JP2002318227A - Method for estimating life of surface treated steel material, surface treated steel material, method for designing surface treated steel material and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of estimating the life of a surface-treated steel material with high accuracy, a method for designing the surface-treated steel material, and a method for manufacturing the surface-treated steel material. SOLUTION: The method for estimating the life of the surface-treated steel material has a process (S21) for calculating the relation between an environmental factor and corrosion quantity on the basis of data showing the relation between the corrosion quantity and an exposure time under a plurality of actual environments and the environmental factor of the data, a process (S22) for determining a dominant environmental factor from the relation between the environmental factor and the corrosion quantity; a process (S23) for measuring the values of the dominant environmental factor in a plurality of regions of a target actual structure or a structure simulating the target actual structure, and a process (S24) for calculating the data showing the corrosion quantity and the exposure time of each of the regions on the basis of the relation between the environmental factor and the corrosion quantity and the measured values of the environmental factor and estimating the advance of corrosion on the basis of the data showing the relation between the corrosion quantity and the exposure time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for estimating the life of a surface-treated steel, a method for designing a surface-treated steel, and a method for producing a surface-treated steel.

[0002]

2. Description of the Related Art Conventionally, there is no technique for estimating the life of a coated steel material. As the closest technique, a test piece is exposed to an environment close to the actual environment, and a method of estimating from the corrosion amount of the test piece, or a test piece by a corrosion acceleration test. A method has been used in which the amount of corrosion is evaluated, and the life is estimated by comparing the results with the amount of corrosion of the corresponding existing long-term exposure test material. In recent years, attempts have been made to investigate the strength of a corrosive environment in which a member is used, using a galvanic couple (ACM sensor or the like) or the like.

[0003]

However, as described above, the method of exposing a test piece to an environment close to the actual environment and estimating the life from the swollen width of the test piece requires a long-term test of several tens of years. I need. In addition, even if there is past exposure data, it was not possible to predict the amount of corrosion quantitatively because it was not used in the same place completely, and only suggested qualitative quality. In addition, the method of estimating the service life based on the relative comparison between the corrosion promotion test and the existing long-term exposed material has a problem that the use environment cannot be appropriately reproduced and it cannot be confirmed whether or not the environment has been reproduced. On the other hand, as a method of clarifying the environment, an AC impedance method or a method of installing an ACM sensor on an actual structure and measuring the local corrosion environment strength at which the member is actually used has been devised. There is a problem that the relationship between environmental strength and the amount of corrosion of painted steel has not been clarified.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a method for predicting the life of a surface-treated steel material capable of predicting the life with high accuracy, and a surface relating to the life prediction It is an object of the present invention to provide a treated steel material, a method for designing a surface-treated steel material, and a method for producing a surface-treated steel material.

[0005]

Means for Solving the Problems (1) According to one aspect of the present invention, a method for predicting the life of a surface-treated steel material includes data showing a relationship between a corrosion amount and an exposure time in a plurality of actual environments and data of the data. A first step of determining the relationship between the environmental factor and the amount of corrosion based on the environmental factor, and measuring the value of the environmental factor at one or more sites in the target actual structure or a structure simulating the actual structure The relationship between the amount of corrosion and the exposure time at the site based on the relationship between the environmental factor and the amount of corrosion in the second step, the first step, and the measured value of the environmental factor measured in the second step. A third step of obtaining data indicating
And a fourth step of predicting the progress of corrosion based on data indicating the relationship between the amount of corrosion and the exposure time in the third step.

(2) A method for predicting the life of a surface-treated steel material according to another aspect of the present invention measures the value of an environmental factor at one or more sites in a target actual structure or a structure simulating the actual structure. A first step to be performed, a relationship between a preset environmental factor and the amount of corrosion, and a measured value of the environmental factor measured in the first step, based on the corrosion amount and the exposure time in the site. A second step of obtaining data indicating the relationship;
A third step of predicting the progress of corrosion based on data indicating the relationship between the amount of corrosion and the exposure time in the second step.

(3) A method for estimating the life of a surface-treated steel material according to another aspect of the present invention is the method of estimating the life of the surface-treated steel material according to the above (1) or (2), wherein when there are a plurality of environmental factors, Determine one or more environmental factors as the dominant environmental factors from the data showing the relationship between the amount of corrosion and the exposure time and the relationship between the environmental factors and the amount of corrosion obtained based on the environmental factors of the data. In the case of (1), the processing based on the environmental factors in the second and subsequent steps, and in the case of (2), the first and subsequent steps are executed by the dominant environmental factors.

