An indoor equivalent accelerated test method based on a galvanic corrosion sensor probe

Abstract

The application provides an indoor equivalent accelerated test method based on a galvanic corrosion sensor probe, and relates to the field of metal corrosion testing. The method comprises the following steps: alternately arranging a plurality of steel material samples to be tested and a counter material and separating them with insulation to obtain a galvanic sensor probe; obtaining a humid air spectrum, a dry air spectrum, a rainfall spectrum and a curve of outdoor corrosion accumulated electric quantity changing with experimental time according to outdoor test data; calculating a time conversion coefficient corresponding to each temperature and humidity interval in the humid air spectrum and the rainfall spectrum; calculating a humid heat test time of the equivalent accelerated test, a salt spray-rainfall time of the equivalent accelerated test and a dry test time of the equivalent accelerated test; determining an indoor equivalent accelerated test scheme to obtain a curve of indoor corrosion accumulated electric quantity changing with experimental time. The method provided by the application can greatly shorten the test time, can more accurately quantitatively compare the corrosion process compared with the coupon method, and has good simulation and reproducibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal corrosion testing, in particular to an indoor equivalent accelerated test method based on a galvanic corrosion sensor probe. BACKGROUND

[0002] In the corrosion process of metals, atmospheric corrosion is one of the most common and widely influential corrosion types, and therefore it is necessary to study the corrosion law of materials in atmospheric environments for the prediction and protection of material corrosion. The current commonly used atmospheric corrosion research methods mainly fall into two categories: outdoor exposure test and indoor accelerated test. Outdoor exposure test usually adopts on-site test of standard corrosion coupons, and collects corrosion data, but natural environmental corrosion damage is a long-term and continuous process, which determines the long-term nature of the test and research work, and because the outdoor exposure coupon recovery cycle is usually in units of years, the data obtained from the sample exposure test is limited and presents a fragmented feature, which is insufficient to reflect the influence of dynamic environmental conditions on the corrosion process, and it is difficult to observe the corrosion process law in detail during the test period.

[0003] Indoor accelerated test can quickly understand the aging behavior of metal materials, but the outdoor environmental factors collected in the traditional test process are single and mostly monthly average values, and the correlation comparison of indoor and outdoor results is mostly qualitative analysis or comparative analysis of overall weight loss from the aspects of corrosion morphology and composition, while the actual service environment is relatively complex and is often affected by multiple factors, resulting in low accuracy of the existing method.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The purpose of the present application is to provide an indoor equivalent accelerated test method based on a galvanic corrosion sensor probe to solve the above problems.

[0006] To achieve the above purpose, the present application adopts the following technical solution:

[0007] An indoor equivalent accelerated test method based on a galvanic corrosion sensor probe, comprising:

[0008] A plurality of steel material samples to be tested and a counter material are alternately arranged and separated by an insulating object to obtain a galvanic sensor probe;

[0009] The galvanic sensor probe is connected with a micro-current meter and placed outdoors to collect and record outdoor test data; the outdoor test data includes real-time corrosion current, corrosion cumulative electric quantity, test time data, temperature data, humidity data and rainfall data;

[0010] Based on the outdoor test data, we obtained the humid air spectrum characterizing the relationship between month-heat and humidity, the dry air spectrum characterizing the relationship between month-dryness and humidity, the rainfall spectrum characterizing the relationship between month-rainfall time and humidity, and the curve of outdoor corrosion accumulation charge changing with experimental time.

[0011] An experimental scheme was developed to determine the corresponding time conversion factors for the humid air spectrum, dry air spectrum, and precipitation spectrum. This experimental scheme included experimental monitoring time, temperature, humidity, and environmental medium parameters. Based on this scheme, the same thermocouple sensor probe was used to measure the cumulative corrosion charge Q corresponding to each temperature and humidity range in the humid air spectrum and the precipitation spectrum indoors. i And the cumulative corrosion charge Q corresponding to the maximum value in the temperature scheme and the maximum value in the humidity scheme. cp ; Calculate Q i / Q cp The time conversion factor α corresponding to each temperature and humidity interval in the humid air spectrum and the precipitation spectrum is obtained. i ;

[0012] Based on the duration of humid heat in the humid air spectrum and the time conversion factor α i The equivalent accelerated test damp heat test time t was calculated. 湿 Based on the rainfall time in the rainfall spectrum and the time conversion factor α i The equivalent accelerated test salt spray-rainfall time t was calculated using the environmental medium conversion factor α'. 盐 Based on the ratio of the drying time to the damp heat treatment time in the dry air spectrum and the damp heat test time t 湿 The equivalent accelerated drying test time t was calculated. 干 ;

[0013] Based on the temperature and humidity of the outdoor test site, the environmental medium scheme, and the damp heat test time t 湿 The salt spray-rainfall time t 盐 and the drying test time t 干 A suitable indoor equivalent accelerated test scheme was determined, and an indoor equivalent accelerated test was conducted according to the scheme to obtain the curve of the change of indoor corrosion accumulation charge with experimental time.

