Method for rapid determination of atmospheric corrosion of steel

Abstract

The present application discloses a method for quickly determining atmospheric corrosion of steel, comprising the following steps: S1. placing a steel sample in a Cl-containing ‑ 、Contains SO4 2‑ and H + S1. Perform a corrosion treatment for a first predetermined time in a treatment solution to obtain a corroded steel sample; S2. Perform a first drying treatment on the corroded steel sample; S3. Perform a wetting treatment for a second predetermined time on the steel sample that has undergone the first drying treatment; S4. Perform a second drying treatment on the steel sample that has undergone the wetting treatment; S5. Determine the corrosion weight loss of the steel sample that has undergone the second drying treatment, thereby determining the corrosion time of the steel in the actual atmospheric environment, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time. The main corrosion products on the steel surface obtained by this method are consistent with the corrosion products obtained by the outdoor atmospheric exposure test, which illustrates the availability, simulation, and acceleration of this method.

Description

Technical Field

[0001] The present application belongs to the technical field of steel anti-corrosion, and in particular, relates to a method for quickly determining the degree of atmospheric corrosion of steel. Background Art

[0002] Weathering steel for unpainted bridges has good atmospheric corrosion resistance, low maintenance costs and excellent environmental performance, and is widely used in the bridge field.

[0003] At present, the study of the corrosion condition of bridge steel generally involves establishing a corrosion test station in the service environment of the bridge to conduct on-site exposure tests to study the corrosion condition of the material in that environment. This method can reflect the true effect of the bridge environment on weathering steel and directly obtain reliable corrosion data. Through on-site exposure tests, the corrosion resistance and corrosion mechanism of different materials in various complex atmospheric environments can be understood, providing a reasonable design basis for the anti-corrosion design and material selection of bridge steel.

[0004] In the natural environment, material corrosion is a long and continuous process. It takes a long time to obtain data, which is difficult to meet the industrial needs of research and production. In order to overcome the shortcomings of field exposure tests and shorten the test cycle, it is necessary to develop indoor accelerated tests and evaluation methods to predict the long-term corrosion behavior and service life of weathering steel for unpainted bridges in the atmospheric environment from the results of short-term accelerated corrosion tests. Summary of the invention

[0005] The embodiment of the present application provides a method for quickly determining the atmospheric corrosion degree of steel, aiming to solve the problem that the prior art lacks a method for quickly determining the atmospheric corrosion degree of steel for atmospheric environments with high air humidity and severe industrial pollution.

[0006] The present application provides a method for quickly determining the atmospheric corrosion degree of steel, the method comprising the following steps:

[0007] S1. Place the steel sample in a Cl-containing - 、Contains SO4 2- and H + The first predetermined time period of the corrosion treatment is carried out in the treatment solution to obtain a corroded steel sample,

[0008] S2. performing a first drying treatment on the corroded steel sample;

[0009] S3. subjecting the steel sample after the first drying treatment to a second predetermined period of wetting treatment;

[0010] S4. subjecting the steel sample after the wet treatment to a second drying treatment;

[0011] S5. Determine the corrosion weight loss of the steel sample after the second drying treatment, and determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time.

[0012] In some embodiments of the present application, the method further includes:

[0013] According to the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, as well as the first predetermined time and the second predetermined time, determine the corrosion time of the steel in the actual atmospheric environment obtained in step S5 as the corrosion time of the steel in the actual atmospheric environment of the first use area.

[0014] In some embodiments of the present application, according to Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, as well as the first predetermined time and the second predetermined time, determine the corrosion time of the steel in the actual atmospheric environment obtained in step S5 as the corrosion time of the steel in the actual atmospheric environment of the first use area, including:

[0015] According to the Cl in the treatment solution - The concentration of Cl in different regions - Sedimentation rate;

[0016] According to the SO4 2- The concentration of SO2 in the atmospheric environment of different regions is matched;

[0017] According to the H + The respective concentrations match the pH of rainwater in rainfall in different regions;

[0018] According to the first predetermined time and the second predetermined time, matching the rainfall time and atmospheric humidity time and their ratio in different regions;

[0019] According to the Cl - Determine the first use area based on the deposition rate, the concentration of SO2, the pH of the rainwater, the rainfall time and the atmospheric wetness time and their ratio;

[0020] The corrosion time of the steel material in the actual atmospheric environment obtained in step S5 is determined as the corrosion time of the steel material in the actual atmospheric environment of the first use area.

[0021] In some embodiments of the present application, when the treatment solution contains Cl - The concentration is 0.5% to 0.8%, SO4 2- The concentration is 0.1% to 0.2%, pH is 6 to 6.5, Cl - The deposition rate is 0.3-0.35 mg·m -2 ·d -1 , and the first scheduled time is 20 to 21 hours, the second scheduled time is 16 to 17 hours, and the first usage area is Sichuan;

[0022] Preferably, when the treatment solution contains Cl - The concentration is 0.5%, SO4 2- The concentration is 0.1%, pH is 6, Cl - The deposition rate is 0.31 mg·m -2 ·d -1 , and when the first scheduled time is 20.18 hours and the second scheduled time is 16.8 hours, the first usage area is Chengdu.

[0023] In some embodiments of the present application, step S1 includes:

[0024] According to the second use area of ​​the steel material, the Cl content in the treatment solution is determined respectively. - 、SO4 2- and H + The respective concentrations.

[0025] In some embodiments of the present application, the Cl in the treatment solution is determined according to the second use area of ​​the steel. - 、SO4 2- and H + The respective concentrations include:

[0026] According to the second use area of ​​the steel material, the Cl of the second use area is determined. - The deposition rate is used to determine the Cl content in the treatment solution. - concentration;

[0027] According to the second use area of ​​the steel material, the concentration of SO2 in the atmosphere of the second use area is determined, thereby determining the concentration of SO4 in the treatment solution. 2- concentration;

[0028] According to the second use area of ​​the steel material, the pH of rainwater in the second use area is determined, thereby determining the pH of H in the treatment solution. + concentration.

[0029] In some embodiments of the present application, the step S1 comprises: according to the second use area of ​​the steel and the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations determine the first predetermined time period;

[0030] In some embodiments of the present application, according to the second use area of ​​the steel material and the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, determining the first predetermined period of time comprises:

[0031] In the accelerated corrosion test of steel, several conversion coefficients and Cl content were obtained independently. - Solution concentration, SO4 content 2- Solution concentration, H + A mapping relationship between acid solution concentration and humid air under different temperature conditions, wherein the mapping relationship between the conversion coefficient and different humid air under different temperature conditions is established based on the humidity acceleration model applied to standard humid air, preferably, the standard humid air is air with temperature T = 40 ° C and humidity RH = 100%;

[0032] Performing statistical analysis based on the raining time and the atmospheric humidity time in the second use area to determine the ratio of the raining time to the humidity time, wherein the humidity time is the time when the relative humidity is ≥ 70%;

[0033] According to the H + The concentration of Cl - The concentration of SO4 2- The concentration and the mapping relationships respectively corresponding to the concentration and the mapping relationships respectively correspond to the concentration and the mapping relationships respectively, and the conversion coefficient is matched to determine the comprehensive acceleration coefficient.

