JP2016197085A - Magnetic flaw detection method - Google Patents

Magnetic flaw detection method Download PDF

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JP2016197085A
JP2016197085A JP2015077947A JP2015077947A JP2016197085A JP 2016197085 A JP2016197085 A JP 2016197085A JP 2015077947 A JP2015077947 A JP 2015077947A JP 2015077947 A JP2015077947 A JP 2015077947A JP 2016197085 A JP2016197085 A JP 2016197085A
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magnetic flux
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JP6550873B2 (en
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俊之 鈴間
Toshiyuki Suzuma
俊之 鈴間
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Nippon Steel Corp
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Nippon Steel and Sumitomo Metal Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a magnetic flaw detection method capable of simply and accurately detecting a flaw existing on the surface of an object to be inspected of the inspection material by arranging a sensor coil to face a surface opposite to the inspection object surface.SOLUTION: A magnetic flaw detection method according to the present invention supplies an AC current to a sensor coil 3 by arranging the sensor coil 3 so as to face a surface S1 opposite to an inspection object surface S2 of an inspection material S, and the inspection material S is magnetized by direct current magnetization means 1 by arranging the direct current magnetizing means 1 such that the magnetic flux density of the surface S1 side (region A1) opposite to the inspection material S is less than the saturation magnetic flux density and becomes smaller than the magnetic flux density of the inspection object surface S2 side (region A2) in the inspection material S, and a flaw D existing on the inspection object surface S2 is detected based on the impedance change of the sensor coil 3.SELECTED DRAWING: Figure 2

Description

本発明は、鋼管や鋼板等の被検査材に存在する欠陥を検出する磁気探傷方法に関する。特に、本発明は、被検査材の検査対象面に存在する欠陥を、検査対象面と反対側の面に対向するようにセンサコイルを配置して簡易に且つ精度良く検出することが可能な磁気探傷方法に関する。   The present invention relates to a magnetic flaw detection method for detecting defects existing in a material to be inspected such as a steel pipe and a steel plate. In particular, the present invention provides a magnetism in which a sensor coil is arranged so as to easily and accurately detect a defect present on an inspection target surface of a material to be inspected so as to face a surface opposite to the inspection target surface. It relates to a flaw detection method.

従来より、鋼管や鋼板等の被検査材に存在する欠陥（きずや腐食など）を非破壊的に検出する方法として、渦流探傷法や漏洩磁束探傷法などの磁気探傷方法が知られている。
渦流探傷法は、センサコイルから被検査材に交流磁界を作用させた場合に、被検査材に誘起される渦電流を遮るような欠陥が存在すると、渦電流の経路が妨げられて、センサコイルのインピーダンスが変化することを利用する探傷方法である。
また、漏洩磁束探傷法（直流漏洩磁束探傷法）は、磁性体からなる被検査材に直流磁界を作用させて磁気飽和するまで磁化した場合に、被検査材に生ずる磁束の経路を妨げるような欠陥が存在すると、この欠陥が存在する部位で磁束が迂回して表面空間に漏洩するため、この漏洩磁束を感磁性センサで検出することで欠陥を検出する探傷方法である。 2. Description of the Related Art Conventionally, magnetic flaw detection methods such as an eddy current flaw detection method and a leakage magnetic flux flaw detection method are known as methods for nondestructively detecting defects (such as flaws and corrosion) existing in a material to be inspected such as a steel pipe and a steel plate.
In the eddy current flaw detection method, when an AC magnetic field is applied to a material to be inspected from the sensor coil, if there is a defect that blocks the eddy current induced in the material to be inspected, the eddy current path is obstructed and the sensor coil This is a flaw detection method that utilizes the fact that the impedance of the wire changes.
Also, the leakage magnetic flux flaw detection method (DC leakage magnetic flux flaw detection method) prevents the magnetic flux path generated in the material to be inspected when the material to be inspected made of magnetic material is magnetized until a magnetic field is saturated by applying a DC magnetic field. If there is a defect, the magnetic flux bypasses and leaks to the surface space at the site where the defect exists, and this is a flaw detection method for detecting the defect by detecting this leakage magnetic flux with a magnetic sensor.

ここで、鋼管内面の検査は、オンラインで直流漏洩磁束探傷や超音波探傷を実施した後、欠陥が検出された箇所をオペレータが目視により再検査して手入れ要否判断や最終的な合否判定を行っている場合が多い。しかし、オンラインで欠陥が検出された箇所が鋼管の長手方向中央付近である場合、鋼管の端部から目視検査することが困難であり、欠陥の過検出や未検出の要因となっている。このため、オペレータが作業し易いように、オンライン装置と比較して軽量でハンドリングし易い装置を用いて、鋼管の外面側から内面を精度良く検査可能な方法の開発が望まれている。
上記鋼管の場合と同様に、鋼板についても、一方の面側から反対側の面を簡易に且つ精度良く検査可能な方法が必要とされる場合がある。 Here, in the inspection of the inner surface of the steel pipe, after performing DC leakage magnetic flux flaw detection and ultrasonic flaw detection on-line, the operator visually re-inspects the location where the defect is detected to determine whether maintenance is necessary or final pass / fail determination. Often done. However, when the part where the defect is detected online is near the center in the longitudinal direction of the steel pipe, it is difficult to visually inspect from the end of the steel pipe, which is a cause of overdetection or non-detection of the defect. For this reason, it is desired to develop a method capable of accurately inspecting the inner surface from the outer surface side of the steel pipe using a device that is lighter and easier to handle than an online device so that the operator can easily work.
As in the case of the steel pipe, there may be a need for a method that can easily and accurately inspect the opposite surface from one surface side of the steel plate.

一般的な渦流探傷法では、表皮効果によって渦電流の浸透深さがセンサコイルを配置する側の面から一定の距離に制限される。このため、被検査材の一方の面（例えば、鋼管の外面）側にセンサコイルを配置して、被検査材の他方の面（例えば、鋼管の内面）を検査することは一般的に困難である。
また、直流漏洩磁束探傷法では、図１（ａ）に示すように、電磁石等の直流磁化手段１やホール素子等の感磁性センサ２を被検査材Ｓの一方の面Ｓ１側に配置し、他方の面Ｓ２を検査する際、他方の面Ｓ２に存在する欠陥Ｄを迂回する磁束Ｂが一方の面Ｓ１から漏洩する程度まで被検査材Ｓ全体を磁気飽和させる必要がある。このため、直流磁化手段１やこれをハンドリングするための装置が大型化し、簡易に検査することができない。 In a general eddy current flaw detection method, the penetration depth of eddy current is limited to a certain distance from the surface on the side where the sensor coil is arranged due to the skin effect. For this reason, it is generally difficult to inspect the other surface (for example, the inner surface of the steel pipe) by arranging the sensor coil on one surface (for example, the outer surface of the steel pipe) of the material to be inspected. is there.
Further, in the DC leakage magnetic flux flaw detection method, as shown in FIG. 1A, a DC magnetizing means 1 such as an electromagnet or a magnetic sensor 2 such as a Hall element is disposed on one surface S1 side of the material S to be inspected. When inspecting the other surface S2, it is necessary to magnetically saturate the entire inspection object S to such an extent that the magnetic flux B that bypasses the defect D existing in the other surface S2 leaks from the one surface S1. For this reason, the DC magnetizing means 1 and a device for handling the same are increased in size and cannot be easily inspected.

上記のような一般的な渦流探傷法や直流漏洩磁束探傷法の問題点を解決するため、一般的な渦流探傷法と同様にセンサコイルによって被検査材に交流磁界を付与すると共に、直流磁化手段で被検査材を磁化して、センサコイルのインピーダンス変化に基づき欠陥を検出する磁気飽和渦流探傷法（ＳＬＯＦＥＣ）と称される方法が提案されている（例えば、特許文献１参照）。
図１（ｂ）に示すように、磁気飽和渦流探傷法は、被検査材Ｓに欠陥が存在しない場合に、直流磁化手段１によって被検査材Ｓ内に相応に磁束Ｂが分布するように磁化し、センサコイル３を配置する面Ｓ１側の被検査材Ｓの透磁率を、センサコイル３のインピーダンスで検出する方法である。図１（ｃ）に示すように、センサコイル３を配置する面Ｓ１と反対側の面Ｓ２に欠陥Ｄが存在すると、磁束Ｂの経路が妨げられて面Ｓ１側に迂回するため、被検査材Ｓにおける面Ｓ１側の磁束密度が大きくなる。これにより、被検査材Ｓの面Ｓ１側の透磁率が低下し、被検査材Ｓの面Ｓ１と磁気回路を形成しているセンサコイル３のインピーダンスが変化する。これにより欠陥Ｄが検出される。 In order to solve the problems of the general eddy current flaw detection method and the DC leakage magnetic flux flaw detection method as described above, an AC magnetic field is applied to the material to be inspected by the sensor coil as in the general eddy current flaw detection method, and a DC magnetizing means is provided. Has proposed a method called a magnetic saturation eddy current flaw detection method (SLOFEC) in which a material to be inspected is magnetized and a defect is detected based on a change in impedance of a sensor coil (see, for example, Patent Document 1).
As shown in FIG. 1B, in the magnetic saturation eddy current flaw detection method, when there is no defect in the material to be inspected S, the direct current magnetization means 1 magnetizes the magnetic flux B to be distributed in the material to be inspected correspondingly. In this method, the magnetic permeability of the material S to be inspected on the surface S1 side on which the sensor coil 3 is arranged is detected by the impedance of the sensor coil 3. As shown in FIG. 1 (c), if a defect D exists on the surface S2 opposite to the surface S1 on which the sensor coil 3 is disposed, the path of the magnetic flux B is obstructed and detours to the surface S1. The magnetic flux density on the surface S1 side in S increases. As a result, the magnetic permeability on the surface S1 side of the inspection material S decreases, and the impedance of the sensor coil 3 forming the magnetic circuit with the surface S1 of the inspection material S changes. Thereby, the defect D is detected.

