A Method for Evaluating the Environmental Adaptability of Ship Hull Steel Based on Atmospheric Corrosion Simulation

Abstract

This invention proposes a method for evaluating the environmental adaptability of ship hull steel based on atmospheric corrosion simulation, enabling a quantitative characterization of its environmental adaptability under complex dynamic environments. Considering the dynamic evolution of the liquid film under the synergistic effects of salt deliquescence and droplet evaporation in the marine atmosphere, and the nonlinear characteristics of corrosion degradation of ship hull steel under the influence of the dynamic liquid film, a dynamic liquid film model is constructed by coupling key environmental factors. Corrosion process simulation is conducted using corrosion electrochemistry principles, and accelerated testing is used to estimate key model parameters. This establishes a quantitative calculation method for the environmental adaptability index of ship hull steel under dynamic environments, improving the environmental adaptability evaluation system for marine metallic materials and providing scientific support for ship structural reliability design, corrosion protection measure optimization, and service life prediction. This invention requires no additional complex scenario adaptation, is highly operable, and effectively improves the efficiency and practicality of evaluating the environmental adaptability of marine materials.

Description

Technical Field

[0001] This invention relates to a method for evaluating the environmental adaptability of ship hull steel based on atmospheric corrosion simulation. It is a method that transforms environmental stress into environmental adaptability indicators. It constructs a dynamic liquid film model coupling salt deliquescence and droplet evaporation processes, targeting the thin liquid film evolution process on the surface of ship hull steel under the complex and dynamic marine atmospheric environment of ship navigation. Then, based on the principles of corrosion electrochemistry, the corrosion process of ship hull steel under the thin liquid film is simulated and analyzed, and the simulation model parameters are estimated through accelerated testing. Based on this, the environmental adaptability indicators of the ship hull steel are calculated. This method is applicable to fields such as the evaluation of atmospheric corrosion environmental adaptability indicators of ship hull steel under dynamic environmental conditions. Background Technology

[0002] As a core structural material of ships, hull steel must continuously withstand the high-salt, high-humidity, and dynamically fluctuating temperature and humidity marine atmospheric environment during long-term voyages. The dynamic evolution of thin liquid films on its surface significantly accelerates the corrosion process, directly threatening the structural reliability and service safety of the ship. Therefore, accurate quantitative assessment of the environmental adaptability indicators of hull steel is of significant engineering practical importance. Currently, assessment methods for the atmospheric corrosion environmental adaptability of hull steel mostly focus on the analysis of corrosion behavior under static liquid films, considering only the influence of single or a few environmental factors, making it difficult to comprehensively characterize the actual environmental adaptability level of hull steel under complex dynamic environments. On the other hand, the dynamic randomness of the marine atmospheric environment leads to significant nonlinear and time-varying characteristics in the corrosion degradation trajectory of hull steel, posing challenges to the quantitative modeling and assessment of the environmental adaptability indicators of hull steel. Existing research has constructed a correlation model of salt deposition amount, humidity, and liquid film thickness based on the principle of thermodynamic equilibrium, and combined this with corrosion electrochemical theory to analyze the coupling relationship between liquid film thickness, corrosion product deposition amount, and corrosion rate. These technical approaches provide important references for overcoming the difficulties in assessing the environmental adaptability of hull steel under dynamic environments.

[0003] Based on this, this invention proposes a method for evaluating the environmental adaptability of ship hull steel based on atmospheric corrosion simulation. First, a dynamic liquid film evolution model is constructed by coupling the deliquescence of salt and the droplet evaporation process. On this basis, the corrosion process of ship hull steel under thin liquid film is simulated by combining the principle of corrosion electrochemistry. The key parameters of the model are estimated through accelerated testing. Finally, the quantitative calculation of the environmental adaptability index of ship hull steel under dynamic marine atmospheric environment is realized, providing a technical solution that is more in line with the actual service scenario for the environmental adaptability assessment of ship hull steel. Summary of the Invention

[0004] The purpose of this invention is to address the challenge of quantitatively calculating the environmental adaptability indicators of ship hull steel under dynamic environmental conditions. This invention provides a method for evaluating the environmental adaptability indicators of ship hull steel based on atmospheric corrosion simulation, enabling a quantitative characterization of the environmental adaptability of ship hull steel under complex dynamic environments. Considering the dynamic evolution of liquid films under the synergistic effects of salt deliquescence and droplet evaporation in the marine atmosphere, and the nonlinear characteristics of corrosion degradation of ship hull steel under the influence of dynamic liquid films, a dynamic liquid film model is constructed by coupling key environmental factors. Corrosion process simulation is conducted using corrosion electrochemistry principles. Accelerated testing is used to estimate key model parameters, thereby establishing a quantitative calculation method for the environmental adaptability indicators of ship hull steel under dynamic environments. This improves the environmental adaptability evaluation system for marine metallic materials, providing scientific support for ship structural reliability design, corrosion protection measure optimization, and service life prediction.