(4) According to another aspect of the present invention, there is provided a method for predicting the life of a surface-treated steel material, wherein the method is performed in or on a target actual structure or a structure simulating the actual structure (hereinafter referred to as an actual structure). A reference position provided on the surface, or a value of environmental data at a reference position provided outside the actual structure or the like as a reference value, a value of environmental data measured at the site in the actual structure or the like, a reference value and Is defined as a part coefficient, the value of the certain environmental factor in each part is calculated based on the correspondence between the reference value and a certain environmental factor and the part coefficient. In the case of the above (1), After the third step, in the case of the above (2), the processing based on the environmental factor from the second step on is executed by the certain environmental factor.

(5) In the method for estimating the life of a surface-treated steel material according to another aspect of the present invention, the reference position is one of the parts.

(6) In a method for predicting the life of a surface-treated steel material according to another aspect of the present invention, the environmental data is defined as an amount of attached salt,
The certain environmental factor is the amount of incoming sea salt.

(7) In the method for predicting the life of a surface-treated steel according to another aspect of the present invention, the data indicating the relationship between the corrosion amount and the exposure time is the data indicating the relationship between the exposure time and the swollen width of the surface-treated steel. Or it is data which shows a secular change of a white rust generation area.

(8) In the method for predicting the life of a surface-treated steel material according to another aspect of the present invention, at least one environmental factor is measured.
Months.

(9) In the method for predicting the life of a surface-treated steel material according to another aspect of the present invention, the environmental factors include flying sea salt, temperature,
Humidity, sunlight exposure or SOx.

(10) In the life prediction method for a surface-treated steel according to another aspect of the present invention, the surface-treated steel is a painted steel.

(11) In the method for predicting the life of a surface-treated steel material according to another aspect of the present invention, the life is predicted after the area to be evaluated is divided into areas having similar environments.

(12) A surface-treated steel material according to another aspect of the present invention is a surface-treated steel material whose life is predicted by the life prediction methods of (1) to (11) above, and the progress of corrosion of each part. Is attached with the data at the time of prediction.

(13) In the surface-treated steel material according to another aspect of the present invention, the data at the time of predicting the progress of corrosion at each part in (12) above is data relating to the blister width or the area where white rust occurs.

(14) A surface-treated steel material according to another aspect of the present invention is provided with the above data or a symbol indicating the same.

(15) In the surface-treated steel material according to another aspect of the present invention, data attached to the surface-treated steel material or data related thereto is sent to the delivery destination as electronic information.

(16) According to another aspect of the present invention, there is provided a method for designing a surface-treated steel material. By selecting from the treated steel materials, or selecting from the surface treated steel materials for which the corrosion progress was not predicted based on the prediction result of the corrosion progress in one or more surface treated steel materials, or designing a new surface treated steel material, Select steel materials to apply to the structure.

(17) In a method of manufacturing a surface-treated steel material according to another aspect of the present invention, a surface-treated steel material designed according to the method (16) for designing a surface-treated steel material is manufactured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 is a flowchart showing the process steps of a method for estimating the life of a coated steel, a method for designing a coated steel, and a method for manufacturing a coated steel according to Embodiment 1 of the present invention. (ST1) At the first stage, product conditions are presented. The product conditions include a corrosive environment (region, site) and required performance (appearance corrosion, structural life). In the first embodiment, it has been found that the swollen width of the paint is a determining factor of the appearance life, and the swollen width of the paint is used as a measurement standard of the life.

(ST2) In the next stage, the process shifts to a process of selecting a material satisfying the product conditions. Specifically, a process of predicting the life of a steel material used in a specific corrosive environment (area, site) and determining the useful life is performed. The life prediction process is performed by the following processes of (S21) to (S26).

(S21) A step of organizing data for estimating the life of the coated steel material. In this process, the relationship between the number of years of exposure (elapsed time) and the amount of corrosion is determined and graphed, and the average temperature (hereinafter, referred to as temperature), the average humidity (hereinafter, referred to as humidity), the amount of incoming sea salt, the temperature, Appropriate selection is made from environmental factors such as humidity, sunlight, sulfur oxides, precipitation, dew condensation time, and amount of attached salt, and the data of each environmental factor is arranged together as environmental data. The corrosion data includes a swollen width, a change in appearance, an area where white rust occurs, and the like. In the first embodiment, an example of the swollen width will be described. The swelling width of the coated steel material indicates the width of the swelled coating film from the end when the coating swells from the cut end due to corrosion of the steel ( See FIG. 6 to be described later).