磁気飽和渦流探傷法は、直流磁化手段１で被検査材Ｓを磁化し、センサコイル３を配置する面Ｓ１と反対側の面Ｓ２に存在する欠陥Ｄによる面Ｓ１側の透磁率の低下を検出するものであるため、一般的な渦流探傷法のように表皮効果の影響によって面Ｓ２に存在する欠陥Ｄを検出できないという事態は生じない。
また、磁気飽和渦流探傷法で用いる直流磁化手段１の目的は、欠陥Ｄの存在しない部位と欠陥Ｄの存在する部位との間でセンサコイル３を配置する面Ｓ１側の透磁率の違いを生じさせてセンサコイルのインピーダンスを変化させることであり、直流漏洩磁束探傷法の場合と異なり、面Ｓ１から磁束Ｂを漏洩させるほどの強磁界を必要としない。このため、直流磁化手段１やこれをハンドリングするための装置を小型・軽量化することが可能であり、簡易に検査可能である。
さらに、直流漏洩磁束探傷法の探傷限界を超える厚みを有する被検査材Ｓ（被検査材Ｓの厚みが大きいため、漏洩磁束が生じるように被検査材Ｓ全体を磁気飽和させることができない）であっても、欠陥Ｄによる透磁率の変化が生じる限りにおいて、検出できる可能性がある。 In the magnetic saturation eddy current flaw detection method, the material S to be inspected is magnetized by the DC magnetizing means 1, and a decrease in the permeability on the surface S1 side due to the defect D existing on the surface S2 opposite to the surface S1 on which the sensor coil 3 is disposed is detected. Therefore, unlike the general eddy current flaw detection method, the situation that the defect D existing on the surface S2 cannot be detected due to the influence of the skin effect does not occur.
Further, the purpose of the DC magnetizing means 1 used in the magnetic saturation eddy current flaw detection method is to produce a difference in magnetic permeability on the surface S1 side where the sensor coil 3 is arranged between a site where the defect D does not exist and a site where the defect D exists. Thus, the impedance of the sensor coil is changed, and unlike the case of the DC leakage magnetic flux flaw detection method, a strong magnetic field sufficient to leak the magnetic flux B from the surface S1 is not required. For this reason, it is possible to reduce the size and weight of the DC magnetizing means 1 and the apparatus for handling it, and it is possible to easily inspect.
Furthermore, with the inspection material S having a thickness exceeding the flaw detection limit of the DC leakage magnetic flux inspection method (because the thickness of the inspection material S is large, the entire inspection material S cannot be magnetically saturated so that leakage magnetic flux is generated). Even if it exists, as long as the change of the magnetic permeability by the defect D arises, there exists a possibility that it can detect.

以上のように、従来提案されている磁気飽和渦流探傷法によれば、従来の一般的な渦流探傷法や直流漏洩磁束探傷法に比べて、簡易に且つ精度良く、センサコイル３を配置する面Ｓ１と反対側の面Ｓ２に存在する欠陥Ｄを検出可能であることが期待できる。
しかしながら、図１（ｂ）、（ｃ）に示すように、直流磁化手段１及びセンサコイル３を単純に被検査材Ｓの検査対象面Ｓ２と反対側の面Ｓ１に配置しただけでは、検査対象面Ｓ２に存在する欠陥Ｄを精度良く検出できない場合がある。 As described above, according to the conventionally proposed magnetic saturation eddy current flaw detection method, the surface on which the sensor coil 3 is arranged is simpler and more accurate than the conventional general eddy current flaw detection method and DC leakage magnetic flux flaw detection method. It can be expected that the defect D existing on the surface S2 opposite to S1 can be detected.
However, as shown in FIGS. 1B and 1C, the direct current magnetizing means 1 and the sensor coil 3 are simply arranged on the surface S1 opposite to the inspection target surface S2 of the material S to be inspected. In some cases, the defect D existing on the surface S2 cannot be detected with high accuracy.

特開２０１０−１２７８５４号公報JP 2010-127854 A

本発明は、以上に説明した従来技術の問題点を解決するべくなされたものであり、被検査材の検査対象面に存在する欠陥を、検査対象面と反対側の面に対向するようにセンサコイルを配置して簡易に且つ精度良く検出することが可能な磁気探傷方法を提供することを課題とする。   The present invention has been made to solve the problems of the prior art described above, and a sensor is provided so that a defect present on the inspection target surface of the inspection object faces the surface opposite to the inspection target surface. It is an object of the present invention to provide a magnetic flaw detection method that can easily and accurately detect a coil by arranging it.

前記課題を解決するため、本発明者らは鋭意検討した結果、図１（ｂ）、（ｃ）に示すような直流磁化手段１及びセンサコイル３の配置では、欠陥Ｄが存在しない場合であっても、被検査材Ｓにおける検査対象面Ｓ２と反対側の面（センサコイル３の配置側の面）Ｓ１側の磁束密度が、検査対象面Ｓ２側の磁束密度よりも大きくなっていることが、欠陥Ｄを精度良く検出できない場合の原因であることを見出した。   In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, the arrangement of the DC magnetizing means 1 and the sensor coil 3 as shown in FIGS. However, the magnetic flux density on the surface S1 side opposite to the surface S2 to be inspected in the inspection object S (surface on the side where the sensor coil 3 is arranged) S1 may be larger than the magnetic flux density on the surface S2 to be inspected. It was found that this is the cause when the defect D cannot be detected with high accuracy.

より具体的に説明すれば、磁気飽和渦流探傷法は、前述のように、センサコイル３を配置する面Ｓ１と反対側の面Ｓ２に存在する欠陥Ｄによる面Ｓ１側の透磁率の低下を検出することで、欠陥Ｄを検出する方法である。したがい、欠陥Ｄを精度良く検出するには（欠陥Ｄの検出能を高めるには）、欠陥Ｄによって面Ｓ１側の透磁率が大きく低下する状態に被検査材Ｓが磁化されていることが有効である。換言すれば、被検査材Ｓにおける面Ｓ１側は、磁束Ｂが欠陥Ｄを迂回して面Ｓ１側の磁束密度が大きくなることで透磁率が大きく低下する状態（磁気飽和近傍領域の手前の状態）に磁化されていることが有効である。一方、被検査材Ｓにおける面Ｓ２側については、欠陥Ｄを迂回する磁束Ｂが多いほど面Ｓ１側の透磁率が大きく低下することから、磁気飽和近傍領域まで磁化されていることが有効である。   More specifically, the magnetic saturation eddy current flaw detection method detects a decrease in the permeability on the surface S1 side due to the defect D existing on the surface S2 opposite to the surface S1 on which the sensor coil 3 is disposed, as described above. This is a method for detecting the defect D. Therefore, in order to detect the defect D with high accuracy (in order to increase the detectability of the defect D), it is effective that the inspection material S is magnetized so that the magnetic permeability on the surface S1 side is greatly reduced by the defect D. It is. In other words, the surface S1 side of the material S to be inspected is a state in which the magnetic flux B bypasses the defect D and the magnetic flux density on the surface S1 side increases and the magnetic permeability is greatly reduced (a state before the magnetic saturation vicinity region). ) Is effective. On the other hand, the surface S2 side of the inspection material S is effectively magnetized to the region near the magnetic saturation because the permeability on the surface S1 side decreases more as the magnetic flux B bypassing the defect D increases. .

