JPH04238250A - Quick evaluation method for intra-metal inclusion by emission spectral analysis method - Google Patents

Abstract

PURPOSE:To simply obtain the number, diameter and content of intra-metal inclusions by the emission spectral analysis method. CONSTITUTION:Luminous pulses corresponding to the intensity range determined in 0 through several hundreds pulses at the initial stage of a discharge among the luminous pulses obtained by a discharge are measured by the emission spectral analysis method, and the number, diameter, content and average diameter of intra-metal inclusions are obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rapidly evaluating the morphology of inclusions in metals using optical emission spectroscopy.

0002

2. Description of the Related Art FIG. 5 is a diagram showing an optical emission spectroscopic analysis method according to the prior art. The horizontal axis represents the emission pulse intensity, and the vertical axis represents the frequency of appearance. The distribution state of the emitted light pulses that appear can be roughly divided into two types: one is solid solution or very fine and uniform distribution in the base metal, and the other is independent in the base metal. It is in a state where it is distributed in clusters. When it is dissolved in solid solution or finely and uniformly distributed in the base material, it is uniformly distributed in the base material in both quantity and size. Therefore, when a discharge is generated at the location, a similar component composition is obtained at any discharge spot location, and therefore a normal distribution-type intensity distribution is shown centered on the emission intensity corresponding to the average content of the target component. In addition, in this state where it is in solid solution with the base metal, it assumes the state of an acid-soluble substance that can be chemically dissolved by acid together with the base metal steel.

On the other hand, electrical discharge occurs near inclusions, which are generally called inclusions and exist in the form of independent oxides without solid solution in the base metal, such as aluminum oxide in steel. In this case, since the content of the target component in the discharge spot becomes very high, inclusions appear on the high-intensity pulse side compared to the solid solution components mentioned above, and their distribution form is also present. Because the number and diameter of each individual item is different, it generally does not have a normal distribution, but instead has an uneven distribution over a wide intensity range from the high intensity side of the normal distribution to the even higher intensity side, as shown by the shaded area in the figure. become. Note that these inclusions are generally in the form of oxides, etc., and therefore are acid-insoluble substances that cannot be completely dissolved by chemical acid dissolution treatment and remain as a residue.

As a means for separately quantifying the above-mentioned acid-soluble substances, that is, substances that are uniformly dissolved in the base material, and acid-insoluble substances, that is, inclusions that are independently present in the base material, by luminescence analysis, The number of luminescence pulses attributed to the acid-soluble substance is N, the number of luminescence pulses attributed to the acid-insoluble substance is N', and the median value Im is determined. Then, the abundance of each is calculated using the following formula.

Acid-soluble substance strength=Im×(N/(N+N′)
) ) ...(5) Acid-insoluble substance strength = Im x (N'/ (N+N') ) ...
...(6) These intensities and pulse numbers are μ-CP in Figure 1.
A/D conversion is performed in U12, and data processing system 13
It is provided as an analytical value converted into concentration using a conversion formula for intensity and concentration created from a known standard sample. In the conventional technology, the number of pulses to be measured ranges from 0 to several thousand pulses for sampling, but the initial discharge of about 0 to about several hundred pulses is simply sampled for the purpose of surface uniformity. It was removed from the sampling range.

[0006]

[Problems to be Solved by the Invention] According to the prior art, it is possible to separately quantify acid-soluble substances and acid-insoluble substances. However, the amount and size of inclusions, which are important for process control analysis in the molten steel manufacturing process and product manufacturing process,
To obtain information on the form of existence such as the number of particles, it is necessary to cut the sample, mirror polish it, and then directly observe it using a microscope, and it has not been possible to obtain information directly from emission spectrometry.

[0007]

[Means for Solving the Problems] The present invention solves the problems of the prior art, and uses an optical emission spectrometry method to analyze the luminescence pulses obtained by discharging from 0 to several hundred pulses at the initial stage of discharge. is measured in time series, and the number, diameter, content, and average diameter of inclusions in the metal are determined based on the following formula, using the luminescence pulses that fall within the intensity range determined in the obtained luminescence pulses as measurement targets. This is a method for rapid morphology evaluation of inclusions in metals using emission spectrometry.