[0014] Preferably, the potential of the dual material is higher than the potential of the sample to be tested;

[0015] The thermocouple sensor probe includes at least four sheet-like samples to be tested.

[0016] Preferably, the mating material is copper or graphite.

[0017] Preferably, the experimental monitoring time is 1000-3000 min, the temperature scheme corresponds to a temperature range of 20-40℃, the humidity scheme corresponds to a relative humidity range of 60%-95%, and the environmental medium scheme corresponds to a solution medium of deionized water or 1-5wt% sodium chloride aqueous solution.

[0018] Preferably, the months in the humid air spectrum, the dry air spectrum, and the rainfall spectrum are calculated according to a single month, two months, a quarter, or any other specified time period.

[0019] Preferably, the environmental medium conversion coefficient a' is a time conversion coefficient experiment The salt fog-rain time t 盐 is the conversion coefficient when the corresponding medium is a sodium chloride aqueous solution, and the salt fog-rain time t 盐 = The total rainfall time Σt i降雨 in the rainfall spectrum × the corresponding time conversion coefficient a i × the environmental medium conversion coefficient a'.

[0020] Preferably, the environmental medium conversion coefficient a' is 0.05-0.12.

[0021] Preferably, the relative humidity corresponding to the humid air spectrum is greater than or equal to 60%, and the relative humidity corresponding to the dry air spectrum is less than 60%.

[0022] Preferably, in the indoor equivalent accelerated test scheme, the temperature corresponding to the damp heat test module is 35℃ or 40℃, the relative humidity is 90%, the environmental medium is deionized water or 1-5wt% sodium chloride aqueous solution; the temperature corresponding to the dry test module is 45℃, the relative humidity is 50%, and the environmental medium is deionized water or 1-5wt% sodium chloride aqueous solution; the temperature corresponding to the salt fog-rain test module is 35℃, and the environmental medium is 5wt% sodium chloride aqueous solution.

[0023] In the indoor equivalent accelerated test scheme, the damp heat test module, the dry test module, and the salt fog-rain test module are cycled according to a quarter or a month.

[0024] Preferably, the indoor equivalent accelerated test method based on the galvanic corrosion sensor probe further comprises:

[0025] The indoor equivalent accelerated test scheme is used for corrosion performance testing of other batches of samples with the same theoretical composition.

[0026] Compared with the prior art, the beneficial effects of the present application include:

[0027] The application provides an indoor equivalent accelerated test method based on a galvanic corrosion sensor probe, which uses a metal sensor probe to replace a traditional coupon, has real-time characteristics of measured data, can synchronously record service performance and environmental data of a material, and is used for indoor accelerated experiments, so that the indoor accelerated experiments are better simulated according to real dynamic outdoor environmental data, and an artificial simulation acceleration method is developed and improved and the correlation between indoor simulation acceleration and outdoor atmospheric exposure is developed.

[0028] The method is based on outdoor testing, spectrum of data is divided, a conversion coefficient of the galvanic probe in different indoor environmental media is determined by using atmospheric corrosion monitoring, a conversion method is optimized, a reasonable temperature and humidity and environmental medium scheme is used, outdoor testing is equivalently simulated, and the correlation between indoor and outdoor tests is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be regarded as a limitation on the scope of the application.

[0030] Figure 1 A physical map of the sample prepared for Example 1;

[0031] Figure 2 A spectrum of the indoor accelerated test of Example 1;

[0032] Figure 3 A schematic diagram of the current and cumulative charge variation trend of the galvanic sensor probe composed of Q235 weathering steel and graphite in Example 1 exposed to the atmospheric environment of Qingdao test station for one year;

[0033] Figure 4 A curve of the corrosion current value and the cumulative charge under different humidity in Example 2;

[0034] Figure 5 A schematic diagram of the galvanic sensor probe composed of Q420 weathering steel and graphite in Example 2;

[0035] Figure 6 A schematic diagram of the conversion coefficient of the Q420 weathering steel-graphite galvanic probe in Example 2 in humid air and standard humid air;

[0036] Figure 7 A spectrum of the indoor accelerated test in Comparative Example 1;

[0037] Figure 8 A graph of the change trend of the corrosion cumulative charge of the Q235 weathering steel-graphite galvanic sensor probe in Example 1 and Comparative Example 1 with time;

[0038] Figure 9The weight loss results of the Q235 coupon in the indoor accelerated test of Comparative Example 2;

[0039] Figure 10 The trend chart of the corrosion accumulated electric quantity of the Q235 weathering steel-graphite electric couple sensor probe in Comparative Example 3 in the indoor non-drying test with time. DETAILED DESCRIPTION

[0040] In order to better illustrate the technical solutions provided in the present application, before the examples, the technical solutions are stated as a whole, as follows:

[0041] An indoor equivalent accelerated test method based on an electric couple corrosion sensor probe, comprising:

[0042] A plurality of steel and iron material samples to be tested (for example, Q235 steel, Q420 steel, Q345 steel and the like) are alternately arranged with a counter material and separated by an insulating material (such as a polyester film, a polytetrafluoroethylene film or a resin and the like) to obtain an electric couple sensor probe;

[0043] Generally, the sample to be tested is prepared into a thin sheet and combined with the counter material.