[0034] Determine the total duration of the first predetermined time and the second predetermined time according to the conversion coefficients corresponding to the plurality of raining times in the raining time of the second use area, the plurality of wet processing times in the atmospheric wet time, and the different wet air under different temperature conditions;

[0035] The first predetermined time period is determined according to the comprehensive acceleration coefficient, the total time period of the first predetermined time period and the second predetermined time period, and the ratio of the raining time to the wet time.

[0036] In some embodiments of the present application, the step S3 includes: according to the second use area of ​​the steel and the Cl in the treatment solution - 、SO4 2- and H + The second predetermined time period is determined by the respective concentrations.

[0037] In some embodiments of the present application, according to the second use area of ​​the steel material and the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, determining the second predetermined period of time, comprises:

[0038] In the accelerated corrosion test of steel, several conversion coefficients and Cl content were obtained independently. - Solution concentration, SO4 content 2- Solution concentration, H + A mapping relationship between acid solution concentration and humid air under different temperature conditions, wherein the mapping relationship between the conversion coefficient and different humid air under different temperature conditions is established based on the humidity acceleration model applied to standard humid air, preferably, the standard humid air is air with temperature T = 40 ° C and humidity RH = 100%;

[0039] Performing statistical analysis based on the raining time and the atmospheric humidity time in the second use area to determine the ratio of the raining time to the humidity time, wherein the humidity time is the time when the relative humidity is ≥ 70%;

[0040] According to the H + The concentration of Cl - The concentration of SO4 2- The concentration and the mapping relationships respectively corresponding to the concentration and the mapping relationships respectively correspond to the concentration and the mapping relationships respectively, and the conversion coefficient is matched to determine the comprehensive acceleration coefficient.

[0041] Determine the total duration of the first predetermined time and the second predetermined time according to the conversion coefficients corresponding to the plurality of raining times in the raining time of the second use area, the plurality of wet processing times in the atmospheric wet time, and the different wet air under different temperature conditions;

[0042] The second predetermined time period is determined according to the comprehensive acceleration coefficient, the total time period of the first predetermined time period and the second predetermined time period, and the ratio of the raining time to the wet time.

[0043] In some embodiments of the present application, the corrosion weight loss curve of the steel in an actual atmospheric environment conforms to the following formula:

[0044] C=At k

[0045] Where C is the corrosion weight loss per unit area of ​​the steel sample, in g / m 2 ;

[0046] t is the experimental time, in months;

[0047] A and k are constants related to the type of steel and the actual atmospheric environment in which the steel is used. The k value is used as a reference for the corrosion rate or the protectiveness of the rust layer, and the A value is often used to reflect the initial corrosion rate of the steel.

[0048] In some embodiments of the present application, A and k of the corrosion weight loss curve are determined as follows:

[0049] Obtain a data set corresponding to the corrosion weight loss and time of a steel sample of a predetermined steel type in an actual atmospheric environment;

[0050] Fitting is performed based on the data set to determine A and k of the corrosion weight loss curve.

[0051] In some embodiments of the present application, if the steel sample is Q345QENH weathering steel and is corroded in the Chengdu atmospheric environment, the corrosion weight loss curve satisfies C=22.9472t 0.85242 ;

[0052] If the steel sample is Q345QD steel and corrodes in the Chengdu atmospheric environment, the corrosion weight loss curve satisfies C=20.29546t 0.94928 .

[0053] In some embodiments of the present application, before step S5, the process further includes repeating steps S1-S4 for N times or more, where N is a positive integer.

[0054] The method provided by the present application comprises: - 、SO4 2- and H + The corrosion treatment is carried out in a treatment solution of, and then drying, wetting and drying are performed alternately. According to the corrosion weight loss curve and the corrosion weight loss, the corrosion time of the steel corresponding to the corroded steel sample in the actual atmospheric environment is determined, so that the atmospheric corrosion of carbon steel in the relevant area can be fully and truly restored, and the atmospheric corrosion of carbon steel can be quickly obtained; the dry-wet alternation of drying, wetting and drying can make carbon steel effectively generate corrosion products, and effectively avoid the fragmentation and difficulty of detection of corrosion products; the method can be applied to atmospheric environments with high air humidity and serious industrial pollution; through the method, the main corrosion products on the surface of the steel are consistent with the corrosion products obtained in the outdoor atmospheric exposure test, and the corrosion weight loss curve conforms to the power function law of the corrosion weight loss in outdoor long-term exposure, which proves the availability, simulation, acceleration and reproducibility of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0056] Figure 1 This is a surface morphology of a Q345QENH steel sample from an indoor experiment in the embodiment;

[0057] Figure 2 This is the surface morphology of the Q345QD steel sample in the indoor experiment in the embodiment;

[0058] Figure 3 The XRD spectrum of the corrosion products of the steel samples in the indoor experiment in the embodiment;

[0059] Figure 4 The graph is a graph showing the relationship between the weight loss and time of the corrosion of the steel sample in the indoor experiment in the embodiment;

[0060] Figure 5 This is the surface morphology of the Q345QENH steel sample in the outdoor actual atmospheric exposure experiment;

[0061] Figure 6 This is the surface morphology of the Q345QD steel sample in the outdoor actual atmospheric exposure experiment;

[0062] Figure 7 This is the XRD spectrum of corrosion products of steel samples in outdoor actual atmospheric exposure experiments;

[0063] Figure 8 This is a graph showing the relationship between the corrosion weight loss and time of steel samples in the outdoor actual atmospheric exposure experiment. DETAILED DESCRIPTION

[0064] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0065] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0066] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two, and the “multiple” in “one or more” means more than two.

[0067] The above invention summary of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each embodiment, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0068] The present application provides a method for quickly determining the atmospheric corrosion degree of steel, the method comprising the following steps:

[0069] S1. Place the steel sample in a Cl-containing - 、Contains SO4 2- and H + The first predetermined time period of the corrosion treatment is carried out in the treatment solution to obtain a corroded steel sample,

[0070] S2. performing a first drying treatment on the corroded steel sample;

[0071] S3. subjecting the steel sample after the first drying treatment to a second predetermined period of wetting treatment;

[0072] S4. subjecting the steel sample after the wet treatment to a second drying treatment;

[0073] S5. Determine the corrosion weight loss of the steel sample after the second drying treatment, and determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time.

