JPH0921767A - Fluorescent x-ray analyzing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the analyzing accuracy of a high content components such as Cr, Ni in stainless steel by excluding the influence of the finished state of the surface of a metal sample. SOLUTION: In the method for fluorescent x-ray analyzing having the steps of irradiating the surface of a sample such as a metal with first-order x-rays, spectrally separating the intrinsic x-ray generated from the element in the sample by analyzing crystal, measuring the intensity of the intrinsic x-ray, and measuring the content of the element, a roughness regression coefficient computing equation of each element to be measured is previously obtained from the relationship between the sample surface roughness and the varying amount of each element to be measured, the surface roughness of the sample surface is previously measured, and the fluorescent x-ray analytical value is corrected according to the correction value calculated from the equation of the measured surface roughness and the each measured element.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to elements contained in solid samples such as metals, especially high content components in stainless steel,
For example, the present invention relates to a fluorescent X-ray analysis method capable of quantifying Cr, Ni and the like with high accuracy.

[0002]

2. Description of the Related Art A fluorescent X-ray analysis method, which is widely used for the analysis of steel, slag, iron ore, and the measurement of the plating thickness of plated steel sheets, is performed by irradiating a sample with primary X-rays emitted from an X-ray tube. , Characteristic X-rays generated from elements in the sample (characteristic X-rays)
Is an analysis method of qualitatively and quantitatively determining an element by measuring the intensity of an intrinsic X-ray by dispersing the element with a dispersive crystal.

An X-ray fluorescence analyzer is composed of an X-ray generator, a spectroscopic / light-receiving unit, a coefficient recording unit and others. X
The ray generator includes an X-ray tube for generating primary X-rays that irradiate the sample, and a power supply device that supplies a high voltage to the X-ray tube. The spectroscopic and light receiving section disperses the generated fluorescent X-rays,
This is the part that receives light by the detector. The coefficient recording section is a section for recording and displaying the detected fluorescent X-ray intensity. In addition, in general, a means for compensating for fluctuations in a power supply and a device is taken for the purpose of increasing the accuracy of reproducing measured values.

In the case of a bulk sample, a sample to be subjected to fluorescent X-ray analysis is prepared by cutting or crushing (a sample that cannot be cut, such as a ferroalloy) into a size that fits in a sample holder. The size is required to have a diameter of 20 mm or more. Since a flat surface of the sample is required for the quantification, the measurement surface must be polished with a belt sander of No. 60 or above or a grindstone. It is necessary to prepare the standard sample and the analytical sample to have the same roughness within a margin of error. In addition, the sample surface should be free from surface defects such as cavities and gas holes, contamination from the polishing material, discoloration due to heating during polishing, and the like.

In the conventional sample preparation, a belt sander is usually used for polishing the sample after cutting, but the cutting surface of the sample is pressed against a rotating belt-shaped polishing cloth to polish the measurement surface of the sample. However, the pressing pressure or the time depended on the experience of the worker. With such a polishing method, it is unavoidable that individual differences occur in the finish state, and not only the reliability of the obtained analysis value becomes low, but also the finish state before and after the replacement of the belt-shaped polishing cloth of the belt sander. It is necessary to prevent a sudden change during this period, which results in shortening the life of the belt-shaped polishing cloth.

As a method of eliminating the polishing defect in the above-mentioned sample preparation, after cutting the sampled metal sample, this analytical cut surface is shot blasted to eliminate individual differences in the finished state and to achieve long-term A method for obtaining stable analysis values (Japanese Patent Publication No. 60-15018) has been proposed.

[0007]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 60-15
The method disclosed in Japanese Patent Laid-Open No. 018 discloses an attempt to make the surface condition of a metal sample uniform by shot blasting, but it is unknown whether the surface roughness is made uniform. In addition, in this method, a low content area (content 1
% Or less than 1%) has been confirmed to be the same as that of the conventional method (belt sander finishing), but no mention has been made of the analysis accuracy of high content components where the effect of surface roughness is remarkable. Therefore, analysis accuracy cannot be improved.