しかしながら、前述のように、図１（ｂ）、（ｃ）に示すような直流磁化手段１及びセンサコイル３の配置では、欠陥Ｄが存在しない場合に、検査対象面Ｓ２と反対側の面Ｓ１側の磁束密度（図１（ｂ）に示す領域Ａ１の磁束密度）が、検査対象面Ｓ２側の磁束密度（図１（ｂ）に示す領域Ａ２の磁束密度）よりも大きい。このため、面Ｓ１側では透磁率が大きく低下する状態（磁気飽和近傍領域の手前の状態）の磁束密度となるように磁化力（磁界強度）を設定した場合、検査対象面Ｓ２側では磁気飽和近傍領域の手前の状態よりも更に小さい磁束密度となり、前段落で説明した面Ｓ２側の有効な磁化状態、すなわち磁気飽和近傍領域に達しないのは明らかである。このため、欠陥Ｄを迂回する磁束Ｂが少なくなって、欠陥Ｄの検出感度が低下する。一方、検査対象面Ｓ２側の磁束密度が磁気飽和近傍領域になるように磁化力（磁界強度）を設定すると、これよりも大きい面Ｓ１側の磁束密度が先に磁気飽和に至るため、透磁率の変化が小さくなって、欠陥Ｄの検出感度が低下する。したがい、いずれにしても、欠陥Ｄを精度良く検出できない場合が生じてしまう。   However, as described above, in the arrangement of the DC magnetizing means 1 and the sensor coil 3 as shown in FIGS. 1B and 1C, when there is no defect D, the surface S1 opposite to the inspection target surface S2. The magnetic flux density on the side (the magnetic flux density in the region A1 shown in FIG. 1B) is larger than the magnetic flux density on the inspection object surface S2 side (the magnetic flux density in the region A2 shown in FIG. 1B). For this reason, when the magnetizing force (magnetic field strength) is set so as to obtain a magnetic flux density in a state in which the magnetic permeability is greatly reduced on the surface S1 side (a state before the magnetic saturation vicinity region), on the inspection target surface S2 side, the magnetic saturation is achieved. It is clear that the magnetic flux density is smaller than that in the state before the neighboring region, and the effective magnetization state on the surface S2 side described in the previous paragraph, that is, the region near the magnetic saturation is not reached. For this reason, the magnetic flux B which bypasses the defect D decreases, and the detection sensitivity of the defect D decreases. On the other hand, if the magnetizing force (magnetic field strength) is set so that the magnetic flux density on the inspection target surface S2 side is in the magnetic saturation vicinity region, the magnetic flux density on the surface S1 side higher than this reaches the magnetic saturation first. , And the detection sensitivity of the defect D decreases. Therefore, in any case, the defect D may not be detected with high accuracy.

本発明者らは、上記の原因から考えて、磁気飽和渦流探傷法によって欠陥Ｄを精度良く検出するには、欠陥Ｄが存在しない場合に、被検査材Ｓにおける検査対象面Ｓ２と反対側の面Ｓ１側の磁束密度が、検査対象面Ｓ２側の磁束密度よりも小さくなっていることが有効であることを見出し、本発明を完成した。   In view of the above causes, the inventors of the present invention can accurately detect the defect D by the magnetic saturation eddy current flaw detection method. When the defect D does not exist, the object S has a surface opposite to the inspection target surface S2. It has been found that it is effective that the magnetic flux density on the surface S1 side is smaller than the magnetic flux density on the inspection target surface S2, and the present invention has been completed.

すなわち、前記課題を解決するため、本発明は、被検査材の検査対象面と反対側の面に対向するようにセンサコイルを配置して該センサコイルに交流電流を通電すると共に、前記被検査材における前記反対側の面側の磁束密度が飽和磁束密度未満で且つ前記被検査材における前記検査対象面側の磁束密度よりも小さくなるように直流磁化手段を配置して該直流磁化手段によって前記被検査材を磁化し、前記センサコイルのインピーダンス変化に基づき、前記検査対象面に存在する欠陥を検出することを特徴とする磁気探傷方法を提供する。   That is, in order to solve the above-described problem, the present invention provides a sensor coil disposed so as to face a surface opposite to a surface to be inspected of a material to be inspected, and supplies an alternating current to the sensor coil, and DC magnetizing means is arranged such that the magnetic flux density on the opposite surface side of the material is less than the saturation magnetic flux density and smaller than the magnetic flux density on the inspection target surface side of the material to be inspected, and the DC magnetizing means uses the DC magnetizing means to There is provided a magnetic flaw detection method characterized by magnetizing a material to be inspected and detecting a defect present on the inspection object surface based on a change in impedance of the sensor coil.

本発明によれば、被検査材における検査対象面と反対側の面（センサコイルの配置側の面）側の磁束密度が飽和磁束密度未満で且つ被検査材における検査対象面側の磁束密度よりも小さくなるように直流磁化手段が配置され、被検査材が磁化される。このため、検査対象面と反対側の面側については、磁束密度が大きくなることで透磁率が大きく低下する状態（磁気飽和近傍領域の手前の状態）に磁化し、検査対象面側については、磁気飽和近傍領域まで磁化することが可能であり、欠陥の検出感度を高めて精度良く欠陥を検出することが可能である。
なお、本発明において、「検査対象面側の磁束密度」とは、被検査材の磁化される領域における検査対象面寄りの領域の磁束密度を意味し、例えば、検査対象面から検査対象面と反対側の面との中間点までの領域の磁束密度を意味する。また、「検査対象面と反対側の面側の磁束密度」とは、被検査材の磁化される領域における検査対象面と反対側の面寄りの領域の磁束密度を意味し、例えば、検査対象面と反対側の面から該反対側の面と検査対象面との中間点までの領域の磁束密度を意味する。 According to the present invention, the magnetic flux density on the surface opposite to the surface to be inspected (surface on the side where the sensor coil is arranged) in the inspection target material is less than the saturation magnetic flux density and the magnetic flux density on the inspection target surface side in the inspection material. The DC magnetizing means is arranged so that it becomes smaller, and the material to be inspected is magnetized. For this reason, the surface side opposite to the surface to be inspected is magnetized in a state in which the magnetic permeability is greatly reduced by increasing the magnetic flux density (the state before the magnetic saturation region). It is possible to magnetize to a region near the magnetic saturation, and it is possible to detect defects with high accuracy by increasing defect detection sensitivity.
In the present invention, “the magnetic flux density on the inspection target surface side” means the magnetic flux density in the region near the inspection target surface in the region to be magnetized of the material to be inspected, for example, from the inspection target surface to the inspection target surface. It means the magnetic flux density in the region up to the midpoint with the opposite surface. Further, “the magnetic flux density on the surface opposite to the surface to be inspected” means the magnetic flux density in the region near the surface to be inspected opposite to the surface to be inspected in the region to be inspected that is magnetized. It means the magnetic flux density in the region from the surface opposite to the surface to the midpoint between the surface opposite to the surface to be inspected.

本発明における被検査材が鋼管や鋼板である場合に、その材料の磁化曲線（Ｂ−Ｈカーブ）から考えて、磁気飽和近傍領域まで磁化されている状態（欠陥を迂回する磁束が多くなる状態）は、例えば、飽和磁束密度の８０％以上１００％以下の磁束密度が得られるまで磁化されている状態であると考えることができる。また、磁気飽和近傍領域の手前の状態に磁化されている状態（磁束密度が大きくなることで透磁率が大きく低下する状態）は、例えば、飽和磁束密度の６０％以上８０％未満の磁束密度が得られるまで磁化されている状態であると考えることができる。   In the case where the material to be inspected in the present invention is a steel pipe or a steel plate, it is magnetized to a region near the magnetic saturation in consideration of the magnetization curve (BH curve) of the material (a state in which a magnetic flux bypassing the defect increases) ) Can be considered to be a state of being magnetized until a magnetic flux density of 80% to 100% of the saturation magnetic flux density is obtained, for example. Moreover, the state magnetized in the state before the magnetic saturation vicinity region (the state in which the magnetic permeability is greatly reduced by increasing the magnetic flux density) is, for example, a magnetic flux density of 60% or more and less than 80% of the saturation magnetic flux density. It can be considered that it is magnetized until it is obtained.