[0074] According to the embodiment of the present application, in step S1, the steel sample is placed in a Cl-containing - 、Contains SO4 2- and H +The treatment liquid can restore the corrosion of the steel sample in the actual atmospheric environment during rainfall; the corrosion treatment for the first predetermined time can make the steel sample reach the corrosion situation in the actual atmospheric environment during rainfall, reflecting the corrosion of the steel by the rainfall duration in the actual area; the steel sample is subjected to a wetting treatment, which can restore the corrosion of the steel in the humid air of the actual atmospheric environment, and the second predetermined time also restores the action time of the humid air in the actual area on the steel, and comprehensively restores the scene of steel corrosion to obtain a corroded steel sample, and based on the weight loss of the steel sample and the corroded steel sample, the corrosion time and corrosion degree of the steel sample in the actual atmospheric environment are determined. The method of the embodiment of the present application obtains the corrosion morphology, corrosion product composition, and corrosion weight loss curve of the corroded steel through corrosion treatment and dry-wet-dry alternating treatment. It is determined that the method of the present application can simulate actual atmospheric corrosion and quickly determine the atmospheric corrosion degree of steel.

[0075] According to the embodiments of the present application, the time of the first drying treatment and the second drying treatment can be freely adjusted according to the time for the steel to generate corrosion products. Considering the efficiency of the method of the present application, in some embodiments, the first drying treatment can be 5 to 6.5 hours, preferably 6 hours; in some embodiments, the second drying treatment can be 5 to 6.5 hours, preferably 6 hours.

[0076] In some embodiments, the treatment liquid may be a solution containing NaCl and Na SO4; the H in the treatment liquid may be determined according to the degree of industrial pollution. + concentration.

[0077] In some embodiments, the method further comprises:

[0078] According to the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, as well as the first predetermined time and the second predetermined time, determine the corrosion time of the steel in the actual atmospheric environment obtained in step S5 as the corrosion time of the steel in the actual atmospheric environment of the first use area.

[0079] According to the embodiments of the present application, corresponding processing conditions can be preset, and the area where the steel is actually used can be matched according to the preset processing conditions, thereby expanding the scope of use of the method of the present application.

[0080] In some embodiments, according to the Cl in the treatment solution - 、SO4 2- and H +The respective concentrations, as well as the first predetermined time and the second predetermined time, determine the corrosion time of the steel in the actual atmospheric environment obtained in step S5 as the corrosion time of the steel in the actual atmospheric environment of the first use area, including:

[0081] According to the Cl in the treatment solution - The concentration of Cl in different regions - Sedimentation rate;

[0082] According to the SO4 2- The concentration of SO2 in the atmospheric environment of different regions is matched;

[0083] According to the H + The respective concentrations match the pH of rainwater in rainfall in different regions;

[0084] According to the first predetermined time and the second predetermined time, matching the rainfall time and atmospheric humidity time and their ratio in different regions;

[0085] According to the Cl - Determine the first use area based on the deposition rate, the concentration of SO2, the pH of the rainwater, the rainfall time and the atmospheric wetness time and their ratio;

[0086] The corrosion time of the steel material in the actual atmospheric environment obtained in step S5 is determined as the corrosion time of the steel material in the actual atmospheric environment of the first use area.

[0087] According to the embodiments of the present application, the common characteristics of different climates and environments are summarized by using the preset processing conditions, such as Cl - The deposition rate, SO2 concentration, pH of rainwater, rainfall time, atmospheric humidity time and their ratio can be used to match the climate and atmospheric environment characteristics of different regions according to these conditions, so that the method of the present application can be extended to regions with such climate and atmospheric environment characteristics.

[0088] In some embodiments, when the treatment solution contains Cl - The concentration is 0.5% to 0.8%, SO4 2- The concentration is 0.1% to 0.2%, pH is 6 to 6.5, Cl - The deposition rate is 0.3-0.35 mg·m -2 ·d -1 , and the first scheduled time is 20 to 21 hours, the second scheduled time is 16 to 17 hours, and the first usage area is Sichuan;

[0089] Preferably, when the treatment solution contains Cl - The concentration is 0.5%, SO42- The concentration is 0.1%, pH is 6, Cl - The deposition rate is 0.31 mg·m -2 ·d -1 , and when the first scheduled time is 20.18 hours and the second scheduled time is 16.8 hours, the first usage area is Chengdu.

[0090] According to the embodiment of the present application, Cl in the treatment solution - 、SO4 2- and H + The concentrations of each, as well as the first predetermined time and the second predetermined time, can be summarized as Cl - When the values ​​of the deposition rate, the concentration of the SO2, the pH of the rainwater, the rainfall time, the atmospheric humidity time and their ratio are the parameters listed above, the above method can be used in Sichuan, preferably Chengdu.

[0091] In some embodiments, step S1 includes:

[0092] According to the second use area of ​​the steel material, the Cl content in the treatment solution is determined respectively. - 、SO4 2- and H + The respective concentrations.

[0093] According to the embodiments of the present application, when the area where the steel is actually used is determined, the concentration of the treatment solution for treating the steel can be determined according to the method of the present application, such as Cl in the treatment solution. - 、SO4 2- and H + The respective concentrations.

[0094] In some embodiments, the Cl in the treatment solution is determined according to the second use area of ​​the steel. - 、SO4 2- and H + The respective concentrations include:

[0095] According to the second use area of ​​the steel material, the Cl of the second use area is determined. - The deposition rate is used to determine the Cl content in the treatment solution. - concentration;

[0096] According to the second use area of ​​the steel material, the concentration of SO2 in the atmosphere of the second use area is determined, thereby determining the concentration of SO4 in the treatment solution. 2- concentration;

[0097] According to the second use area of ​​the steel material, the pH of rainwater in the second use area is determined, thereby determining the pH of H in the treatment solution. +concentration.

[0098] According to the embodiment of the present application, the region where the steel is actually used can be matched according to the preset conditions, and the key climate characteristics of steel corrosion in the actual second use region can be collected, such as Cl - The deposition rate, the concentration of SO2 in the atmosphere, pH, etc. are used to determine the concentration of each ion in the treatment solution of the method of the present application, thereby expanding the application direction of the method of the present application.

[0099] In some embodiments, the step S1 comprises: according to the second use area of ​​the steel material and the Cl in the treatment solution - 、SO4 2- and H + The first predetermined time period is determined by the respective concentrations.

[0100] According to an embodiment of the present application, when the area where the steel is actually used is determined, the first predetermined time period can be determined according to the method of the present application, and the first predetermined time period is the processing time for simulating rainfall and rainwater in an accelerated experiment.

[0101] In some embodiments, according to the second use area of ​​the steel material and the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, determining the first predetermined period of time comprises:

[0102] In the accelerated corrosion test of steel, several conversion coefficients and Cl content were obtained independently. - Solution concentration, SO4 content 2- Solution concentration, H + A mapping relationship between acid solution concentration and humid air under different temperature conditions, wherein the mapping relationship between the conversion coefficient and different humid air under different temperature conditions is established based on the humidity acceleration model applied to standard humid air, preferably, the standard humid air is air with temperature T = 40 ° C and humidity RH = 100%;

[0103] Performing statistical analysis based on the raining time and the atmospheric humidity time in the second use area to determine the ratio of the raining time to the humidity time, wherein the humidity time is the time when the relative humidity is ≥ 70%;

[0104] According to the H + The concentration of Cl - The concentration of SO4 2- The concentration and the mapping relationships respectively corresponding to the concentration and the mapping relationships respectively correspond to the concentration and the mapping relationships respectively, and the conversion coefficient is matched to determine the comprehensive acceleration coefficient.