[0044] The electric couple sensor probe is connected with a micro-current meter and placed outdoors to collect and record outdoor test data (generally, high-frequency data recording is adopted, for example, once per minute, or other frequencies can also be adopted) ; the outdoor test data includes real-time corrosion current, corrosion accumulated electric quantity, test corresponding month data, test time data, temperature data, humidity data and rainfall data;

[0045] Due to the influence of atmospheric environment and meteorological changes, the corrosion between the electric couple sensor probes in different environments is relatively compared, and thus the size of the measured current can be used as a representation parameter of the corrosion speed.

[0046] The meteorological and environmental factors include temperature, humidity, rainfall, PM2.5, PM10, SO2, NO2, CO, O3, atmospheric pressure, wind direction, wind speed, irradiation and ultraviolet intensity and the like. After comprehensive consideration, the temperature, humidity and rainfall data are selected for evaluation, and the month and quarter differences are also considered, and the month data also needs to be recorded.

[0047] According to the outdoor test data, a humid air spectrum representing the month-humid heat action time-temperature and humidity relationship, a dry air spectrum representing the month-dry action time-temperature and humidity relationship, a rainfall spectrum representing the month-rainfall time-temperature and humidity relationship and a curve of the outdoor corrosion accumulated electric quantity changing with the test time are obtained;

[0048] The humid air spectrum, the dry air spectrum and the rainfall spectrum can be displayed in a curve form or in a table form. In order to more intuitively display the process data, the table form is adopted in the present application.

[0049] determining an experimental scheme of each corresponding time conversion coefficient experiment according to the humid air spectrum, the dry air spectrum and the rainfall spectrum, the experimental scheme including an experimental monitoring time, a temperature scheme, a humidity scheme and an environmental medium scheme; according to the experimental scheme, using the same galvanic sensor probe to determine the corrosion cumulative charge Q corresponding to each temperature and humidity interval in the humid air spectrum and the rainfall spectrum i and the maximum value in the humidity scheme cp ; calculating Q i / Q cp to obtain the time conversion coefficient α i corresponding to each temperature and humidity interval in the humid air spectrum and the rainfall spectrum

[0050] calculating the humid heat test time t 湿 according to the humid heat action time in the humid air spectrum and the time conversion coefficient α i ; calculating the salt spray-rainfall time t 盐 according to the rainfall time in the rainfall spectrum and the time conversion coefficient α i and the environmental medium conversion coefficient α'; calculating the dry test time t 干 of the equivalent accelerated test according to the ratio of the dry action time to the humid heat action time in the dry air spectrum and the humid heat test time t 湿 ;

[0051] The dry air environment has less impact on corrosion, and the corrosion current measured in the dry environment is extremely small at several nA levels, and the corresponding corrosion cumulative charge value is relatively small, and the action time obtained during the test is also relatively short. Therefore, if the conversion coefficient and the dry test time of the equivalent accelerated test are calculated according to the humid heat action and the rainfall, it is easy to be affected by the test deviation, so the ratio of the dry action time to the humid heat action time = the ratio of the dry test time t 干 of the equivalent accelerated test to the humid heat test time t 湿 is used, and the dry test time t 干 of the equivalent accelerated test is obtained on the basis of t 湿 .

[0052] According to the temperature and humidity of the place where the outdoor test is located (generally refers to the local maximum temperature and humidity), the environmental medium scheme, the humid heat test time t 湿 , the salt spray-rainfall time t 盐 and the dry test time t 干determining an indoor equivalent accelerated test scheme, performing indoor equivalent accelerated test according to the indoor equivalent accelerated test scheme, and obtaining a curve of indoor corrosion accumulated electric quantity changing with test time.

[0053] In an optional embodiment, the potential of the counter material is higher than the potential of the sample to be tested.

[0054] The electric couple sensor probe comprises at least 4 pieces of the sample to be tested.

[0055] The plurality of samples to be tested can ensure the accuracy of detection.

[0056] In an optional embodiment, the counter material is copper or graphite.

[0057] In an optional embodiment, the test monitoring time is 1000-3000 min, the temperature scheme corresponds to a temperature range of 20-40℃, the humidity scheme corresponds to a relative humidity range of 60%-95%, and the environmental medium scheme corresponds to a solution medium of deionized water or 1-5wt% sodium chloride aqueous solution.