[0008] Generally, in order to maintain the accuracy of analysis, standardization of polishing work is performed so that the accuracy is kept within a certain level. However, for high content components such as Cr and Ni in stainless steel, the steel is produced during the steelmaking process. In order to reduce the amount of expensive ferro-alloy used in, the accuracy of analysis is desired to be improved.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, eliminate the influence of the finish state of the surface of a metal sample, and quantify with high accuracy even high content components such as Cr and Ni in stainless steel. It is to provide a fluorescent X-ray analysis method.

[0010]

Means for Solving the Problems In order to achieve the above object, the inventors of the present invention repeatedly conducted experiments and examinations on a simpler method, and when the surface roughness of the measurement surface was intentionally changed in the same sample. When the fluorescent X-ray analysis value has a strong correlation with the surface roughness of the measurement surface, and when the content of the element to be measured changes with different samples, the surface roughness of the measurement surface and the fluorescence X
Although the regression coefficient of the line analysis value changes, it was found that there is also a strong correlation, and the change in the regression coefficient can be obtained from the fluorescent X-ray analysis value level by a linear regression equation. Based on this, it was clarified that the variation of the fluorescent X-ray analysis value due to the surface roughness of the measurement surface can be reduced by correcting the fluorescent X-ray analysis value due to the surface roughness of the measurement surface, and the present invention was reached.

That is, according to the present invention, the surface of a sample such as a metal is irradiated with primary X-rays, the characteristic X-rays generated from the elements in the sample are dispersed by a dispersive crystal, and the intensity of the characteristic X-rays is measured. In the fluorescent X-ray analysis method for measuring the amount, the roughness regression coefficient calculation formula of each measurement element is obtained in advance from the relationship between the sample surface roughness and the change amount of each measurement element, and the surface roughness of the sample surface is measured in advance. Then, the fluorescent X-ray analysis value is corrected by the measured surface roughness and the correction value calculated from the roughness regression coefficient calculation formula of each measurement element.

Further, the surface of a sample such as a metal is irradiated with primary X-rays, the characteristic X-rays generated from the elements in the sample are dispersed by a dispersive crystal, the intensity of the characteristic X-rays is measured, and the content of the element is measured. In the fluorescent X-ray analysis method described above, the surface roughness Ra of the sample surface of the metal or the like is measured in advance, and the roughness regression coefficient A of the following formula (1) of each measurement element obtained by an experiment and the measured surface roughness The fluorescent X-ray analysis method is characterized in that the fluorescent X-ray analysis value is corrected by Ra according to the following formula (2). A = a × [X] i + b ………………………… (1) Equation [X] f = A × Ra + [X] i …………………… (2) Equation However, A: roughness regression coefficient, a, b: constants for each element obtained by experiment, [X] i: fluorescent X-ray analysis value (%),
[X] f: corrected fluorescent X-ray analysis value (%), Ra: sample surface roughness (μm)

In the present invention, the roughness regression coefficient arithmetic expression of each measurement element is obtained in advance from the relationship between the sample surface roughness and the change amount of each measurement element, and the surface roughness of the sample surface is measured in advance and measured. By correcting the fluorescent X-ray analysis value with the corrected surface roughness and the correction value calculated from the roughness regression coefficient calculation formula of each measurement element, the variation of the fluorescent X-ray analysis value due to the surface roughness of the measurement surface is corrected. It is possible to reduce the amount, and it is possible to quantify with high accuracy even high content components such as Cr and Ni in stainless steel, which can contribute to the reduction of the expensive alloy iron usage in the steel making process.

Further, according to the present invention, the surface roughness Ra of the surface of the sample such as the metal is measured in advance, and the surface is measured with the roughness regression coefficient A of the formula (1) of each measurement element previously obtained by the experiment. By correcting the fluorescent X-ray analysis value by the expression (2) with the roughness Ra, the variation in the fluorescent X-ray analysis value due to the surface roughness of the measurement surface can be reduced, and the Cr and Ni content in the stainless steel can be reduced. As described above, the high content component can be quantified with high accuracy, and it can contribute to the reduction of the amount of expensive alloy iron used in the steelmaking process.

