Method for total immersion corrosion test of metal material

Abstract

The invention discloses a metal material total immersion corrosion test method which is characterized by comprising the following steps: preparing a sample; measuring and weighing the sample; preparing an etchant solution, namely preparing the etchant solution from distilled water, sodium chloride and sulfuric acid according to test requirements; performing a test process; cleaning the sample; and weighing the sample dried for 24 hours, and calculating the weightlessness and corrosion rate of the sample. Through the implementation of the method, the total immersion corrosion test can be carried out by using the existing experimental equipment and equipment, the requirements of corrosion-resistant steel and weathering-resistant steel product development are met, corrosion test data can be provided for subject research, and the product progress is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material corrosion, and in particular to a method for full immersion corrosion testing of metal materials. Background Art

[0002] Metal materials will corrode when exposed to air or immersed in seawater for a long time, especially when they are in corrosive media for a long time. Corrosion also brings great risks to the use of metal materials. Therefore, corrosion resistance is one of the important performance indicators of metal materials. The main methods for evaluating the corrosion resistance of metals include salt spray test, periodic immersion corrosion test, full immersion corrosion test and electrochemical test, among which full immersion corrosion test is one of the frequently used evaluation methods.

[0003] At present, physical and chemical laboratories often carry out salt spray corrosion and periodic immersion corrosion tests. During the development of steel products, users put forward some special corrosion performance requirements, and full immersion corrosion tests are required to evaluate the corrosion resistance of steel products. Since there is no full immersion corrosion test equipment in the physical and chemical laboratory, it is urgent to use the existing equipment, materials and experimental environment to carry out full immersion corrosion tests on metal materials. Summary of the invention

[0004] The purpose of the present invention is to provide a method for full immersion corrosion testing of metal materials to meet the demand for corrosion performance in the product development process.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for full immersion corrosion testing of a metal material, comprising:

[0007] First, sample preparation

[0008] The blank sample should be cut from the plate or strip along the rolling direction, machined into a sheet sample, and a hole should be drilled in the center of the upper part of the sample for hanging; in order to ensure that the sample surface is smooth and free of processing rust, the machined sheet sample is water-grinded on metallographic sandpaper and then polished to completely remove the surface rust;

[0009] Fifth, sample measurement and weighing

[0010] After the final grinding and polishing, the samples should be promptly degreased and washed with water, magnesium oxide paste, etc., and then degreased and washed with alcohol or other chloride-free reagents. After rapid drying, they should be stored in a desiccator and allowed to cool to room temperature before measuring the area and weighing.

[0011] Sixth, prepare the corrosion solution

[0012] According to the test requirements, distilled water, sodium chloride and sulfuric acid are used to prepare the corrosion solution;

[0013] Seventh, the test process

[0014] Place the sample horizontally in the beaker using a nylon tie and a glass rod, adjust the tie length to ensure that the sample is in the middle of the beaker, add 500mL of corrosion solution, and seal the beaker mouth with a sealing film; place one sample in each beaker and conduct a full immersion corrosion test; place all sealed beakers in a constant temperature water bath, and set the constant temperature and corrosion time according to the test requirements; during the test, frequently observe the changes in the sample and solution and make records;

[0015] Fifth, sample cleaning

[0016] After the scheduled time, take out the sample, rinse it with water first, then wipe off the corrosion products with a brush, and clean it with ultrasound; soak the sample cleaned by the above method in a cleaning solution prepared by sulfuric acid, corrosion inhibitor, and distilled water, let it stand for 5 minutes, and wipe off the corrosion products with a brush until it is completely removed; then wash it with alcohol and blow it dry, and quickly place it in the drying period, and weigh it again after 24 hours; at the same time, take two samples with the same material, state, size, etc. as the sample to be tested (i.e., the sample of the corrosion test), treat them according to the same procedure as the sample to be tested, and then clean and dry them in the same way in an uncorroded state;

[0017] Sixth, weigh the samples that have been dried for 24 hours and calculate the weight loss and corrosion rate of the samples.