[0058] Through experiments, it is found that the corrosion current curve tends to be stable at 500-800 min, and in order to ensure accuracy, a certain extension is made, preferably 1000-3000 min. The temperature scheme corresponds to the annual average maximum and minimum temperature in the corrosion scenario, excluding extreme cases, and finally is set to 20-40℃. During specific tests, the temperature of the actual detection site also needs to be considered, and appropriate values are selected within the range. For relative humidity, it is generally believed that when the relative humidity is less than 60%, the environment is relatively dry, and the overall evaluation of corrosion is less affected. When the relative humidity is higher than 95%, it is included in the rainfall spectrum, and sodium chloride aqueous solution is used instead of deionized water as the environmental medium to simulate rainfall, so the relative humidity range is set to 60%-95%.

[0059] In an optional embodiment, the months in the humid air spectrum, the dry air spectrum, and the rainfall spectrum are calculated according to a single month, two months, a quarter, or any other specified time period.

[0060] In an optional embodiment, the environmental medium conversion coefficient a' is a time conversion coefficient experiment is the deionized water medium, and the salt spray-rainfall time t 盐 is the conversion coefficient when the corresponding medium is sodium chloride aqueous solution, the salt spray-rainfall time t 盐 is the total rainfall time Σt i降雨 in the rainfall spectrum, a i is the corresponding time conversion coefficient a, and a' is the environmental medium conversion coefficient.

[0061] Outdoor humid air and rainfall conditions cannot be directly equated with deionized water and salt water. If sodium chloride solution is used as a conversion factor, only the conversion of temperature and humidity is considered. The solution medium needs to be further considered during salt spray testing.

[0062] In one optional implementation, the environmental medium conversion factor α' is 0.05-0.12.

[0063] In one optional implementation, the relative humidity corresponding to the humid air spectrum is greater than or equal to 60%, and the relative humidity corresponding to the dry air spectrum is less than 60%.

[0064] In one optional implementation, in the indoor equivalent accelerated testing scheme, the temperature corresponding to the damp heat test module is 35°C or 40°C, the relative humidity is 90%, and the environmental medium is deionized water or a 1-5wt% sodium chloride aqueous solution; the temperature corresponding to the drying test module is 45°C, the relative humidity is 50%, and the environmental medium is deionized water or a 1-5wt% sodium chloride aqueous solution; the temperature corresponding to the salt spray-rainfall test module is 35°C, and the environmental medium is a 5wt% sodium chloride aqueous solution.

[0065] In order to more quickly simulate the long-term corrosion process outdoors, indoor accelerated testing should select the highest temperature and humidity values ​​or those near them in the environmental range as the benchmark conditions for accelerated testing. Equivalent conversion is generally converted to test conditions with stronger corrosiveness in order to achieve rapid simulation.

[0066] In the aforementioned indoor equivalent accelerated testing scheme, the damp heat test module, the drying test module, and the salt spray-rainfall test module are cycled according to quarters or months.

[0067] After determining the modules, the number of cycles needs to be determined based on the outdoor climate characteristics. Since outdoor environments are generally characterized by alternating or mixed periods of dryness, heat and humidity, and rainfall, the equivalence test also needs to be adapted to these climate characteristics. For example, in areas with four distinct seasons, a cycle is performed once per quarter; in areas with only two seasons, a cycle is performed every two quarters. Each cycle includes a "heat and humidity test module, a dryness test module, and a salt spray-rainfall test module."

[0068] In an optional implementation, the indoor equivalent accelerated testing method based on the galvanic corrosion sensor probe further includes:

[0069] The aforementioned indoor equivalent accelerated testing scheme was used to test the corrosion performance of other batches of test samples with the same theoretical composition.

[0070] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0071] Example 1

[0072] This embodiment provides an indoor equivalent accelerated testing method based on a galvanic corrosion sensor probe, comprising the following steps:

[0073] 1. The corrosion sensor consists of a pair of electrodes made of Q235 carbon steel (anode) and graphite (cathode), each 1 mm thick, isolated by a thin plastic gasket (0.1 mm) and secured with nylon bolts. Both types of electrodes are connected to a single interface, which is then connected to a microammeter and a data logger via wires. Four parallel probe samples were prepared to ensure experimental accuracy (samples are shown in the image). Figure 1 (As shown).

[0074] 2. A Q235 steel-graphite probe was placed at the Qingdao Atmospheric Test Station for a one-year exposure experiment. Corrosion current was monitored using a micro-ammeter, and real-time meteorological and environmental data of the test station were monitored simultaneously. The monitoring period was from May 2023 to April 2024. 3. The cumulative corrosion current of the sensor probe after one year of outdoor placement was calculated to be 17.67 C. Environmental data from the Qingdao test station (such as annual temperature, humidity, number of rainfalls, rainfall amount, salt spray, and condensation) were collected. The outdoor test station's humid air spectrum (90% > RH > 60%), dry air spectrum (RH ≤ 60%), and rainfall spectrum were statistically analyzed. The results for May and June are shown in Tables 1 and 2 below.

