JPH10282020A - Method of measuring composition and thickness of oxidized scale of steel plate and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of the characteristic of oxidized scale on line as index of the optimum removing conditions of the oxidized scale by irradiating the surface of a steel plate with X rays to detect the peak intensity of a number of diffraction X rays radiated. SOLUTION: The surface of a steel plate 7 is irradiated with X rays from an X-ray detector 1 and a number of diffraction X rays radiated from the surface of the steel plate 7 are detected by a spectroscope 2 having an X-ray detector. The data detected are analyzed by a work station 5 to determine the composition and the thickness of the oxidized scale. In other words, the composition and the thickness of the oxidized scale are determined based on the peak intensities of these diffraction X rays and the peak intensities of a number of diffraction X rays of various Fe oxides previously registered. In this process, as the steel plate 7 is so wide to allow varying of the composition and the thickness of the oxidized scale across the width thereof, a support base 3 of the X-ray generator 1 and the spectroscope 2 is reciprocated on a rail 4, thereby enabling quick and accurate determination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optimization of conditions for removing oxide scale formed on the surface of a steel sheet in a steel sheet manufacturing process, and more particularly, to a method for measuring the characteristics of the oxide scale, which is an index, quickly and accurately on-line. And a method and apparatus for measuring the composition and thickness of the oxide scale.

[0002]

2. Description of the Related Art Oxidation scale generated on the surface of a steel sheet during the manufacturing process of the steel sheet significantly impairs the formability, paintability, plating property and weldability of the steel sheet. The product is removed by passing it through a liquid or the like and washing it.

However, parameters directly related to the production conditions such as the pressure and amount of the high-pressure water, the concentration of the pickling solution and the immersion time (sheet passing speed) depended on the empirical rules of the operator, so that the surface of the steel sheet was oxidized. Such as running out of scale or taking more action than necessary
Since problems such as a decrease in product yield and an increase in manufacturing cost occur, it has been desired to provide a means for quickly measuring oxide scale characteristics, which can be an index of oxide scale removal conditions.

[0004] In general, a technique for performing component analysis or the like using X-rays as an excitation source has high reliability and is widely used industrially. In the laboratory, the X-ray diffraction method is the best for classifying the type of oxide scale. However, in the steel sheet manufacturing process, since the passing speed is high, the X-ray diffraction method using a conventional goniometer is used. According to the method, since the peaks of each composition cannot be measured simultaneously and at the same time, there is a problem that the method lacks quickness and cannot be used as an index for determining the conditions for removing the oxide scale online.

Further, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-37187 (quantitative analysis of thin layers), there is a method for measuring the composition and thickness of a plating layer using fluorescent X-rays. However, there is also a problem that this is lacking in speed.

Further, there are steel plates having a width of several tens cm to more than 100 cm, and the thickness and the composition of the oxide scale vary in the width direction. Therefore, it is necessary to collect data in the width direction. Was.

In any case, there has been no method for quickly and accurately measuring the properties of oxide scale, which can be an index for determining the optimum oxide scale conditions, for a running steel sheet in a manufacturing process.

[0008]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and has characteristics of an oxide scale that can be an index of an optimum condition for removing oxide scale generated in a steel sheet manufacturing process. It is an object of the present invention to propose a method and an apparatus for measuring the composition and thickness of an oxide scale of a steel sheet, which enables the on-line measurement.

[0009]

Means for Solving the Problems In order to determine the optimum conditions for removing the oxide scale of the steel sheet during the manufacturing process online and feed it forward to the oxide scale removing step, the inventors have proposed an oxide scale on the steel sheet surface. The present invention has been achieved by noting that it is effective to measure the composition and thickness quickly and accurately and to use diffraction X-rays for that purpose. That is, the gist of the present invention is as follows.