したがって、前記直流磁化手段は、前記被検査材における前記反対側の面側の磁束密度が飽和磁束密度の６０％以上８０％未満となり、前記被検査材における前記検査対象面側の磁束密度が飽和磁束密度の８０％以上１００％以下となるように、前記被検査材を磁化することが好ましい。
なお、被検査材における反対側の面側の磁束密度が飽和磁束密度の６０％以上８０％未満となり、検査対象面側の磁束密度が飽和磁束密度の８０％以上１００％以下となるか否かは、例えば、被検査材の形状・寸法・材質や、直流磁化手段（電磁石など）の形状・寸法・材質・配置・通電する電流値等をパラメータとした数値解析（有限要素解析など）を実施することによって評価可能であり、この評価結果を実際に探傷を行う際に用いる直流磁化手段の条件に反映させれば良い。 Therefore, in the DC magnetizing means, the magnetic flux density on the opposite surface side of the inspection material is 60% or more and less than 80% of the saturation magnetic flux density, and the magnetic flux density on the inspection object surface side of the inspection material is saturated. It is preferable to magnetize the material to be inspected so that the magnetic flux density is 80% or more and 100% or less.
Whether or not the magnetic flux density on the opposite surface side of the material to be inspected is 60% or more and less than 80% of the saturation magnetic flux density, and the magnetic flux density on the inspection target surface side is 80% or more and 100% or less of the saturation magnetic flux density. Performs numerical analysis (such as finite element analysis) using parameters such as the shape / dimension / material of the material to be inspected, the shape / dimension / material / arrangement of the DC magnetizing means (electromagnet, etc.), etc. The evaluation result can be reflected in the conditions of the DC magnetizing means used when actually performing flaw detection.

前記被検査材が板材である場合、前記直流磁化手段は、前記検査対象面に対向するように配置され、前記検査対象面に沿った磁界を形成する電磁石又は永久磁石であることが好ましい。   When the material to be inspected is a plate material, the DC magnetizing means is preferably an electromagnet or a permanent magnet that is disposed so as to face the surface to be inspected and forms a magnetic field along the surface to be inspected.

上記の好ましい構成によれば、直流磁化手段が板材の検査対象面に対向するように配置（板材の検査対象面と反対側の面よりも検査対象面に近い位置に配置）され、板材の検査対象面に沿った（検査対象面に略平行な）磁界を形成するため、被検査材における検査対象面と反対側の面（センサコイルを配置する面）側の磁束密度を検査対象面側の磁束密度よりも小さくすることが可能である。   According to said preferable structure, it arrange | positions so that a DC magnetization means may oppose the test object surface of a board | plate material (it arrange | positions in the position near a test object surface rather than the surface opposite to the test object surface of a board | plate material), and test | inspects a board material In order to form a magnetic field along the target surface (substantially parallel to the surface to be inspected), the magnetic flux density on the surface opposite to the surface to be inspected (surface on which the sensor coil is disposed) side of the material to be inspected is It is possible to make it smaller than the magnetic flux density.

前記被検査材が管材であり、前記検査対象面が管材の内面である場合、前記直流磁化手段は、前記管材の内面に対向するように配置され、前記管材の内面に沿った磁界を形成する電磁石又は永久磁石であることが好ましい。   When the material to be inspected is a tube material and the surface to be inspected is an inner surface of the tube material, the DC magnetizing means is arranged to face the inner surface of the tube material, and forms a magnetic field along the inner surface of the tube material. An electromagnet or a permanent magnet is preferred.

上記の好ましい構成によれば、直流磁化手段が検査対象面である管材の内面に対向するように配置（管材の外面よりも内面に近い位置に配置）され、管材の内面に沿った磁界を形成するため、センサコイルを配置する管材の外面側の磁束密度を内面側の磁束密度よりも小さくすることが可能である。   According to said preferable structure, it arrange | positions so that a DC magnetization means may oppose the inner surface of the pipe material which is a test object surface (positioned in the position nearer to the inner surface than the outer surface of a pipe material), and forms the magnetic field along the inner surface of a pipe material Therefore, it is possible to make the magnetic flux density on the outer surface side of the pipe material on which the sensor coil is arranged smaller than the magnetic flux density on the inner surface side.

また、前記被検査材が管材であり、前記検査対象面が管材の内面である場合、前記直流磁化手段は、前記管材の軸方向に挿通され、直流電流が通電される電流貫通棒であってもよい。   Further, when the material to be inspected is a tube material and the inspection object surface is an inner surface of the tube material, the direct current magnetization means is a current through-rod inserted in the axial direction of the tube material and through which a direct current is passed. Also good.

上記の好ましい構成によっても、電流貫通棒に直流電流を通電することで、電流貫通棒の周囲に磁界（管材の内面に沿った磁界）が形成され、電流貫通棒に近い管材の内面側の磁束密度の方が大きくなるため、センサコイルを配置する管材の外面側の磁束密度を内面側の磁束密度よりも小さくすることが可能である。また、管材の内面全体を検査するに際しては、直流磁化手段としての電流貫通棒は動かさずに、センサコイルだけを管材の外面に沿って動かせばよいので、ハンドリングし易く、検査が極めて簡易になるという利点も有する。   Even with the above preferred configuration, when a direct current is applied to the current through bar, a magnetic field (a magnetic field along the inner surface of the tube material) is formed around the current through bar, and the magnetic flux on the inner surface side of the tube material close to the current through bar. Since the density becomes larger, it is possible to make the magnetic flux density on the outer surface side of the pipe material on which the sensor coil is arranged smaller than the magnetic flux density on the inner surface side. In addition, when inspecting the entire inner surface of the tube material, it is only necessary to move the sensor coil along the outer surface of the tube material without moving the current passing rod as the DC magnetizing means. It also has the advantage of.

さらに、前記被検査材が管材であり、前記検査対象面が管材の内面である場合、前記直流磁化手段は、前記管材の外面に対向するように配置され、前記管材の内面に沿った磁界を形成する電磁石又は永久磁石であり、前記直流磁化手段の各磁極端面の中心を結ぶ直線が、前記管材の内面又は前記管材の内面より内側を通るようにしてもよい。   Further, when the material to be inspected is a tube material and the surface to be inspected is an inner surface of the tube material, the direct current magnetization means is disposed so as to face the outer surface of the tube material, and generates a magnetic field along the inner surface of the tube material. It may be an electromagnet or a permanent magnet to be formed, and a straight line connecting the centers of the magnetic pole end faces of the DC magnetization means may pass through the inner surface of the tube material or the inner surface of the tube material.

直流磁化手段によって形成される磁界のうち、直流磁化手段の各磁極端面の中心を結ぶ直線上の磁界強度が最も大きいと考えられる。
上記の好ましい構成によれば、直流磁化手段の各磁極端面の中心を結ぶ直線（この直線上の磁界強度が最も大きくなると考えられる）が、管材の内面又は管材の内面より内側（管材の中心側）を通るため、センサコイルを配置する管材の外面側の磁束密度を内面側の磁束密度よりも小さくすることが可能である。また、直流磁化手段及びセンサコイルの双方が管材の外面側に位置するため、ハンドリングし易く、検査が極めて簡易になるという利点も有する。 Among the magnetic fields formed by the DC magnetizing means, it is considered that the magnetic field intensity on the straight line connecting the centers of the magnetic pole end faces of the DC magnetizing means is the largest.
According to the above preferred configuration, the straight line connecting the centers of the magnetic pole end faces of the DC magnetizing means (the magnetic field strength on this straight line is considered to be the largest) is the inner surface of the tube material or the inner surface of the tube material (the center side of the tube material). ), The magnetic flux density on the outer surface side of the pipe material on which the sensor coil is disposed can be made smaller than the magnetic flux density on the inner surface side. In addition, since both the direct current magnetizing means and the sensor coil are located on the outer surface side of the pipe material, there are also advantages that the handling is easy and the inspection becomes extremely simple.

本発明によれば、被検査材の検査対象面に存在する欠陥を、検査対象面と反対側の面に対向するようにセンサコイルを配置して簡易に且つ精度良く検出することが可能である。   According to the present invention, it is possible to easily and accurately detect a defect present on an inspection target surface of a material to be inspected by arranging a sensor coil so as to face a surface opposite to the inspection target surface. .

図１は、直流漏洩磁束探傷法と磁気飽和渦流探傷法との違いを説明するための模式図である。FIG. 1 is a schematic diagram for explaining the difference between the DC leakage magnetic flux flaw detection method and the magnetic saturation eddy current flaw detection method. 図２は、本発明の第１実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。FIG. 2 is a diagram schematically showing an apparatus configuration for executing the magnetic flaw detection method according to the first embodiment of the present invention. 図３は、０．２５％炭素鋼の磁化曲線及び本実施形態に係る磁気探傷方法における被検査材の磁化状態の一例を示す図である。FIG. 3 is a diagram showing an example of the magnetization curve of 0.25% carbon steel and the magnetization state of the material to be inspected in the magnetic flaw detection method according to the present embodiment. 図４は、０．２５％炭素鋼の磁化曲線及び従来の磁気探傷方法における被検査材の磁化状態の一例を示す図である。FIG. 4 is a diagram illustrating an example of a magnetization curve of 0.25% carbon steel and a magnetization state of a material to be inspected in a conventional magnetic flaw detection method. 図５は、本発明の第２実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。FIG. 5 is a diagram schematically showing a device configuration for executing the magnetic flaw detection method according to the second embodiment of the present invention. 図６は、本発明の第３実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。FIG. 6 is a diagram schematically showing a device configuration for executing the magnetic flaw detection method according to the third embodiment of the present invention. 図７は、本発明の第４実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。FIG. 7 is a diagram schematically showing an apparatus configuration for executing the magnetic flaw detection method according to the fourth embodiment of the present invention.