[0075] Table 1 Temperature and humidity spectrum of Qingdao experimental station in May and June

[0076]

[0077] Table 2 Rainfall Environmental Spectrum of Qingdao Atmospheric Experiment Station in May and June

[0078]

[0079] 4. Determine the conversion factor. Monitor the corrosion current values ​​of four groups of Q235 steel-graphite galvanometer corrosion probes under different temperatures and humidity levels in an indoor humidity chamber for one day. Temperatures were set at 20℃, 25℃, 30℃, and 35℃, and humidity levels were set at 70%, 80%, and 90%, for a total of 12 temperature and humidity conditions. Integrate the values ​​to obtain the cumulative corrosion charge Q under the 12 temperature and humidity conditions. Select 35℃ and 90% humidity as the baseline conditions for the accelerated test. The measured cumulative corrosion charge Q...cp The baseline corrosion charge, with a time conversion factor α. i =Q i / Q cp Thus, the conversion factor table between humid air and standard humid air was obtained, and the results are shown in Table 3 below.

[0080] Table 3 Conversion factor between humid air and standard humid air (35℃, 90%)

[0081]

[0082] 5. Based on Qingdao's climate characteristics, a "humid and hot (35℃, 90%) - dry (45℃, 50%) - salt spray (35℃, 5% NaCl neutral solution)" cycle was selected as the acceleration method for the single-cycle accelerated experiment. Since distinct seasons and a maritime climate are Qingdao's most prominent climatic features, each season was used as one cycle in the indoor equivalent simulation. The acceleration cycle was repeated four times, corresponding to the four seasons in Qingdao: May-June, July-August, October-January, and February-April. The acceleration solution was a 5% NaCl solution, with an acceleration factor of 0.075 between water and the 5% NaCl solution.

[0083] 6. Determine the exposure time of each indoor accelerated cycle test module. Based on the results of the above steps, statistically analyze the outdoor humid air spectrum and precipitation spectrum for the four seasons. The exposure time of different temperature and humidity ranges in the humid air spectrum and precipitation spectrum is recorded as the humid air exposure time t. i潮湿空气 and the duration of rainfall t i降雨 Then, based on the duration t of outdoor humid air exposure. i潮湿空气 With time conversion factor α i Determine the time t of the damp heat test module in each cycle acceleration test. 湿 =∑α i t i潮湿空气 (i=1,2,3...12); then, based on the time ratio of dry outdoor air (RH<60%) to humid air (RH>60%) and the time t of the damp heat test module... 湿 Determine the drying test module time t 干 =t i干燥空气 / t i潮湿空气 ×t 湿 Since the conversion between the environmental spectrum of the salt spray accelerated test and the equivalent of standard humid air only considers the conversion of the environment to the water medium, and the solution medium of the salt spray test is 5% NaCl, it is necessary to further determine the acceleration factor α' between the water medium and the 5% NaCl solution. Therefore, the salt spray test module time t... 盐 =∑α i t i降雨α' (i=1,2,3...12). The data from the four seasons are sequentially converted to obtain four indoor accelerated test spectra, forming the overall indoor accelerated test spectrum (e.g., ...). Figure 2 As shown, the corrosion charge increases rapidly outdoors from May to August, corresponding to a relatively long accelerated test time.

[0084] 7. An indoor "humid heat-drying-salt spray" cycle was conducted. The current and accumulated charge of the thermocouple sensor probe during the indoor accelerated test were collected and analyzed over time. The accumulated charge value in the indoor equivalent accelerated simulation was 17.38 C. Comparison of the indoor and outdoor accumulated charge values ​​indicates that the experimental error in Example 1 was... At the same time, compare the trend of changes in the accumulated electrical charge due to corrosion indoors and outdoors (e.g.) Figure 3 As shown in the figure, the corrosion rate trends of indoor and outdoor environments are roughly the same, and the corrosion patterns are similar.

[0085] Figure 3 This is a schematic diagram showing the trend of current and cumulative charge changes of the galvanometer sensor probe composed of Q235 weathering steel and graphite in Example 1 after one year of exposure to atmospheric conditions at the Qingdao test station. The first 2500 minutes correspond to May to August in Qingdao, which is summer and autumn. Temperature and humidity are at their highest levels of the year, and the corrosion current value is also correspondingly high. The cumulative charge due to corrosion increases significantly during this stage. The climate environment in winter and spring has less impact on corrosion.

[0086] Example 2

[0087] This embodiment provides an indoor equivalent accelerated testing method based on a galvanic corrosion sensor probe, comprising the following steps:

[0088] 1. The corrosion sensor consists of four pairs of galvanic electrodes, each 1 mm thick, made of Q420 weathering steel (anode) and graphite (cathode). These insulating gaskets prevent internal short circuits, and the thin gaskets (0.1 mm) ensure a sufficiently close gap between adjacent electrodes to promote galvanic corrosion. Both types of electrodes are connected to an interface, which is then wired to a microammeter and a data logger. Four parallel probe samples were prepared to ensure experimental accuracy.