[0105] Determine the total duration of the first predetermined time and the second predetermined time according to the conversion coefficients corresponding to the plurality of raining times in the raining time of the second use area, the plurality of wet processing times in the atmospheric wet time, and the different wet air under different temperature conditions;

[0106] The first predetermined time period is determined according to the comprehensive acceleration coefficient, the total time period of the first predetermined time period and the second predetermined time period, and the ratio of the raining time to the wet time.

[0107] According to the embodiment of the present application, the concentration of each relevant ion in the treatment liquid is used to find the corresponding conversion coefficient, and the reciprocals of the conversion coefficients are added together to obtain the comprehensive acceleration coefficient. The sum of the actual multiple raining times and the corresponding conversion coefficients is obtained by multiplying the actual multiple wet times and the corresponding conversion coefficients, which is the total duration of the first predetermined duration and the second predetermined duration. The first predetermined duration can be calculated using the ratio of the raining time to the wet time.

[0108] In the embodiment of the basic application, in the accelerated corrosion test of steel, several conversion coefficients and Cl content are independently obtained. - Solution concentration, SO4 content 2- Solution concentration, H + The mapping relationship between the acid solution concentration and the humid air under different temperature conditions can be specifically adopted from the mapping relationship shown in the conversion coefficient table of steel in various environmental factors provided in "Aircraft Corrosion / Aging Control and Calendar Life Extension Technology" (shown in Tables 1 to 4), using the standard humid time and the conversion coefficient of the solution. The standard humid air can be temperature T = 40°C, humidity RH = 100%, and the conversion coefficient α = 1. Based on the existing data and the conversion coefficient of structural steel at different temperatures and relative humidity, the conversion coefficient of carbon steel can be obtained by correction and extrapolation based on the humidity acceleration model (HallbergePeck) model.

[0109] Table 1 Conversion coefficients of carbon steel humid air and standard humid air.

[0110]

[0111] Table 2 Conversion coefficients of carbon steel substrate in pure water medium relative to NaCl solutions of different concentrations.

[0112]

[0113] Table 3 Conversion coefficients of carbon steel substrate in pure water medium relative to different concentrations of H2SO4.

[0114]

[0115] Table 4 Conversion coefficients of carbon steel substrate in pure water medium relative to Na2SO4 solutions of different concentrations.

[0116]

[0117] According to the embodiment of the present application, some conversion coefficients and Cl-containing - Solution concentration, SO4 content 2- Solution concentration, H + The mapping relationship between the acid solution concentration and the humid air under different temperature conditions can be re-established by using other standards or based on experiments.

[0118] According to the embodiment of the present application, the comprehensive acceleration coefficient can be determined by the following steps:

[0119] Case 1: Comprehensive acceleration coefficient of Chengdu and Lhasa

[0120] Step 1: Cl in the treatment solution - Acceleration factor of solution:

[0121] Cl in Chengdu - The deposition rate is 0.31 mg·m -2 ·d -1 ;

[0122] Cl - The deposition rate is 0.31 mg·m -2 ·d -1 ;

[0123] Step 2: Determine the acceleration factor for different ion concentrations

[0124] Referring to Table 2, considering the acceleration and correlation, Cl - The solution concentration is 0.5%. The conversion coefficient α relative to pure water is 0.485, and the acceleration coefficient is its reciprocal 2.062, that is, the carbon steel substrate is subjected to 0.5% NaCl salt spray for 1 hour, which is equivalent to 2.06 hours under standard humid air conditions.

[0125] The pH value of precipitation in Chengdu is 6.3, and the pH value of precipitation in Lhasa is 6. Considering the consistency of the acceleration of the test with the actual environment, the solution used in the accelerated environmental spectrum test in Chengdu and Lhasa was adjusted to pH=6 with dilute sulfuric acid. Since pH=-log (the concentration of hydrogen ions in the acid), [H + ]=0.000001mol / L, then H +The corresponding concentration is 0.5×0.000001mol / L, and its molecular weight is 98.08, so the mass concentration of sulfuric acid is 0.5×98.08×0.000001g / L=0.04904mg / L. As shown in Table 3, the conversion coefficient corresponding to 0.1mg / L is α=0.571, and the acceleration coefficient is its reciprocal 1.751. By extrapolation, the acceleration coefficient corresponding to 0.04904mg / L is 1.7289, that is, the carbon steel substrate is subjected to salt spray at pH=6 for 1h, which is equivalent to 1.73h under standard humid air conditions.

[0126] SO4 2- Acceleration factor of solution: The SO2 concentration in Chengdu, Lhasa and other areas is relatively low, basically at the lower limit of P1 level, close to P0 level, so reducing SO4 2- The solution concentration is 0.1%. As shown in Table 4, the carbon steel substrate has a 0.1% SO4 2- Exposure of the solution to salt spray for 1 hour is equivalent to 1.80 hours under standard humid air conditions.

[0127] Comprehensive acceleration factor in step 3 accelerated test:

[0128] The comprehensive acceleration coefficients in Chengdu and Lhasa are: T21=2.06+1.73+1.80=5.59, that is, 1 hour of carbon steel in the cyclic salt spray acceleration test is equivalent to 5.59 hours under standard humid air conditions.

[0129] Case 2 Comprehensive acceleration coefficient of Yajiang and Litang areas

[0130] Step 1: Cl in the treatment solution - Acceleration factor of solution:

[0131] Cl in Yajiang area - The deposition rate is 0.31 mg·m -2 ·d -1 ;

[0132] Cl in Litang area - The deposition rate is 0.31 mg·m -2 ·d -1 ;

[0133] Step 2: Determine the acceleration factor for different ion concentrations

[0134] Referring to Table 2, considering the acceleration and correlation, Cl - The solution concentration is 0.5%. The conversion coefficient α relative to pure water is 0.485, and the acceleration coefficient is its reciprocal 2.062, that is, the carbon steel substrate is subjected to 0.5% NaCl salt spray for 1 hour, which is equivalent to 2.06 hours under standard humid air conditions.

[0135] The pH value of precipitation in Yajiang area is 6.8, and the pH value of precipitation in Litang area is also 6.8, which is close to neutral. The pH value of the solution used in the accelerated environmental spectrum test in Yajiang and Litang areas is not adjusted, so no additional H+ is added to the solution, so the acceleration parameters are not provided here.

[0136] SO4 2- Acceleration coefficient of solution: SO2 concentration in Yajiang and Litang areas is relatively low, basically at the lower limit of P1 level, close to P0 level, so reducing SO4 2- The solution concentration is 0.1%. As shown in Table 4, the carbon steel substrate is 2- Exposure of the solution to salt spray for 1 hour is equivalent to 1.80 hours under standard humid air conditions.

