JPH10318948A - Method and apparatus for analyzing nonmetallic inclusions in metal - Google Patents

Abstract

(57) Abstract: The present invention provides a method and an apparatus for accurately and quickly performing quantitative evaluation of the composition and amount of inclusions in a metal. SOLUTION: Non-metallic inclusions contained in the molten metal are moved to the surface of the molten metal by cold crucible floating melting, and then the molten metal is solidified. The method for analyzing non-metallic inclusions in metal, wherein the amount of elements constituting the non-metallic inclusions is measured by X-ray fluorescence analysis using a wavelength dispersive spectrometer. A solidified metal holder 13 is rotatably provided below the elevating mechanism 16, and the upper part of the elevating mechanism 16 is engaged with the solidified metal transport mechanism 17, and is movable between the melting device 2 and the X-ray fluorescence analyzer 18. It is an apparatus for analyzing non-metallic inclusions in metals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for analyzing nonmetallic inclusions in metals.

[0002]

2. Description of the Related Art Turkdogan Symposium Pro is a method for evaluating nonmetallic inclusions in metals.
Ceedings, p105-112 (1994), discloses a method of dissolving a metal piece by a cold crucible levitation melting method and observing inclusions discharged on the surface with an electron microscope. Further, Japanese Patent Application Laid-Open No. 7-239327 discloses a method for evaluating the cleanliness of a metal based on the area of the inclusion aggregate discharged onto the surface of a metal piece melted and solidified by the cold crucible floating melting method. .

[0003]

[Problems to be Solved by the Invention] Turkdogan
Symposium Proceedings, p10
5-112 (1994) merely points out a problem as an evaluation method based on the characteristics of the cold crucible itself, and is an industrially inexpensive and quick method for evaluating non-metallic inclusions over a wide range of metal surfaces. Not a thing. Further, in the method of evaluating by the area of inclusions described in JP-A-7-239327, the total amount can be evaluated to some extent, but slag-based or powder-based inclusions having a low melting point cause deformation or coalescence. Therefore, high melting point inclusions such as alumina can be analyzed.However, even in alumina, the manner of aggregation of nonmetallic inclusions transferred to the surface differs depending on the dissolution conditions. However, there are problems such as a difference in measured values. The method of the present invention has been made to advantageously solve such problems, and provides an apparatus and method capable of accurately and quickly analyzing the total amount of nonmetallic inclusions and the amount of constituent main components. It is intended to do so.

[0004]

A feature of the present invention is that nonmetallic inclusions contained in a molten metal are moved to the surface of the molten metal, and then the solidified molten metal is irradiated with X-rays. A method for analyzing non-metallic inclusions in a metal, which comprises irradiating and generating characteristic X-rays by X-ray fluorescence analysis using a wavelength dispersive spectrometer to measure the amount of elements constituting the non-metallic inclusions. . And a solidified metal holder rotatably provided at the lower part of the elevating mechanism, wherein the upper part of the elevating mechanism is engaged with the solidified metal transport mechanism, and is movable between the melting device and the X-ray fluorescence analyzer. This is a device for analyzing non-metallic inclusions in metals.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors analyzed the sample surface after cold crucible levitation melting by X-ray fluorescence analysis, which is a technique for analyzing the average composition and components of steel or the like. Alternatively, it has been developed to analyze (evaluate) the amount of nonmetallic inclusions in aluminum or the like. That is, usually, in the fluorescent X-ray analysis, since the average composition near the metal surface through which X-rays are transmitted is analyzed, it is difficult to quantitatively evaluate low-concentration inclusions scattered in the metal,
By collecting inclusions in the metal on the surface without contamination from the crucible by floating dissolution, quantitative analysis (evaluation) of the amount of inclusions in the metal by X-ray fluorescence analysis becomes possible.

[0006] Inclusions collected on the metal surface by floating dissolution are difficult to collect at one point on the surface, and exist over a wide range of the top and side surfaces of the metal. In analyzing the amount of inclusions scattered over such a wide range, in the conventional method of measuring the area where inclusions exist, it is necessary to measure while changing the position of the area of the scattered inclusions. It takes a long time to measure. In addition, in such a method, the amount of each type of inclusion cannot be evaluated because the existing element is not known. On the other hand, as a method of analyzing elements, in the method of measuring the amount of inclusions with an energy dispersive measurement device of a scanning electron microscope, which has been conventionally used for the composition analysis of inclusions, the composition of each inclusion is analyzed. Analysis of all inclusions requires a huge amount of time.