[0005] Therefore, the present invention needs to establish the following basic settings: Setting 1: The environmental adaptability index of hull steel refers to the performance under specific environmental conditions. s The depth corrosion rate of the ship hull steel θ , represented as: (1) in, Indicates under specific environmental conditions s The degradation amount (corrosion depth) of the steel corrosion in the lower hull. t Indicates corrosion time.

[0006] Setting 2: The deliquescence process of salts on the surface of ship hull steel in the marine atmosphere only considers the deliquescence of NaCl particles.

[0007] Based on the above settings, the present invention provides a method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation, which is implemented through the following steps: Step 1: Evaluation of the morphological evolution of thin liquid films; The marine atmospheric environment is characterized by high salinity and high humidity. Under certain relative humidity, NaCl salt particles in the air easily deposit on the surface of ship steel, causing water vapor to preferentially condense or adsorb at these sites, eventually growing into main droplets. Through a series of continuous processes, a thin liquid film forms on the metal surface. According to the principle of thermodynamic equilibrium, when the system is under isothermal conditions, after the thin liquid film reaches a steady state through relaxation, it will form a gas-liquid two-phase equilibrium system with water molecules in the gas phase. In this equilibrium state, the partial pressure parameters of water molecules in the gas phase and the concentration distribution of each component in the liquid phase system show a one-to-one correspondence. The atmospheric relative humidity is determined by the partial pressure of water vapor. (2) In the formula: This refers to atmospheric relative humidity, expressed in % %. This is the partial pressure of water vapor in the atmosphere, measured in Pa. This is the partial pressure of saturated water vapor in the atmosphere, expressed in Pa.

[0008] Furthermore, the equilibrium state of the gas-liquid two-phase system can be established and measured by determining the relative humidity of a closed space corresponding to different mass fractions of NaCl solutions at different temperatures. When a NaCl solution of a known concentration is placed in a closed container, the partial pressure of water vapor above the solution gradually approaches the saturated vapor pressure of that concentration at that temperature. When the system reaches equilibrium, the relative humidity inside the container is measured; this humidity corresponds to the equilibrium relative humidity at that solution concentration. Through fitting the experimental data, the following equilibrium relationships are obtained between the mass fraction of NaCl in the liquid film, the density of the NaCl solution, and the atmospheric relative humidity: (3) (4) in, This represents the mass fraction of NaCl, expressed in % (%). This refers to atmospheric relative humidity, expressed in % %. This is the solution density, expressed in g / mL. a 1, a 2, a 3, b 1, b 2, b 3 represents the parameter to be estimated.

[0009] The relationship between the amount of NaCl deposited per unit area on a steel surface and the mass fraction of NaCl, the density of the NaCl solution, and the thickness of the liquid film is as follows: (5) in, d This represents the amount of NaCl deposited on the steel surface, expressed in g / cm³. 2 ; h The thickness at the center of the thin liquid film is expressed in cm.

[0010] Therefore, when environmental conditions are constant, the thickness of the thin liquid film at its center in equilibrium can be expressed as: (6) Due to the significant climate variations in the marine atmospheric environment, when the relative humidity in the air is low, the liquid film on the metal surface is highly volatile. The evaporation rate of the liquid film can be calculated using the following formula: (7) in, E The evaporation rate of the liquid film on the steel surface is expressed in cm / h. T This refers to the ambient temperature, expressed in °C. p The ambient air pressure is expressed in Pa. uThe ambient wind speed is expressed in m / s. a , b , c , d , e For fixed parameters, take respectively , , , , .

[0011] Within a certain time range, given an initial liquid film thickness, the dynamic change of the liquid film thickness satisfies the following equation: (8) in, h (0, t )for t The thickness of the liquid film at the center of the liquid film at that moment, in cm; t 1, t 2 represents two moments within a certain time range, with the unit being hours (h). The unit is h.