[0137] Comprehensive acceleration factor in step 3 accelerated test:

[0138] The comprehensive acceleration coefficients of Yajiang and Litang areas are: T22=2.06+1.80=3.86, that is, 1 hour of carbon steel in the cyclic salt spray acceleration test is equivalent to 3.86 hours under standard humid air conditions.

[0139] In some embodiments, the temperature of the treatment liquid can be determined according to the actual atmospheric temperature of the use area or the temperature of rainwater when it rains in the use area, and can be 10-40° C. Specifically, the temperature of the treatment liquid can be 15° C., 20° C., 25° C., 30° C., 35° C., etc.

[0140] In some embodiments, the rainy time in the second usage area can be the annual rainy time, the rainy time in multiple years, or the rainy time within a specified period; the specified period can be a representative monthly, quarterly, or plum rain season time, etc.; the wet time in the second usage area can be the annual wet time, the wet time in multiple years, or the wet time within a specified period; the specified period can be a representative monthly, quarterly, or plum rain season, etc.

[0141] In some embodiments, the multiple raining times may be 3, 4, 5, 8, or 10, 20, 50, 100, 365, etc., or 1 times, 2 times, 3 times, 4 times, 7 times, etc., of the above times.

[0142] In some embodiments, the multiple wetting times can be 3, 4, 5, 8, or 10, 20, 50, 100, 365, etc., or 1 times, 2 times, 3 times, 4 times, 7 times, etc., of the above times.

[0143] According to the embodiment of the present application, four regions, namely Chengdu, Litang, Yajiang and Lhasa, can be selected to collect annual meteorological data, Cl -The deposition rate and pH value of Cl- at the above four locations are similar, which is Cl - The deposition rate is 0.31 mg·m -2 ·d -1 The annual meteorological data can be 2017, 2018, etc.

[0144] The statistical results of the atmospheric environment spectrum in the four regions of Chengdu, Yajiang, Litang and Lhasa are shown in Table 5-8.

[0145] Table 5 Chengdu atmospheric environment spectrum.

[0146]

[0147] Table 6 Yajiang atmospheric environment spectrum.

[0148]

[0149]

[0150] Table 7 Litang atmospheric environment spectrum.

[0151]

[0152] Table 8 Lhasa atmospheric environment spectrum.

[0153]

[0154] In some embodiments, the environmental spectra of the four locations of Du, Litang, Yajiang and Lhasa, specifically the rainfall time and the atmospheric humidity time; and the mapping relationship between the conversion coefficient and the different humid air under different temperature conditions, specifically the mapping relationship shown in Table 2; the standard humidity time of carbon steel can be calculated based on the above.

[0155] Standard wet time for carbon steel at 4 locations:

[0156] According to the atmospheric environment spectra of Chengdu, Yajiang, Litang and Lhasa in Tables 4 to 8 and the data in Table 1, the atmospheric environment spectrum in Chengdu is equivalent to the action of standard humid air for 518.6 hours throughout the year; the atmospheric environment spectrum in Yajiang is equivalent to the action of standard humid air for 215.3 hours throughout the year; the atmospheric environment spectrum in Litang is equivalent to the action of standard humid air for 65.4 hours throughout the year; and the atmospheric environment spectrum in Lhasa is equivalent to the action of standard humid air for 162.6 hours throughout the year.

[0157] The calculation process is as follows (taking Chengdu as an example):

[0158] 1) According to the conversion coefficients in Table 1, convert the humid air at each temperature in the Chengdu environmental spectrum.

[0159] Hours:

[0160] T11=175×0.01327+157×0.02084+106×0.03103+219×0.03725+117×0.02334+159×0.03665+118×0.05457+236×0.06551+137× 0.04026+219×0.06322+135×0.09414+264×0.11301+80×0.06818+72×0.10708+25×0.15945+7×0.19142+10×0.11961=129.1h

[0161] 2) According to the conversion coefficient in Table 1, convert the number of rainfall hours in the Chengdu environmental spectrum:

[0162] T12=519×0.04430+590×0.07791+986×0.13440+528×0.22765+166×0.37896+8×0.62046=389.5h

[0163] 3) Summarize the above calculation results to get the number of hours in Chengdu that are equivalent to the standard humid air throughout the year:

[0164] T1=T11+T12=129.1+389.5=518.6h; that is, the sum of the first predetermined time length×the comprehensive acceleration coefficient and the second predetermined time length is 518.6h;

[0165] Preferably, the ratio of rainy time to wet time in Chengdu is 6:5, that is, the ratio of the first predetermined time length to the second predetermined time length is 6:5.

[0166] In summary, in order to obtain the corrosion degree of steel in the actual atmospheric climate of Chengdu in one year, the first predetermined time period may be 80.7 hours, and the processing time of the second predetermined time period may be 67.2 hours.

[0167] In order to obtain the corrosion degree of steel in the actual atmospheric climate of Chengdu for 3 months, the first predetermined processing time may be 20.18 hours, and the second predetermined processing time may be 16.8 hours.

[0168] Alternatively, in order to obtain the corrosion degree of steel in the actual atmospheric climate of Chengdu in one year, the first predetermined processing time can be 20.18 hours, the second predetermined processing time can be 16.8 hours, and the methods S1-S4 of the present application are performed 4 times.

[0169] In some embodiments, the ratio of raining time to wet time can be applied to areas with rainfall ≥ 1400 mm, and can also be applied to other rainy areas. The ratio of raining time to wet time can be 1.1 to 1.4:1, preferably 6:5; any other ratio of raining time to wet time is not required, as long as it is consistent with the actual situation of the second use area.

[0170] In some embodiments, the step S3 comprises: according to the second use area of ​​the steel and the Cl in the treatment solution - 、SO4 2- and H + The second predetermined time period is determined by the respective concentrations.

[0171] According to an embodiment of the present application, when the area where the steel is actually used is determined, the second predetermined time can be determined according to the method of the present application, and the second predetermined time is the processing time of simulating humid air in the atmospheric environment in the accelerated experiment. Humid air in the embodiment of the present application is defined as air with a relative humidity of ≥70%.

[0172] In some embodiments, according to the second use area of ​​the steel material and the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, determining the second predetermined period of time, comprises:

[0173] In the accelerated corrosion test of steel, several conversion coefficients and Cl content were obtained independently. - Solution concentration, SO4 content 2- Solution concentration, H + A mapping relationship between acid solution concentration and humid air under different temperature conditions, wherein the mapping relationship between the conversion coefficient and different humid air under different temperature conditions is established based on the humidity acceleration model applied to standard humid air, preferably, the standard humid air is air with temperature T = 40 ° C and humidity RH = 100%;

[0174] Performing statistical analysis based on the raining time and the atmospheric humidity time in the second use area to determine the ratio of the raining time to the humidity time, wherein the humidity time is the time when the relative humidity is ≥ 70%;

[0175] According to the H + The concentration of Cl - The concentration of SO4 2- The concentration and the mapping relationships respectively corresponding to the concentration and the mapping relationships respectively correspond to the concentration and the mapping relationships respectively, and the conversion coefficient is matched to determine the comprehensive acceleration coefficient.

[0176] Determine the total duration of the first predetermined time and the second predetermined time according to the conversion coefficients corresponding to the plurality of raining times in the raining time of the second use area, the plurality of wet processing times in the atmospheric wet time, and the different wet air under different temperature conditions;

[0177] The second predetermined time period is determined according to the comprehensive acceleration coefficient, the total time period of the first predetermined time period and the second predetermined time period, and the ratio of the raining time to the wet time.

[0178] In some embodiments, the corrosion weight loss curve of the steel in an actual atmospheric environment conforms to the following formula:

[0179] C=At k

[0180] Where C is the corrosion weight loss per unit area of ​​the steel sample, in g / m 2 ;

[0181] t is the experimental time, in months;

[0182] A and k are constants related to the type of steel and the actual atmospheric environment in which the steel is used. The k value is used as a reference for the corrosion rate or the protectiveness of the rust layer, and the A value is often used to reflect the initial corrosion rate of the steel.

[0183] According to the embodiment of the present application, the corrosion weight loss curve is linearly related to the type of steel and is power function related to the time of the actual atmospheric environment in which the steel is used, which is consistent with the above description.

[0184] In some embodiments, A and k of the corrosion weight loss curve are determined as follows:

[0185] Obtain a data set corresponding to the corrosion weight loss and time of a steel sample of a predetermined steel type in an actual atmospheric environment;

[0186] Fitting is performed based on the data set to determine A and k of the corrosion weight loss curve.

[0187] According to an embodiment of the present application, a steel sample of a predetermined steel type undergoes corrosion in an actual atmospheric environment, and its weight loss density and time are recorded simultaneously, and the recorded data are processed to obtain relevant parameters of the corrosion weight loss curve.

[0188] In some embodiments of the present application, if the steel sample is Q345QENH weathering steel and is corroded in the Chengdu atmospheric environment, the corrosion weight loss curve satisfies C=22.9472t 0.85242 ;

[0189] If the steel sample is Q345QD steel and corrodes in the Chengdu atmospheric environment, the corrosion weight loss curve satisfies C=20.29546t0.94928 .

[0190] In some embodiments, before step S5, steps S1-S4 are repeated N times or more, where N is a positive integer.

[0191] When the second use area is Chengdu, the corrosion treatment time is 20 to 21 hours, and the wet treatment time is 16 to 17 hours, in some embodiments, if it is necessary to obtain the atmospheric corrosion degree of the steel sample in the actual atmospheric environment within 3 months, the corrosion weight loss curve is used, and steps S1-S4 are processed once in sequence; in other embodiments, if it is necessary to obtain the atmospheric corrosion degree of the steel sample in the actual atmospheric environment within 6 months, the corrosion weight loss curve is used, and steps S1-S4 are repeated once, that is, steps S1-S4 are processed once and then processed again.

[0192] The same is true for other situations. If the atmospheric corrosion degree within 12 months is to be obtained, steps S1 to S4 are repeated 3 times, that is, steps S1 to S4 are processed 4 times in total.

[0193] Example

[0194] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0195] A method for quickly determining the degree of atmospheric corrosion of steel, the method comprising the following steps:

[0196] S1. Place the steel sample in a Cl-containing - 、Contains SO4 2- and H + The first predetermined time period of the corrosion treatment is carried out in the treatment solution to obtain a corroded steel sample,

[0197] S2. performing a first drying treatment on the corroded steel sample;

[0198] S3. subjecting the steel sample after the first drying treatment to a second predetermined period of wetting treatment;

[0199] S4. subjecting the steel sample after the wet treatment to a second drying treatment;

[0200] S5. Determine the corrosion weight loss of the steel sample after the second drying treatment, determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time;

[0201] S6. According to the second use area of ​​the steel, respectively determine the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations.

[0202] If the second use area is Chengdu, Sichuan, the steel needs to be exposed to atmospheric corrosion in Chengdu for 3 months. The specific steps are as follows:

[0203] Two types of weathering steel, Q345QENH and Q345QD, were used as test materials. The chemical compositions of Q345QENH and Q345QD are shown in Table 5. The cutting size of the test wire used in the accelerated corrosion test was 50mm (length) × 25mm (width) × 3mm (thickness), and the sample size used in the outdoor exposure test was 100mm (length) × 50mm (width) × 3mm (thickness). The cut samples were polished with 120#, 240#, 400#, and 800# sandpapers in turn, degreased with acetone, rinsed with deionized water, dehydrated with ethanol solution, dried with a hair dryer, and then stored in a desiccator. Before the test, the sample size was measured with a vernier caliper, and the initial weight was measured with a balance with an accuracy of 0.1mg.

[0204] Table 5 Chemical composition of test materials.

[0205]

[0206] The atmospheric exposure test was carried out in Chengdu, Sichuan with reference to the ISO-4542 standard. The indoor simulation test referred to the environmental parameters of Chengdu, Sichuan, and took into account the main environmental factors affecting stainless steel corrosion and the pH value of rainwater. Salt spray test and dry-wet alternating test were used to conduct accelerated corrosion tests of different cycles on the two weathering steels.

[0207] The rust removal of the sample was carried out according to the national standard GB / T16545-2015 "Removal of Corrosion Products on Corrosion Test Specimens of Metals and Alloys", and the rust removal liquid was used to clean the corrosion products on the surface of the sample. The rust removal liquid is 500ml hydrochloric acid, 3.5g hexamethylenetetramine, and a 1000ml solution prepared with distilled water. The rusted sample was placed in the room temperature and soaked for 10 minutes, then cleaned with a brush, and then rinsed with deionized water and brushed lightly until there was no corrosion product on the surface. Then it was cleaned with deionized water, dried with cold air, and stored in a desiccator. After being placed for 24 hours, it was weighed. Three parallel samples were taken from each group, and the weight loss values ​​were measured respectively, and the average value was calculated. The experiment was analyzed from the aspects of corrosion weight loss, product morphology, and rust layer composition, and the appropriate experimental conditions were selected according to the objectives.

[0208] Example 1

[0209] The samples of two kinds of weathering steel, Q345QENH and Q345QD, were placed in a mixed solution of 0.5% NaCl, 0.1% Na2SO4, pH=6 for corrosion treatment. The temperature was set at 40°C and the salt spray test was carried out for 20.175h in a standard salt spray test machine. Then, the samples were subjected to a dry-wet alternating test in a high-low temperature and humidity chamber in the order of "dry→wet→dry". The drying module was set to 6h, the relative humidity was set to 25%RH±5%RH, and the temperature was set to 60±5°C; the wet module was set to 16.975h, the relative humidity was set to 95%RH±5%RH, and the temperature was set to 40±5°C. The total test time was 49.15h. The above "salt spray test + dry-wet alternating test" was carried out for 2 cycles, with a total of 98.3h.