In X-ray fluorescence analysis, primary X-rays are converted to metal (sample).
And the shape and shape of non-metallic inclusions by measuring the intensity of characteristic X-rays generated by elements in the sample within the irradiation range (area, depth) with a detector Instead, the intensity of characteristic X-rays corresponds to the amount of inclusions,
It is possible to accurately analyze (evaluate) slag-based or powder-based inclusions that are likely to be deformed or coalesced. In particular, in the case of alumina, no measurement error occurs due to the difference in inclusion agglomeration caused by dissolution conditions, and the accuracy is significantly improved as compared with the conventional inclusion area measurement method. In the fluorescent X-ray analysis, if the area of the irradiated X-rays is increased, a wide range of analysis can be performed at a time, so that the inclusions scattered in the cold crucible dissolved sample can be quickly analyzed.

Furthermore, since the elements and amounts in a sample can be simultaneously analyzed by X-ray fluorescence analysis, the surface of a dissolved metal (sample) is analyzed by X-ray fluorescence analysis without analyzing individual inclusions. Thus, the components and amounts of the inclusions can be rapidly analyzed simultaneously. As the metal part to be analyzed by the fluorescent X-ray, only the part where the inclusions move and assemble on the surface of the sample may be used. However, if the metal part assembles in a band shape on the side surface of the metal sample after dissolution, the sample is rotated. By that
Primary X-rays can be irradiated along the belt-like portion where the inclusions exist, and the aggregated inclusions can be measured efficiently.

As an X-ray detector of a fluorescent X-ray analyzer,
There are an energy dispersive type using a Si semiconductor or the like and a wavelength dispersive type using a dispersive crystal. In the wavelength dispersive type, a dispersive crystal can be selected so as to increase the sensitivity of the element to be analyzed. By using a spectral crystal such as RAP (Rubidium hydrogen phthalate) with good analytical sensitivity, O, F,
The amount of light elements contained in inclusions such as Na, Mg, Al, Si, and Ca can be accurately measured by the wavelength dispersion type, and the amount of minute amounts of slag or powder inclusions can be accurately evaluated.

[0010] By cold crucible levitation melting,
In order to quickly transport the non-metallic inclusions moving and assembled to the metal (sample) surface to the X-ray fluorescence spectrometer, in the present invention, as a device for taking out a sample after levitation melting / cooling and solidification from a crucible, for example, a magnet or A sample is sucked and taken out by an elevating mechanism (cylinder or the like) provided with a sample holder such as a suction cup, and is conveyed to a fluorescent X-ray analyzer provided near the crucible. At this time, it can be constituted by a position setting mechanism for positioning the collection site of the non-metallic inclusions at the X-ray irradiation position for analysis, a handling device having a mechanism for tilting the sample, and the like. In addition, it is preferable that a sample rotating mechanism is provided in such a handling device so as to analyze inclusions while rotating the sample. Further, the sample may be transferred to a sample holding pad portion of a sample rotating device installed in the X-ray fluorescence analyzer by a handling device, and the sample may be fixed and rotated by the pad for analysis. With such a configuration, analysis can be performed efficiently, and the amount of inclusions can be quickly analyzed.

[0011]

Next, an embodiment of the present invention will be described. As shown in FIG. 1, in a container 2 capable of controlling an inert gas or a reduced pressure atmosphere 1 as a non-oxidizing atmosphere, FIG.
A metal crucible (cold crucible) 5 having a water cooling mechanism 4 which is constituted by metal segments 3 divided in the circumferential direction as shown in FIG. The crucible 5 is surrounded by a coil 8 through which a high-frequency current 7 provided by a high-frequency transmitter 6 flows. When a target metal sample 9 whose weight is measured in advance is placed in the crucible 5 and an electric current 7 is applied to the induction coil 8, the metal 9 is melted by the generated electromagnetic force 10 and floats in the crucible 5. Non-metallic inclusions have a lower specific gravity than molten metal 9,
In addition, a reaction to the force by which the induced electromagnetic force 10 pushes the molten metal 9 inward acts on the non-metallic inclusion, and
Move to 1. After a certain time, the current 7 flowing through the induction coil 8
, The molten metal 9 solidifies, and the nonmetallic inclusions gather on the surface of the floating body to form an island-like aggregate 12.