以下、添付図面を適宜参照しつつ、本発明の実施形態に係る磁気探傷方法について説明する。   Hereinafter, a magnetic flaw detection method according to an embodiment of the present invention will be described with reference to the accompanying drawings as appropriate.

＜第１実施形態＞
図２は、本発明の第１実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。
本実施形態に係る磁気探傷方法は、被検査材Ｓが板材である。
本実施形態に係る磁気探傷方法では、板材Ｓの検査対象面Ｓ２と反対側の面Ｓ１に対向するようにセンサコイル３を配置する。センサコイル３としては、一般的な過流探傷法で用いるものと同様の構成のセンサコイルを用いることが可能である。また、検査対象面Ｓ１に対向するように直流磁化手段（本実施形態では電磁石）１を配置する。電磁石１は、検査対象面Ｓ２に沿った磁界を形成可能である。そして、センサコイル３に交流電流を通電すると共に、電磁石１のコイルに直流電流を通電する。これにより、欠陥Ｄが存在しない場合に、板材Ｓにおける反対側の面Ｓ１側の磁束密度（図２に示す領域Ａ１の磁束密度）が飽和磁束密度未満で且つ板材Ｓにおける検査対象面Ｓ２側の磁束密度（図２に示す領域Ａ２の磁束密度）よりも小さくすることが可能である。そして、センサコイル３のインピーダンス変化に基づき、検査対象面Ｓ２に存在する欠陥Ｄを検出することができる。センサコイル３のインピーダンス変化の検出方法についても、一般的な過流探傷法で用いるものと同様の方法を用いることが可能である。 <First Embodiment>
FIG. 2 is a diagram schematically showing an apparatus configuration for executing the magnetic flaw detection method according to the first embodiment of the present invention.
In the magnetic flaw detection method according to the present embodiment, the inspection material S is a plate material.
In the magnetic flaw detection method according to the present embodiment, the sensor coil 3 is arranged so as to face the surface S1 of the plate S opposite to the inspection target surface S2. As the sensor coil 3, it is possible to use a sensor coil having the same configuration as that used in a general overcurrent flaw detection method. Moreover, the direct current magnetization means (electromagnet in this embodiment) 1 is arranged so as to face the inspection target surface S1. The electromagnet 1 can form a magnetic field along the inspection target surface S2. Then, an alternating current is passed through the sensor coil 3 and a direct current is passed through the coil of the electromagnet 1. Thereby, when there is no defect D, the magnetic flux density on the opposite surface S1 side of the plate material S (the magnetic flux density in the region A1 shown in FIG. 2) is less than the saturation magnetic flux density, and the plate S is on the inspection target surface S2 side. It is possible to make it smaller than the magnetic flux density (the magnetic flux density in the region A2 shown in FIG. 2). And based on the impedance change of the sensor coil 3, the defect D which exists in the test object surface S2 can be detected. As a method for detecting the impedance change of the sensor coil 3, a method similar to that used in a general overcurrent flaw detection method can be used.

本実施形態に係る磁気探傷方法によれば、電磁石１のコイルに通電する直流電流の電流値を調整することで、検査対象面Ｓ２と反対側の面Ｓ１側（図２に示す領域Ａ１）については、磁束が欠陥Ｄを迂回して磁束密度が大きくなることで透磁率が大きく低下する状態（磁気飽和近傍領域の手前の状態）に磁化することができる。一方、検査対象面Ｓ２側（図２に示す領域Ａ２）については、磁気飽和近傍領域まで磁化することが可能である。このため、欠陥Ｄの検出感度を高めて精度良く欠陥Ｄを検出することが可能である。   According to the magnetic flaw detection method according to the present embodiment, the surface S1 side (region A1 shown in FIG. 2) opposite to the inspection target surface S2 is adjusted by adjusting the current value of the direct current that is passed through the coil of the electromagnet 1. The magnetic flux can be magnetized to a state where the magnetic permeability is greatly reduced by bypassing the defect D and the magnetic flux density is increased (a state before the region near magnetic saturation). On the other hand, the inspection target surface S2 side (region A2 shown in FIG. 2) can be magnetized to the region near magnetic saturation. For this reason, it is possible to detect the defect D with high accuracy by increasing the detection sensitivity of the defect D.

図３は、０．２５％炭素鋼の磁化曲線及び本実施形態に係る磁気探傷方法における板材Ｓの磁化状態の一例を示す図である。
本実施形態の板材Ｓが鋼材である場合、図３に示すような磁化曲線（Ｂ−Ｈカーブ）から考えて、磁気飽和近傍領域まで磁化されている状態（欠陥Ｄを迂回する磁束が多くなる状態）は、例えば、飽和磁束密度Ｂｍａｘ（例えば、磁界強度が１００００［Ａ／ｍ］のときに得られる磁束密度）の８０％以上１００％以下の磁束密度が得られるまで磁化されている状態であると考えることができる。したがって、板材Ｓにおける検査対象面Ｓ２側の磁束密度（図２に示す領域Ａ２の磁束密度）が飽和磁束密度Ｂｍａｘの８０％以上１００％以下の磁束密度となるように磁化することが好ましい。
また、磁気飽和近傍領域の手前の状態に磁化されている状態（磁束密度が大きくなることで透磁率が大きく低下する状態）は、例えば、飽和磁束密度Ｂｍａｘの６０％以上８０％未満の磁束密度が得られるまで磁化されている状態であると考えることができる。したがって、板材Ｓにおける反対の面Ｓ１側の磁束密度（図２に示す領域Ａ１の磁束密度）が飽和磁束密度Ｂｍａｘの６０％以上８０％未満の磁束密度となるように磁化することが好ましい。 FIG. 3 is a diagram illustrating an example of a magnetization curve of 0.25% carbon steel and a magnetization state of the plate material S in the magnetic flaw detection method according to the present embodiment.
In the case where the plate material S of the present embodiment is a steel material, in view of the magnetization curve (BH curve) as shown in FIG. 3, the state of being magnetized to the magnetic saturation vicinity region (the magnetic flux bypassing the defect D increases). For example, the state is magnetized until a magnetic flux density of 80% to 100% of a saturation magnetic flux density Bmax (for example, a magnetic flux density obtained when the magnetic field strength is 10,000 [A / m]) is obtained. You can think of it. Therefore, it is preferable to magnetize the magnetic flux density on the inspection object surface S2 side in the plate material S (the magnetic flux density in the region A2 shown in FIG. 2) to be 80% to 100% of the saturation magnetic flux density Bmax.
Moreover, the state magnetized in the state before the magnetic saturation vicinity region (the state in which the magnetic permeability is greatly reduced by increasing the magnetic flux density) is, for example, a magnetic flux density of 60% or more and less than 80% of the saturation magnetic flux density Bmax. It can be considered that the magnetized state is obtained until is obtained. Therefore, it is preferable to magnetize such that the magnetic flux density on the opposite surface S1 side of the plate S (the magnetic flux density in the region A1 shown in FIG. 2) is 60% or more and less than 80% of the saturation magnetic flux density Bmax.

