JP2001281227A - Setting method for particle-size condition of magnetic particles used for wet fluorescent magnetic-particle flaw detection and fluorescent magnetic particles used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a setting method, for the particle-size condition of fluorescent magnetic particles, in which a particle size adapted to the surface state of an object to be inspected can be detected easily so that a contrast with a magnetic-particle pattern and with an inspection face other than a defect part is made clear when a wet fluorescent magnetic-particle flaw detection is performed and that a defect pattern is discriminated easily and to provide fluorescent magnetic particles which are used suitably when the particle-size condition is set. SOLUTION: An inspection solution wherein two or more kinds of fluorescent magnetic particles which are covered with fluorescent substances in different fluorescent amounts and whose particle sizes are different are mixed is sprayed on a test body which is of the same kind as the object to be inspected. Under a magnetization condition, the test body is irradiated with ultraviolet rays. A state that the two or more kinds of fluorescent magnetic particles are stuck to the test body is observed. On the basis of this observation result, an optimum condition regarding the particle size of the fluorescent magnetic particles used for the wet fluorescent magnetic-particle flaw detection is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting a defect existing on or near a surface of a test material which is a magnetic material such as a steel material or the like. The present invention relates to a setting method and a fluorescent magnetic powder used for the method.

[0002]

2. Description of the Related Art In general, a magnetic particle flaw detection test is used as an excellent test method as a method for detecting a defect existing on or near a surface of a test body made of a ferromagnetic material such as steel. As shown in the magnetic particle inspection test I of the Japan Non-Destructive Inspection Association, the principle is as follows.

When a magnetic flux flow is generated in a ferromagnetic specimen by a magnetizing operation, if a defect exists on the surface layer of the specimen, the flow of the magnetic flux is hindered, and the magnetic flux bypasses the flaw to flow. The part leaks into the air. When the fine iron powder is brought close to the part where the magnetic flux is leaking into the air, the iron powder is adsorbed by the magnetic poles at both ends of the defect part and also adsorbs each other, so that the defect having a width wider than the width of the defect is obtained. An instruction pattern is formed.

[0004] The iron powder used above is called magnetic powder, and the pattern formed by the adhesion of the magnetic powder is called magnetic powder pattern. In general, there are two methods for applying magnetic powder: a dry method and a wet method. The dry method has a lower ability to detect surface defects than the wet method, but is applied to flaw detection of extremely rough surfaces, internal defects, and high-temperature portions.

On the other hand, the magnetic particle flaw detection by the wet method, which is an object of the present invention, is a method in which magnetic particles are applied using a flow of a fluid, so that the magnetic particles can be dispersed even on a test piece having a complicated shape. It is widely used because it can sufficiently spread a test liquid, which is a turbid liquid, to every corner and has a higher defect detection capability than the dry method. As the above-mentioned magnetic powder, a substance having various colors and fluorescent properties is used to give a contrast by color and brightness to the surface of the fine powder of the ferromagnetic material.
A magnetic powder having a property of forming a defect indication pattern that can be clearly identified is required.

The main component of the magnetic powder is fine iron powder produced by a chemical treatment such as electrolysis and reduction, and a fluorescent substance or a pigment is adhered to the iron powder with an adhesive to protect the surface. The fluorescent magnetic powder (hereinafter, simply referred to as fluorescent magnetic powder) is obtained by bonding a fluorescent substance to fine iron powder, and generates fluorescent light by ultraviolet rays. That is, in the case of magnetic particle flaw detection using fluorescent magnetic powder, the test surface is irradiated with ultraviolet rays using an ultraviolet irradiation device to generate fluorescent light and observe the magnetic powder pattern.

The magnetic particle flaw detection using magnetic powder and fluorescent magnetic powder has been described above. The biggest point of the magnetic particle flaw detection test is that a color having a high contrast with the color of the test surface in order to make it easy to identify a defective magnetic powder pattern. The problem is to increase the contrast with the test surface other than the defective portion of the defect magnetic powder pattern by supplying the magnetic powder having the defect to the defective portion and preventing the magnetic powder from adhering to the test surface other than the defective portion as much as possible.

