope / belt includes a polypropylene rope or other non-metallic belt.

[0014] Preferably, the cover center of the vessel cover has a hole with a diameter less than 5 mm.

[0015] The vessel cover includes 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 a hole.

[0018] Preferably, the aluminum alloy intergranular corrosion constant temperature corrosion control device can be arranged in a multi-array manner to realize multi-batch sample multi-station test.

[0019] According to the aluminum alloy intergranular corrosion constant temperature corrosion control device provided by the application, the control method of the aluminum alloy intergranular corrosion constant temperature corrosion control device is provided.

[0020] Step S1: set the temperature of the test box to a predetermined temperature;

[0021] Step S2: fill the vessel with intergranular corrosion solution and place it in the test box for constant temperature heating for a predetermined time;

[0022] Step S3: after pretreatment of the intergranular corrosion sample, clamp the non-observation side of the sample with the clamp;

[0023] Step S4: one end of the thin rope / belt is passed through the hole of the clamp and fixed, and the other end is passed through the vessel cover and wound on the test box support and fixed;

[0024] Step S5: the sample is placed in the vessel, completely immersed in the intergranular corrosion solution, and the clamped surface is below the solution by a distance.

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

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

[0027] In the step S3, the clamp clamps the non-observation surface of the test sample, and the clamping depth is not greater than 2 mm;

[0028] In the step S5, the distance is 25 mm, the test sample is hung in the middle of the solution, and the side and bottom cannot contact the container.

[0029] Preferably, the material type in the step S6 includes 2xxx, 6xxx, 7xxx aluminum alloy and 5xxx aluminum alloy, and the corrosion time set is 6 hours and 24 hours, respectively.

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

[0031] 1. The present application realizes temperature control of intergranular corrosion solution based on heat conduction and heat convection of the test box without damaging the test sample, and solves the problem of accurate control of corrosion temperature in the method of intergranular corrosion of aluminum alloy.

[0032] 2. The present application realizes clamping method on the non-observation surface with a simple device, provides a more accurate corrosion environment, and the temperature difference changes only ±0.2℃ during the test process. The simple device realizes a more reliable corrosion process, meets the standard requirements, and observes a more typical continuous distribution intergranular corrosion phenomenon.

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

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

[0035] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments 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 of the present application.

[0037] Figure 2 It is a whole view of the multi-station of the constant temperature corrosion control device for intergranular corrosion of aluminum alloy of the present application.

[0038] Reference numerals: 1. Vessel; 2. Sample; 3. Fixture; 4. String / belt; 5. Test chamber support; 6. Test chamber; 7. Vessel lid. Detailed Implementation

[0039] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0040] This invention includes a test chamber and a beaker containing an intergranular etching solution placed inside for constant temperature control. The sample is clamped to its surface using an engineering material clamp to prevent reaction with the solution. A polypropylene rope is threaded through the clamp holes and suspended from the low-temperature test chamber support, with a pre-set suspension height. The sample is immersed in the intergranular etching solution. After etching for 6 or 24 hours, the sample is removed, rinsed clean with an ultrasonic cleaner, and allowed to air dry. After polishing, a sample meeting the test standards is obtained and examined under a microscope at 100–500x magnification.

[0041] Example 1

[0042] According to the present invention, a constant temperature corrosion control device for intergranular corrosion of aluminum alloys is provided, such as... Figure 1 As shown, the system includes a test chamber unit and a corrosion unit. The test chamber unit includes a test chamber 6 and a test chamber support 5. The corrosion unit includes a vessel 1, a sample 2, a clamp 3, a string / belt 4, and a vessel lid 7. The vessel 1 contains an intergranular corrosion solution and is placed in the test chamber 6. The sample 2 is clamped to the surface of the sample 2 by the clamp 3. The clamp 3 is connected to the test chamber support 5 via the string / belt 4 passing through the vessel lid 7. The test chamber support 5 is located at the top of the test chamber 6 and can accommodate parallel testing of three or more sample products.

[0043] The test chamber unit has a temperature control function, with temperature settings including 30℃ and 35℃, temperature variation ±2℃, and a time setting function.

