JP2005262218A - Inspection method of weld zone, welding method and welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method of a weld zone under multilayer welding, a method which is applicable to a case even where radiographic testing or ultrasonic flaw detection is difficult to perform, and which has a short testing time, easy automation and effective detection for a flaw between or inside welding layers, and also to provide a welding method using this inspection method as well as welding equipment for the implementation of the welding method. <P>SOLUTION: The inspection method of a weld zone under multilayer welding is characterized in that an eddy current flaw detection is performed on a welding layer each time it is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for inspecting a welded portion, a welding method using the inspection method, and a welding apparatus used for carrying out the welding method. More specifically, a weld inspection method characterized by inspecting a welded portion of multi-layer welding by applying an eddy current test (ECT), a welding method using the inspection method, and the welding method The present invention relates to a welding apparatus used for performing the above.

  In the welding of thick plate stainless steel used for a pressure vessel or the like, multilayer welding construction (multilayer deposition) is performed in which two or more weld layers are stacked. As a volume inspection (nondestructive inspection) method for welding by multi-layer welding, a radiation transmission test (RT) is used (Japanese Patent No. 2848494). Further, when RT is difficult to apply, such as welding at a construction site, an ultrasonic flaw detection test (UT) is used.

  However, there are cases where it is difficult to apply the UT due to material characteristics such as welding of austenitic stainless steel. In this case, a multilayer PT that performs a penetration flaw detection test (PT) on each weld layer at the time of welding is applied. Here, PT means that a penetrating liquid is applied to an inspection target, the inside of the surface of the inspection target is filled with the permeating liquid by capillary action, and the excess permeating liquid on the surface is wiped off. This is a method for obtaining and observing a spraying instruction pattern, and can inspect whether there is an opening flaw on the surface of the inspection object. Multi-layer PT is used as an alternative to volume inspection by RT or UT by performing PT for each weld layer at the time of multi-layer welding.

  However, PT can only detect opening flaws on the surface of the inspection object, and defects in each weld layer cannot be detected even when PT is performed for each weld layer. Therefore, it cannot be said that the volume inspection is sufficient.

  Furthermore, PT needs to be coated with a penetrating liquid (penetration flaw detection agent) on the object to be inspected and wiped off so as not to leave dirt. Therefore, the inspection time becomes long and automation is difficult. In addition, waste such as wiping paper is generated, and when wiping is insufficient, there may be a problem that dirt remains in the welded portion. Furthermore, problems such as inapplicability in a high temperature environment, difficulty in reproducibility, and cumbersome storage of records due to recording with photographs and the like have been pointed out.

  As a technique used for nondestructive inspection of a metal material, an eddy current test (ECT) is known in addition to the RT, UT and PT. In this method, an alternating current coil is brought close to an inspection object (derivative), an eddy current is generated in the inspection object by electromagnetic induction, and a change in the current is detected to detect defects in the inspection object. It is a method for detecting the presence or absence of a thin film, and its application to an inspection method (soundness diagnosis method) of a welded portion of a thin plate is known (Japanese Patent Laid-Open No. 5-223788).

However, since the detectable region of ECT is limited to the vicinity of the surface, it has been considered difficult to apply as a completion inspection after multilayer welding of thick plate stainless steel or the like from the viewpoint of detectability. Therefore, it has been desired to develop a volume inspection method for a welded part that can be applied when RT or UT is difficult and that does not have the problems of conventional multilayer PTs.
JP-A-5-223788 Japanese Patent No. 2848494

  The present invention is a method for inspecting a welded portion used when RT or UT is difficult to apply, such as when performing volume inspection of welding of austenitic stainless steel thick plates at a construction site, and is a conventional multilayer PT To provide a method for inspecting a welded portion having excellent characteristics such as being free from the above-mentioned problems, that is, having a short inspection time and being easy to automate, and being effective in detecting defects occurring in each weld layer. Is an issue. It is another object of the present invention to provide a welding method using the inspection method and a welding apparatus used for carrying out the welding method.

  This invention achieves the said subject by the structure characterized by performing ECT about this welding layer for every formation of each welding layer of multilayer welding construction. As a result of the study, the present inventor found that the problems of the prior art were solved by using ECT instead of PT and performing ECT for each weld layer formation, and completed the present invention. .