After the metal sample 9 is cooled, the lid 24 of the container 2 is opened, and the upper part of the elevating mechanism (cylinder) 16 as shown in FIG. Rotating shaft 1 with motor 15
After the metal sample 9 in the crucible 5 is adsorbed by the sample holder 13 (magnet) provided at the tip of the rotating shaft 14, the lifting mechanism 16 is operated to raise the metal sample 9 and take it out of the container 2. Thereafter, the sample transport mechanism 17 is operated to move the elevating mechanism 16 to the X-ray fluorescence analyzer 18,
Next, the elevating mechanism 16 is operated to lower the metal sample 9 to the analysis position in the X-ray fluorescence analyzer 18. After the positioning, the rotating shaft 14 is rotated by the motor 15, and the primary X-rays 22 are irradiated from the X-ray tube 19 to the position of the aggregate 12 of the nonmetallic inclusions of the metal sample 9 while rotating the metal sample 9. , The characteristic X-rays 23 generated from the irradiated part,
Inclusions in the metal sample 9 are analyzed by a detector 21 using RAP (rubidium hydrogen phthalate) as the spectral crystal 20.

Next, examples of the method of the present invention will be described. Example 1 As a metal sample, a width of 1400 mm and a thickness of 2 was obtained using a continuous casting machine.
From a low carbon aluminum killed steel slab that was cast at a casting speed of 1.8 m / min using a 45 mm mold, the slab width direction was 1/4.
And a half part, a sample of 20 mm in the casting direction, 20 mm in the thickness direction, and 30 mm in the width direction is collected, and has an inner diameter of 40 mm, a depth of 40 mm, and an upper end of 20 to 40 m.
Up to m, the induction coil is melted by applying a power of 30 kW to the induction coil in an Ar atmosphere at atmospheric pressure using a cold crucible composed of metal segments divided into eight in the circumferential direction and having a hemispherical cross-sectional shape. Then, after the nonmetallic inclusions in the metal sample were moved to the surface, the power was immediately dropped to solidify.

The non-metallic inclusions collected in the form of islands on the solidified sample surface were analyzed with a wavelength dispersive X-ray fluorescence apparatus using RAP (rubidium hydrogen phthalate) as a spectral crystal. The measurement was performed with a primary X-ray intensity of 50 kV, 1 μA, an irradiation length of 15 mm, and an irradiation time of 60 seconds. From the characteristic X-ray intensity of Al, Si, Ca, Na, etc. obtained by performing the analysis five times with the X-ray irradiation position shifted to measure all the island-like inclusions on the sample surface, the alumina, The contents of calcia and sodium oxide were measured. Further, as a conventional analysis method, the area of the island-shaped nonmetallic inclusion portion of the sample measured by X-ray fluorescence was measured by an image analyzer, and the composition was measured by an energy dispersive analyzer of a scanning electron microscope.

FIGS. 4, 5 and 6 show a comparison between the results analyzed by Example 1 and the results analyzed by the conventional analysis method. The analysis result of Example 1 shows a good correlation with the analysis result by the scanning electron microscope, and the inclusion area measurement result by the image analyzer mainly measuring the amount of alumina shown in FIG. 7 and the scanning electron microscope The accuracy is improved as compared with the relationship with the alumina analysis result by the method. In addition, FIG.
FIG. 7 shows relative values when the maximum value of the amount of alumina, the amount of calcia, the amount of sodium oxide, and the amount of inclusions is set to 10. Further, the required time was 10 minutes, which was reduced to about 1/7 compared to 66 minutes of the inclusion composition analysis method using a scanning electron microscope.

Example 2 As a metal sample, a low carbon aluminum killed steel slab continuously cast at a casting speed of 1.8 m / min using a mold having a width of 1400 mm and a thickness of 245 mm was used.
/ 2 parts, 20mm in casting direction, 20m in thickness direction
m, take a 30mm sample in the width direction, inner diameter 40m
m, a depth of 40 mm, and a hemispherical cross-sectional shape from 20 mm to 40 mm from the upper end, using a cold crucible consisting of eight metal segments divided in the circumferential direction, applying 30 kW of power to the induction coil under an atmospheric pressure Ar atmosphere. The solution was applied and dissolved, held for 5 minutes after dissolution, and after the nonmetallic inclusions in the metal sample were moved to the surface, the power was dropped for 20 seconds to solidify.

After cooling the sample, the lid of the dissolving device is opened, the sample is taken out of the crucible by a handling device having an electromagnet attached to the tip and capable of moving up and down and right and left, and the wavelength dispersion set near the crucible is set. Of the non-metallic inclusions is irradiated with primary X-rays while being rotated by a rotation mechanism provided in the handling device, and the characteristic X-rays generated from the irradiated portions are RAP (Rubidium hydrogen phthalate) was measured by a spectroscope using a spectroscopic crystal.