[0210] The corrosion weight loss of the steel sample after the second drying treatment is determined, so as to determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, that is, the steel is corroded in the actual atmosphere for 6 months, and the corrosion degree of the steel sample is used as the atmospheric corrosion degree of the steel at the corrosion time.

[0211] Figure 1 (a) and Figure 2 (a) are the surface morphologies of Q345QENH and Q345QD after two cycles of testing. It can be seen that the corrosion products of both steels are clustered. The surface products of Q345QD have larger pores and cracks, while Q345QENH has fewer pores and cracks, and the surface products are relatively dense. Figure 5 (a) and Figure 6 (a) Surface morphologies of Q345QENH and Q345QD samples after 6 months of outdoor exposure. Comparison shows that the morphologies of corrosion products on the surfaces of the two samples are similar.

[0212] Example 2

[0213] The samples of two kinds of weathering steel, Q345QENH and Q345QD, were placed in a mixed solution of 0.5% NaCl, 0.1% Na2SO4, pH=6 as the test solution for corrosion treatment. The temperature was set at 40°C in a standard salt spray test machine for 20.175h of salt spray test. Then, the samples were subjected to dry-wet alternating test in a high-low temperature and humidity chamber in the order of "dry→wet→dry", where the drying module was set to 6h, the relative humidity was set to 25%RH±5%RH, and the temperature was set to 60±5°C; the wetting module was set to 16.975h, the relative humidity was set to 95%RH±5%RH, and the temperature was set to 40±5°C. The total test time was 49.15h.

[0214] Determine the corrosion weight loss of the steel sample after the second drying treatment, and determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, that is, the steel is corroded in the actual atmosphere for 3 months, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time.

[0215] Example 3

[0216] The experimental materials are Q345QENH weathering steel and Q345QD bridge steel. The samples are first subjected to a 20.175h salt spray test in a standard salt spray test machine with a mixed solution of 0.5% NaCl + 0.1% Na2SO4 and pH = 6 as the test solution, and the temperature is set to 40°C. Then, the samples are subjected to a dry-wet alternating test in a high-low temperature and humidity chamber in the order of "dry → wet → dry". The drying module is set to 6h, the relative humidity is set to 25% RH ± 5% RH, and the temperature is set to 60 ± 5°C; the wet module is set to 16.975h, the relative humidity is set to 95% RH ± 5% RH, and the temperature is set to 40 ± 5°C. The total test time is 49.15h. The above "salt spray test + dry-wet alternating test" is carried out for 3 cycles, accumulating 147.45h.

[0217] The corrosion weight loss of the steel sample after the second drying treatment is determined, so as to determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, that is, the steel is corroded in the actual atmosphere for 9 months, and the corrosion degree of the steel sample is used as the atmospheric corrosion degree of the steel at the corrosion time.

[0218] Example 4

[0219] The experimental materials are Q345QENH weathering steel and Q345QD bridge steel. The samples are first subjected to a 20.175h salt spray test in a standard salt spray test machine with a mixed solution of 0.5% NaCl + 0.1% Na2SO4 and pH = 6 as the test solution, and the temperature is set to 40°C. Then, the samples are subjected to a dry-wet alternating test in a high-low temperature and humidity chamber in the order of "dry → wet → dry". The drying module is set to 6h, the relative humidity is set to 25% RH ± 5% RH, and the temperature is set to 60 ± 5°C; the wet module is set to 16.975h, the relative humidity is set to 95% RH ± 5% RH, and the temperature is set to 40 ± 5°C. The total test time is 49.15h. The above "salt spray test + dry-wet alternating test" is carried out for 4 cycles, accumulating 196.6h.

[0220] Determine the corrosion weight loss of the steel sample after the second drying treatment, and determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, that is, the steel is corroded in the actual atmosphere for 12 months, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time.

[0221] Figure 4 This is the change diagram of the sample corrosion weight loss after each cycle test, where the horizontal axis is the number of cycles and the vertical axis is the weight loss density. Regression analysis was performed on the sample corrosion weight loss data, and the fitting equation for Q345QENH was: C = 23.59414t 0.82951 , the fitting equation of Q345QD is: C = 23.79753t 0.89849 The correlation coefficient of the fitting equation is 0.99. Figure 1 (b) and Figure 2 (b) are the surface morphologies of Q345QENH and Q345QD after 4 cycles of testing. It can be seen that the corrosion products of the two steels are denser than those after 2 cycles. The surface products of Q345QD still have large pores and cracks, while Q345QENH has fewer pores and cracks, and the surface products are relatively dense. Figure 5 (b) and Figure 6 (b) are the surface morphologies of the samples of Q345QENH and Q345QD after 6 months of outdoor exposure. Comparison shows that the morphologies of corrosion products on the surfaces of the two are similar.

[0222] Figure 3 The XRD analysis results of the corrosion products on the surface of the samples after the test are recorded at various time points in Examples 1-4 (a is Q345QD; b is Q345QENH), where the abscissa is the diffraction angle and the ordinate is the intensity of the diffraction peak, indicating that the Figure 1The entire diffraction area is scanned at an angle of 2θ. The intensities of the diffraction peaks at different diffraction angles are shown in the figure. The corrosion products are mainly γ-FeOOH, β-FeOOH, α-FeOOH, Fe3O4 and Fe2O.

[0223] Outdoor actual atmospheric corrosion experiment

[0224] Referring to ISO-4542 standard, atmospheric exposure tests were carried out on Q345QENH weathering steel and Q345QD bridge steel in Chengdu, Sichuan. The sampling time was 3, 6, 9 and 12 months respectively. As shown in the figure, obvious corrosion products appeared on the surface of the samples.

[0225] Figure 7 In order to conduct outdoor atmospheric corrosion experiments on two types of weathering steel, the corrosion products of the outdoor exposure test at each time point (a is Q345QD; b is Q345QENH) were recorded for XRD detection and analysis results, where the abscissa is the diffraction angle and the ordinate is the intensity of the diffraction peak, indicating that the Figure 1 Scan the entire diffraction area at an angle of 2θ. The intensity of the diffraction peaks at different diffraction angles is shown in the figure. The corrosion products on the sample surface are mainly γ-FeOOH, β-FeOOH, α-FeOOH, Fe3O4 and Fe2O, and they do not change much with the increase of exposure time. Figure 3 By comparison, it can be seen that the main corrosion products of the two are consistent.

[0226] Figure 8 This is a graph showing the weight loss changes during the 12-month outdoor exposure test, where the horizontal axis is the number of cycles and the vertical axis is the weight loss density. The indoor simulation test weight loss curve is consistent with the power function law of the outdoor long-term exposure weight loss. The fitting equation for Q345QENH is: C = 22.9472t 0.85242 The correlation coefficient of the fitting equation is 0.99, and the fitting equation of Q345QENH is: C = 20.29546t 0.94928 The correlation coefficient of the fitting equation is 0.99, which shows that the corrosion weight loss curve of the sample conforms to the power function law, the corrosion rate decreases with the increase of time, and the rust layer has an inhibitory effect on the corrosion of the sample. Figure 4 By comparison, it can be seen that the corrosion weight loss of the two groups of steels is extremely similar and closely related. The method of the present application successfully restores the actual outdoor atmospheric corrosion experiment. The method of the present application can be used to conduct accelerated experiments to quickly determine the degree of corrosion of steel in a specific actual atmosphere.