In particular, when fluorescent magnetic powder is used, if the amount of magnetic powder deposited on the test surface increases, the contrast between the magnetic powder pattern and the test surface other than the defective portion becomes unclear, and it becomes easy to identify the defective pattern. If it is difficult, it is necessary to clean the test surface, remove the adhered magnetic powder, and then perform the flaw detection again. On the other hand, in order to respond to the recent automation of equipment and establish a test method that can obtain the same result no matter who performs the test without being affected by the skill of the inspector, it is important to set conditions at the initial stage of the test. Becomes

As described above, in the wet-type fluorescent magnetic particle flaw detection method using fluorescent magnetic powder, the contrast between the magnetic powder pattern and the test surface other than the defect portion is made clear, the defect pattern can be easily identified, and the test piece is easily identified. It is important to find a magnetic powder suitable for the surface condition of the magnet.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a method for inspecting a wet-type fluorescent magnetic particle to make the contrast between a magnetic particle pattern and an inspection surface other than a defect portion clear and to facilitate identification of the defect pattern. It is an object of the present invention to provide a method for setting a particle size condition of a fluorescent magnetic powder capable of easily finding a particle size suitable for the surface condition of a body and a fluorescent magnetic powder suitably used when setting the particle size condition. And

[0011]

According to a first aspect of the present invention, a test solution mixed with a fluorescent magnetic powder is sprayed on an object to be inspected, and a magnetic powder pattern is observed by irradiating an ultraviolet ray under the magnetization condition of the object to be inspected. A method for setting a particle size condition of magnetic powder used for wet-type fluorescent magnetic particle flaw detection, wherein a test solution coated with a fluorescent substance having a different amount of fluorescence and mixed with two or more types of fluorescent magnetic powder having different particle sizes is used.
The test object is sprayed on the same type of test object as the test object, and the test object is irradiated with ultraviolet light under magnetizing conditions, and the adhesion state of the two or more fluorescent magnetic powders to the test object is observed. A method for setting the particle size condition of the magnetic powder used for the wet-type fluorescent magnetic particle flaw detection, wherein the optimum condition regarding the particle size of the fluorescent magnetic powder used for the wet-type fluorescent magnetic particle flaw detection is determined based on the above.

A second aspect of the present invention is a fluorescent magnetic powder used for setting a particle size condition of a magnetic powder used for wet fluorescent magnetic particle flaw detection, wherein a fluorescent material having a different amount of fluorescence is coated for each particle size range. It is a fluorescent magnetic powder. In the first invention, the two or more kinds of fluorescent magnetic powders are
These mixed powders may be added to and contained in the test solution, or may be separately added to and contained in the test solution.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The adsorption performance of a magnetic powder is determined as a comprehensive result of various factors such as the particle size of the magnetic powder, magnetic properties, colorant, surface condition of a test specimen, type and size of a defect. In particular, the particle size of the magnetic powder is delicately related to the dispersibility and uniform suspendability in the test solution, the ability to adsorb to defective portions, and the discernability of the magnetic powder pattern, and has a great influence on the magnetic particle flaw detection test.

In general, a magnetic powder having a large particle size has a high sedimentation speed in a magnetic powder dispersion, and it may be difficult to uniformly disperse the magnetic powder on a test piece. Of the magnetic powder pattern adheres to the test surface other than the defective portion due to the roughness of the test surface, and all of them deteriorate the discrimination of the magnetic powder pattern. Generally, magnetic powder having a small particle size is used for flaw detection of fine defects, and magnetic powder having a large particle size is used for flaw detection of relatively large defects.