FIGS. 2A to 2C are characteristic diagrams showing the relationship between the exposure time (elapsed time) of the coated steel material and the amount of corrosion in certain areas a to c. Data such as the amount of sea salt, humidity, and temperature are attached.
Then, it is assumed that data of many areas including the data of FIG. 2 is stored in the database. In addition, it is assumed that the area is classified into, for example, a coastal area, a mountain area, an urban area, and the like. In estimating the life, it is preferable to classify the area to be surveyed into areas having similar environments to some extent. The similar environment refers to an area where the temperature and temperature changes are similar, an area where the humidity and temperature changes are similar, and the like. Taking Japan as an example, it is classified into Hokkaido, the Nansei Islands of Okinawa, and the Pacific coast. If the classification and evaluation are performed in this manner, the life can be predicted easily and in a short period of time, and the prediction accuracy is improved.

If the data corresponding to the processing (S22) described later is insufficient, the aging bulging width is predicted. For example, in the processing described below, when the data of the exposure years (elapsed years) uses the data of the fifth year, and when there is only the data of the third and sixth years, the data is missing by referring to these data. Year data may be supplemented.

(S22) A step of classifying and quantifying environmental factors to determine a dominant environmental factor. In this process, environmental data such as temperature, humidity, and amount of sea salt coming from the above-mentioned database are collected, environmental factors are plotted with respect to the amount of corrosion, and the following processing is performed to determine the coefficient of determination of both. It is determined that the coefficient having a relatively large coefficient of determination is the dominant environmental factor that controls the corrosion rate.

The method for determining the dominant environmental factor will be specifically described. From the data in the database as shown in FIGS. 2A to 2C, data to be used is narrowed down based on product conditions. For example, if the location of the product is coastal,
The data to be used is narrowed down to the coastal area data from the database data. Then, the logarithm of each of the environmental factor (independent variable) X and the corrosion amount (dependent variable) Y is calculated and converted into a linear model to perform a regression analysis. Further, it determined by (1) the coefficient of determination R ² for the following equation (2).

## EQU1 ## logY = a + blogX (1)

[0029]

(Equation 2)

In determining the constants a and b in the above equation (1), the constants a and b, which are environmental factors, as well as the amount of incoming sea salt, humidity, and temperature are determined. In the examples of FIGS. 2A to 2C, the constants a and b are respectively applied by applying the amount of corrosion and the amount of incoming sea salt in the areas a to c after five years to the above equation (1). And the coefficient of determination. Also,
The coefficient of determination for humidity, temperature, and the like is obtained in the same manner.

When the determination coefficients for the amount of incoming sea salt, humidity, and temperature are determined as described above, the environmental factors having the largest determination coefficient are determined by comparing the mutual magnitudes with each other. Determined as a factor.

After determining the dominant environmental factor, the constants a and b in the above equation (1) for the environmental factor are determined for at least three years (for example, two years, five years, and seven years). (It is desirable that the number of years is large as described later). FIGS. 3A to 3C show two years of exposure and five years of exposure.
When the constants a and b of the above equation (1) corresponding to the years 7 and 7 are obtained, the relationship between the dominant environmental factor obtained by the above equation (1) and the amount of corrosion is conceptually shown. It is a characteristic diagram.

(S23) A step of installing galvanic pairs at a plurality of target sites of the actual structure to be measured and measuring a dominant environmental factor. In this step, since the environment is microscopically different in the actual structure, the dependence of the corrosion rate of each part on the environmental factor is quantified with respect to the external environment. Japan's climate has four seasons, and it changes greatly in one year.
It is good to measure continuously for one year, but it is quite possible to estimate even one month of measurement from climate data in each region of Japan.

At the time of the measurement, for example, the measurement is performed using a galvanic pair at a plurality of portions of the actual structure or a structure simulating the actual structure requested by the customer. Depending on the part (for example, inside the building or in a narrow place), the amount of incoming sea salt cannot be measured. Therefore, the sampling of the amount of incoming sea salt and the measurement using a galvanic pair are performed outdoors, and each part is connected to a galvanic pair. Only the measurement of is performed. Since the output of the galvanic pair can quantify the environmental data from the relationship between the relative humidity and the amount of attached salt, the degree of the environmental data (for example, the amount of incoming sea salt, temperature, humidity, etc.) can be calculated from the output of the galvanic pair by the following equation (3). , (4). Actually, the ratio of the amount of attached salt when the outdoors is set to 1 (partial coefficient relating to the amount of attached salt: the part coefficient is the amount of incoming sea salt,
It can be calculated for various environmental factors such as temperature and humidity. ), Site A is expressed as an attached salt content ratio of 0.2, and site B is expressed as an attached salt content ratio of 0.01.