JIS is used as an evaluation index of sample surface roughness.
B 0601-1982 In the definition and display of the surface roughness, the center line average roughness Ra, the maximum height Rmax, and the amplitude of fine irregularities are evaluated as the evaluation items of the sectional curve and the roughness curve.
Although three types of ten-point average roughness Rz are adopted, the centerline average roughness Ra has the strongest correlation with the fluorescent X-ray analysis value from the experiment and accurately represents the surface state. R
It is appropriate to adopt a.

There are many methods for measuring surface roughness, such as a stylus method, use of reflected light distribution by laser light, specular reflectance method, contrast gloss method, speckle pattern method, and scene phenomenon. It is suitable to adopt the needle method or the use of the reflected light distribution by laser light. In the experiment of the present invention, the stylus method was adopted, but the repetitive measurement accuracy was ± 0.05 μm when the center line average roughness Ra was 1.9 μm, and the influence on the fluorescent X-ray analysis value is shown in Table 1. As shown in, about Cr:
It is estimated to be about 0.006% at 18%. Therefore, the variation of the fluorescent X-ray analysis value can be reduced by correcting the center line average roughness Ra.

[0017]

[Table 1]

[0018]

【Example】

Example 1 In order to investigate the relationship between the centerline average roughness Ra and the fluorescent X-ray analysis value, as shown in Table 2, three types of standard samples (12 samples of the same composition) were prepared, and as shown in Table 3. The polishing conditions were changed to 4 steps, and 3 polishing samples were prepared under each polishing condition. The prepared sample No. The center line average roughness Ra of 36 pieces of 1 to 3 was measured by the stylus method, and Table 4
X-ray fluorescence analysis of Cr, Ni, Mn is performed under the conditions shown in
The relationship between the centerline average roughness Ra and the fluorescent X-ray analysis value was investigated. The results are shown in FIGS.

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

As shown in FIGS. 1 to 12, as the value of the centerline average roughness Ra becomes larger (the sample surface becomes rougher),
The X-ray fluorescence analysis shows a low value and has a strong correlation. Further, from the plots of the new and old abrasive paper # 100, the centerline average roughness Ra becomes low and the fluorescent X-ray analysis value becomes high after many uses. Further, the regression coefficients (A) between the surface roughness and the fluorescent X-ray analysis values are smaller as the contents of Cr, Ni, and Mn are lower. The relationship is illustrated in FIGS. 4, 8 and 12, and the regression coefficient (A) can be calculated by the fluorescent X-ray analysis value. From the above results, the following correction formula was derived. A = a × [X] i + b ………………………… (1) Equation [X] f = A × Ra + [X] i …………………… (2) Equation However, A: roughness regression coefficient, a, b: constants for each element obtained by experiment, [X] i: fluorescent X-ray analysis value (%),
[X] f: corrected fluorescent X-ray analysis value (%), Ra: sample surface roughness (μm)

Example 2 In order to confirm the effect of the above correction formula, an online actual sample 1
Center line average roughness Ra by 0 stylus method, fluorescent X-ray analysis and chemical analysis of Cr, Ni, and Mn under the conditions shown in Table 4 above were carried out to find the difference between the fluorescent X-ray analysis value and the chemical analysis value. Table 5 shows the variation estimated by R / d ₂ .

[0024]

[Table 5]

As shown in Table 5, when the center line average roughness Ra is corrected for Cr and Ni, the analysis accuracy of the fluorescent X-ray analysis is about 4 as compared with the case where the center line average roughness Ra is not corrected.
It has improved by 0%. For Mn, centerline average roughness R
The effect of a correction was not recognized, but the reason is that the roughness regression coefficient (A) is small. Therefore, in the application of the centerline average roughness Ra correction formula in the present invention, the content should be within the range determined by experiments, and is limited to elements in the high content region such as Cr and Ni.