X-rays are irradiated from the X-ray generator onto the surface of the steel sheet, and a large number of diffraction X-ray peak intensities of Fe and various Fe oxides emitted from the steel sheet surface are detected by an X-ray detector.
It is registered in advance as its diffraction X-ray peak intensity
A method for measuring the composition and thickness of the oxide scale of a steel sheet, characterized by quantifying the composition and thickness of the oxide scale based on the peak intensities of many diffraction X-rays of Fe and various Fe oxides ( 1st invention).

The first invention is characterized in that the X-ray generator and the X-ray detector are simultaneously repetitively moved at a high speed in the width direction of the steel sheet to measure the variation of the composition and thickness of the oxide scale in the width direction of the steel sheet. The method for measuring the composition and thickness of an oxide scale of a steel sheet according to (2nd invention).

[0012] The steel sheet according to the first or second invention, wherein the fluctuation of the distance between the steel sheet and the X-ray generator and the X-ray detector due to the vertical movement of the steel sheet is constantly monitored and kept constant. Method for measuring composition and thickness of oxide scale (third invention).

The X-ray generator and the X-ray detector are supported by a structure made of an alloy having a small coefficient of thermal expansion to suppress a change in the positional relationship between the steel plate, the X-ray generator and the X-ray detector due to a temperature change. The method for measuring the composition and thickness of an oxide scale of a steel sheet according to the eleventh, second or third invention, characterized by the above (fourth invention).

When a change in the diffraction angle is detected by a minute detection element having a large number of channels attached to a diffraction X-ray detector, the change is corrected by a piezoelectric element and the diffraction X-ray is detected.
The method for measuring the composition and thickness of an oxide scale of a steel sheet according to the first, second, third or fourth invention, wherein a line peak is detected at a predetermined diffraction angle (fifth invention).

By detecting the shift of the position of the specific diffraction X-ray peak of Fe by the minute X-ray detecting element having a large number of channels provided in the spectroscope, the position of the diffraction X-ray peak due to the temperature change and vibration of the steel sheet is detected. The method for measuring the composition / thickness of the oxide scale of a steel sheet according to the first, second, third, fourth or fifth invention which corrects the fluctuation of (6th invention).

A thermal expansion coefficient supporting a spectroscope including an X-ray generator for irradiating the surface of the steel sheet with X-rays and a number of X-ray detectors for simultaneously detecting a number of diffraction X-ray peak intensities emitted from the surface of the steel sheet. The composition of the oxide scale was determined from the relationship between the support made of an alloy with a small size and the information on the peak intensities of a large number of diffracted X-rays from the spectrometer and the previously registered intensities of the diffracted X-rays of Fe and Fe oxide. A workstation that quantifies the thickness, the X-ray detector includes minute X-ray detectors having a number of channels near it, and the spectrometer diffracts by signals from these minute X-ray detectors Equipped with a piezoelectric element that corrects fluctuations in the X-ray peak angle, and a function that the support base repeatedly moves in the width direction of the steel plate, and a rangefinder is used to constantly monitor the distance from the steel plate to compensate for the fluctuation. A method for measuring the composition and thickness of an oxide scale of a steel sheet having a function of correcting (7th invention).

Here, the specific diffraction X-ray peak of Fe is preferably measured on a (110), (200) or (211) plane having a high intensity.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As described above, the present invention mainly irradiates the surface of a traveling steel plate during a manufacturing process with high-intensity X-rays,
The diffraction X-ray peak intensities of Fe and various Fe oxides are simultaneously measured, and the composition and thickness of the oxide scale are quantified quickly and accurately.
This is to realize optimization of conditions for removing oxide scale.

That is, since the diffraction X-ray peaks emitted from the steel sheet are detected by a large number of X-ray detectors, a large number of diffraction X-ray peaks of Fe and various Fe oxides can be simultaneously measured. The measured information can be
The composition and thickness of the oxide scale are instantaneously input to a workstation in which the number of diffraction X-ray peaks of Fe oxide and the relationship between the intensity of the diffraction X-ray peak and the oxide scale thickness are registered in advance. It can be quantified.