[0035]

## EQU00003 ## Site coefficient = Amount of salt attached to site / Amount of salt attached outdoors ... (3)

## EQU00004 ## Flying sea salt amount of the part A = outdoor flying sea salt amount.times.partial coefficient of the part A (4)

For example, the actual structure will be described below with reference to a housing member such as a prefab or a steel house. The data of the amount of incoming sea salt in the one month test is
Take data on the amount of salt attached to painted steel. On the other hand, the amount of salt attached to each use site such as the eaves, the back of a cabin, and the inside of a wall is measured by a galvanic pair. The amount of attached salt is obtained from a calibration curve indicating the relationship between the output of the galvanic couple prepared in advance and the amount of attached salt. From the relationship between the amount of incoming sea salt and the amount of attached salt measured outdoors, although indirect from the output of the galvanic pair,
The amount of incoming sea salt at each site, such as the eaves, the back of the hut, and the inside of the wall, is obtained.

(S24) A step of estimating a swollen width of each part with respect to a dominant environmental factor. In this step, the swollen width is estimated based on the numerically dominant environmental factors of each part.

More specifically, the measured values of the dominant environmental factors (for example, the amount of incoming sea salt at each site such as the eaves, the back of a cabin, and the inside of a wall) are applied to the characteristics shown in FIGS. Obtain data on corrosion rate and age. FIGS. 3A to 3C
For example, if the incoming sea salt amount is a (mmd), the corresponding corrosion amounts Ya2, Ya5, and Ya7 are obtained. Then, the logarithms of the years of exposure (independent variable) T and the amount of corrosion (dependent variable) Y are taken, converted into a linear model, and regression analysis is performed to obtain constants α and β.

LogY = α + βlogT (5)

FIGS. 4A to 4C conceptually illustrate the relationship between the number of years of exposure (elapsed years) and the amount of corrosion (bulging width) outdoors and in the parts A and B obtained by the above equation (5). FIG. 3 is a characteristic diagram schematically shown.

(S25) A step of predicting the life of each part with respect to the dominant environmental factor. In this step, the life is calculated by comparing the swollen width shown in FIG. 4 with a threshold of the swollen width that determines the life.

(S26) The step of determining the service life. In this step, the life expectancy is determined by multiplying the above-described life expectancy by a safety factor (depending on the application).

(ST3) The above processing (S21) through (S3)
According to 26), the specification of the coated steel material satisfying the product conditions is obtained. Next, a process until the coated steel material is manufactured and sold will be described. (S31) The material of the coated steel is selected. Here, a material is selected from steel materials whose service life (for example, 30 years) has been satisfied by the above processing.

The following modification can be considered for the selection of the material. For example, prediction of corrosion amount and life (S2
4, S25) Material selection may be performed based only on the result. Originally, it is preferable to go through the above-mentioned processing (S26), but it is also possible to select a material only by the result of the above-mentioned processing (S24) or (S25).

Further, in the above processing (S26), for example, when all the steel materials whose life is to be predicted do not satisfy the service life, it is found that the corrosion resistance is clearly higher than that of the steel whose prediction was made. May be selected. Since a certain degree of correspondence can be given to steel materials of the same system, for example, a steel material of the same system and high corrosion resistance as a steel material predicted to have the longest life may be selected.

Further, for example, when all the steel materials whose life is to be predicted do not satisfy the service life, a new steel material may be designed based on the prediction result. If a minor design modification is made to a steel material, the fact that the degree of improvement in corrosion resistance can be predicted is used. It is possible to change the coating thickness of the steel material whose life is to be predicted, change the type of chemical conversion treatment, change the temperature control in the baking process, change the plating adhesion amount, and the like. In the present invention, any of material selection, material selection, and material design shall be included in the concept of design.

(S32) Order, manufacture and sale of materials are performed.

FIG. 2 is a flowchart showing the steps of the coating process in the above process (S32).
Through (S47). (S41) Degreasing step of steel: Oil and dirt attached to the surface of the steel before coating are removed. (S42) Polishing step of steel: The oxide film on the surface of the steel is removed with a brush to activate the surface. The post-process chemical conversion property is improved. (S43) Chemical conversion treatment step: A phosphate treatment or a chromate treatment is performed. It has a pretreatment role to improve coating film adhesion and a functional role to improve corrosion resistance of steel materials. In the case where the life of the steel material is known by the above-described processing, and when a longer life is expected, the chemical processing is reflected. (S44) Painting step: a step of coating a paint. Roll coating and spray coating are common. (S45) Baking step: drying and curing of the paint. A coating is formed. Painting and baking may be repeated 2.3 times depending on the required corrosion resistance. (S46) Inspection step: Inspection of the coating film for pinholes, uneven gloss, and color tone. (S47) Attaching step of protective film: Although it may not be performed, there is a case where the protective film is attached and shipped at the request of the customer.