[0018] Further, the specific steps include:

[0019] (1) Sample preparation

[0020] Cut the blank sample in the rolling direction of the steel plate, and process it into a sample with the specification of 50mm×25mm×4mm through the machining process of sawing machine, milling machine and grinder, and drill a hole at the center of the upper part of the sample with a diameter of Φ2.5mm; water-grind the machined sample on metallographic sandpaper, and then polish it to completely remove the surface rust, so as to ensure that the surface of the sample is smooth and free of any rust;

[0021] (6) Sample measurement and weighing

[0022] Degrease the sample that has been sanded and polished, then add alcohol to an ultrasonic cleaner, put the degreased sample in, and clean it for 10-20 minutes to thoroughly clean the surface of the sample; dry the surface of the sample with a hair dryer, quickly store it in a desiccator, and measure the area and weigh it after leaving it for 2 hours;

[0023] (7) Preparation of corrosion solution

[0024] Add 2500mL of distilled water to a beaker, weigh 122.5g of NaCl and add it to the distilled water, stir until the NaCl is completely dissolved, use a measuring cylinder to measure 190mL of H2SO4, slowly pour it into the above solution, and stir continuously with a glass rod to prepare a NaCl-H2SO4 corrosion solution;

[0025] (8) Test process

[0026] Use nylon tie and glass rod to hang the sample horizontally in the beaker, and adjust the length of the tie to make the sample in the middle of the beaker; add 500mL NaCl-H2SO4 corrosion solution to immerse the sample completely, and seal the beaker mouth with sealing film; to ensure the accuracy of the experimental data, only one sample is placed in each beaker; all sealed beakers are placed in a constant temperature water bath, and the temperature is set to 20-30℃ according to the test requirements. The test time is 72 hours; during the test, observe the changes of samples and solutions frequently every 24 hours and make records;

[0027] (9) Sample cleaning

[0028] After 72 hours, take out the sample, rinse the surface with high-purity water first, and wipe off the surface corrosion products with a brush; add 1000mL of distilled water to a beaker, then add 100mL of H2S04, stir continuously, and finally add an organic corrosion inhibitor, stir and mix evenly; soak the above-cleaned sample in the cleaning solution, let it stand, and then use a brush to wipe off the corrosion products until it is completely removed; the cleaned sample is then cleaned with alcohol, blown dry, and quickly placed in a drying period, and weighed after being stored for 24 hours; at the same time, take two samples with the same material, state, size, etc. as the sample to be tested, and after being processed according to the same procedure as the sample to be tested, use the same method to clean and dry them in an uncorroded state;

[0029] (6) Take out the samples that have been dried for 24 hours and weigh them, and calculate the weight loss and corrosion rate of each sample.

[0030] Furthermore, the machined samples were water-grinded on metallographic sandpapers with grits of 120 and 320.

[0031] Furthermore, the samples that had been sandpaper ground and polished were fully degreased with water and magnesium oxide paste.

[0032] Furthermore, the temperature was set to 25°C according to the test requirements.

[0033] Furthermore, 1.5 mL of organic corrosion inhibitor was finally added.

[0034] Furthermore, let it stand for 5 minutes, and then use a brush to wipe off the corrosion products until they are completely removed.

[0035] Compared with the prior art, the beneficial technical effects of the present invention are:

[0036] Through the implementation of the above methods, full immersion corrosion tests can be carried out using existing experimental equipment and instruments to meet the requirements for the development of corrosion-resistant steel and weathering steel products. It can provide corrosion test data for research projects and accelerate product progress. DETAILED DESCRIPTION

[0037] A method for full immersion corrosion testing of a metal material comprises the following steps:

[0038] (1) Sample preparation. Cut the blank sample in the rolling direction of the steel plate, and process it into a sample with the specifications of 50mm×25mm×4mm through sawing, milling, grinding and other machining processes. Drill a hole at the center of the upper part of the sample with a diameter of Φ2.5mm. The machined sample is water-grinded on metallographic sandpaper with a grit of 120 or 320, and then polished to completely remove the surface rust and ensure that the sample surface is smooth and free of any rust.