[0026]

As described above, according to the method of the present invention, fluorescent X-ray analysis is performed for elements in a high content region such as Cr and Ni in austenitic stainless steel and Cr in ferritic stainless steel. About 40% analysis accuracy
Can be improved.

[Brief description of drawings]

1 is a sample No. 1 in Example 1. FIG. It is a graph which shows the relationship between the center line average roughness Ra of 1 and the fluorescent X-ray-analysis value of Cr.

2 is a sample No. 1 in Example 1. FIG. It is a graph which shows the relationship between the center line average roughness Ra of 2 and the fluorescent X-ray-analysis value of Cr.

3 is a sample No. 1 in Example 1. FIG. 3 is a graph showing the relationship between the centerline average roughness Ra of No. 3 and the fluorescent X-ray analysis value of Cr.

FIG. 4 is a graph showing a relationship between a fluorescent X-ray analysis value of Cr and a centerline average roughness Ra regression coefficient in Example 1.

5 is a sample No. 1 in Example 1. FIG. 2 is a graph showing the relationship between the centerline average roughness Ra of No. 1 and the fluorescent X-ray analysis value of Ni.

6 is a sample No. 1 in Example 1. FIG. It is a graph which shows the relationship between the center line average roughness Ra of 2 and the fluorescent X-ray analysis value of Ni.

7 is a sample No. 1 in Example 1. FIG. 3 is a graph showing the relationship between the centerline average roughness Ra of No. 3 and the fluorescent X-ray analysis value of Ni.

FIG. 8 is a graph showing a relationship between a fluorescent X-ray analysis value of Ni and a centerline average roughness Ra regression coefficient in Example 1.

9 is a sample No. 1 in Example 1. FIG. It is a graph which shows the relationship between the center line average roughness Ra of 1 and the fluorescent X-ray analysis value of Mn.

10 is a sample No. 1 in Example 1. FIG. It is a graph which shows the relationship between the center line average roughness Ra of 2 and the fluorescent X-ray analysis value of Mn.

11 is a sample No. 1 in Example 1. FIG. 3 is a graph showing the relationship between the center line average roughness Ra of No. 3 and the fluorescent X-ray analysis value of Mn.

FIG. 12 is a graph showing a relationship between a fluorescent X-ray analysis value of Mn and a centerline average roughness Ra regression coefficient in Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takushi Taniguchi 1850 Minato Minato, Wakayama, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Works

Claims (2)

[Claims] 1. A surface of a sample such as a metal is irradiated with a primary X-ray,
In the fluorescent X-ray analysis method in which the characteristic X-rays generated from the elements in the sample are dispersed by a dispersive crystal to measure the intensity of the characteristic X-rays, and the content of the element is measured, the sample surface roughness and the change of each measured element are measured in advance. The roughness regression coefficient calculation formula of each measurement element is calculated from the relationship with the amount, the surface roughness of the sample surface is measured in advance, and it is calculated from the measured surface roughness and the roughness regression coefficient calculation formula of each measurement element. A fluorescent X-ray analysis method, wherein the fluorescent X-ray analysis value is corrected by the correction value. 2. Irradiating the surface of a sample such as a metal with a primary X-ray,
In the fluorescent X-ray analysis method for measuring the content of an element by measuring the intensity of the characteristic X-ray by dispersing the characteristic X-ray generated from the element in the sample with a dispersive crystal, the surface roughness of the sample surface of the metal or the like. Ra is measured in advance and the fluorescent X-ray analysis value is corrected by the following equation (2) according to the roughness regression coefficient A of the following equation (1) and the measured surface roughness Ra of each measurement element previously obtained by experiments. A fluorescent X-ray analysis method comprising: A = a × [X] i + b ………………………… (1) Equation [X] f = A × Ra + [X] i …………………… (2) Equation However, A: roughness regression coefficient, a, b: constants for each element obtained by experiment, [X] i: fluorescent X-ray analysis value (%),
[X] f: corrected fluorescent X-ray analysis value (%), Ra: sample surface roughness (μm)