Here, the advantage of using the diffracted X-ray for the measurement of the composition and thickness of the oxide scale is that, unlike the fluorescent X-ray method, the type of oxide can be separated and the X-ray intensity is stable. That is.

The data to be registered in the workstation may be a relationship (calibration curve) between the scale thickness and the X-ray intensity, which is prepared in advance using a standard sample.

Subsequently, the composition and thickness of the oxidized scale determined in the work station are input to a process computer, and various oxidized scale removal methods (high-pressure water injection method,
The optimal conditions for removing oxide scale can be determined according to the pickling method and mechanical method typified by sulfuric acid and hydrochloric acid). If this is done, it becomes possible to automatically control the conditions for removing oxide scale.

Next, in order to determine the optimum conditions for removing oxide scale, it is important to improve the measurement accuracy of the composition and thickness of oxide scale. In the present invention, the measurement accuracy can be improved by the methods listed below.

The composition and thickness of the oxide scale of the steel sheet vary in the sheet width direction. Therefore, the support for supporting the X-ray generator and the X-ray detector is repeatedly moved in the width direction of the plate at high speed to measure the peak intensity of each diffracted X-ray in the width direction of the plate, and a representative value of these data is obtained. This makes it possible to determine more accurate conditions for removing oxide scale.

The variation in the temperature of the steel plate, the X-ray generator and the X-ray detector due to a change in the ambient temperature is achieved by forming the support for supporting the X-ray generator and the X-ray detector from an alloy having a small thermal expansion coefficient. It is possible to reduce the measurement accuracy due to a change in the ambient temperature.

The traveling steel plate moves up and down during the manufacturing process. Therefore, a distance sensor is attached to the support and the monitor is constantly monitored, and when the distance from the steel plate exceeds an allowable range, the support is changed instantaneously. Can be prevented from deteriorating the measurement accuracy due to the change in the distance.

A minute X-ray detecting element having a large number of channels is arranged in the vicinity of the X-ray detector mainly used by the X-ray detector to detect a change in the angle of the diffracted X-ray, and the change is detected by a piezoelectric element. By performing the correction, more accurate measurement accuracy can be obtained.

By correcting the fluctuation of the diffraction X-ray peak position due to the temperature change and the vibration of the steel sheet by the detected specific diffraction X-ray peak of Fe, more accurate measurement accuracy can be obtained.

Thus, according to the present invention, the composition and thickness of the oxidized scale of a running steel sheet during the manufacturing process can be measured accurately and quickly, and the optimum oxidized scale can be immediately determined using the measurement results as an index. Scale removal conditions can be determined. Therefore, the present invention can be applied to an in-line oxide scale removing step, and feedforward of an oxide scale removing condition with no remaining oxide scale can be performed without overaction.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing an example of a measuring device for measuring the composition and thickness of an oxide scale suitable for the present invention. In FIG. 1, 1 is an X-ray generator, 2 is a spectroscope equipped with a large number of X-ray detectors and the like, 3 is an X-ray generator 1 and a spectroscope 2
Reference numeral 4 denotes a rail for the support 3 extending in the width direction of the steel plate, and reference numeral 5 denotes a work station for data analysis.
6 is a process computer, 7 is a steel plate and 8 is a roll for guiding the steel plate.

The surface of the steel plate 7 is irradiated with X-rays from the X-ray generator 1, and a number of diffraction X-ray peaks emitted from the surface of the steel plate 7 are detected by the spectroscope 2 having an X-ray detector. The detected data is used to quantify the composition and thickness of the oxide scale from a number of analytical X-ray peaks and their intensities at a data analysis workstation 5.

At this time, since the steel plate 7 is relatively wide, the composition and thickness of the oxide scale may be different in the width direction of the steel plate.
Reciprocate on rail 4. In addition, since the support 3 is made of an alloy having a very small coefficient of thermal expansion, a change in the optical arrangement of the steel plate 7, the X-ray generator 1, and the spectroscope 2 due to a temperature change can be minimized. Further, a distance sensor (not shown) is installed on the support 3 to monitor the vertical movement of the steel plate 7 to be passed. If the fluctuation exceeds an allowable range, a height adjusting device (shown in FIG. (Omitted), the fluctuation due to the vertical movement is instantaneously corrected.