[0227] Based on the examples and outdoor actual atmospheric corrosion experiments, the corrosion process of weathering steel in the Chengdu atmospheric environment was conducted using the method of the present application. The corrosion morphology, corrosion product composition and corrosion weight loss law obtained were very similar to the outdoor exposure test results, and had simulation, acceleration and reproducibility. It was confirmed that the method of the present application truly restored the corrosion behavior law in the Chengdu atmospheric environment, and could quickly evaluate and predict the atmospheric corrosion performance of the steel, providing guidance for engineering applications.

[0228] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for quickly determining the degree of atmospheric corrosion of steel, characterized in that: The method comprises the following steps: determining H + The concentration of Cl - The concentration of SO4 2- concentration, determining a first predetermined time and a second predetermined time, steps S1 to S5; Determine the H + The concentration of Cl - The concentration of SO4 2- Concentrations include: According to the second use area of ​​the steel material, the Cl of the second use area is determined - The deposition rate is used to determine the Cl content in the treatment solution. - concentration; According to the second use area of ​​the steel material, the concentration of SO2 in the atmosphere of the second use area is determined, thereby determining the concentration of SO4 in the treatment solution. 2- concentration; According to the second use area of ​​the steel material, the pH of rainwater in the second use area is determined, thereby determining the pH of H in the treatment solution. + concentration; Determining the first scheduled duration and the second scheduled duration includes: In the accelerated corrosion test of steel, several conversion coefficients and Cl content were obtained independently. - Solution concentration, SO4 content 2- Solution concentration, H + A mapping relationship between acid solution concentration and humid air under different temperature conditions, wherein the mapping relationship between the conversion coefficient and different humid air under different temperature conditions is established based on the humidity acceleration model applied to standard humid air; Performing statistical analysis based on the raining time and the atmospheric humidity time in the second use area to determine the ratio of the raining time to the humidity time, wherein the humidity time is the time when the relative humidity is ≥ 70%; According to the H + The concentration of Cl - The concentration of SO4 2- The concentration and the mapping relationships respectively corresponding to the concentration and the mapping relationships respectively correspond to the concentration and the mapping relationships respectively, and the conversion coefficient is matched to determine the comprehensive acceleration coefficient. Determine the total duration of the first predetermined duration and the second predetermined duration according to a plurality of raining times in the raining time of the second use area, a plurality of wet processing times in the atmospheric wet time, and conversion coefficients corresponding to different humid air under different temperature conditions; Determine the first predetermined time duration and the second predetermined time duration according to the comprehensive acceleration coefficient, the total time duration of the first predetermined time duration and the second predetermined time duration, and the ratio of the raining time to the wet time; S1. Place the steel sample in a Cl-containing - 、Contains SO4 2- and H + performing a corrosion treatment in a treatment solution of a first predetermined time to obtain a corroded steel sample; S2. performing a first drying treatment on the corroded steel sample; S3. subjecting the steel sample after the first drying treatment to a second predetermined time period of wetting treatment, wherein the wetting treatment is a humid air treatment; S4. subjecting the steel sample after the wet treatment to a second drying treatment; S5. Determine the corrosion weight loss of the steel sample after the second drying treatment, and determine the corrosion time of the steel in the actual atmospheric environment corresponding to the corroded steel sample based on the corrosion weight loss curve of the steel in the actual atmospheric environment, and use the corrosion degree of the steel sample as the atmospheric corrosion degree of the steel at the corrosion time.

2. The method according to claim 1, characterized in that According to the Cl in the treatment solution - 、SO4 2- and H + The respective concentrations, as well as the first predetermined time and the second predetermined time, determine the corrosion time of the steel in the actual atmospheric environment obtained in step S5 as the corrosion time of the steel in the actual atmospheric environment of the first use area, including: According to the Cl in the treatment solution - The concentration of Cl in different regions - Sedimentation rate; According to the SO4 2- The concentration of SO2 in the atmospheric environment of different regions is matched; According to the H + The respective concentrations match the pH of rainwater in rainfall in different regions; According to the first predetermined time and the second predetermined time, matching the rainfall time and atmospheric humidity time and their ratio in different regions; According to the Cl - Determine the first use area based on the deposition rate, the concentration of SO2, the pH of the rainwater, the rainfall time and the atmospheric wetness time and their ratio; The corrosion time of the steel material in the actual atmospheric environment obtained in step S5 is determined as the corrosion time of the steel material in the actual atmospheric environment of the first use area.

3. The method according to claim 2, characterized in that When the treatment solution contains Cl - The concentration is 0.5% to 0.8%, SO4 2- The concentration is 0.1% to 0.2%, the pH is 6 to 6.5, and the Cl- deposition rate is 0.3 to 0.35 mg·m -2 ·d -1 , and the first scheduled time is 20 to 21 hours, and the second scheduled time is 16 to 17 hours, the first usage area is Sichuan.

4. The method according to claim 2, characterized in that: When the concentration of Cl- in the treatment solution is 0.5%, SO4 2- The concentration of 0.1%, pH 6, and Cl- deposition rate were 0.31 mg·m -2 ·d -1 , and when the first scheduled time is 20.18 hours and the second scheduled time is 16.8 hours, the first usage area is Chengdu.

5. The method according to claim 1, characterized in that: The standard humid air is air with a temperature of T=40° C. and a humidity of RH=100%.

6. The method according to claim 1, characterized in that The corrosion weight loss curve of the steel in the actual atmospheric environment conforms to the following formula: C=And k Where C is the corrosion weight loss per unit area of ​​the steel sample, in g / m 2 ; t is the experimental time, in months; A and k are constants related to the type of steel and the actual atmospheric environment in which the steel is used. The k value is used as a reference for the corrosion rate or the protectiveness of the rust layer, and the A value is often used to reflect the initial corrosion rate of the steel.

7. The method according to claim 6, characterized in that A and k of the corrosion weight loss curve are determined as follows: Obtain a data set corresponding to the corrosion weight loss and time of a steel sample of a predetermined steel type in an actual atmospheric environment; Fitting is performed based on the data set to determine A and k of the corrosion weight loss curve.

8. The method according to claim 7, characterized in that If the steel sample is Q345QENH weathering steel and corrodes in the Chengdu atmospheric environment, the corrosion weight loss curve satisfies C=22.9472t 0.85242 ; If the steel sample is Q345QD steel and corrodes in the Chengdu atmospheric environment, the corrosion weight loss curve satisfies C=20.29546t 0.94928 .

9. The method according to claim 1, characterized in that: Before S5, the method further includes repeating steps S1 to S4 for N times or more, wherein N is a positive integer.

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