[0008] Number of existing items (N) = K1 × Σ (F)
・・・・・・(1)
Diameter (r) = K2 x I
・・・・・・(2)
Content (V)=K3×Σ(F×I)
・・・・・・(3) Average diameter (R)=K4×Σ(F×I)/Σ(F) ・・・
...(4) where F: frequency of appearance of luminescence pulses at intensity I. K1 to K4: Correction coefficients to ensure consistency with actual measured values obtained from microscopic measurements. I: From Il (Lower) to Iu (
The target is an initial discharge of about n=0 to several hundred pulses with the discharge start being zero in the intensity range of Upper) and the number of discharge sampling times. At this time, if the intensity I is divided into stages and measured, the abundance ratio of each diameter range corresponding to each intensity range can also be determined. The present invention will be explained below based on the drawings.

FIG. 1 is a schematic diagram of an optical emission spectrometer. The sample 1 is attached to a light emitting stand 5, and a discharge is caused between the sample 1 and the electrode 3 under the optimal conditions of the discharge circuit 4 in an argon atmosphere. (The part that participates in this light emission is referred to as the light emitting section 6). The light generated by this discharge is guided to a diffraction grating 9 through a condensing lens 7, and is separated into components. The light intensity of this spectroscopic spectrum 8 is measured by each photomultiplier tube 10. (The part that takes part in this light collection and photometry is called the spectroscopic part 11). Next, the measured light intensity is μ-CPU
A/D conversion is performed in 12, and data processing system 13
It is converted to component content (%). (The part that takes part in this A/D conversion and component content (%) conversion is referred to as a data processing device 14).

FIG. 2 is a diagram showing the emission spectroscopic evaluation method according to the present invention. The horizontal axis represents the emission pulse intensity, and the vertical axis represents the frequency of appearance. The distribution state of the emitted light pulses that appear can be roughly divided into two types: one is solid solution or very fine and uniform distribution in the base metal, and the other is independent in the base metal. It is in a state where it is distributed in clusters. When solid solution or finely and uniformly distributed in the base material, the amount,
Since both size and size are uniformly distributed in the base material, if a discharge is made to the relevant location, a normal distribution type intensity distribution centered on the emission intensity corresponding to the average content of the target component will occur at any discharge spot location. shows.

On the other hand, electric discharge occurs near inclusions such as substances such as aluminum oxide in steel, which are generally called inclusions and exist in the form of independent oxides without solid solution in the base metal. In this case, since the content of the target component in the discharge spot becomes very high, inclusions appear on the high-intensity pulse side compared to the solid solution components mentioned above, and their distribution form is also present. Because the number and diameter of each individual item is different, it generally does not have a normal distribution, but instead has an uneven distribution over a wide intensity range from the high intensity side of the normal distribution to the even higher intensity side, as shown by the shaded area in the figure. become. When the emission distribution from these inclusions is investigated in more detail, the following findings are obtained.

[0012] In the early stage of discharge, the state of existence of individual inclusions is such that the melting phenomenon due to discharge and the discharge phenomenon due to thermoelectrons have not completely progressed, so the light emission pulse information at this sampling timing is This is information that directly reflects the form of existence. (2) The larger the diameter of each inclusion, the larger the content of the target component in the discharge spot, and therefore the luminescence intensity increases in proportion to the diameter during discharge. ■Generally when taking the form of oxides, etc.
Due to its high insulating properties, during discharge, a large amount of charge energy can be retained around the boundary between the inclusion and the base metal, so the luminous intensity emitted during discharge increases in proportion to the size of the inclusion. Pulses are generated, and the timing at which they occur is that particularly many high-intensity light emission pulses appear in the early stages of discharge when there is little melting of inclusions. (2) Also, from the above findings, the value obtained by integrating the individual pulse intensities and the number of occurrences increases in proportion to the total content of inclusions.

FIG. 3 shows the time-series range of emission pulses sampled by this method. The horizontal axis shows the cumulative number of pulses to show the time course, and the vertical axis shows the number of generated pulses classified by intensity (large, medium, small). The sample is
In order to differentiate the light emission from the light emitted from the surface undulations, the samples were mirror-polished and then separated into samples with a high inclusion content and samples with a low inclusion content using a microscope before conducting experiments.

As a result, it has been found that high-intensity pulses from inclusions appear specifically in the range of 0 to several hundred pulses at the initial stage of discharge. This phenomenon is caused by the fact that the sampling range of the initial discharge, which was simply removed in the conventional technology for the purpose of homogenizing the structure and stabilizing the discharge, is directly affected by inclusions because the melting and uniformity of the surface structure has not progressed. It shows that it reflects the state of existence. Based on the above knowledge, we devised the formula shown below to determine the average diameter, number, content, etc. of inclusions.

[0015] Number of existing pieces (N) = K1 × Σ (F)
・・・・・・(1)
Diameter (r) = K2 x I
・・・・・・(2)
Content (V)=K3×Σ(F×I)
・・・・・・(3) Average diameter (R)=K4×Σ(F×I)/Σ(F) ・・・
...(4) where F: frequency of appearance of luminescence pulses at intensity I. K1 to K4: Correction coefficients to ensure consistency with actual measured values obtained from microscopic measurements. I: From Il (Lower) to Iu (
The target is an initial discharge of about n=0 to several hundred pulses with the discharge start being zero in the intensity range of Upper) and the number of discharge sampling times. At this time, if the intensity I is divided into stages and measured, the abundance ratio for each diameter range corresponding to each intensity range can be determined.

FIG. 4 shows an example using this evaluation method. The vertical axis represents the emission intensity, and the horizontal axis represents the number of emission pulses. The sampling target range is the number of light emission pulses from 0 to 512 and the light emission intensity of about 1000 or more. As shown in this figure, a high-intensity luminescence pulse is observed specifically in the initial pulse of about 0 to 200, and this range directly reflects information from inclusions existing on the sample surface. This is the part where you are. Note that in the prior art, this range was removed from the sampling target range as abnormal light emission due to surface non-uniformity in the early stage of discharge.

FIG. 6 shows an example in which the average diameter of inclusions was determined using this evaluation method. If the vertical axis is the average diameter of inclusions obtained by direct observation with a microscope, and the horizontal axis is the value obtained from equation (6) of this evaluation method, the correlation coefficient is r = 0.9 as shown in the figure.
We were able to obtain a high correlation with 3.

Table 1 shows the results of similarly determining correlations for other areas, volumes, numbers, and average diameters. The horizontal axis shows the area ratio, volume ratio, number of particles, and average diameter, and the vertical axis shows only the new PDA value obtained by this evaluation method and the number of high-intensity pulses. As a result, it can be seen that the correlation coefficient shows a higher value when weighted by multiplying the number of pulses by the intensity, rather than simply calculating the correlation based on the number of high-intensity pulses. In addition, although this evaluation method took up aluminum oxide present in steel as an example in the example, this method can also be applied to inclusions in other metals.

[0019]

[Table 1]

[0020]

[Effect of the invention] In the prior art, in order to obtain information on the existence form such as the amount, size, number, etc. of inclusions, which is important for performing process control analysis in the manufacturing process of molten steel or product manufacturing process, etc., it is necessary to cut the sample. However, by using the present invention, it has become possible to directly observe this using a microscope more quickly than by direct emission spectrometry.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical emission spectrometer.

FIG. 2 is a diagram showing the emission spectroscopic evaluation method according to the present invention.

FIG. 3 shows a time-series range of sampled light emission pulses.

FIG. 4 is an example using the evaluation method of the present invention, showing the relationship between the luminescence intensity and the number of luminescence pulses.

FIG. 5 shows a conventional emission spectrometry method.

FIG. 6 is an example of determining the average diameter of inclusions using the table method of the present invention.

[Explanation of symbols]

1 Sample 3 Electrode 4 Discharge circuit 5. Luminous stand 6 Light emitting part 7 Condensing lens 8 Spectrum 9 Diffraction grating 10 Photomultiplier tube 11 Spectroscopic section 12 μ-CPU 13 Data processing system 14 Data processing device

Claims (1)

[Claims] Claim 1: Using optical emission spectrometry, among the luminescent pulses obtained by the discharge, about 0 to several hundred pulses at the initial stage of the discharge are measured in chronological order, and the intensity range determined in the obtained luminescent pulses is measured. A rapid evaluation method for inclusions in metal using optical emission spectrometry, which is characterized by determining the number, diameter, content, and average diameter of inclusions in metal based on the following formula using the corresponding luminescence pulse as the measurement target. . Number of existing pieces (N) = K1 x Σ (F)
・・・・・・(1)
Diameter (r) = K2 x I
・・・・・・(2)
Content (V)=K3×Σ(F×I)
・・・・・・(3) Average diameter (R)=K4×Σ(F×I)/Σ(F) ・・・
...(4) where F: frequency of appearance of luminescence pulses at intensity I. K1 to K4: Correction coefficients to ensure consistency with actual measured values obtained from microscopic measurements. I: From Il (Lower) to Iu (
The target is an initial discharge of about n=0 to several hundred pulses with the discharge start being zero in the intensity range of Upper) and the number of discharge sampling times.