In addition, the spectrometer 2 detects the diffraction X due to the temperature change and vibration of the steel plate 7 by the specific diffraction line peak of Fe.
A function to correct the fluctuation of the line peak position is provided. That is, the spectroscope 2 is finely moved to an optimum position (initial position) by a piezoelectric element or the like.

These are extremely important for improving the measurement accuracy in online measurement of a running steel plate.

FIGS. 2A and 2B are explanatory views of a spectroscope conforming to the present invention. FIG. 2A is a side view, and FIG.
It is an arrow view.

In these figures, 2 is a spectroscope, 9 and 10
Numeral 11 denotes an X-ray detector, and 12 denotes a minute X-ray detecting element having a number of channels for correcting the X-ray detection position.

In the spectroscope 2, the X-ray detectors 9, 10 and 11 provided in the spectroscope 2 detect respective desired diffraction X-ray peaks from the diffraction X-rays radiated from the steel plate 7. I do. The minute X-ray detection element 12 is, for example, an array of minute photodiodes arranged in the direction of the diffraction angle, and monitors the X-ray intensity so as to be maximum in a predetermined channel. When the deviation of the diffraction X-ray peak is monitored by the minute X-ray detection element 12, the position of the spectroscope 2 is corrected by a high-speed moving piezoelectric element (not shown) provided in the spectroscope 2.

Thus, the data obtained at the workstation 5 is transferred to the process computer 6 as an index for feeding forward the oxidation scale removal conditions of the steel sheet, where the optimum oxidation scale removal conditions are determined.

Next, C: 0.002 atom%, Si: 1.0 atom
%, Mn: Steel slab containing 1.0 atom%
After hot rolling, in the process of removing primary scale by injecting high-pressure water onto the steel sheet surface and winding it on a coil, from the end of rolling to winding on the coil, a steel sheet having an oxidized scale during traveling, oxidation With respect to each steel sheet from which the scale was removed, the diffraction X-ray spectra of αFe and Fe oxide were measured by the above-described apparatus.

FIG. 3 shows a graph of the diffraction X-ray spectrum of αFe of the steel sheet from which the oxide scale has been removed, and FIG. 4 shows a graph of the diffraction X-ray spectrum of αFe and Fe oxide of the steel sheet having the oxide scale. As is clear from these figures, the αFe diffraction X-ray peak intensity in FIG. 4 is smaller than that in FIG. 3, and it is found that the oxide scale affects the decrease in αFe diffraction X-ray peak intensity.

FIG. 5 is a graph showing the relationship between the oxide scale thickness and the diffraction X-ray peak intensity, which was measured for steel sheets having different oxide scale thicknesses, which were hot rolled using the same materials as described above. As is clear from FIG. 5, as the oxide scale thickness increases, the diffraction X-ray peak intensity of αFe decreases, but the diffraction X-ray peak intensity of Fe oxides A and B increases.

At this time, for the Fe oxide A, the relationship between its thickness: t and its diffraction X-ray peak intensity: I is represented by the following equation (1). I = a (1-e- ^bt ) --- (1) where a: constant b: constant

Accordingly, the same formula holds for the Fe oxide B, and if these formulas are registered in the workstation 5, the diffraction X-ray peak intensities of the Fe oxides A and B can be detected. Thus, the thickness of the oxide scale can be known.

[0045]

According to the present invention, X-rays are irradiated on the surface of a steel sheet,
According to the present invention, the composition and thickness of the oxide scale are determined by simultaneously detecting the diffraction X-ray peaks of Fe and various Fe oxides from the surface of the steel sheet. However, the composition and thickness of the oxide scale in the width direction of the sheet can be corrected in response to variations in the composition and thickness of the sheet, the vertical movement of the running steel sheet, and temperature changes. Since the thickness can be quantified, it is suitable as an index for determining the optimum oxidation scale removal condition, and if the removal condition is feed forward,
It can greatly contribute to the improvement of the productivity and work efficiency of the steel sheet.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus for measuring the composition and thickness of an oxide scale suitable for the present invention.