[0044] The vessel 1 includes a glass beaker and a polytetrafluoroethylene (PTFE) beaker, with a capacity of 100-200 mL. The string / belt includes polypropylene rope or other non-metallic ribbon. The lid of the vessel has a center hole with a diameter of less than 5 mm, and the material includes PTFE and plastic film. The clamp 3 is made of engineering materials, such as non-metallic materials, and has holes.

[0045] In addition, such as 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-batch sample multi-station testing, better serve the intergranular corrosion test, and achieve and obtain more accurate corrosion state and corrosion depth.

[0046] Embodiment two

[0047] According to the present application, a control method for a constant temperature corrosion control device for intergranular corrosion of aluminum alloy is provided, comprising:

[0048] Step S1: set the temperature of the test box to a predetermined temperature, for example 30℃.

[0049] Step S2: fill the intergranular corrosion solution into the vessel and place it in the test box for constant temperature heating for a predetermined time, for example 5 minutes, to ensure that the temperature of the intergranular corrosion solution meets the standard requirements.

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

[0051] Step S4: one end of the string / belt is passed through the hole of the clamp and fixed, and the other end is passed through the cover of the vessel and wound on the test box support and fixed. One end of the polypropylene rope is passed through the hole of the clamp and knotted and fixed. The other end is passed through the cover of the vessel and wound on the test box support and knotted and fixed.

[0052] Step S5: the sample is placed in the vessel and completely immersed in the intergranular corrosion solution, and the clamped surface is below the solution by a distance, which includes 25mm. The sample is suspended in the middle of the solution, and the side and bottom should not touch the container.

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

[0054] Specifically, the device operation method of the present application is described as follows: turn on the test box, and set the temperature to 30°C. Put 150 mL of intergranular corrosion solution (57 g of NaCl in 990 mL of water + 10 mL of 30% H2O2) into a 200 mL glass beaker, and place it in the low-temperature test box for constant temperature heating for 5-10 minutes. The intergranular corrosion sample with a size of 40 mm x 25 mm is pretreated, and then the sample is clamped by a clamp so that the observation surface perpendicular to the rolling direction of the plate is clamped. The clamping depth should not be greater than 2 mm to obtain a comprehensive corrosion surface. One end of a polypropylene rope is passed through the hole of the clamp and knotted to fix it. The other end is passed through a polytetrafluoroethylene cover and wound around the test box support and knotted to fix it. The sample is completely immersed in the intergranular corrosion solution, and the clamped surface is 25 mm below the liquid level. The sample is suspended in the middle of the solution, and no surface is in contact with the container. Cover the cover, and set the corrosion time of 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 clamp with a hole is made of engineering materials, which can be plastic and other non-metallic materials. The thin rope / belt used for fixing can be a polypropylene rope or other non-metallic ribbon. The vessel cover can be made of polytetrafluoroethylene material, and a hole with a diameter of less than 5 mm is punched in the center of the cover.

[0055] Further, the device and test method of the present application are illustrated by assuming that the sample sample is a 2219 plate, and the intergranular corrosion test of 2xxx series aluminum alloy is carried out according to GB / T 7998-2023 “Aluminum Alloy Intergranular Corrosion Sensitivity Evaluation Method”.

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

[0057] The sample 2 is subjected to intergranular corrosion in the device as shown in Figure 1 , clamped by the clamp 3 at 1 mm, fixed to the test box support 5 by the polypropylene rope 4, completely immersed in the beaker 1 containing 150 mL of analytical pure corrosion solution (57 g of NaCl in 990 mL of laboratory secondary water + 10 mL of 30% H2O2), covered with the vessel cover 7, corroded in a relatively closed corrosion environment for 6 hours, and the temperature control range of the test box 6 is 29.9°C to 30.2°C.

[0058] The corroded sample is cleaned at least 5 times by an ultrasonic cleaning instrument until the corrosion products are removed. The sample is cut at a distance of at least 5 mm from the observation surface by a cutting machine, and after grinding and polishing, the intergranular corrosion result is evaluated under a metallographic microscope and a confocal microscope, and the typical and continuously distributed intergranular corrosion depth is 0.17 mm, which is a standard intergranular corrosion of grade 4.

[0059] Similarly, assuming that the sample sample is 2024 plate, GB / T 7998-2023 "Aluminum alloy intergranular corrosion sensitivity evaluation method" is used to carry out 2xxx series aluminum alloy intergranular corrosion test.