[0012] Furthermore, due to the "coffee ring effect" observed in the morphological changes of liquid droplets evaporating from a solid surface—meaning the liquid film thickness changes over time while the radius of the thin liquid film's base remains constant—the geometric dimensions of the liquid film satisfy the following equation over a given time period: (9) In the formula, R The radius of the thin liquid film is in cm; h ( r , t The thickness of the liquid film varies with the radius of the bottom surface. r and time t The function of variation is expressed in cm.

[0013] Step Two: Accelerate the implementation of the experiment; To simulate the long-term corrosion process of materials under natural environments in a short-term test cycle, and to study the corrosion behavior and mechanism of a certain metal in a humid and hot marine atmospheric environment, the corrosion progress can be accelerated by increasing the stress level of a certain environmental factor through accelerated testing, thereby obtaining corrosion weight loss.

[0014] The corrosion depth of the test material can be obtained by utilizing the mass difference of the sample before and after the accelerated test. D This is used to characterize the corrosion kinetics of metallic materials. The corrosion depth is calculated using formula (10): (10) in, D The corrosion depth of the sample is (μm). M i andM j The values ​​are the mass (g) of the corrosion test specimen before the accelerated test and after the corrosion products have been removed. M b The mass loss (g) of the blank sample during the pickling process; ρ 1 represents the density of the metal; A The exposed area (cm²) of the corrosion test specimen 2 ).

[0015] Step 3: Simulation analysis of corrosion of ship hull steel under thin liquid film; Under the influence of a dynamic liquid film, the atmospheric corrosion rate initially increases and then decreases with increasing liquid film thickness. Based on the principles of corrosion electrochemistry, the corrosion behavior of metals under the liquid film is controlled by the cathodic oxygen reduction process; therefore, the cathodic limiting current density can be used to characterize the corrosion rate of the metal.

[0016] When the liquid film thickness is greater than At this time, the cathode limiting current density is minimally affected by changes in liquid film thickness, and the corrosion rate gradually stabilizes at a low level.

[0017] When the liquid film thickness is less than And greater than At this time, the cathodic limiting current increases as the liquid film thickness decreases, and the cathodic limiting current density follows the following formula: (11) in, ρ is the cathode limiting current density, in A / m²; F is the Faraday constant. ρ is the oxygen diffusion coefficient in the liquid phase, with units of m² / s; This represents the oxygen concentration at the gas-liquid interface, expressed in mol / m³. h The thickness at the center of the thin liquid film is expressed in meters (m).

[0018] When the liquid film thickness is less than And greater than As the thickness of the liquid film further decreases, the increasing trend of the cathode limiting current will slow down and tend to a certain value.

[0019] When the liquid film thickness is less than At this point, the cathode limiting current begins to decrease rapidly as the liquid film thickness decreases, and the cathode limiting current density follows the following formula: (12) in, B This is the merging coefficient. b The parameter is fixed and is set to 1.897.

[0020] During corrosion, corrosion products are deposited along with the metal surface, inhibiting further dissolution. Therefore, the inhibitory effect of corrosion products needs to be considered when correcting for the cathodic limiting current density. The corrosion product coverage rate can be calculated using the following formula: (13) in, The coverage of corrosion products; c t It represents the total molar amount of corrosion products deposited per unit surface area (related to the corrosion rate). c a This represents the amount of moles of metal available for dissolution per unit surface area, which needs to be determined experimentally. k , c The parameters to be estimated need to be obtained through experiments.

[0021] The inhibitory effect of corrosion product deposition can be modeled by multiplying the cathodic limiting current density of the metal corrosion reaction by the corrosion product coverage rate: (14) in, This is the corrected cathode limiting current density, in A / m².

[0022] To determine the critical point that tends to a constant value, as well as the relevant parameters of corrosion product coverage, the parameters can be estimated by nonlinear model fitting based on the accelerated test data obtained in step two.

[0023] Step 4: Environmental adaptability index assessment; According to equation (14), the cathode limiting current density Conversion to mass loss rate of steel : (15) in, The rate of metal mass loss per unit time is expressed in g / m²·h. The value represents the rate of change in corrosion depth, expressed in mm / year. This is the atomic weight of the metal, expressed in grams (g). n ν represents the valence of the metal.

