JPH05264481A - On-line measuring method for amount of adhered cr to chromate-treated film on plated steel plate - Google Patents

Abstract

PURPOSE:To perform on-line measurement of the amount of Cr of chromate- treated film which is formed on the surface of zinc or zinc alloy plated steel plate. CONSTITUTION:When performing on-line measurement of the amount of Cr of chromate-treated film on a plate steel plate by the fluorescent X-ray analysis, the amount of adhered Cr of the film is obtained by subtracting the Cr content within the steel plate which is compensated by a ladle value in a steel- manufacturing stage from the amount of adhered Cr which is obtained from a measured X-ray strength of Cr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accurately measuring the Cr deposition amount of a chromate-treated coating formed on the surface of a zinc or zinc alloy plated steel sheet online by fluorescent X-ray analysis.

[0002]

2. Description of the Related Art When measuring the amount of Cr deposited on a chromate-treated coating formed on a plated steel sheet, a fluorescent X-ray analysis has been mainly performed so far in the past, or the formed coating is redissolved and then liquid analysis such as atomic absorption method is performed. Was being done.

[0003]

However, these methods have the following problems.

First, in a fluorescent X-ray analysis in off-line, when the Cr deposition amount is as high as several hundreds mg / m ² , the Cr content in the base steel is small, but the Cr deposition amount is small. The degree of influence cannot be ignored, and it is impossible to accurately measure the Cr deposition amount in the chromate-treated film.

Further, when the formed film is redissolved and liquid analysis such as atomic absorption method is performed, it takes a lot of measurement time because it is an offline batch measurement, and it is applied to an actual machine in which continuous processing is performed. Is extremely difficult.

The present invention was devised in view of the above problems of the prior art. Based on the on-line fluorescence X-ray analysis method, the present invention is improved to measure the Cr deposition amount of the chromate-treated film with high accuracy. It is something that can be done.

[0007]

Therefore, according to the method of the present invention, C of a chromate-treated film on a plated steel sheet is analyzed by fluorescent X-ray analysis.
r When measuring the adhesion amount online, the measured Cr
The basic characteristic is to obtain the Cr adhesion amount of the film by subtracting the Cr content in the steel sheet corrected by the ladle value at the steel making stage from the Cr adhesion amount obtained from the X-ray intensity of.

When performing the above subtraction, the Cr content in the steel sheet corrected by the ladle value in the steelmaking stage is further corrected by the measured X-ray intensity of Zn, and then used for the subtraction, the accuracy is obtained. Will be better.

The above-mentioned structure of the method of the present invention was created as a result of the following consideration, which will be described in detail below.

When the amount of Cr deposited on the chromate-treated film is measured by an on-line fluorescent X-ray analyzer, the X-rays incident on the steel plate are reflected as shown in FIG. The line intensity I _Cr is detected.

[0011]

[ _Formula 1] I _Cr = I _FCr + I _BCr However, I _FCr : X-ray intensity of Cr on the chromate treatment film side I _BCr : X-ray intensity of Cr on the base steel plate side

Therefore, the detected X-ray intensity I _Cr is increased by the X-ray intensity of Cr on the base steel sheet side, and it may be possible to correct it by considering it as a certain value. However, since the Cr content of the base steel sheet differs depending on the steel type, when the Cr content in the steel is high, the detected Cr amount will be added.

That is, the actually detected amount of Cr is influenced by the Cr content in the base steel sheet as shown in FIG. Therefore, the inventors of the present invention have come up with the idea of the method of the present invention in consideration of correcting the Cr content in the base steel sheet by the ladle value at the time of steel making.

On the other hand, the Cr content of the base steel sheet is attenuated by the thickness of the plating film between the base material and the chromate-treated film. If this film is zinc plated, the detected Zn X
It can be corrected by the line intensity. That is, the Cr adhesion amount S (mg / m ² ) of the chromate-treated film on the zinc plating film can be obtained by the following regression equation ( ² ).

[0015]

## EQU2 ## S = (aX + b) -a (dz + e) .EXP
(-CY) where, a, b, c, d , e: constant X (= I _Cr): X-ray intensity of total Cr (K _CPS) Z: Cr content of the base steel sheet (ladle value) Y: the Zn X-ray intensity (K _CPS )

In actual measurement, as shown in FIG. 3, the ladle value at the steel making stage of the base steel sheet is calculated by the high-level computer 1.
More transmitted to the process computer 2 installed in the plating line, and further transferred to the fluorescent X-ray analyzer 3 of the plating line.
It is possible to accurately measure the Cr adhesion amount of the chromate-treated film by calculating this by the above-mentioned equation (2).

[0017]

EXAMPLES Specific examples of the method of the present invention will be described below.

The inventors of the present invention produced a pure zinc plated steel sheet with a Zn deposition amount of 20 g / m ^{2 on} an electric zinc plating line for a cold rolled steel sheet whose Cr content in the steel was found to be 0.052 wt% in advance. Immediately after that, chromate treatment was applied.

At the same time, in a fluorescent X-ray apparatus installed online, the C value in the steel can be changed by inputting the ladle value from the host computer.
Comparisons were made between the case where the r content was corrected, the case where it was corrected with a commonly used constant value of 0.02 wt%, and the value measured by chemical analysis off-line. The results are shown in Table 1 below.

[0020]

[Table 1]

From Table 1 above, when the Cr content in steel is corrected by inputting the ladle value from the host computer, the measurement accuracy is remarkably improved as compared with the case where it is not corrected, and the chemistry is offline. It can be seen that there is almost no error from the analysis.

[0022]

According to the measuring method of the present invention described above in detail, the C of the chromate-treated film formed on the surface of the plated film is C.
r It is possible to accurately measure the amount of adhesion online.

[Brief description of drawings]

Fig. 1 Cr of chromate treated film by X-ray fluorescence analysis
It is explanatory drawing which shows the state of reflection of the X-rays which injected into the steel plate in the case of measuring the adhesion amount.

FIG. 2 is a graph showing the influence of the Cr content in a base steel sheet and the X-ray intensity of zinc when the Cr content is detected by fluorescent X-ray analysis.

FIG. 3 is a flowchart showing a calculation process of the method of the present invention.

[Explanation of symbols]

 1 Host computer 2 Process computer 3 Fluorescent X-ray analyzer

Claims (2)

[Claims] 1. A ladle at a steelmaking stage, which is used for online measurement of the Cr deposition amount of a chromate-treated coating on a plated steel sheet by fluorescent X-ray analysis, from the Cr deposition amount obtained from the measured X-ray intensity of Cr. A Cr adhesion amount online measuring method for a chromate-treated film on a plated steel plate, characterized in that the Cr content in the steel plate corrected by the value is subtracted to obtain the Cr adhesion amount of the film. 2. The Cr content online measuring method for a chromate-treated coating on a plated steel sheet according to claim 1, wherein the Cr content in the steel sheet corrected by the ladle value in the steelmaking stage is further measured. Cr calculated from the measured X-ray intensity of Cr after correction with the X-ray intensity of
The online method for measuring the Cr deposition amount of a chromate-treated coating on a plated steel sheet according to claim 1, wherein the Cr deposition amount of the coating is obtained by subtracting the value from the deposition amount.