[0060] The sample is processed along the rolling direction to form 3 intergranular corrosion samples with a size of 40mm*25mm*0.5mm, and the thickness of 0.5mm is the original thickness of the material. The sample is pretreated in a solution containing 100g / L sodium hydroxide for 15 minutes. The rest of the steps are the same as in Example 1. After microscopic evaluation, there is no intergranular corrosion.

[0061] From the above analysis, it can be seen that the test box corrosion device of the embodiment is convenient for aluminum alloy intergranular corrosion, and realizes the synchronous test of multiple batches and multiple stations.

[0062] In summary, the present application has the advantages of simple structure, obvious effect in the experimental process, and realization of the inspection and measurement of the intergranular corrosion state and depth of aluminum alloy. In the case of 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 application can be variously changed and varied. Any approved change, equivalent replacement, improvement, etc. within the spirit and originality of the present application is included in the protection of the present application.

[0063] The method of the present application overcomes the shortcomings of existing detection techniques without damaging the sample, and provides an intergranular corrosion test method suitable for aluminum alloy intergranular corrosion test. The test box is used for constant temperature control, and a corrosion test system integrating corrosion and clamping is realized. The problem of precise control of corrosion temperature in the intergranular corrosion method of aluminum alloy is solved, the problem of insufficient corrosion of each surface is solved, and multiple batches of samples can be tested in multiple stations, which better serves the intergranular corrosion test and realizes and obtains more accurate corrosion state and corrosion depth. It is suitable as a test method for intergranular corrosion corrosion depth method.

[0064] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the present application.

[0065] The specific embodiments of the present application are described above. It should be understood that the present application 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 essential content of the present application. The embodiments of the present application and the features in the embodiments can be arbitrarily combined without conflict.

Claims

1. A constant-temperature corrosion control device for intergranular corrosion of aluminum alloys, characterized in that, include: Includes a test chamber unit and a corrosion unit; The test chamber unit includes a test chamber (6) and a test chamber support (5); The corrosion unit includes a vessel (1), a sample (2), a clamp (3), a string / belt (4), and a vessel lid (7); The vessel (1) contains an intergranular corrosion solution and is placed in the test chamber (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 chamber support (5) through a thin rope / belt (4) passing through the vessel cover (7). The test chamber support (5) is located at the top of the test chamber (6) and can meet the parallel testing of 3 or more sample products. The test chamber unit has a temperature control function, with temperature settings including 30℃ and 35℃, temperature variation ±2℃, and a time setting function; The constant temperature corrosion control device for intergranular corrosion of aluminum alloys can be arranged in a multi-array manner to realize multi-station testing of multiple batches of samples.

2. The isothermal corrosion control device for intergranular corrosion of aluminum alloys according to claim 1, characterized in that, The vessel (1) includes a glass beaker and a polytetrafluoroethylene beaker; The container has a capacity of 100-200 mL.

3. The isothermal corrosion control device for intergranular corrosion of aluminum alloys according to claim 1, characterized in that, The cord / belt includes polypropylene cord or other non-metallic ribbon.

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

5. The isothermal corrosion control device for intergranular corrosion of aluminum alloys according to claim 1, characterized in that, The fixture (3) is made of engineering materials, including non-metallic materials; The clamp (3) has holes.

6. A control method for a isothermal 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 5, and the control method, include: Step S1: Set the temperature of the test chamber to the preset temperature; Step S2: Fill a container with intergranular corrosion solution and place it in the test chamber for a predetermined time to maintain a constant temperature; Step S3: After pretreating the intergranular corrosion sample, clamp the non-viewable side of the sample with a fixture. Step S4: Pass one end of the thin rope / belt through the hole of the clamp and fix it, and pass the other end through the container lid, wrap it around the test chamber 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 below the solution by a certain distance; Step S6: Cover the surface of the vessel with the vessel lid, and conduct a corrosion test in the test chamber according to the material type and time settings.

7. The control method of the isothermal corrosion control device for intergranular corrosion of aluminum alloys according to claim 6, characterized in that, The predetermined time in step S2 is 5 minutes; In step S3, the clamp holds the non-observation surface of the sample, and the clamping depth is no more than 2 mm. In step S5, the distance is 25mm, and the sample is suspended in the middle of the solution, with its sides and bottom not in contact with the container.

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

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