The data of the above processing (S25) and / or (S26) is attached to the coated steel material manufactured as described above. This attachment includes not only mechanical attachment but also a case where the painted steel material and its data are associated with each other. For example, data when predicting the progress of corrosion of each of the above-described parts (such as data regarding the swollen width of steel material) or a symbol indicating the same is added to the painted steel material,
Alternatively, the data or data related thereto is sent to the delivery destination as electronic information. This electronic information may be stored in a recording medium such as an FD, or may be sent (transmitted) to a delivery destination via a network.

In the first embodiment, as described above,
By grasping the dominant environmental factors, it was possible to quantitatively and accurately obtain the progress of corrosion of painted steel materials, so that it was possible to give a quantitative view on the amount of corrosion and life of actual structures. ing. In the conventional exposure test, since such treatment was not performed, it was only possible to suggest qualitative quality as to the corrosion amount and the life of the actual structure.

Embodiment 2 In the above embodiment, an example in which flying sea salt is a dominant environmental factor is described (an example described later also describes an example in which the amount of flying sea salt is a dominant environmental factor). ), However, the dominant environmental factors of the present invention are not limited thereto. In an environment surrounded by four seas, such as in Japan, the amount of incoming sea salt is strongly correlated with corrosion as the dominant environmental factor, but in extremely inland areas, temperature is the dominant environmental factor, Humidity may be the dominant environmental factor.
Sulfur oxides can also dominate in very limited urban areas. The present invention is effective even in such an environment, and the life expectancy of the coated steel material can be easily and quickly performed. Further, in the above embodiment, the case where the dominant environmental factor is one has been described, but the present invention can be applied to the case where the dominant environmental factor is two or more. For example, in a coastal region where humidity is high, two factors, the amount of incoming sea salt and the temperature, may be the dominant environmental factors.

The environmental factors include the amount of incoming sea salt, the temperature, the humidity, the amount of sunshine (the amount of ultraviolet radiation) and the like as described above.
For these environmental factors, the corrosion factors are measured by a galvanic couple (ACM sensor or the like), a thermometer, a hygrometer, and an ultraviolet ray meter, respectively.

In this embodiment, an example has been described in which the life of a painted steel material is predicted by using the swollen width as corrosion data. However, in the present invention, the appearance change of the painted steel material and the area where white rust occurs are described. And the like, and the life can be predicted in the same manner.

Embodiment 3 FIG. Further, in the first embodiment, the process of obtaining the dominant environmental factor has been described. For example, if the dominant environmental factor of the coated steel materials A to C is obtained once in a certain area, the same is obtained from the next time onward. When the dominant environmental factor is determined by the condition, the dominant environmental factor previously determined can be treated as a predetermined one. In such a case, the processing up to the processing (22) in FIG. 1 can be omitted.

Embodiment 4 FIG. Further, in the first embodiment described above, the life prediction and the like of the coated steel material have been described. However, the surface-treated steel material of the present invention includes, in addition to the coated steel material, a chemically treated steel material and a plated steel material.

FIGS. 6 (A) to 6 (C) are explanatory views showing the secular change of the coated steel material, the chemical conversion treated steel material and the plated steel material. The coated steel material 20 is, as shown in FIG.
A plating layer 32, a chemical conversion layer 33, and a coating film 34 are sequentially formed on iron 31. Since the coating film 34 has higher corrosion resistance than the plating layer 32 or the like, before the coating film 34 ages, the plating layer 32 ages, and its cut end is oxidized to white rust 35, and the portion expands. As a result, the cut end of the coating film 34 swells. The width W from the end of the swollen coating film 34 is called the swollen width, and is a parameter indicating the degree of corrosion. Further, as shown in FIG. 1B, the chemical conversion treated steel material 21 is formed by sequentially forming a plating layer 32 and a chemical conversion treatment layer 33 on an iron 31. Since the chemical conversion treatment layer 33 has low corrosion resistance, when the plating layer 32 is exposed by corrosion, the plating layer 32 is oxidized to white rust 36. Further, the plated steel material 22 has a plating layer 32 formed on an iron 31 as shown in FIG. The plating layer 32 is oxidized to become white rust 36, and when the plating layer 32 is peeled off, the iron 31 is oxidized to generate red rust 37.

The painted steel 20, the chemically treated steel 21, and the plated steel 22 change with time as described above, and therefore, the appearance life is: life of painted steel> life of chemically treated steel> life of plated steel. There is a relationship. INDUSTRIAL APPLICABILITY The present invention is useful when applied to the prediction of the life of a steel material having a long life, and its usefulness is particularly remarkable when applied to a chemical conversion treated steel material and a painted steel material.