[0024] Further, an environmental adaptability index was obtained, namely the rate of change in corrosion depth of the steel. : (16) in, The rate of metal mass loss per unit time is expressed in g / m²·h. The value represents the rate of change in corrosion depth, expressed in mm / year. This is the atomic weight of the metal, expressed in grams (g). n The valence of the metal. F It is Faraday's constant; This is the density of the metal, expressed in g / cm³. 3 .

[0025] The advantages and beneficial effects of this invention are as follows: ① This invention constructs a dynamic liquid film model by coupling the salt deliquescence and droplet evaporation processes. It does not rely on simplified static environmental assumptions and can realistically reproduce the dynamic influence of factors such as temperature, humidity and salt deposition in the marine atmosphere on the evolution of the liquid film. The model fits the actual service scenario and has clear calculation logic, which facilitates parameter adjustment and verification in engineering applications. ② This invention conducts corrosion simulation of ship hull steel under thin liquid film based on the principle of corrosion electrochemistry, and estimates the model parameters by combining accelerated tests. It not only makes full use of the quantitative advantages of electrochemical theory, but also ensures the authenticity of the parameters through experimental data. It realizes the accurate calculation of the environmental adaptability index of ship hull steel under dynamic environment, and the evaluation accuracy is significantly better than the traditional static corrosion evaluation method. ③ This invention is designed around the dynamic marine atmosphere, which is the core service environment of ship hull steel. It forms a complete technical chain from liquid film evolution to corrosion assessment. It can directly provide targeted index support for ship material selection and corrosion protection strategy formulation. It does not require additional complex scenario adaptation, is highly operable, and can effectively improve the efficiency and practicality of environmental adaptability evaluation of ship materials. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method described in this invention.

[0027] Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e It is a distribution map of temperature, humidity, atmospheric pressure, wind speed, and salt deposition.

[0028] Figure 3 This is a graph showing the trend of liquid film changes over time.

[0029] Figure 4 This is the limiting current density diagram of the cathode of 30CrMnSiA high-strength steel.

[0030] Figure 5 This is a corrosion rate diagram of 30CrMnSiA high-strength steel. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments; A shipboard test rig was mounted on the compass deck platform of a certain type of vessel. Environmental data was continuously collected using an onboard weather station, including parameters such as temperature, humidity, atmospheric pressure, and wind speed. Simultaneously, the salt deposition on the surface of a 30CrMnSiA high-strength steel sample was collected. The data collection lasted for 744 hours, and the distribution of temperature, humidity, atmospheric pressure, wind speed, and salt deposition was obtained as follows: Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e As shown.

[0032] Step 1: Evaluation of the morphological evolution of thin liquid films; The equilibrium relative humidity corresponding to different mass fractions of NaCl solutions at different temperatures is shown in Table 1.

[0033] Table 1. Equilibrium relative humidity corresponding to NaCl solutions of different mass fractions

[0034] According to Table 1, since the data points basically overlap in the two temperature ranges of 20~25℃ and 80℃, the image is further fitted in the range of 20~80℃. According to equations (3)-(4), the estimated parameters of the relationship between the mass fraction of NaCl in the solution, the solution density and the relative humidity of the atmosphere are shown in Table 2.

[0035] Table 2. Parameters to be estimated in the relationship between the mass fraction of NaCl in the solution, the density of the solution, and the relative humidity.

[0036] Based on equations (6)-(9), the evolution process of the liquid film is simulated using the original environmental data to obtain the changes in liquid film thickness at different times. The trend of liquid film change over time is as follows: Figure 3 As shown.

[0037] Step Two: Accelerate the implementation of the experiment; A periodic immersion test was conducted on 30CrMnSiA high-strength steel according to GB / T 19746-2018, "Corrosion of Metals and Alloys - Salt Solution Immersion Test". The test environment temperature was 40±1℃, and the relative humidity was 85±1%. Three groups of samples were suspended on a spoke-type test frame and circulatedly immersed in a simulated seawater solution (Cl- mass fraction of 4%) for 15 minutes, followed by exposure to the ambient atmosphere for 45 minutes. The sampling times were 48h, 96h, 144h, 288h, 432h, and 576h.

[0038] Based on the accelerated test, the corrosion depth of 30CrMnSiA high-strength steel after 576 hours of accelerated testing is shown in Table 3.