図４は、０．２５％炭素鋼の磁化曲線及び従来の磁気探傷方法（図１（ｂ）、（ｃ）参照）における板材Ｓの磁化状態の一例を示す図である。
図１（ｂ）、（ｃ）を参照して説明した従来の磁気探傷方法では、欠陥Ｄが存在しない場合に、検査対象面Ｓ２と反対側の面Ｓ１側の磁束密度（図１（ｂ）に示す領域Ａ１の磁束密度）が、検査対象面Ｓ２側の磁束密度（図１（ｂ）に示す領域Ａ２の磁束密度）よりも大きい。このため、図４に示すように、面Ｓ１側（図１（ｂ）に示す領域Ａ１）では透磁率が大きく低下する状態（磁気飽和近傍領域の手前の状態）の磁束密度（例えば、飽和磁束密度Ｂｍａｘの６０％以上８０％未満の磁束密度）となるように磁化力（磁界強度）を設定した場合、検査対象面Ｓ２側（図１（ｂ）に示す領域Ａ２）では磁気飽和近傍領域の手前の状態よりも更に小さい磁束密度となり、前段落で説明した面Ｓ２側の有効な磁化状態、すなわち磁気飽和近傍領域（例えば、飽和磁束密度Ｂｍａｘの８０％以上１００％以下の磁束密度）に達しないのは明らかである。このため、欠陥Ｄを迂回する磁束Ｂが少なくなって、欠陥Ｄの検出感度が低下する。一方、検査対象面Ｓ２側の磁束密度が磁気飽和近傍領域になるように磁化力（磁界強度）を設定すると、これよりも大きい面Ｓ１側の磁束密度が先に磁気飽和に至るため、透磁率の変化が小さくなって、欠陥Ｄの検出感度が低下する。したがい、いずれにしても、欠陥Ｄを精度良く検出できない場合が生じてしまう。 FIG. 4 is a diagram showing an example of a magnetization curve of 0.25% carbon steel and a magnetization state of the plate material S in a conventional magnetic flaw detection method (see FIGS. 1B and 1C).
In the conventional magnetic flaw detection method described with reference to FIGS. 1B and 1C, when there is no defect D, the magnetic flux density on the surface S1 side opposite to the inspection target surface S2 (FIG. 1B). Is larger than the magnetic flux density on the inspection target surface S2 side (the magnetic flux density of the region A2 shown in FIG. 1B). For this reason, as shown in FIG. 4, the magnetic flux density (for example, saturation magnetic flux) in a state in which the magnetic permeability is greatly reduced (the state before the magnetic saturation vicinity region) on the surface S1 side (region A1 shown in FIG. 1B). When the magnetizing force (magnetic field strength) is set so that the magnetic flux density is 60% or more and less than 80% of the density Bmax), the region near the magnetic saturation is in the inspection target surface S2 side (region A2 shown in FIG. 1B). The magnetic flux density is smaller than that in the previous state, and reaches the effective magnetization state on the surface S2 side described in the previous paragraph, that is, the magnetic saturation vicinity region (for example, the magnetic flux density of 80% to 100% of the saturation magnetic flux density Bmax). Obviously not. For this reason, the magnetic flux B which bypasses the defect D decreases, and the detection sensitivity of the defect D decreases. On the other hand, if the magnetizing force (magnetic field strength) is set so that the magnetic flux density on the inspection target surface S2 side is in the magnetic saturation vicinity region, the magnetic flux density on the surface S1 side higher than this reaches the magnetic saturation first. , And the detection sensitivity of the defect D decreases. Therefore, in any case, the defect D may not be detected with high accuracy.

本実施形態に係る磁気探傷方法によれば、従来の磁気探傷方法と異なり、図３に示すような板材Ｓの磁化状態を実現可能であるため、欠陥Ｄの検出感度を高めて精度良く欠陥Ｄを検出することが可能である。また、直流漏洩磁束探傷法の場合と異なり、面Ｓ１から磁束を漏洩させるほどの強磁界を必要としないため、電磁石１やこれをハンドリングするための装置を小型・軽量化することが可能であり、簡易に検査可能である。   According to the magnetic flaw detection method according to the present embodiment, unlike the conventional magnetic flaw detection method, the magnetized state of the plate material S as shown in FIG. 3 can be realized. Therefore, the detection sensitivity of the defect D is increased and the defect D is accurately detected. Can be detected. Unlike the case of the DC leakage magnetic flux flaw detection method, a strong magnetic field that leaks the magnetic flux from the surface S1 is not required, so that the electromagnet 1 and a device for handling it can be reduced in size and weight. It can be easily inspected.

＜第２実施形態＞
図５は、本発明の第２実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。
本実施形態に係る磁気探傷方法は、被検査材Ｓが管材である点が第１実施形態と異なる。
本実施形態に係る磁気探傷方法でも、第１実施形態と同様に、管材Ｓの検査対象面である内面Ｓ２と反対側の面である外面Ｓ１に対向するようにセンサコイル３を配置する。また、内面Ｓ２に対向するように電磁石１を配置する。電磁石１は、内面Ｓ２に沿った磁界を形成可能である。そして、センサコイル３に交流電流を通電すると共に、電磁石１のコイルに直流電流を通電する。これにより、欠陥Ｄが存在しない場合に、管材Ｓにおける外面Ｓ１側の磁束密度（図５に示す領域Ａ１の磁束密度）が飽和磁束密度未満で且つ管材Ｓにおける内面Ｓ２側の磁束密度（図５に示す領域Ａ２の磁束密度）よりも小さくすることが可能である。そして、センサコイル３のインピーダンス変化に基づき、内面Ｓ２に存在する欠陥Ｄを検出することができる。 Second Embodiment
FIG. 5 is a diagram schematically showing a device configuration for executing the magnetic flaw detection method according to the second embodiment of the present invention.
The magnetic flaw detection method according to the present embodiment is different from the first embodiment in that the material to be inspected S is a tube material.
Also in the magnetic flaw detection method according to the present embodiment, the sensor coil 3 is disposed so as to face the outer surface S1 that is the surface opposite to the inner surface S2 that is the inspection target surface of the tube material S, as in the first embodiment. Further, the electromagnet 1 is arranged so as to face the inner surface S2. The electromagnet 1 can form a magnetic field along the inner surface S2. Then, an alternating current is passed through the sensor coil 3 and a direct current is passed through the coil of the electromagnet 1. Thereby, when there is no defect D, the magnetic flux density on the outer surface S1 side in the tube material S (the magnetic flux density in the region A1 shown in FIG. 5) is less than the saturation magnetic flux density and the magnetic flux density on the inner surface S2 side in the tube material S (FIG. 5). The magnetic flux density of the region A2 shown in FIG. And based on the impedance change of the sensor coil 3, the defect D which exists in the inner surface S2 can be detected.

管材Ｓにおける内面Ｓ２側の磁束密度（図５に示す領域Ａ２の磁束密度）が飽和磁束密度Ｂｍａｘの８０％以上１００％以下の磁束密度となるように磁化し、管材Ｓにおける外面Ｓ１側の磁束密度（図５に示す領域Ａ１の磁束密度）が飽和磁束密度Ｂｍａｘの６０％以上８０％未満の磁束密度となるように磁化することが好ましい点は、第１実施形態と同様である。   The tube material S is magnetized so that the magnetic flux density on the inner surface S2 side (the magnetic flux density in the region A2 shown in FIG. 5) is 80% to 100% of the saturation magnetic flux density Bmax, and the magnetic flux on the outer surface S1 side in the tube material S. It is the same as in the first embodiment that the magnetization (the magnetic flux density in the region A1 shown in FIG. 5) is preferably magnetized so that the magnetic flux density is 60% or more and less than 80% of the saturation magnetic flux density Bmax.

本実施形態に係る磁気探傷方法によれば、管材Ｓの内面Ｓ２に存在する欠陥Ｄを簡易に且つ精度良く検出することが可能である。   According to the magnetic flaw detection method according to the present embodiment, it is possible to easily and accurately detect the defect D existing on the inner surface S2 of the tube material S.

＜第３実施形態＞
図６は、本発明の第３実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。
本実施形態に係る磁気探傷方法は、直流磁化手段１が電流貫通棒である点が第２実施形態と異なる。
本実施形態に係る磁気探傷方法でも、第２実施形態と同様に、管材Ｓの検査対象面である内面Ｓ２と反対側の面である外面Ｓ１に対向するようにセンサコイル３を配置する。また、電流貫通棒１を管材Ｓの軸方向に挿通する。電流貫通棒１は、その周囲に（すなわち、管材Ｓの内面Ｓ２に沿った）磁界を形成可能である。そして、センサコイル３に交流電流を通電すると共に、電流貫通棒１に直流電流を通電する。これにより、欠陥Ｄが存在しない場合に、管材Ｓにおける外面Ｓ１側の磁束密度（図６に示す領域Ａ１の磁束密度）が飽和磁束密度未満で且つ管材Ｓにおける内面Ｓ２側の磁束密度（図６に示す領域Ａ２の磁束密度）よりも小さくすることが可能である。そして、センサコイル３のインピーダンス変化に基づき、内面Ｓ２に存在する欠陥Ｄを検出することができる。 <Third Embodiment>
FIG. 6 is a diagram schematically showing a device configuration for executing the magnetic flaw detection method according to the third embodiment of the present invention.
The magnetic flaw detection method according to this embodiment is different from the second embodiment in that the DC magnetizing means 1 is a current through bar.
Also in the magnetic flaw detection method according to the present embodiment, the sensor coil 3 is disposed so as to face the outer surface S1 that is the surface opposite to the inner surface S2 that is the inspection target surface of the tube material S, as in the second embodiment. Further, the current through bar 1 is inserted in the axial direction of the tube material S. The current penetration rod 1 can form a magnetic field around it (that is, along the inner surface S2 of the tube material S). Then, an alternating current is passed through the sensor coil 3 and a direct current is passed through the current through bar 1. Thereby, when there is no defect D, the magnetic flux density on the outer surface S1 side in the tube material S (the magnetic flux density in the region A1 shown in FIG. 6) is less than the saturation magnetic flux density and the magnetic flux density on the inner surface S2 side in the tube material S (FIG. 6). The magnetic flux density of the region A2 shown in FIG. And based on the impedance change of the sensor coil 3, the defect D which exists in the inner surface S2 can be detected.