  The present invention provides a method for inspecting a welded part in multi-layer welding according to claim 1, wherein the welded layer is subjected to ECT for each welded layer formation. To do. Multi-layer welding means a welding method characterized in that a multi-layer weld layer is formed by repeating welding on the weld, and as described above, welding of thick stainless steel in the production of pressure vessels Etc.

  The method for inspecting a welded portion according to the present invention is characterized in that ECT is performed on the weld layer every time the weld layer is formed. The conditions of ECT are not particularly limited, and can be implemented under the same conditions as known ECT for welds applied to inspection of thin plates.

  ECT is a high-speed and simple volume inspection method, and the present inventor has found that even if ECT is performed for each formation of the weld layer, the inspection time is not particularly long and automation is easy. . That is, the problem of the multi-layer PT that the inspection time is long and automation is difficult is solved.

  Moreover, since each welding layer of multilayer welding construction is thin, there is little problem of ECT detection. That is, by performing ECT for each weld layer, the problem of the prior art that volume inspection is difficult from the viewpoint of detectability is solved.

  Furthermore, the ECT has a feature that the sensitivity in the depth direction can be adjusted by selecting the frequency. Therefore, by appropriately selecting the operating frequency in accordance with the thickness of the welded portion, it is also effective in detecting defects that occur between the weld layers, such as insufficient penetration between the weld layers, and defects that occur inside the weld layers. Therefore, the problem of the multilayer PT, that is, the problem that only the opening flaw on the surface of each weld layer can be detected and is insufficient as a volume inspection is solved.

  The present invention provides the welding method according to claim 2, wherein the welding layer forming step and the inspection step of performing ECT on the weld layer at the end of the weld layer forming step are repeated a plurality of times. . Since the welding layer forming step and the inspection step are repeated a plurality of times, the welding method of the present invention performs multilayer welding.

  Since the welding method of the present invention uses the above-described inspection method for welds, in which ECT is performed every time the weld layer is formed, the same effect as the effect described for the inspection method, that is, the inspection time. It is short and easy to automate, and is effective in detecting defects in the weld layer and in the weld layer. Therefore, the welding method of the present invention enables highly reliable welding with few defects and high productivity.

  According to a third aspect of the present invention, there is provided a welding apparatus for use in multi-layer welding construction, comprising a welding construction means and an eddy current test means. This apparatus has both a welding construction means and an eddy current testing test means, forms a weld layer by the welding construction means, performs ECT of the formed welding layer by the eddy current testing test means, and repeats this. Thus, the welding method of the present invention can be carried out.

  The type of welding performed by the welding means is not particularly limited as long as it is used for ordinary multilayer welding, and examples include arc welding, gas welding, resistance welding, electron beam welding, and laser beam welding. The eddy current testing means is usually composed of an ECT probe and its attached device, but the means is arranged so that ECT can be performed immediately after the weld layer is formed by the welding construction means. Is preferable for shortening the construction time and improving productivity.

  In particular, it is preferable that the welding means and the eddy current flaw detection test means are provided in conjunction with each other. Here, the term "provided so as to be linked" means that when the welding construction means and the eddy current flaw detection testing means move together and the welding construction means moves to weld another part after welding a part A, This means that the eddy current flaw detection test means moves to the part A together with the movement of the welding construction means, and both are arranged so that ECT can be performed on the part A.

  Claim 4 corresponds to this preferred embodiment, and provides the welding apparatus as described above, wherein the welding construction means and the eddy current flaw detection test means are provided so as to interlock with each other. To do. As mentioned above, ECT is easy to automate. Therefore, it is preferable to automate the welding construction means because both the weld formation process and the inspection process are automated, and the productivity is greatly improved. That is, the apparatus which combined the ECT probe for welding parts and the automatic welding machine is a more preferable aspect of the welding apparatus of this invention.

  The weld inspection method of the present invention is applied to inspection of welds in multi-layer welding construction where RT and UT are difficult to apply, and is a volume inspection method that replaces the conventional multi-layer PT. The inspection time is short and automation is easy. As a result, the productivity of welding is improved. Further, since no waste is generated and the inspection is performed without contact with the object to be inspected, there is no problem that dirt remains on the object to be inspected.

  Further, it is effective for detecting not only opening flaws on the surface of each weld layer but also defects occurring in each weld layer or inside the weld layer, and is an excellent volume inspection method.