[0057]

FIG. 7 is a characteristic diagram of a coated steel material in a certain area obtained by the processing (S21) of the above-described first embodiment (a characteristic diagram corresponding to FIG. 2 described above). Here, data with exposure years of 1 to 7 years are depicted. A large number of such data will be used in the above processing (S22).

Tables 1 and 2 show the coefficient of determination obtained when determining the dominant environmental factor in the above processing (S22), and the coefficient of determination at 5 years and 7 years after exposure. Are shown respectively. From Tables 1 and 2, from among the determination coefficients of temperature, humidity and the amount of incoming sea salt, the determining coefficient of the amount of incoming sea salt is the highest, so that the dominant environmental factors of the coated steel materials A to C in this area are It is determined as the amount of incoming sea salt.

[0059]

[Table 1]

[0060]

[Table 2]

FIGS. 8 to 10 are characteristic diagrams respectively showing the relationship between the amount of incoming sea salt, the swelling width of the coated steel material two years, five years, and seven years after the exposure. 3 (A) to 3 (C). In addition, unit md of flying sea salt amount
d is mg / dm ² · day (the amount of sea salt captured per day in an area of 10 cm × 10 cm square).

FIG. 11 is a characteristic diagram showing the predicted value of the swollen width of the coated steel material obtained outdoors by the above-described process (S24) in the elapsed years. In the case where the life is when the swollen width of the coated steel material reaches 5 mm, as shown in FIG.
It is possible to predict that the coated steel material B has an appearance life of about 6 years and the coated steel material C has an appearance life of 30 years or more.

FIGS. 12 to 14 are characteristic diagrams showing the predicted values of the swollen widths of the coated steel materials A to C outdoors and for the portions A and B, and the predicted values of the swollen widths with the elapsed years. In the illustrated example, the ratio of the amount of attached salt in the outdoor area, the site A and the site B is 1: 0.2: 0.01.

[0064]

As described above, according to the present invention, the value of an environmental factor is measured at one or more sites in a target real structure or a structure simulating the real structure, and the environmental factor, the amount of corrosion, and the like are measured. Based on the relationship and the measured values of the environmental factors, data showing the relationship between the amount of corrosion and the exposure time was obtained, and the progress of corrosion was predicted based on the data. In addition, it is possible to accurately predict the long-term life of a surface-treated steel material. Note that the present invention relates to a prefab,
This invention is particularly effective for designing a housing member such as a steel house.

[Brief description of the drawings]

FIG. 1 is a flowchart showing processing steps of a life prediction method, a design method, and a steel material manufacturing method of a coated steel material according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the number of years of exposure of a coated steel material and the amount of corrosion in certain areas a to c.

FIG. 3 is a characteristic diagram showing a relationship between a dominant environmental factor of two years, five years and seven years of exposure and a corrosion amount.

FIG. 4 is a characteristic diagram conceptually showing the relationship between the number of years of exposure and the amount of corrosion in an outdoor area, site A and site B.

FIG. 5 is a flowchart showing a process of a coating process in the process (S32) of FIG. 1;

FIG. 6 is an explanatory view showing the secular change of a coated steel material, a chemical conversion steel material, and a plating steel material.

FIG. 7 is a characteristic diagram obtained by the process (S21) of FIG.

FIG. 8 is a characteristic diagram showing the relationship between the amount of incoming sea salt and the swollen width after two years.

FIG. 9 is a characteristic diagram showing the relationship between the amount of incoming sea salt after 5 years and the swollen width.

FIG. 10 is a characteristic diagram showing the relationship between the amount of incoming sea salt after seven years and the swollen width.

FIG. 11 is a characteristic diagram showing predicted values of blister widths of painted steel materials A to C outdoors.

FIG. 12 is a characteristic diagram showing a predicted value of a swollen width of a coated steel material A outdoors, a part A and a part B.

FIG. 13 is a characteristic diagram showing a predicted value of a swollen width of a painted steel material B with respect to an outdoor area, an area A, and an area B.

FIG. 14 is a characteristic diagram showing a predicted value of a swollen width of a painted steel material C outdoors and at locations A and B.