[0039] (2) Sample measurement and weighing. Degrease the sandpaper-ground and polished samples with water, magnesium oxide paste, etc., then add alcohol to an ultrasonic cleaner, place the degreased samples in the cleaner, and wash for 15 minutes to thoroughly clean the sample surface. Dry the sample surface with a hair dryer, and quickly store it in a desiccator. After 2 hours, measure the area and weigh it.

[0040] (3) Prepare the corrosion solution. According to the requirements of this test, add 2500 mL of distilled water to a beaker, weigh 122.5 g of NaCl and add it to the distilled water. Stir until the NaCl is completely dissolved. Use a measuring cylinder to measure 190 mL of H2SO4 and slowly pour it into the above solution. Stir continuously with a glass rod to prepare the NaCl-H2SO4 corrosion solution.

[0041] (4) Test process. Use nylon tie and glass rod to hang the sample horizontally in the beaker. Adjust the length of the tie to make the sample in the middle of the beaker. Add 500mL NaCl-H2SO4 corrosion solution to immerse the sample completely. Seal the mouth of the beaker with a sealing film. To ensure the accuracy of the experimental data, only one sample is placed in each beaker. Place all sealed beakers in a constant temperature water bath. Set the temperature to 25℃ according to the test requirements. The test time is 72 hours. During the test, observe the changes of samples and solutions frequently every 24 hours and make records.

[0042] (5) Sample cleaning. After 72 hours, take out the sample, rinse the surface with high-purity water first, and wipe off the surface corrosion products with a brush. Add 1000mL of distilled water to a beaker, then add 100mL of H2S04, stir continuously, and finally add 1.5mL of organic corrosion inhibitor, stir and mix evenly. Soak the above-cleaned sample in the cleaning solution, let it stand for 5 minutes, and then use a brush to wipe off the corrosion products until it is completely removed. The cleaned sample is then cleaned with alcohol, blown dry, and quickly placed in a drying period. After keeping it for 24 hours, weigh it again. At the same time, take two samples with the same material, state, size, etc. as the sample to be tested (i.e., the sample for the corrosion test), and treat them according to the same procedure as the sample to be tested (surface treatment, cleaning, weighing, etc.), and then clean and dry them in the same way in an uncorroded state.

[0043] (6) Take out the samples that have been dried for 24 hours and weigh them, and calculate the weight loss and corrosion rate of each sample.

[0044] Application effect of the present invention: Through the implementation of the above method, full immersion corrosion tests can be carried out using existing experimental equipment and instruments to meet the requirements for the development of corrosion-resistant steel and weathering steel products, and corrosion test data can be provided for research projects to accelerate product progress.

[0045] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for full immersion corrosion testing of metal materials, characterized in that: include: First, sample preparation The blank sample should be cut from the plate or strip along the rolling direction, machined into a sheet sample, and a hole should be drilled in the center of the upper part of the sample for hanging; in order to ensure that the sample surface is smooth and free of processing rust, the machined sheet sample is water-grinded on metallographic sandpaper and then polished to completely remove the surface rust; Second, sample measurement and weighing After the final grinding and polishing, the samples should be promptly degreased and washed with water, magnesium oxide paste, etc., and then degreased and washed with alcohol or other chloride-free reagents. After rapid drying, they should be stored in a desiccator and allowed to cool to room temperature before measuring the area and weighing. Third, prepare the corrosion solution According to the test requirements, distilled water, sodium chloride and sulfuric acid are used to prepare the corrosion solution; Fourth, the test process Place the sample horizontally in the beaker using a nylon tie and a glass rod, adjust the tie length to ensure that the sample is in the middle of the beaker, add 500mL of corrosion solution, and seal the beaker mouth with a sealing film; place one sample in each beaker and conduct a full immersion corrosion test; place all sealed beakers in a constant temperature water bath, and set the constant temperature and corrosion time according to the test requirements; during the test, frequently observe the changes in the sample and solution and make records; Fifth, sample cleaning After the scheduled time, take out the sample, rinse it with water first, then wipe off the corrosion products with a brush, and clean it with ultrasound; soak the sample cleaned by the above method in a cleaning solution prepared by sulfuric acid, corrosion inhibitor, and distilled water, let it stand, and wipe off the corrosion products with a brush until it is completely removed; then wash it with alcohol and blow it dry, and quickly place it in the drying period, and weigh it again after 24 hours; at the same time, take two samples with the same material, state, size, etc. as the sample to be tested, and after processing them according to the same procedure as the sample to be tested, clean and dry them in the same way in an uncorroded state; Sixth, weigh the samples that have been dried for 24 hours and calculate the weight loss and corrosion rate of the samples.