Non-metallic inclusions gathered in the form of islands on the solidified sample surface are fixed by pads and magnets of a sample rotating device installed in a wavelength dispersive X-ray fluorescence analyzer so as to be rotatable around the central axis of the sample. Then, while rotating at a rotation speed of 6 rpm, the primary X-ray intensity is 50 kV, 1 μA, and the irradiation wavelength is 15 m.
m and irradiation time were set to 120 seconds. Al, S
The contents of alumina, calcia, and sodium oxide in the sample were measured from characteristic X-ray intensities such as i, Ca, and Na. As a conventional analysis method, an island-shaped nonmetallic inclusion portion of a sample measured by a fluorescent X-ray device was measured by an energy dispersive measuring device of a scanning electron microscope.

As shown in FIGS. 8, 9 and 10, the second embodiment
And the result of the scanning electron microscope showed a good correlation. In addition, the required time was 5 minutes, which was reduced to about 1/13 compared to 66 minutes of the inclusion composition analysis method using a scanning electron microscope. 8 to 10 show relative values when the maximum value of the amount of alumina, the amount of calcia, and the amount of sodium oxide is set to 10.

[0020]

According to the method of the present invention, the composition and amount of inclusions in a metal can be quantitatively evaluated with high accuracy and speedy, so that appropriate measures for reducing inclusions can be implemented efficiently and quality can be improved. Can be improved. In addition, quality evaluation and judgment can be performed by incorporation into a production line on-line, and excellent effects such as efficiency of a product manufacturing process can be obtained, and the industrial effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a cold crucible flotation melting apparatus.

FIG. 2 is a diagram showing an example of a crucible, (a) is a plan view,
(B) is an elevation sectional view.

FIG. 3 is a side view showing an embodiment of the device of the present invention.

FIG. 4 is a chart showing an analysis relationship of an amount of alumina in a metal by a fluorescent X-ray analysis method and a scanning microscope energy dispersive analysis method.

FIG. 5 is a chart showing an analysis relationship of the amount of calcia in a metal by a fluorescent X-ray analysis method and a scanning microscope energy dispersive analysis method.

FIG. 6 is a table showing an analysis relationship of the amount of sodium oxide in a metal by a fluorescent X-ray analysis method and a scanning microscope energy dispersive analysis method.

FIG. 7 is a table showing the relationship between the amount of alumina measured by a scanning microscope energy dispersive analysis method and the area measured by an image analysis method.

FIG. 8 is a table showing the analysis relationship of the amount of alumina in a metal by X-ray fluorescence analysis and energy dispersive analysis under a scanning microscope.

FIG. 9 is a table showing the analysis relationship of the amount of calcia in metal by X-ray fluorescence analysis and energy dispersive analysis under a scanning microscope.

FIG. 10 is a chart showing an analysis relationship of an amount of sodium oxide in a metal by a fluorescent X-ray analysis method and a scanning microscope energy dispersive analysis method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Atmosphere 2 Container (melting apparatus) 3 Metal segment divided in the circumferential direction 4 Water-cooling mechanism 5 Water-cooled metal crucible 6 High-frequency oscillator 7 High-frequency current 8 Induction coil 9 Metal sample 10 Electromagnetic force 11 Metal piece melt outer periphery 12 Inclusion Island-like assembly 13 Sample holder 14 Rotary axis 15 Motor 16 Lifting mechanism 17 Sample transport mechanism 18 X-ray fluorescence analyzer 19 X-ray tube 20 Spectral crystal 21 Detector 22 Primary X-ray 23 Characteristic X-ray 24 Container lid

Claims (3)

[Claims] Claims: 1. Dissolving in a non-oxidizing atmosphere by a cold crucible floating melting method to move nonmetallic inclusions contained in the molten metal to the surface of the molten metal, and then solidify the molten metal, Irradiating X-rays and measuring the amount of elements constituting the non-metallic inclusions by X-ray fluorescence analysis using a wavelength-dispersive spectrometer on the generated characteristic X-rays, wherein non-metallic inclusions in the metal are characterized. Object analysis method. 2. An element constituting nonmetallic inclusions by irradiating the surface of a solidified metal with X-rays while rotating the solidified metal and subjecting the generated characteristic X-rays to X-ray fluorescence analysis using a wavelength dispersive spectrometer. The method for analyzing nonmetallic inclusions in a metal according to claim 1, wherein the amount is measured. 3. A solidified metal holder is rotatably provided at a lower portion of a lifting mechanism, and an upper portion of the lifting mechanism is engaged with a solidified metal transport mechanism, and is movable between a melting device and a fluorescent X-ray analyzer. An apparatus for analyzing non-metallic inclusions in metals, characterized by the following: