JPH0754300B2 - Rapid Evaluation of Inclusions in Metals by Emission Spectroscopy - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rapid morphological evaluation method for inclusions in metals by optical emission spectroscopy.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a conventional optical emission spectroscopy. The horizontal axis represents emission pulse intensity, and the vertical axis represents frequency of appearance. The distribution of emitted light pulses is roughly divided into two types: one is a solid solution in the base metal or is very fine and evenly distributed, and the other is independent in the base metal. It is in the state of being distributed as a lump. In the state of being solid-dissolved in the base material or finely and uniformly distributed, both the amount and the size are uniformly distributed in the base material. Therefore, when a discharge is made to the location, the composition of the composition is similar at any discharge spot location, and therefore a normal distribution type intensity distribution centered on the emission intensity corresponding to the average content of the target component is exhibited. Further, in the state of being solid-dissolved with the base material in this way, it takes a state of an acid-soluble substance which can be chemically dissolved by an acid together with the steel of the base material.

On the other hand, a discharge, which is generally called an inclusion, does not form a solid solution in the base material and exists in the form of an independent oxide or the like, for example, an inclusion such as aluminum oxide in steel. In that case, since the content of the target component in the discharge spot becomes very high, the inclusions appearing on the high intensity pulse side as compared with the solid solution component described above, and the distribution form thereof also exists. Since the number and diameter are different from each other, it is not a normal distribution type in general, and as shown by the shaded area in the figure, it is distributed unevenly in a wide intensity range from the high intensity side to the high intensity side of the normal distribution. become. These inclusions are
Since it generally takes the form of an oxide or the like, it is an acid-insoluble substance that cannot be completely dissolved by a chemical acid dissolution treatment and remains as a residue.

As a means for separately and quantitatively determining the above-mentioned acid-soluble substance, that is, the substance which is uniformly solid-dissolved in the base material and the acid-insoluble substance, that is, inclusions which independently exist in the base material, by luminescence analysis, The number of emission pulses attributed to the acid-soluble substance is N, the number of emission pulses attributed to the acid-insoluble substance is N ', and the median Im is determined. Then, the abundance of each is calculated by the following formula.

Acid-soluble substance strength = Im × (N / (N + N ′)) (5) Acid-insoluble substance strength = Im × (N ′ / (N + N ′)) ・ ・ ・ ・ ・ ・ ( 6) These intensities and the number of pulses are A / D converted in the μ-CPU 12 in FIG. Be served. In the prior art, the number of pulses to be measured is 0 to several thousand pulses of discharge and sampling is performed, but the initial discharge of 0 to about several hundreds of pulses is simply performed for the purpose of surface homogenization. It was removed from the sampling range.

[0006]

In the prior art, it is possible to separately quantify an acid-soluble substance and an acid-insoluble substance.
However, the amount and size of inclusions that are important for performing process control analysis in the manufacturing process of molten steel, product manufacturing process, etc.
In order to obtain information on the existence form such as the number, it was necessary to cut the sample, mirror-polish it, and then directly observe it with a microscope, which could not be directly obtained by emission spectroscopy.

[0007]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the problems of the prior art, and of the emission pulses obtained by discharge using emission spectroscopy, about 0 to several hundreds of pulses at the initial stage of discharge. Is measured in time series, and the emission pulse corresponding to the intensity range defined in the obtained emission pulse is measured, and the number of inclusions in the metal, the diameter, the content, and the average diameter are determined based on the following formula. It is a rapid morphological evaluation method for inclusions in a metal by an emission spectroscopy.

Number of existing (N) = K1 × Σ (F) (1) Direct diameter (r) = K2 × I (2) Content (V) = K3 × Σ (F × I) ··· (3) Average diameter (R) = K4 × Σ (F × I) / Σ (F) ··· (4) where F: at intensity I Frequency of light emission pulses. K1 to K4: correction coefficients for achieving consistency with the actual measurement values obtained by microscope measurement. I: Initial discharge of about n = 0 to several hundreds of pulses with the discharge start as zero in the intensity range of Il (Lower) to Iu (Upper) and the number of discharge samplings. At this time, if the intensity I is divided and measured stepwise, the existence ratio for each diameter range corresponding to each intensity range can also be obtained. The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an emission spectroscopic analyzer. The sample 1 is attached to the light emitting stand 5 and is discharged between the electrode 3 and the electrode 3 under the optimum conditions of the discharge circuit 4 under an argon atmosphere. (The part that participates in this light emission is called the light emitting part 6). The light generated by this discharge is guided to the diffraction grating 9 through the condenser lens 7, and is separated into each component. The light intensity of the spectral spectrum 8 thus split is measured by each photomultiplier tube 10. (The part that participates in this light collection and photometry is called the spectroscopic part 11). Next, the measured light intensity is μ-CP
A / D conversion in U12, data processing system 1
In 3, the component content rate (%) is converted. (This A / D
The part involved in the conversion and the conversion of the component content (%) is referred to as the data processing device 14).

FIG. 2 is a diagram showing an emission spectral evaluation method according to the present invention. The horizontal axis represents emission pulse intensity, and the vertical axis represents frequency of appearance. The distribution of emitted light pulses is roughly divided into two types: one is a solid solution in the base metal or is very fine and evenly distributed, and the other is independent in the base metal. It is in the state of being distributed as a lump. When solid-dissolved or finely and uniformly distributed in the base material, the amount and size are evenly distributed in the base material. The normal distribution type intensity distribution centering on the emission intensity corresponding to the average content of the components is shown.

On the other hand, a discharge, which is generally called an inclusion, does not form a solid solution in the base material but exists in the form of an independent oxide, for example, an inclusion such as aluminum oxide in steel. In that case, since the content of the target component in the discharge spot becomes very high, the inclusions appearing on the high intensity pulse side as compared with the solid solution component described above, and the distribution form thereof also exists. Since the number and diameter are different from each other, it is not a normal distribution type in general, and as shown by the shaded area in the figure, it is distributed unevenly in a wide intensity range from the high intensity side to the high intensity side of the normal distribution. become. The light emission distribution from these inclusions will be investigated in more detail, and the following findings will be obtained.

At the initial stage of discharge, the existence state of each inclusion is such that the melting phenomenon due to discharge and the discharge phenomenon due to thermoelectrons do not progress completely, so that the light emission pulse information at this sampling timing shows the presence of inclusions. It is information that directly reflects the form. As the diameter of each inclusion increases, the content of the target component in the discharge spot increases, so that the emission intensity increases in proportion to the diameter during discharge. Generally when taking the form of oxides,
Due to its high insulation, a large amount of charge energy can be retained around the boundary between the inclusions and the base metal during discharge, so the emission intensity emitted during discharge is high in proportion to the size of the inclusions. As a pulse is generated, and as a timing of generation, a particularly large number of high-intensity light emission pulses appear at the beginning of discharge in which the phenomenon of melting of inclusions is small. Further, based on the above findings, the value obtained by integrating the individual pulse intensities and the number of generated pulses increases in proportion to the total content of inclusions.

FIG. 3 shows a time-series range of light emission pulses sampled by this method. The abscissa shows the time transition by taking the number of integrated pulses, and the ordinate shows the number of generated pulses by intensity (large, medium, small). The sample is
In order to distinguish it from the luminescence generated from the surface undulations, after performing mirror polishing, the experiment is conducted by dividing into a sample with a large amount of inclusions and a sample with a small amount of inclusions by a microscope.

As a result, it has been found that a high-intensity pulse from the inclusion appears specifically in about 0 to several hundreds of pulses at the initial stage of discharge. This phenomenon is because the sampling range of the initial discharge, which was simply removed in the prior art for the purpose of homogenizing the structure and stabilizing the discharge, does not directly advance the melting and homogenization of the surface structure, and thus the inclusions are directly included. It indicates that the existing state is reflected. Based on the above findings, the following formula was devised to determine the average diameter, number, content, etc. of inclusions.

Number of existing (N) = K1 × Σ (F) (1) Direct diameter (r) = K2 × I (2) Content (V) = K3 × Σ (F × I) ··· (3) Average diameter (R) = K4 × Σ (F × I) / Σ (F) ··· (4) where F: at intensity I Frequency of light emission pulses. K1 to K4: correction coefficients for achieving consistency with the actual measurement values obtained by microscope measurement. I: Initial discharge of about n = 0 to several hundreds of pulses with the discharge start as zero in the intensity range of Il (Lower) to Iu (Upper) and the number of discharge samplings. At this time, if the intensity I is divided and measured stepwise, it is possible to obtain the existence ratio for each diameter range corresponding to each intensity range.

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

FIG. 6 shows an example in which the average diameter of inclusions is obtained by this evaluation method. The vertical axis represents the average diameter of inclusions obtained by direct observation with a microscope, and the horizontal axis represents the value obtained from the equation (6) of this evaluation method. As shown in the figure, the correlation coefficient is r = 0.9.
A high correlation with 3 could be obtained.

Similarly, Table 1 shows the results of the correlation obtained for other areas, volumes, numbers, and average diameters. The horizontal axis shows the area ratio, the volume ratio, the number of existing particles, and the average diameter, and the vertical axis shows only the new PDA value obtained by this evaluation method and simply the number of high-intensity pulses. As a result, it can be seen that the correlation coefficient is higher when the number of pulses is multiplied by the weight and weighted than when the correlation is obtained only by the number of high-intensity pulses. Note that the present evaluation method takes aluminum oxide present in steel as an example in the examples, but the present method can also be applied to inclusions in other metals.

[0019]

[Table 1]

[0020]

According to the prior art, in order to obtain information on the existence form such as the amount, size, and number of inclusions, which is important for performing process control analysis in the manufacturing process of molten steel or product manufacturing process, the sample is cut. However, it was necessary to deal with direct observation with a microscope after mirror polishing, but by using the present invention, it was possible to directly obtain it more rapidly than by emission spectroscopy.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an emission spectroscopic analyzer.

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

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

FIG. 4 shows the relationship between the emission intensity and the number of emission pulses in an example according to the evaluation method of the present invention.

FIG. 5 shows a conventional optical emission spectroscopy.

FIG. 6 is an example in which the average diameter of inclusions is determined by the method of the present invention.

[Explanation of symbols]

 1 Sample 3 Electrode 4 Discharge Circuit 5 Light Stand 6 Light Emitting Section 7 Condensing Lens 8 Spectral Spectrum 9 Diffraction Grating 10 Photomultiplier Tube 11 Spectroscopic Section 12 μ-CPU 13 Data Processing System 14 Data Processing Device

Front page continued (72) Inventor Shigeaki Ogibayashi 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Co., Ltd. Kimitsu Works (56) References JP 62-277539 (JP, A) JP 61- 250545 (JP, A) JP-A-53-77582 (JP, A) JP-A-57-37252 (JP, A)

Claims (1)

[Claims] 1. An emission spectrum analysis method is used to time-sequentially measure about 0 to several hundreds of pulses at the initial stage of discharge among emission pulses obtained by discharge, and the intensity range is determined within the obtained emission pulse. Rapid evaluation method of inclusions in metal by emission spectroscopy, characterized in that the number of existing inclusions, diameter, content, and average diameter of inclusions in metal are determined based on the corresponding emission pulse based on the following formula: . Number of existing (N) = K1 × Σ (F) (1) Direct diameter (r) = K2 × I (2) Content (V) = K3 × Σ (F) × I) ··· (3) Average diameter (R) = K4 × Σ (F × I) / Σ (F) ··· (4) where F: of the emission pulse at the intensity I Frequency of appearance. K1 to K4: correction coefficients for achieving consistency with the actual measurement values obtained by microscope measurement. I: The initial discharge of about n = 0 to several hundreds of pulses is targeted with the discharge start as zero in the intensity range from Il (Lower) to Iu (Upper) and the number of discharge samplings.