[Procedure amendment]

[Submission date] June 6, 2002 (2002.6.6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 9

[Correction method] Change

[Correction contents]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] Claim 12

[Correction method] Change

[Correction contents]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

(9) In the method for predicting the life of a surface-treated steel material according to another aspect of the present invention, the environmental factor is the amount of incoming sea salt, temperature, humidity, sunlight irradiation amount or SOx.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

(S21) A step of organizing data for estimating the life of the coated steel material. In this process, the relationship between the number of years of exposure (elapsed time) and the amount of corrosion is determined and graphed, and the average temperature (hereinafter, referred to as temperature), the average humidity (hereinafter, referred to as humidity), the amount of incoming sea salt, the temperature, Appropriate selection is made from environmental factors such as humidity, sunlight, sulfur oxides, precipitation, dew condensation time, and amount of attached salt, and the data of each environmental factor is arranged together as environmental data. The corrosion data includes a swollen width, a change in appearance, an area where white rust occurs, and the like. In the first embodiment, an example of the swollen width will be described. The swelling width of the coated steel material indicates the width of the swelled coating film from the end when the coating swells from the cut end due to corrosion of the steel ( See FIG. 6 to be described later).

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

[0029]

(Equation 2)

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction contents]

For example, the actual structure will be described below with reference to a housing member such as a prefab or a steel house. In a one-month test, data on the amount of sea salt coming from outside and data on the amount of salt attached to the coated steel are collected. On the other hand, the amount of salt attached to each use site such as the eaves, the back of a cabin, and the inside of a wall is measured by a galvanic pair. The amount of attached salt is obtained from a calibration curve indicating the relationship between the output of the galvanic couple prepared in advance and the amount of attached salt. From the relationship between the amount of incoming sea salt and the amount of attached salt measured outdoors, the amount of incoming sea salt at each site, such as the eaves, the back of the cabin, and the inside of the wall, can be obtained indirectly from the output of the galvanic couple.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

More specifically, the measured values of the dominant environmental factors (for example, the amount of incoming sea salt at each site such as the eaves, the back of a cabin, and the inside of a wall) are applied to the characteristics shown in FIGS. Obtain data on corrosion rate and age. FIGS. 3A to 3C
The amount Oite the example corrosion corresponding thereto in the case were for example airborne sea salt amount a (mdd) Ya2, Ya5, Ya7
Ask for. Then, the logarithms of the years of exposure (independent variable) T and the amount of corrosion (dependent variable) Y are taken, converted into a linear model, and regression analysis is performed to obtain constants α and β.

LogY = α + βlogT (5)

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0047

[Correction method] Change

[Correction contents]

FIG . 5 is a flowchart showing the steps of the coating process in the above process (S32).
Through (S47). (S41) Degreasing step of steel: Oil and dirt attached to the surface of the steel before coating are removed. (S42) Polishing step of steel: The oxide film on the surface of the steel is removed with a brush to activate the surface. The post-process chemical conversion property is improved. (S43) Chemical conversion treatment step: A phosphate treatment or a chromate treatment is performed. It has a pre-treatment role to improve coating film adhesion and a functional role to improve corrosion resistance of steel materials. In the case where the life of the steel material is known by the above-described processing, and when a longer life is expected, the chemical processing is reflected. (S44) Painting step: a step of coating a paint. Roll coating and spray coating are common. (S45) Baking step: drying and curing of the paint. Form a coating. Paint according to corrosion resistance is required, it may repeat the baking 2, 3 times. (S46) Inspection step: Inspection of the coating film for pinholes, uneven gloss, and color tone. (S47) Attaching step of protective film: Although it may not be performed, there is a case where the protective film is attached and shipped at the request of the customer.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Change

[Correction contents]

FIGS. 6 (A) to 6 (C) are explanatory views showing the secular change of the coated steel material, the chemical conversion treated steel material and the plated steel material. The coated steel material 20 is, as shown in FIG.
Plating layer 31 , chemical conversion layer 32, and coating film on iron 30
33 are sequentially formed. Since the coating film 33 has higher corrosion resistance than the plating layer 31 or the like, before the coating film 33 ages, the plating layer 31 ages, and its cut end is oxidized to white rust 35, and the site expands. Paint film
The cut end of 33 is swollen. The swollen coating film
The width W from the end of 33 is called the swollen width, and is a parameter indicating the degree of corrosion. In addition, the chemical conversion treated steel material 21 has a plating layer 31 and a chemical conversion treatment layer 32 sequentially formed on iron 30 as shown in FIG. Since the chemical conversion layer 32 has low corrosion resistance, when the plating layer 31 is exposed by corrosion, the plating layer 31 is oxidized to form white rust 36. Further, the plated steel material 22 has a plating layer 31 formed on an iron 30 as shown in FIG. The plating layer 31 is oxidized to become white rust 36, and when the plating layer 31 is peeled off, the iron 30 is oxidized to generate red rust 37.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction contents]

FIG. 11 is a characteristic diagram showing the predicted value of the swollen width of the coated steel material obtained outdoors by the above-described process (S24) in the elapsed years. In the case where the life is when the swollen width of the painted steel material reaches 5 mm, the painted steel material A is 3 from FIG.
It is possible to predict that the coated steel material B has an appearance life of about 6 years and the coated steel material C has an appearance life of 30 years or more.

Continued on the front page F term (reference) 2G050 AA01 AA07 BA02 BA05 BA06 BA09 BA10 BA20 DA01 EB02 EB03 EB07 EB10 EC10 2G055 AA03 AA07 BA07 BA09 BA12 CA01 CA07 CA25 DA08 FA02 FA06

Claims (17)

[Claims] A first step of obtaining a relationship between an environmental factor and a corrosion amount based on data indicating a relationship between the corrosion amount and an exposure time in a plurality of real environments and an environmental factor of the data; A second step of measuring the value of the environmental factor at one or more sites in a real structure or a structure simulating the real structure, and a relationship between the environmental factor and the amount of corrosion in the first step,
A third step of obtaining data indicating the relationship between the amount of corrosion at the site and the exposure time based on the measured values of the environmental factors measured in the second step; and the amount of corrosion and the exposure in the third step. And a fourth step of predicting the progress of corrosion based on data indicating a relationship with time. 2. A first step of measuring a value of an environmental factor at one or more sites in a target actual structure or a structure simulating the actual structure; And the measured value of the environmental factor measured in the first step,
A second step of obtaining data indicating the relationship between the amount of corrosion and the exposure time at the site; and a third step of predicting the progress of corrosion based on the data indicating the relationship between the amount of corrosion and the exposure time in the second step. And a method for predicting the life of a surface-treated steel material. 3. When there are a plurality of said environmental factors, data indicating the relationship between the corrosion amount and the exposure time in a plurality of real environments and the relationship between the environmental factors and the corrosion amount obtained based on the environmental factors of the data. From the relationship, one or more environmental factors are determined as the dominant environmental factors. 3. The method according to claim 1, wherein the method is performed based on a dominant environmental factor. 4. A reference position provided in or on the surface of the target real structure or a structure simulating the real structure (hereinafter referred to as a real structure or the like), or provided outside the real structure or the like. The value of the environmental data at the given reference position is used as a reference value, and the value of the environmental data measured at the site in the actual structure or the like, and the ratio between the reference value and the site coefficient is used as the site coefficient. The value of the certain environmental factor in each part is calculated based on the correspondence between the certain environmental factor and the part coefficient. The method according to any one of claims 1 to 3, wherein a process based on an environmental factor after the second step is performed by the certain environmental factor. 5. The method according to claim 4, wherein the reference position is one of the parts. 6. The method for predicting the life of a surface-treated steel material according to claim 4, wherein the environmental data is the amount of attached salt and the certain environmental factor is the amount of incoming sea salt. 7. The data representing the relationship between the amount of corrosion and the exposure time is data representing aging of the blister width or white rust occurrence area of the surface-treated steel material.
The method for estimating the life of a surface-treated steel material according to any one of the above. 8. The method for predicting the life of a surface-treated steel material according to claim 1, wherein the measurement of the environmental factor is at least one month. 9. The method according to claim 1, wherein the environmental factors are incoming sea salt, temperature, humidity, sunlight irradiation amount, or SOx. 10. The method for predicting the life of a surface-treated steel material according to claim 1, wherein the life is predicted before the area to be evaluated is divided into regions having similar environments. 11. The method according to claim 1, wherein the surface-treated steel material is a painted steel material. 12. A surface-treated steel material whose life is predicted by the life-treatment method for a surface-treated steel material according to any one of claims 1 to 11, wherein data when the progress of corrosion of each of the parts is predicted is attached. A surface-treated steel material characterized by being made. 13. The surface-treated steel material according to claim 12, wherein the data at the time of predicting the progress of corrosion at each part is data relating to a swollen width or a white rust generation area. 14. The data or a symbol indicating the data is added to a surface-treated steel material.
Or a surface-treated steel material according to 13. 15. The surface-treated steel material according to claim 12, wherein the data or data related thereto is sent as electronic information to a delivery destination. 16. A method of selecting one or more surface-treated steel materials whose corrosion has been predicted by the method for predicting the life of a surface-treated steel material according to claim 1, or the one or more surface-treated steel materials. By selecting from surface-treated steel materials for which corrosion progress was not predicted based on the prediction results of corrosion progress in, or designing new surface-treated steel materials, the steel materials are selected for application to actual structures. How to design surface-treated steel. 17. A method for producing a surface-treated steel material, characterized by producing a surface-treated steel material designed by the method for designing a surface-treated steel material according to claim 16.