管材Ｓにおける内面Ｓ２側の磁束密度（図６に示す領域Ａ２の磁束密度）が飽和磁束密度Ｂｍａｘの８０％以上１００％以下の磁束密度となるように磁化し、管材Ｓにおける外面Ｓ１側の磁束密度（図６に示す領域Ａ１の磁束密度）が飽和磁束密度Ｂｍａｘの６０％以上８０％未満の磁束密度となるように磁化することが好ましい点は、第２実施形態と同様である。   Magnetization is performed so that the magnetic flux density on the inner surface S2 side in the tube material S (the magnetic flux density in the region A2 shown in FIG. 6) is 80% to 100% of the saturation magnetic flux density Bmax, and the magnetic flux on the outer surface S1 side in the tube material S. Similar to the second embodiment, the magnetizing is preferably performed so that the density (the magnetic flux density in the region A1 shown in FIG. 6) is 60% or more and less than 80% of the saturation magnetic flux density Bmax.

本実施形態に係る磁気探傷方法によれば、管材Ｓの内面Ｓ２に存在する欠陥Ｄを簡易に且つ精度良く検出することが可能である。特に、本実施形態に係る磁気探傷方法によれば、管材Ｓの内面全体を検査するに際しては、電流貫通棒１は動かさずに、センサコイル３だけを管材Ｓの外面Ｓ１に沿って動かせばよいので、ハンドリングし易く、検査が極めて簡易になるという利点も有する。   According to the magnetic flaw detection method according to the present embodiment, it is possible to easily and accurately detect the defect D existing on the inner surface S2 of the tube material S. In particular, according to the magnetic flaw detection method according to this embodiment, when inspecting the entire inner surface of the tube material S, only the sensor coil 3 needs to be moved along the outer surface S1 of the tube material S without moving the current through bar 1. Therefore, it has the advantage that it is easy to handle and the inspection becomes extremely simple.

＜第４実施形態＞
図７は、本発明の第４実施形態に係る磁気探傷方法を実行するための装置構成を模式的に示す図である。
本実施形態に係る磁気探傷方法は、電磁石１が管材Ｓの外面Ｓ１に対向するように配置されると共に、電磁石１の形状が異なる点が第２実施形態と異なる。
本実施形態に係る磁気探傷方法でも、第２実施形態と同様に、管材Ｓの検査対象面である内面Ｓ２と反対側の面である外面Ｓ１に対向するようにセンサコイル３を配置する。電磁石１は、前述のように外面Ｓ１に対向するように配置され、内面Ｓ２に沿った磁界を形成可能である。本実施形態の電磁石１は、第２実施形態と異なり、管材Ｓの外面Ｓ１に対向する各磁極端面１ａ、１ｂの中心を結ぶ直線Ｌ（この直線Ｌ上の磁界強度が最も大きくなると考えられる）が、管材Ｓの内面Ｓ２又は管材Ｓの内面Ｓ２より内側を通る（図７に示す例では内面Ｓ２より内側を通っている）形状とされている。そして、センサコイル３に交流電流を通電すると共に、電磁石１のコイルに直流電流を通電する。これにより、欠陥Ｄが存在しない場合に、管材Ｓにおける外面Ｓ１側の磁束密度（図７に示す領域Ａ１の磁束密度）が飽和磁束密度未満で且つ管材Ｓにおける内面Ｓ２側の磁束密度（図７に示す領域Ａ２の磁束密度）よりも小さくすることが可能である。そして、センサコイル３のインピーダンス変化に基づき、内面Ｓ２に存在する欠陥Ｄを検出することができる。 <Fourth embodiment>
FIG. 7 is a diagram schematically showing an apparatus configuration for executing the magnetic flaw detection method according to the fourth embodiment of the present invention.
The magnetic flaw detection method according to the present embodiment is different from the second embodiment in that the electromagnet 1 is disposed so as to face the outer surface S1 of the tube material S and the shape of the electromagnet 1 is different.
Also in the magnetic flaw detection method according to the present embodiment, the sensor coil 3 is disposed so as to face the outer surface S1 that is the surface opposite to the inner surface S2 that is the inspection target surface of the tube material S, as in the second embodiment. The electromagnet 1 is disposed so as to face the outer surface S1 as described above, and can form a magnetic field along the inner surface S2. Unlike the second embodiment, the electromagnet 1 of the present embodiment is a straight line L connecting the centers of the magnetic pole end surfaces 1a and 1b facing the outer surface S1 of the tube material S (the magnetic field strength on the straight line L is considered to be the largest). However, the inner surface S2 of the tube material S or the inner surface S2 of the tube material S is passed through (in the example shown in FIG. 7, the shape passes through the inner surface S2). Then, an alternating current is passed through the sensor coil 3 and a direct current is passed through the coil of the electromagnet 1. Thereby, when there is no defect D, the magnetic flux density on the outer surface S1 side in the tube material S (the magnetic flux density in the region A1 shown in FIG. 7) is less than the saturation magnetic flux density and the magnetic flux density on the inner surface S2 side in the tube material S (FIG. 7). The magnetic flux density of the region A2 shown in FIG. And based on the impedance change of the sensor coil 3, the defect D which exists in the inner surface S2 can be detected.

管材Ｓにおける内面Ｓ２側の磁束密度（図７に示す領域Ａ２の磁束密度）が飽和磁束密度Ｂｍａｘの８０％以上１００％以下の磁束密度となるように磁化し、管材Ｓにおける外面Ｓ１側の磁束密度（図７に示す領域Ａ１の磁束密度）が飽和磁束密度Ｂｍａｘの６０％以上８０％未満の磁束密度となるように磁化することが好ましい点は、第２実施形態と同様である。   Magnetization is performed such that the magnetic flux density on the inner surface S2 side of the tube material S (the magnetic flux density in the region A2 shown in FIG. 7) is 80% to 100% of the saturation magnetic flux density Bmax, and the magnetic flux on the outer surface S1 side of the tube material S. It is the same as that of the second embodiment in that the magnetization (the magnetic flux density in the region A1 shown in FIG. 7) is preferably magnetized so that the magnetic flux density is 60% or more and less than 80% of the saturation magnetic flux density Bmax.

本実施形態に係る磁気探傷方法によれば、管材Ｓの内面Ｓ２に存在する欠陥Ｄを簡易に且つ精度良く検出することが可能である。特に、本実施形態に係る磁気探傷方法によれば、電磁石１及びセンサコイル３の双方が管材Ｓの外面Ｓ１側に位置するため、ハンドリングし易く、検査が極めて簡易になるという利点も有する。   According to the magnetic flaw detection method according to the present embodiment, it is possible to easily and accurately detect the defect D existing on the inner surface S2 of the tube material S. In particular, according to the magnetic flaw detection method according to the present embodiment, since both the electromagnet 1 and the sensor coil 3 are located on the outer surface S1 side of the tube material S, there is an advantage that the handling is easy and the inspection becomes extremely simple.

なお、第１、第２、第４実施形態では、直流磁化手段１として電磁石を用いており、被検査材Ｓに作用させる磁界強度を変更し易い点で好ましいものの、本発明はこれに限るものではなく、直流磁化手段１として永久磁石を用いることも可能である。   In the first, second, and fourth embodiments, an electromagnet is used as the DC magnetizing means 1, which is preferable in that the magnetic field intensity applied to the material to be inspected S can be easily changed, but the present invention is not limited to this. Instead, it is also possible to use a permanent magnet as the DC magnetizing means 1.