2. The method for full immersion corrosion test of metal materials according to claim 1, characterized in that: The specific steps include: (1) Sample preparation Cut the blank sample in the rolling direction of the steel plate, and process it into a sample with the specification of 50mm×25mm×4mm through the machining process of sawing machine, milling machine and grinder, and drill a hole at the center of the upper part of the sample with a diameter of Φ2.5mm; water-grind the machined sample on metallographic sandpaper, and then polish it to completely remove the surface rust, so as to ensure that the surface of the sample is smooth and free of any rust; (2) Sample measurement and weighing Degrease the sample that has been sanded and polished, then add alcohol to an ultrasonic cleaner, put the degreased sample in, and clean it for 10-20 minutes to thoroughly clean the surface of the sample; dry the surface of the sample with a hair dryer, quickly store it in a desiccator, and measure the area and weigh it after leaving it for 2 hours; (3) Preparation of corrosion solution Add 2500mL of distilled water to a beaker, weigh 122.5g of NaCl and add it to the distilled water, stir until the NaCl is completely dissolved, use a measuring cylinder to measure 190mL of H2SO4, slowly pour it into the above solution, and stir continuously with a glass rod to prepare a NaCl-H2SO4 corrosion solution; (4) Test process Use nylon tie and glass rod to hang the sample horizontally in the beaker, and adjust the length of the tie to make the sample in the middle of the beaker; add 500mL NaCl-H2SO4 corrosion solution to immerse the sample completely, and seal the beaker mouth with sealing film; to ensure the accuracy of the experimental data, only one sample is placed in each beaker; all sealed beakers are placed in a constant temperature water bath, and the temperature is set to 20-30℃ according to the test requirements. The test time is 72 hours; during the test, observe the changes of samples and solutions frequently every 24 hours and make records; (5) Sample cleaning After 72 hours, take out the sample, rinse the surface with high-purity water first, and wipe off the surface corrosion products with a brush; add 1000mL of distilled water to a beaker, then add 100mL of H2S04, stir continuously, and finally add an organic corrosion inhibitor, stir and mix evenly; soak the above-cleaned sample in the cleaning solution, let it stand, and then use a brush to wipe off the corrosion products until it is completely removed; the cleaned sample is then cleaned with alcohol, blown dry, and quickly placed in a drying period, and weighed after being stored for 24 hours; at the same time, take two samples with the same material, state, size, etc. as the sample to be tested, and after being processed according to the same procedure as the sample to be tested, use the same method to clean and dry them in an uncorroded state; (6) Take out the samples that have been dried for 24 hours and weigh them, and calculate the weight loss and corrosion rate of each sample.

3. The method for full immersion corrosion testing of metal materials according to claim 2, characterized in that: The machined samples were water-grinded on metallographic sandpapers of 120 and 320 grit.

4. The method for full immersion corrosion testing of metal materials according to claim 2, characterized in that: The samples that have been sandpaper ground and polished were thoroughly degreased with water and magnesium oxide paste.

5. The method for full immersion corrosion test of metal materials according to claim 1, characterized in that: The temperature was set to 25°C according to the test requirements.

6. The method for full immersion corrosion testing of metal materials according to claim 1, characterized in that: Finally, 1.5 mL of organic corrosion inhibitor was added.

7. The method for full immersion corrosion testing of metal materials according to claim 1, characterized in that: Let it sit for 5 minutes, then use a brush to scrub off the corrosion products until they are completely removed.