As described above, in wet-type fluorescent magnetic particle flaw detection, it is important to use fluorescent magnetic powder having an appropriate particle size according to the surface condition of the target object to be inspected and the dispersion liquid. Hereinafter, embodiments of the present invention will be described. Prepare a test specimen of the same type (identity) as the test specimen,
The particle size of the fluorescent magnetic powder is adjusted using this test body. If the properties of the test object are different from those of the test object, the optimum particle size for the test object cannot be found, so the test sample must be of the same type (properties) as the test object. It is preferable that However, it is not necessary to perform the particle size adjustment for all the test objects, and for a plurality of test objects manufactured under the same specifications, one test object may be extracted and used as a test object. .

The optimum particle size for fluorescent magnetic particle flaw detection of this test piece is determined as follows, and the obtained particle size is determined as the optimum particle size for fluorescent magnetic particle flaw detection of the test object. The test solution mixed with the fluorescent magnetic powder is sprayed on the test sample, and the test sample is irradiated with ultraviolet light under magnetizing conditions to observe the state of adhesion of the fluorescent magnetic powder to the test sample. A test solution coated with two or more types of fluorescent magnetic powders coated with fluorescent substances having different fluorescent amounts and having different particle sizes is used.

Thus, by observing the state of attachment of the fluorescent magnetic powder to the test sample, it becomes clear at a glance how the magnetic powder of which particle size is attached, and the optimum particle size condition can be easily determined. It becomes possible. Here, it is preferable to use, as the fluorescent substance having a different amount of fluorescence, a substance having a different wavelength of ultraviolet light at which the highest luminance can be obtained when irradiating the ultraviolet light. If separately, the difference in the adhesion state according to the particle size of the magnetic powder can be easily found from the color distribution state on the surface of the test specimen.

The two or more kinds of fluorescent magnetic powders may be mixed into the test solution by mixing two or more kinds of fluorescent magnetic powders separately into the test solution, or a mixed powder of two or more kinds of fluorescent magnetic powders may be mixed. ,
That is, fluorescent magnetic powder coated with a fluorescent substance having a different amount of fluorescence for each particle size range may be mixed into the test solution.

[0019]

EXAMPLES The present invention will be described below more specifically based on examples. In the present embodiment, the end groove of the steel pipe (: bevel surface) (mirror finished surface) and non-processed surface (: non-bevel surface) (black scale material surface)
The optimum particle size condition was investigated.

Specifically, the procedure was performed as shown in FIGS. 1 and 2 are views showing a state where a test solution 4 is sprayed on a non-bevel surface 2 and a bevel surface 3 of a steel pipe 1 as a test body. FIG. FIG. 2 is an explanatory view of the steel pipe 1 as viewed from the side. In the present embodiment, first, a solution (inspection liquid) 4 containing fluorescent magnetic powder (hereinafter also referred to as fluorescent magnetic powder or magnetic powder) coated with a fluorescent paint from a spray nozzle 6 while rotating the steel pipe 1 by a turning roller 5. Was sprayed.

The test liquid was sprayed on both the non-bevel surface 2 and the bevel surface 3. The steel pipe is a magnetized yoke 7
Magnetized. Next, with respect to the non-bevel surface and the bevel surface, the inner and outer surfaces of the steel pipe were irradiated with ultraviolet rays at the observation position E in the figure, and the adhesion of the fluorescent paint was visually observed. Table 1 shows the test conditions.

In this embodiment, the fluorescent magnetic powder having a particle size of 3 to 5 μm: 50 parts by mass, and the fluorescent magnetic powder having a particle size of 8 to 10 μm:
50 parts by mass of the mixed magnetic powder was used. The former particle size: 3 to
As the 5 μm fluorescent magnetic powder, use is made of a fluorescent magnetic powder coated with a fluorescent paint capable of obtaining the brightest fluorescent luminance (highest luminance) with ultraviolet rays having a wavelength of 320 to 330 nm.
As the fluorescent magnetic powder of 8 to 10 μm, a fluorescent magnetic powder coated with a fluorescent paint capable of obtaining the brightest fluorescent luminance (highest luminance) with ultraviolet light having a wavelength of 390 to 400 nm was used.

The concentration of the magnetic powder in the test solution was 0.9 g / l, the application time of the magnetic powder was 10 seconds by the continuous method, and the ultraviolet intensity on the test surface was 10 g / l.
It was set to 00 μW / cm ² . Table 1 shows the test results obtained.
As shown in Table 1, magnetic powder having a particle size of 3 to 5 μm adhered to the non-beveled surface having a coarse roughness on the flaw detection surface, and a small amount of magnetic powder having a particle size of 8 to 10 μm adhered as a background. On the other hand, a small amount of magnetic powder of 3 to 5 μm was adhered to the bevel surface, which was a mirror surface, as a background.

From the above results, according to the present invention, the particle diameter of the adhered particles on the flaw detection surface could be clearly distinguished. As a result, the necessity of adjusting the particle size, the mixing ratio, and the bulk density, which were originally required, became clear, the optimum conditions could be appropriately found, and the discriminability of defects during actual flaw detection was greatly improved.

(Comparative Example) Table 1 shows the test conditions. In this comparative example, the same method as in the above example was used except that fluorescent magnetic powder having a particle diameter of 3 to 10 μm coated with a fluorescent paint having an ultraviolet wavelength of 320 to 400 nm to obtain the highest luminance was used. The test was conducted under the following conditions.

Table 1 shows the test results. As shown in Table 1, the particle size adhering to the non-bevel surface was not known, and no information was obtained to improve the suitability of the particle size and the flaw detection conditions. Did not. Although the embodiments have been described above, as shown in the above-described embodiments, according to the present invention, it is possible to set an optimal test solution and facilitate identification of a defective pattern.

In the above-described embodiment, two types of magnetic powder having different particle diameters are distinguished by the degree of green-yellow depth by the combination of the fluorescent substance and the filter of the ultraviolet irradiation lamp. May be identified. The magnetizing method in the present invention is not limited to the gap method, and other magnetizing methods such as those defined in JISGO565 may be used.
There is no problem even if it is more than a kind.

[0028]

[Table 1]

[0029]

According to the present invention, it is possible to find out which particle size of the magnetic powder is appropriate for the surface condition of the specimen, and to obtain an appropriate inspection technique by selecting the magnetic powder. As a result, the contrast between the magnetic powder pattern and the test surface other than the defect portion is made clear, and the defect can be easily identified.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a magnetic particle flaw detection method.

FIG. 2 is an explanatory view showing a magnetic particle flaw detection method.

[Explanation of symbols]

 Reference Signs List 1 steel pipe (specimen) 2 non-bevel face of steel pipe 3 bevel face of steel pipe 4 test solution 5 turning roller 6 spray nozzle 7 magnetized yoke E observation position

Claims (2)

[Claims] An inspection liquid mixed with a fluorescent magnetic powder is sprayed on an object to be inspected, and particles of the magnetic powder used for wet-type fluorescent magnetic particle flaw detection in which a magnetic particle pattern is observed by irradiating an ultraviolet ray under the magnetization condition of the object to be inspected. In the diameter condition setting method, a test solution coated with a fluorescent substance having a different amount of fluorescence and mixed with two or more kinds of fluorescent magnetic powders having different particle sizes is sprayed on a test object of the same type as the test object. Irradiating the test specimen with ultraviolet light under magnetizing conditions;
A wet method comprising: observing a state of adhesion of each of the two or more kinds of fluorescent magnetic powders to a specimen; and determining an optimum condition regarding a particle diameter of the fluorescent magnetic powder used for the wet fluorescent magnetic powder flaw detection based on the observation result. Method for setting particle size conditions of magnetic powder used for fluorescent magnetic particle flaw detection. 2. A fluorescent magnetic powder used for setting a particle size condition of a magnetic powder used for wet-type fluorescent magnetic particle flaw detection,
A fluorescent magnetic powder coated with a fluorescent substance having a different amount of fluorescence for each particle size range.