１・・・直流磁化手段
２・・・感磁性センサ
３・・・センサコイル
Ｓ１・・・検査対象面と反対側の面
Ｓ２・・・検査対象面
Ａ１・・・検査対象面と反対側の面側
Ａ２・・・検査対象面側
Ｄ・・・欠陥 DESCRIPTION OF SYMBOLS 1 ... DC magnetization means 2 ... Magnetic sensor 3 ... Sensor coil S1 ... Surface S2 on the opposite side to inspection object surface ... Inspection object surface A1 ... On the opposite side to inspection object surface Surface side A2 ... Inspection target surface side D ... Defect

Claims (6)

被検査材の検査対象面と反対側の面に対向するようにセンサコイルを配置して該センサコイルに交流電流を通電すると共に、前記被検査材における前記反対側の面側の磁束密度が飽和磁束密度未満で且つ前記被検査材における前記検査対象面側の磁束密度よりも小さくなるように直流磁化手段を配置して該直流磁化手段によって前記被検査材を磁化し、
前記センサコイルのインピーダンス変化に基づき、前記検査対象面に存在する欠陥を検出することを特徴とする磁気探傷方法。 A sensor coil is arranged so as to face the surface of the material to be inspected opposite to the surface to be inspected, and an alternating current is passed through the sensor coil, and the magnetic flux density on the opposite surface side of the material to be inspected is saturated. DC magnetizing means is disposed so as to be less than the magnetic flux density and smaller than the magnetic flux density on the surface to be inspected in the test material, and the test material is magnetized by the DC magnetizing means,
A magnetic flaw detection method, comprising: detecting a defect existing on the inspection target surface based on a change in impedance of the sensor coil. 前記直流磁化手段は、前記被検査材における前記反対側の面側の磁束密度が飽和磁束密度の６０％以上８０％未満となり、前記被検査材における前記検査対象面側の磁束密度が飽和磁束密度の８０％以上〜１００％以下となるように、前記被検査材を磁化することを特徴とする請求項１に記載の磁気探傷方法。   In the DC magnetizing means, the magnetic flux density on the opposite surface side of the inspection material is 60% or more and less than 80% of the saturation magnetic flux density, and the magnetic flux density on the inspection object surface side of the inspection material is the saturation magnetic flux density. 2. The magnetic flaw detection method according to claim 1, wherein the material to be inspected is magnetized so as to be 80% to 100%. 前記被検査材は板材であり、
前記直流磁化手段は、前記検査対象面に対向するように配置され、前記検査対象面に沿った磁界を形成する電磁石又は永久磁石であることを特徴とする請求項１又は２に記載の磁気探傷方法。 The material to be inspected is a plate material,
3. The magnetic flaw detection according to claim 1, wherein the DC magnetizing unit is an electromagnet or a permanent magnet that is arranged to face the inspection target surface and forms a magnetic field along the inspection target surface. Method. 前記被検査材は管材であり、
前記検査対象面は前記管材の内面であり、
前記直流磁化手段は、前記管材の内面に対向するように配置され、前記管材の内面に沿った磁界を形成する電磁石又は永久磁石であることを特徴とする請求項１又は２に記載の磁気探傷方法。 The material to be inspected is a pipe material,
The inspection target surface is an inner surface of the pipe material,
3. The magnetic flaw detection according to claim 1, wherein the DC magnetizing means is an electromagnet or a permanent magnet that is arranged to face the inner surface of the tube material and forms a magnetic field along the inner surface of the tube material. Method. 前記被検査材は管材であり、
前記検査対象面は前記管材の内面であり、
前記直流磁化手段は、前記管材の軸方向に挿通され、直流電流が通電される電流貫通棒であることを特徴とする請求項１又は２に記載の磁気探傷方法。 The material to be inspected is a pipe material,
The inspection target surface is an inner surface of the pipe material,
3. The magnetic flaw detection method according to claim 1, wherein the DC magnetizing means is a current penetrating rod that is inserted in an axial direction of the tube material and is supplied with a DC current. 前記被検査材は管材であり、
前記検査対象面は前記管材の内面であり、
前記直流磁化手段は、前記管材の外面に対向するように配置され、前記管材の内面に沿った磁界を形成する電磁石又は永久磁石であり、
前記管材の外面に対向する前記直流磁化手段の各磁極端面の中心を結ぶ直線が、前記管材の内面又は前記管材の内面より内側を通ることを特徴とする請求項１又は２に記載の磁気探傷方法。 The material to be inspected is a pipe material,
The inspection target surface is an inner surface of the pipe material,
The DC magnetizing means is an electromagnet or a permanent magnet that is disposed so as to face the outer surface of the pipe material and forms a magnetic field along the inner surface of the pipe material,
3. The magnetic flaw detection according to claim 1, wherein a straight line connecting the centers of the magnetic pole end faces of the DC magnetization means facing the outer surface of the tube material passes through the inner surface of the tube material or the inner surface of the tube material. Method.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019060723A (en) * 2017-09-27 2019-04-18 日立造船株式会社 Eddy current flaw detector and eddy current flaw detection method
CN117589862A (en) * 2024-01-18 2024-02-23 湖北工业大学 Magnetic chromatography detection device and method

Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5223389A (en) * 1975-08-15 1977-02-22 Nippon Steel Corp Eddy current flaw detection method for internal surfaces of steel pipe s
JPS52105885A (en) * 1976-03-02 1977-09-05 Nippon Kokan Kk Method of detecting seam of electrically welded steel pipe and device for following up the seam
JPS5585249A (en) * 1978-12-22 1980-06-27 Hitachi Ltd Vortex flow detector
US4477776A (en) * 1981-11-02 1984-10-16 Magnetic Analysis Corporation Apparatus and process for flux leakage testing using transverse and vectored magnetization
JPS6358253A (en) * 1986-08-29 1988-03-14 Idemitsu Petrochem Co Ltd Method and device for eddy current flaw detection
JPH05164745A (en) * 1991-12-13 1993-06-29 Nkk Corp Method and device for detecting flaw of steel body
JPH0843358A (en) * 1994-07-27 1996-02-16 Kawasaki Steel Corp Eddy-current flaw detecting method for steel pipe
JPH09210967A (en) * 1996-01-30 1997-08-15 Sumitomo Metal Ind Ltd Flaw detecting device
JP2004257912A (en) * 2003-02-27 2004-09-16 Hitachi Ltd Method and device for inspecting wall thickness reduction
JP2004279055A (en) * 2003-03-12 2004-10-07 Sumitomo Metal Ind Ltd Method and apparatus for measuring carburization depth on inner surface of steel pipe
US20070222438A1 (en) * 2006-03-23 2007-09-27 Dale Reeves Electromagnetic flaw detection apparatus for inspection of a tubular
JP2010127854A (en) * 2008-11-28 2010-06-10 Non-Destructive Inspection Co Ltd Method and apparatus for evaluating defect of tubular object
US20120306483A1 (en) * 2009-11-16 2012-12-06 Innospection Group Limited Electromagnet inspection apparatus and method
CN104215688A (en) * 2014-08-22 2014-12-17 国家电网公司 Separable online electromagnetic non-destructive detection device for high-voltage transmission line

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5223389A (en) * 1975-08-15 1977-02-22 Nippon Steel Corp Eddy current flaw detection method for internal surfaces of steel pipe s
JPS52105885A (en) * 1976-03-02 1977-09-05 Nippon Kokan Kk Method of detecting seam of electrically welded steel pipe and device for following up the seam
JPS5585249A (en) * 1978-12-22 1980-06-27 Hitachi Ltd Vortex flow detector
US4477776A (en) * 1981-11-02 1984-10-16 Magnetic Analysis Corporation Apparatus and process for flux leakage testing using transverse and vectored magnetization
JPS6358253A (en) * 1986-08-29 1988-03-14 Idemitsu Petrochem Co Ltd Method and device for eddy current flaw detection
JPH05164745A (en) * 1991-12-13 1993-06-29 Nkk Corp Method and device for detecting flaw of steel body
JPH0843358A (en) * 1994-07-27 1996-02-16 Kawasaki Steel Corp Eddy-current flaw detecting method for steel pipe
JPH09210967A (en) * 1996-01-30 1997-08-15 Sumitomo Metal Ind Ltd Flaw detecting device
JP2004257912A (en) * 2003-02-27 2004-09-16 Hitachi Ltd Method and device for inspecting wall thickness reduction
JP2004279055A (en) * 2003-03-12 2004-10-07 Sumitomo Metal Ind Ltd Method and apparatus for measuring carburization depth on inner surface of steel pipe
US20070222438A1 (en) * 2006-03-23 2007-09-27 Dale Reeves Electromagnetic flaw detection apparatus for inspection of a tubular
JP2010127854A (en) * 2008-11-28 2010-06-10 Non-Destructive Inspection Co Ltd Method and apparatus for evaluating defect of tubular object
US20120306483A1 (en) * 2009-11-16 2012-12-06 Innospection Group Limited Electromagnet inspection apparatus and method
CN104215688A (en) * 2014-08-22 2014-12-17 国家电网公司 Separable online electromagnetic non-destructive detection device for high-voltage transmission line

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019060723A (en) * 2017-09-27 2019-04-18 日立造船株式会社 Eddy current flaw detector and eddy current flaw detection method
CN111133308A (en) * 2017-09-27 2020-05-08 日立造船株式会社 Eddy current flaw detection device and eddy current flaw detection method
JP7048028B2 (en) 2017-09-27 2022-04-05 日立造船株式会社 Eddy current flaw detection system and eddy current flaw detection method
US11320401B2 (en) 2017-09-27 2022-05-03 Hitachi Zosen Corporation Eddy current flaw detection device and eddy current flaw detection method
CN111133308B (en) * 2017-09-27 2023-01-24 日立造船株式会社 Eddy current flaw detection method
CN117589862A (en) * 2024-01-18 2024-02-23 湖北工业大学 Magnetic chromatography detection device and method

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