FIG. 2 is an explanatory diagram of a spectroscope compatible with the present invention.
(a) is a side view. (b) is a view on arrow AA 'of (a).

FIG. 3 is a graph of a diffraction X-ray spectrum of αFe of a steel sheet from which oxide scale has been removed.

FIG. 4 shows αFe and various values of a steel sheet having an oxide scale.
It is a graph of the diffraction X-ray spectrum of Fe oxide.

FIG. 5 is a graph showing the relationship between oxide scale thickness and diffraction X-ray peak intensity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray generator 2 Spectrometer 3 Support stand 4 Rail 5 Workstation 6 Process computer 7 Steel plate 8 Roll 9,10,11 X-ray detector 12 Micro X-ray detector

Claims (7)

[Claims] 1. A steel sheet surface is irradiated with X-rays from an X-ray generator, and a large number of diffraction X-ray peak intensities of Fe and various Fe oxides emitted from the steel sheet surface are detected by an X-ray detector.
It is registered in advance as its diffraction X-ray peak intensity
A method for measuring the composition and thickness of an oxide scale of a steel sheet, wherein the composition and thickness of the oxide scale are quantified based on the peak intensities of many diffraction X-rays of Fe and various Fe oxides. 2. The method according to claim 1, wherein the X-ray generator and the X-ray detector are simultaneously repetitively moved at a high speed in the width direction of the steel sheet to measure the variation in the composition and thickness of the oxide scale in the width direction of the steel sheet. Item 4. The method for measuring the composition and thickness of an oxide scale of a steel sheet according to Item 1. 3. The steel sheet according to claim 1, wherein the fluctuation of the distance between the steel sheet and the X-ray generator and the X-ray detector due to the vertical movement of the steel sheet is constantly monitored and kept constant. For measuring the composition and thickness of the oxide scale. 4. An X-ray generator and an X-ray detector are supported by a structure made of an alloy having a small coefficient of thermal expansion, and a change in a positional relationship between the steel plate, the X-ray generator and the X-ray detector due to a temperature change is provided. The method for measuring the composition and thickness of an oxide scale of a steel sheet according to claim 1, wherein the composition is suppressed. 5. When a change in a diffraction angle is detected by a minute detection element having a large number of channels attached to a diffraction X-ray detector, the change is corrected by a piezoelectric element and the diffraction X-ray is detected.
The method for measuring the composition and thickness of an oxide scale of a steel sheet according to claim 1, wherein the line peak is detected at a predetermined diffraction angle. 6. The oxidation scale of a steel sheet according to claim 1, wherein the specific diffraction X-ray peak of Fe corrects the fluctuation of the diffraction X-ray peak position due to the temperature change and vibration of the steel sheet. How to measure composition and thickness. 7. A heat source that supports a spectroscope including an X-ray generator that irradiates X-rays on the surface of a steel sheet and a number of X-ray detectors that simultaneously detect a number of diffraction X-ray peak intensities emitted from the surface of the steel sheet. From the relationship between the support made of an alloy having a small expansion coefficient, the information on the many peaks of the diffraction X-rays from the spectrometer, and the previously registered peak intensities of the diffractions of Fe and Fe oxide, the oxide scale A workstation for quantifying the composition and thickness of the X-ray detector. The X-ray detector is equipped with minute X-ray detectors having a large number of channels in the vicinity, and the spectrometer is used to detect signals from these minute X-ray detectors. Equipped with a piezoelectric element that corrects the fluctuation of the diffraction X-ray peak angle, and the support base has a function to repeatedly move in the width direction of the steel sheet. To A method for measuring the composition and thickness of an oxide scale of a steel sheet having a function of correcting.