[0089] 2. The Q420 probe was placed at the Lhasa Atmospheric Test Station for a five-month exposure experiment from December 2024 to May 2025. Corrosion current data was monitored using a micro-ammeter, and real-time meteorological and environmental data of the test station were monitored simultaneously.

[0090] 3. The exposure time at various temperatures and humidity levels was statistically analyzed. The effect of RH < 60% on metal corrosion was negligible. The humid air spectrum (90% > RH > 60%) and rainfall spectrum of the outdoor test station were statistically analyzed.

[0091] 4. Determine the conversion factor. Monitor the corrosion current values ​​of four sets of Q420 steel-graphite galvanometer corrosion probes for 1000 minutes under different temperatures and humidity conditions in a humid heat chamber. The temperature values ​​are 25℃, 30℃, and 35℃, and the humidity values ​​are 70%, 80%, and 90%, for a total of nine temperature and humidity environmental conditions. Integrate the values ​​to obtain the cumulative corrosion current under the nine temperature and humidity conditions. The result is as follows Figure 4 As shown; 35℃ and 90% were selected as the baseline conditions for the accelerated test, and the corrosion accumulation charge was measured. To establish a baseline corrosion charge, a conversion factor table for humid air and standard humid air was obtained, which was then used to create a 3D surface plot of temperature-relative humidity-equivalent conversion factor. The accumulated charge under different temperature and humidity conditions is shown in Table 4, and the conversion factors for humid air and standard humid air are shown in Table 5.

[0092] Table 4. Accumulated electricity under different temperature and humidity conditions (unit / C)

[0093]

[0094] Table 5 Conversion factors between humid air and standard humid air

[0095]

[0096] 5. Considering the characteristics of Lhasa's climate, the acceleration method for the single-cycle accelerated test was selected as "humid heat (35℃, 90%) - dryness (45℃, ≤50%) - salt spray (35℃, 5% NaCl neutral solution)". The test was divided into winter and spring seasons, with 0:00 on February 13, 2025 as the dividing line. The test was repeated twice, with the acceleration solution being 5% NaCl solution, and the acceleration factor between water and 5% NaCl solution was 0.075.

[0097] 6. Determine the exposure time of each indoor accelerated test module. The damp heat test (solution medium: deionized water) time is determined based on the exposure time of outdoor winter humid air and the conversion factor for standard humid air. Since the equivalent conversion between the salt spray accelerated test environmental spectrum and standard humid air only considers the environmental conversion to the water medium, and the accelerating solution medium for the salt spray test is 5% NaCl, the acceleration factor between the water medium and the 5% NaCl solution is 0.075. Following the above steps, the indoor equivalent acceleration spectra for spring and winter are obtained, ultimately yielding the total indoor accelerated test spectrum.

[0098] 7. Conduct indoor "humid heat-salt spray" cycles, collect the current value of the galvanometer sensor probe during the indoor accelerated test, compare the magnitude of the accumulated electrical charge value of indoor and outdoor corrosion and the change curve with the test time, and intuitively reflect the correlation between indoor and outdoor corrosion patterns.

[0099] Figure 5 This is a schematic diagram of the thermocouple sensor probe composed of Q420 weathering steel and graphite in Example 2. Four sets of Q420 steel and graphite are arranged alternately, each with a thickness of 1mm, and are insulated by thin plastic gaskets (0.1mm) in between. They are fixed with nylon bolts and sealed with an epoxy epoxy layer.

[0100] Figure 6 This is a schematic diagram showing the conversion factor (time conversion factor) between humid air and standard humid air (35℃, 90%) for the Q420 weathering steel-graphite thermocouple probe in Example 2. Under low temperature and low humidity conditions, the difference in conversion factor is small; under high temperature and high humidity conditions, the difference in conversion factor increases.

[0101] Comparative Example 1

[0102] The experiment was conducted following the method and steps of Example 1. The difference from Example 1 is that the accelerated test cycle in Comparative Example 1 was not conducted quarterly, but rather a single cycle was used to simulate a year of outdoor testing. The experimental results show that the corrosion accumulation charge value in the indoor accelerated simulation of Comparative Example 1 is 15.75 C, and the experimental error is... The actual accumulated electricity from corrosion differs from that from the outdoor results, and the trend of the accumulated electricity change curve also differs significantly from the outdoor results, resulting in a poor fit.

[0103] Figure 7 To compare the indoor accelerated test spectrum in Example 1, a single cycle of "humid heat (35℃, 90%) - dry (45℃, ≤50%) - salt spray (35℃, 5% NaCl neutral solution)" was used to simulate the results of an outdoor test over a year, calculated on a full-year basis. The test time for each part of the single cycle was consistent with the total test time for each part of the quarterly cycle.