[0039] Table 3 Corrosion Depth of Three Groups of 30CrMnSiA High-Strength Steel Samples

[0040] Step 3: Simulation analysis of corrosion of ship hull steel under thin liquid film; Using the corrosion depth data in Table 3 as input, nonlinear fitting can be used to obtain the critical point where the corrosion rate tends to a constant value and the relevant parameters of corrosion product coverage, as shown in Table 4.

[0041] Table 4. Critical point at which corrosion rate tends to a constant value and related parameters of corrosion product coverage.

[0042] Furthermore, based on the corrosion rate variation trend and corrosion product inhibition effect under different film thicknesses, the cathodic limiting current density of metal corrosion under thin liquid film can be calculated. The magnitude of the cathodic limiting current density at each time point can be obtained according to equations (11)-(14), such as... Figure 4 As shown.

[0043] Step 4: Environmental adaptability index assessment; Based on the results of step three, the corresponding corrosion rate can be obtained using formulas (15)-(16), such as Figure 5 As shown.

[0044] The results show that the method proposed in this invention can calculate the environmental adaptability index of metal corrosion based on multiple types of environmental stress, thus achieving the expected purpose.

[0045] In summary, this invention relates to a method for evaluating the environmental adaptability of ship hull steel based on atmospheric corrosion simulation. It is a method that transforms environmental stress into environmental adaptability indicators. The specific steps of this method are: 1. Thin liquid film morphology evolution assessment; 2. Corrosion simulation analysis of ship hull steel under thin liquid film; 3. Accelerated testing and parameter estimation; 4. Determining environmental adaptability indicator assessment. This invention is applicable to fields such as environmental adaptability indicator assessment under dynamic environmental conditions, and has high practicality and operability.

Claims

1. A method for evaluating the environmental adaptability of ship hull steel based on atmospheric corrosion simulation, establishing the following settings: Setting 1: The environmental adaptability index of hull steel refers to the performance under specific environmental conditions. s The depth corrosion rate of the ship hull steel θ , represented as: （1） in, Indicates under specific environmental conditions s The amount of corrosion degradation of the steel in the lower hull; t Indicates corrosion time; Setting 2: The deliquescence process of salts on the surface of ship hull steel in the marine atmosphere only considers the deliquescence of NaCl particles; Based on the above settings, the feature is that it includes the following steps: Step 1: Evaluation of the morphological evolution of thin liquid films; When the system is under isothermal conditions, after the thin liquid film reaches a steady state through relaxation, it will form a gas-liquid two-phase equilibrium system with water molecules in the gas phase environment. In this equilibrium state, the partial pressure parameter of water molecules in the gas phase corresponds one-to-one with the concentration distribution of each component in the liquid phase system, and the atmospheric relative humidity is determined by the partial pressure of water vapor. （2） In the formula: This refers to atmospheric relative humidity, expressed in % %. This is the partial pressure of water vapor in the atmosphere, measured in Pa. This is the partial pressure of saturated water vapor in the atmosphere, expressed in Pa. Step Two: Accelerate the implementation of the experiment; The corrosion depth of the test material is obtained by using the mass difference of the sample before and after the accelerated test. D Used for characterizing the corrosion kinetics of metallic materials; Step 3: Simulation analysis of corrosion of ship hull steel under thin liquid film; Under the influence of dynamic liquid film, the atmospheric corrosion rate first increases and then decreases with the increase of liquid film thickness; the corrosion behavior of metal under liquid film is controlled by the cathodic oxygen reduction process, and the corrosion rate of metal is characterized by the cathodic limiting current density. Step 4: Environmental adaptability index assessment.

2. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 1, characterized in that: In step one, the equilibrium relative humidity of the gas-liquid two-phase system is established and measured in a closed space by measuring the relative humidity of NaCl solutions with different mass fractions at different temperatures. When a NaCl solution of known concentration is placed in a closed container, the partial pressure of water vapor above the solution gradually approaches the saturated vapor pressure of the solution at that temperature. When the system is in equilibrium, the relative humidity inside the container is measured; this humidity corresponds to the equilibrium relative humidity at the solution concentration. Through fitting the experimental data, the following equilibrium relationships are obtained between the mass fraction of NaCl in the liquid film, the density of the NaCl solution, and the atmospheric relative humidity: （3） （4） in, This represents the mass fraction of NaCl, expressed in % (%). This refers to atmospheric relative humidity, expressed in % %. This is the solution density, expressed in g / mL. a 1, a 2, a 3, b 1, b 2, b 3 represents the parameter to be estimated; The relationship between the amount of NaCl deposited per unit area on a steel surface and the mass fraction of NaCl, the density of the NaCl solution, and the thickness of the liquid film is as follows: （5） in, d This represents the amount of NaCl deposited on the steel surface, expressed in g / cm³. 2 ; h The thickness at the center of the thin liquid film is expressed in cm.

3. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 1 or 2, characterized in that: In step one, when environmental conditions are constant, the thickness of the thin liquid film at its center in equilibrium is expressed as: （6） When the relative humidity in the air is low, the liquid film on the metal surface evaporates very easily. The evaporation rate of the liquid film can be calculated using the following formula: （7） in, E The evaporation rate of the liquid film on the steel surface is expressed in cm / h. T This refers to the ambient temperature, expressed in °C. p The ambient air pressure is expressed in Pa. u The ambient wind speed is expressed in m / s. a , b , c , d , e For fixed parameters, take respectively , , , , ; Within a certain time range, given an initial liquid film thickness, the dynamic change of the liquid film thickness satisfies the following equation: （8） in, h (0, t )for t The thickness of the liquid film at the center of the liquid film at that moment, in cm; t 1, t 2 represents two moments within a certain time range, with the unit being hours (h). The unit is h.

4. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 3, characterized in that: In step one, the thickness of the liquid film changes over time, while the radius of the bottom surface of the thin liquid film does not change over time. Within a certain time period, the geometric dimensions of the liquid film satisfy the following formula: （9） In the formula, R The radius of the thin liquid film is in cm; h ( r , t The thickness of the liquid film varies with the radius of the bottom surface. r and time t The function of variation is expressed in cm.

5. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 1, characterized in that: In step two, the corrosion depth is calculated as follows: （10） in, D The corrosion depth of the sample; M i and M j These represent the mass of the corrosion test specimen before the accelerated test and after the corrosion products have been removed, respectively. M b This refers to the mass loss of the blank sample during the pickling process; ρ 1 represents the density of the metal; A This represents the exposed area of ​​the corrosion test specimen.

6. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 1, characterized in that: In step three, when the liquid film thickness is less than And greater than At this time, the cathodic limiting current increases as the liquid film thickness decreases, and the cathodic limiting current density follows the following formula: （11） in, ρ is the cathode limiting current density, in A / m²; F is the Faraday constant. ρ is the oxygen diffusion coefficient in the liquid phase, with units of m² / s; This represents the oxygen concentration at the gas-liquid interface, expressed in mol / m³. h The thickness of the thin liquid film at its center is expressed in meters (m). When the liquid film thickness is less than At this point, the cathode limiting current begins to decrease rapidly as the liquid film thickness decreases, and the cathode limiting current density follows the following formula: （12） in, B This is the merging coefficient. b These are fixed parameters.

7. A method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 1 or 6, characterized in that: In step three, the cathode limiting current density is corrected to account for the inhibition effect of corrosion products; the corrosion product coverage is introduced and calculated using the following formula: （13） in, The coverage of corrosion products; c t This represents the total molar amount of corrosion products deposited per unit surface area; c a This indicates the amount of moles used for metal dissolution per unit surface area, which needs to be obtained experimentally. k , c The parameters to be estimated need to be obtained through experiments.

8. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 7, characterized in that: In step three, the inhibition of corrosion product deposition is modeled by multiplying the cathodic limiting current density of the metal corrosion reaction by the corrosion product coverage: （14） in, This is the corrected cathode limiting current density, in A / m².

9. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 1, characterized in that: In step four, the cathode limiting current density is... Conversion to mass loss rate of steel : （15） in, The rate of metal mass loss per unit time is expressed in g / m²·h. The value represents the rate of change in corrosion depth, expressed in mm / year. This is the atomic weight of the metal, expressed in grams (g). n ν represents the valence of the metal.

10. The method for evaluating the environmental adaptability index of ship hull steel based on atmospheric corrosion simulation according to claim 9, characterized in that: In step four, the environmental adaptability index, namely the rate of change of corrosion depth of the steel, is further obtained. : （16） in, The rate of metal mass loss per unit time is expressed in g / m²·h. The value represents the rate of change in corrosion depth, expressed in mm / year. This is the atomic weight of the metal, expressed in grams (g). n The valence of the metal. F It is Faraday's constant; This is the density of the metal, expressed in g / cm³. 3 .

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