  Furthermore, the multilayer PT cannot be applied in a high temperature environment due to the necessity of applying a penetrating solution, but the weld inspection method of the present invention by ECT can be applied in a high temperature environment.

  The method for inspecting a welded portion of the present invention further has features such as excellent reproducibility and excellent recordability because a detection result is obtained as an electric signal.

  The welding method of the present invention uses this excellent inspection method, and the welding apparatus of the present invention also has means for carrying out this excellent inspection method. By using the welding apparatus of the invention, highly reliable welding with few defects can be performed with high productivity.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. However, this mode is an example of the present invention, and the scope of the present invention is not limited to this mode.

  FIG. 1 is a conceptual diagram showing an example of a welding apparatus of the present invention. The welding apparatus in the example of FIG. 1 has an automatic welder 1 as welding construction means and an ECT device 4 as eddy current flaw detection testing means. The automatic welding machine 1 has a welding torch 2, and welding is performed by the welding torch 2. In this example, the welding method is not particularly limited. For example, in the case of arc welding, the welding torch 2 is an arc generating means, in the case of electron beam welding, it is an electron beam generating means, and in the case of gas welding, it is a gas burner. The automatic welding machine 1 has a function of supplying a current for generating an arc or electron beam and a gas for gas welding to the welding torch 2 and controlling the same.

  The ECT device 4 has an ECT probe 3, and the ECT probe 3 has a coil for passing an alternating current, and has a function of generating an eddy current in the inspection object and detecting a change in the current. The ECT device 4 supplies alternating current for generating an eddy current to the ECT probe 3 and processes a signal detected by the ECT probe 3.

  The weld base materials 61 and 62 are arranged so that their side surfaces are aligned, and the weld line 5 is placed on the abutted portion, and the weld line 5 is melted and solidified by the welding torch 2 to form a weld layer. It is formed. The welding torch 2 is scanned along the welding line in the direction of the arrow in the figure, but the welding torch 2 and the ECT probe 3 are interlocked, and the ECT probe 3 is also along the welding line in the direction of the arrow in the figure. ECT is performed on the formed weld. As described above, the welding apparatus of the example of FIG. 1 performs the inspection by ECT simultaneously with the welding operation by automatic welding, and the volume inspection becomes possible by applying this to each layer at the time of the multilayer welding operation.

  FIG. 2 is a perspective view of the ECT probe 3 used in the welding apparatus of the example of FIG. As described above, when the ECT probe 3 uses a coil that passes alternating current and applies a time-varying magnetic field to a material to be inspected made of a conductor such as a metal, eddy current or magnetization generated in the material to be inspected is This is based on the principle that changes due to defects such as cracks existing in the material to be inspected. In this case, the lift-off, which is the distance between the coil and the material to be inspected, is an important parameter that affects the output characteristics of the eddy current sensor. Therefore, in order to keep the lift-off constant, the ECT probe 3 is attached to a sensor jig (not shown) having a pair of guide rolls, and the bottom face is positioned above a predetermined height with respect to the lower face of the guide rolls. Thus, the ECT probe 3 is fixed.

  The ECT probe 3 has a coil in which a detection coil 8 for detecting a change in eddy current and an excitation coil 9 for generating eddy current are wound around a core 7 as constituent elements. Moreover, it is a rotary probe, and it detects by rotating while moving forward in the welding line direction. In this example, an appropriate lift-off is provided between the ECT probe 3 and the material to be inspected, but it is possible to make a diagnosis by lightly contacting the material to be inspected without providing a lift-off. It is also possible to use other probes, for example, point contact type probes.

It is a conceptual diagram which shows an example of the welding apparatus of this invention. It is a perspective view of the ECT probe used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Automatic welding machine 2 Welding torch 3 ECT probe 4 ECT apparatus 5 Welding wire 61, 62 Welding base material 7 Core 8 Detection coil 9 Excitation coil

Claims (4)

  A method for inspecting a welded part in a multi-layer welding process, wherein an eddy current flaw detection test is performed on each welded layer every time the welded layer is formed.   A welding method characterized by repeating a welding layer forming step and an inspection step of performing an eddy current flaw detection test on the weld layer every time the welding layer forming step is completed.   A welding apparatus for use in multi-layer welding, comprising welding means and eddy current testing means. The welding apparatus according to claim 3, wherein the welding construction means and the eddy current flaw detection testing means are interlocked.

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