[0104] Figure 8 The graphs show the trends of corrosion accumulation over time for the Q235 weathering steel-graphite galvanometer sensor probes in Example 1 and Comparative Example 1, both indoors and outdoors. It can be seen that the final corrosion accumulation values ​​for the outdoor test, indoor single-cycle test, and indoor quarterly cyclic test were 17.67 C, 15.75 C, and 17.38 C, respectively. The indoor quarterly accelerated test showed a smaller error value compared to the outdoor test, and the corrosion accumulation trend was consistent in July and August, with similar corrosion growth rates in each stage, indicating a high correlation between indoor and outdoor results. In Comparative Example 1, the corrosion accumulation trend of the single-cycle indoor accelerated test differed significantly from that of the outdoor test.

[0105] Comparative Example 2

[0106] In Comparative Example 2, Q235 carbon steel plates were selected as the experimental material. The elemental composition of the carbon steel is shown in Table 6 below. The plate size was 25×50×3mm, and a total of 12 parallel plates were used for indoor accelerated testing. During the indoor test, 3 plates were taken out for each quarter cycle. According to GB / T 16545 standard, rust remover (500mL hydrochloric acid + 500mL distilled water + 3.5g hexamethylenetetramine) was used to remove corrosion products from the sample surface. The mass loss of the plates before and after the test was measured using a precision analytical balance. The mass loss of the plates in different quarters (e.g., ...) was used to analyze the mass loss of the plates in different quarters. Figure 9 (As shown) is used as the corrosion rate to calculate the average corrosion rate for each season. Compared with the accumulated electrical charge due to corrosion, the results of the pads only provide discrete, stage-specific average corrosion data, and cannot continuously and in real time reflect the corrosion patterns during the experiment.

[0107] Table 6 Chemical element composition of Q235 carbon steel

[0108]

[0109] Figure 9 The results of the accelerated indoor weight loss test on Q235 coated tablets show that the weight losses at each stage were 40.15 mg, 177.35 mg, 211.9 mg, and 252.3 mg, respectively. It can be seen that the weight loss rate was fastest in July and August, consistent with the general trend in outdoor corrosion during the same period, but the corrosion rate trend during this period cannot be compared. From October to April of the following year, the weight loss increased at a uniform rate, while the accumulated electrical charge from outdoor corrosion increased slowly, indicating a difference in corrosion trends.

[0110] Comparative Example 3

[0111] The experiment was conducted following the method and steps of Example 1. The difference from Example 1 is that in Comparative Example 3, each cycle was a "humid heat-salt spray" cycle, without a drying experiment. Quarterly cycles were also performed, for a total of four "humid heat-salt spray" cycle tests. The experimental results show that in Comparative Example 3, the second stage of the indoor accelerated simulation corrosion accumulation charge change over time corresponds to the outdoor period of July-August, with a faster growth rate. However, due to the lack of a drying experiment and prolonged exposure to a humid environment, the total corrosion accumulation charge value was 22.38C. The experimental error was [missing information]. However, the actual outdoor corrosion-accumulated electricity has a significant error compared to Comparative Example 1 (which only used one cycle). Nevertheless, the trend of accumulated electricity is more consistent with the outdoor accumulated electricity trend chart than Comparative Example 1 (which only used one cycle).

[0112] Figure 10 The graph shows the trend of corrosion accumulation charge over time for the Q235 weathering steel-graphite galvanometer sensor probe in Example 3 during an indoor, non-drying test. The results show that the total corrosion accumulation charge is 22.38 C, which has a significant error of 26.7% compared to the total corrosion accumulation charge outdoors.

[0113] This application employs a thermocouple sensor probe instead of a traditional plate-mounted probe to monitor corrosion current data, meteorological data, and environmental data in real time. Compared to the traditional plate-mounted method, it provides a new benchmark for comparing indoor and outdoor correlations, enabling more precise quantitative comparison of the corrosion process, and offering better simulation and reproducibility. Simultaneously, it uses atmospheric corrosion monitoring methods to determine the conversion factor of the thermocouple probe under different indoor environmental media, using the accumulated corrosion charge Q under different environmental conditions as the conversion standard, providing a new method in addition to polarization curves and weight loss methods. This is suitable for studying the outdoor atmospheric corrosion behavior of various metal steels and for rapidly evaluating their corrosion resistance.

[0114] The indoor equivalent test scheme confirmed in this application can be used for subsequent corrosion performance evaluation of similar metals to be tested.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method of indoor equivalent accelerated test based on a galvanic couple sensor probe, characterized in that, The application relates to a method for testing the corrosion performance of a steel sample, and belongs to the field of corrosion testing. The method comprises the following steps: alternately arranging a plurality of steel sample to be tested and a counter material and separating the samples by insulation to obtain an electric couple sensor probe; connecting the electric couple sensor probe with a micro-current meter and placing the probe outdoors to collect and record outdoor test data; the outdoor test data comprises real-time corrosion current, corrosion cumulative electric quantity, test time data, temperature data, humidity data and rainfall data; obtaining a humid air spectrum representing the relationship between month, humidity action time and temperature and humidity, a dry air spectrum representing the relationship between month, dry action time and temperature and humidity, a rainfall spectrum representing the relationship between month, rainfall time and temperature and humidity and a curve of outdoor corrosion cumulative electric quantity changing with experimental time according to the outdoor test data; An experimental scheme is determined according to the humid air spectrum, the dry air spectrum and the rainfall spectrum, the experimental scheme including an experimental monitoring time, a temperature scheme, a humidity scheme and an environmental medium scheme; according to the experimental scheme, the same galvanic couple sensor probe is used to measure the corrosion cumulative electric quantity Q corresponding to each temperature and humidity interval in the humid air spectrum and the rainfall spectrum i and the maximum value in the temperature scheme and the maximum value in the humidity scheme cp ; the corrosion cumulative electric quantity Q corresponding to each temperature and humidity interval in the humid air spectrum and the rainfall spectrum is calculated i / Q cp , and the time conversion coefficient α i is obtained. According to the hygrothermal action time in the humid air spectrum, the time conversion coefficient a i The hygrothermal test time t of the equivalent accelerated test is calculated 湿 ; According to the rainfall time in the rainfall spectrum, the time conversion coefficient α i and the environmental medium conversion coefficient α', the salt spray-rainfall time t of the equivalent accelerated test is calculated 盐 ; According to the ratio of the dry action time in the dry air spectrum to the hygrothermal action time and the hygrothermal test time t 湿 , the dry test time t of the equivalent accelerated test is calculated 干 ; According to the temperature and humidity of the outdoor test site, the environmental medium scheme, the humid heat test time t 湿 , the salt spray-rainfall time t 盐 , and the drying test time t 干 , an indoor equivalent accelerated test scheme is determined, and an indoor equivalent accelerated test is performed according to the indoor equivalent accelerated test scheme to obtain a curve of indoor corrosion accumulated electric quantity changing with experimental time.

2. The indoor equivalent accelerated test method based on the galvanic couple sensor probe according to claim 1, characterized in that, the potential of the counter material is higher than that of the sample to be tested; the electric couple sensor probe comprises at least four sheet-shaped samples to be tested.

3. The indoor equivalent accelerated test method based on the galvanic couple sensor probe according to claim 2, characterized in that, The counter material is copper or graphite.

4. The indoor equivalent accelerated test method based on the galvanic couple sensor probe according to claim 1, characterized in that, The experimental monitoring time is 1000-3000 min, the temperature scheme corresponds to a temperature range of 20-40 DEG C, the humidity scheme corresponds to a relative humidity range of 60%-95%, and the environmental medium scheme corresponds to a solution medium of deionized water or 1-5 wt% sodium chloride aqueous solution.

5. The indoor equivalent accelerated test method based on the galvanic couple sensor probe according to claim 1, characterized in that, The months in the humid air spectrum, the dry air spectrum and the rainfall spectrum are calculated according to single months, two months, seasons or other specified time periods.

6. The indoor equivalent accelerated test method based on the galvanic couple sensor probe according to claim 1, characterized in that, The environmental medium conversion coefficient a' is a time conversion coefficient 盐 The conversion coefficient corresponding to the medium is the conversion coefficient of sodium chloride aqueous solution, and the salt rain-rain time t 盐 = The total sum of the rainfall time ∑t in the rainfall spectrum i降雨 × The corresponding time conversion coefficient a i × The environmental medium conversion coefficient a'.

7. The indoor equivalent accelerated test method based on the galvanic couple sensor probe according to claim 6, characterized in that, The environmental medium conversion coefficient alpha' is 0.05-0.

12.

8. The galvanic couple sensor probe based indoor equivalent accelerated test method according to claim 1, characterized in that, The relative humidity corresponding to the humid air spectrum is greater than or equal to 60%, and the relative humidity corresponding to the dry air spectrum is less than 60%.

9. The galvanic couple sensor probe based indoor equivalent accelerated test method according to claim 1, characterized in that, In the indoor equivalent acceleration test scheme, the temperature of the humid heat test module is 35 DEG C or 40 DEG C, the relative humidity is 90%, the environmental medium is deionized water or 1-5 wt% sodium chloride aqueous solution; the temperature of the dry test module is 45 DEG C, the relative humidity is 50%, and the environmental medium is deionized water or 1-5 wt% sodium chloride aqueous solution; the temperature of the salt spray-rainfall test module is 35 DEG C, and the environmental medium is 5 wt% sodium chloride aqueous solution. In the indoor equivalent acceleration test scheme, the humid heat test module, the dry test module and the salt spray-rainfall test module are cycled according to seasons or months.

10. The indoor galvanic couple sensor probe based equivalent accelerated test method according to any one of claims 1 to 9, characterized in that, The application further relates to a method for testing the corrosion performance of a steel sample. The method comprises the following steps: using the indoor equivalent acceleration test scheme to test the corrosion performance of other batches of samples with the same theoretical composition.

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