JP2020112424A - Build-up metal part inspection method and valve manufacturing method using the same - Google Patents

Abstract

To provide a build-up metal part inspection method that can detect internal defects of a build-up metal part, and a valve manufacturing method using the same.SOLUTION: A build-up metal part inspection method is characterized by comprising an inspection step of detecting internal defects of a build-up metal part having crystal of a dendrite structure and grain boundary carbide of 10 μm or less in the grain boundary of the crystal by using an ultrasonic-flaw detector. Also, a valve manufacturing method is characterized by comprising the inspection step of detecting the internal defects of the build-up metal part having the crystal of the dendrite structure and the grain boundary carbide of the size of 10 μm or less in the grain boundary of the crystal by using the ultrasonic-flaw detector, and a manufacturing step of manufacturing a valve including the build-up metal part passing through the inspection step.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for inspecting a metal deposit and a valve manufacturing method using the method.

For the purpose of improving the performance of the metal, a metal deposit may be formed by overlaying the metal surface. The technique described in Patent Document 1 is known as a technique for detecting a defect in a metal deposit. Patent Document 1 discloses a valve that is used by being attached to a pipe of a nuclear power plant and is cobalt-free, yet has excellent wear resistance, impact resistance, and corrosion resistance, and can maintain good fluid sealability for a long period of time. Providing a valve is described (see abstract). In the technique described in Patent Document 1, a defect on the valve seat surface is detected by a penetrant inspection (PT inspection) (see paragraph 0028).

JP, 2016-33451, A

The technique described in Patent Document 1 only detects defects on the surface of the metal deposit. Therefore, the technique described in Patent Document 1 cannot detect the internal defect in the metal deposit.
It is an object of the present invention to provide a method for inspecting a metal-deposited part capable of detecting an internal defect in the metal-deposited part, and a valve manufacturing method using the method.

The present invention is characterized by including an inspection step of detecting, by an ultrasonic flaw detector, an internal defect in a metal-filled portion having a dendride structure crystal and a grain boundary carbide having a size of 10 μm or less at a grain boundary between the crystals. A method for inspecting a metal deposit. Other solutions will be described later in the embodiments for carrying out the invention.

According to the present invention, it is possible to provide a method for inspecting a metal-deposited part capable of detecting an internal defect in the metal-deposited part, and a method for manufacturing a valve using the method.

It is sectional drawing of the valve which concerns on this embodiment. It is a microscope picture about the cross-section organization of the heap metal part formed in the valve seat. It is the A section enlarged photograph of FIG. 2A. It is a microscope picture about the cross-sectional structure of the heap metal part formed by the arc welding method which is a conventional method. It is a flow chart which shows the manufacturing method of the valve concerning this embodiment. FIG. 6 is a process drawing that is performed in the method for manufacturing a valve according to the present embodiment. It is a perspective view of the test body used for examination of the influence on an ultrasonic flaw detection test. FIG. 6B is a sectional view taken along line BB of FIG. 6A. It is a graph which shows the evaluation result of an ultrasonic flaw detection test.

Hereinafter, a mode for carrying out the present invention (this embodiment) will be described with reference to the drawings. However, the present invention is not limited to the following contents, and can be implemented by arbitrarily modifying it without departing from the gist of the present invention. Further, the same members will be denoted by the same reference numerals, and overlapping description will be omitted. Furthermore, the embodiments may be combined in any manner without departing from the scope of the invention.

The method for manufacturing a valve according to this embodiment uses the method for inspecting a metal deposit portion according to this embodiment. Therefore, for convenience of description, first, the structure of the valve (including the metal-filled portion) according to the present embodiment will be described, and the method of inspecting the metal-plated portion will be described in the valve manufacturing method described later. However, the method of inspecting the metal-filled portion of the present embodiment does not necessarily have to be performed in the valve manufacturing method of the present embodiment. That is, the inspection of the metal deposit portion does not necessarily have to be performed together with the manufacture of the valve. For example, the valve seat having the metal-plated portion may be inspected by using the metal-plated portion inspection method, and the valve seat having the inspection completed may be shipped as a product (that is, without manufacturing the valve). In addition, for example, an internal valve inspection method may be used for an existing valve, valve seat, or the like to detect an internal defect of the inspection metal deposit.

FIG. 1 is a sectional view of a valve 10 according to this embodiment. The valve 10 is installed, for example, in a pipe (not shown) through which a fluid flows in a nuclear facility. The valve 10 includes a valve box 1, a valve seat 2, a valve body 3, a valve rod 4, and a handle wheel 5 as valve members constituting the valve 10. On the surface of the valve seat 2, a metal deposit 21 that contacts the valve body 3 is formed. On the surface of the valve body 3, a metal deposit 31 that contacts the valve seat 2 is formed. When the handle wheel 5 rotates, the valve rod 4 and the valve body 3 rotate and drive vertically. When the valve rod 4 is driven downward, the heap portion 31 of the valve body 3 comes into contact with the heap portion 21 of the valve seat 2 while rotating. That is, while the rotating valve body 3 slides on the surface of the valve seat 2, the valve body 3 comes into close contact with the valve seat 2. As a result, the valve 10 is closed.

The metal deposits 21, 31 are formed on the valve member surfaces of both the valve seat 2 and the valve body 3 (either one of the valve member surfaces may be used). Each of the heap metallurgical portion 21 and the metal heap metal portion 31 has a crystal of dendride structure and a grain boundary carbide having a size of 10 μm or less (preferably 5 μm or less) at a grain boundary between the crystals. Therefore, in the following description, for simplification of the description, both the metal depositing portions 21 and 31 will be described by exemplifying the metal depositing portion 21.

FIG. 2A is a micrograph of the cross-sectional structure of the metal deposit 21 formed on the valve seat 2. The metal structure shown in FIG. 2A can be formed, for example, by overlaying a metal raw material by laser additive manufacturing. In FIG. 2A, a white portion is a crystal 21a (metal crystal) having a dendrite structure. Further, the black portion is the grain boundary carbide 21b formed at the grain boundary between the crystals 21a. Dense grain boundary carbides 21b are scatteredly formed in the heap portion 21 of the present embodiment. The grain boundary carbides 21b precipitated at the grain boundaries of the crystal 21a are extremely small and the number thereof is also small.

FIG. 2B is an enlarged photograph of part A of FIG. 2A. In the metal deposit 21 of the present embodiment, the size of the grain boundary carbide 21b is 10 μm or less. The size here refers to the length of a line segment connecting the furthest portions of the grain boundary carbide 21b. In the example of FIG. 2B, the grain boundary carbide 21b has a size of about 2 μm to 3 μm. The grain boundary carbide 21b is formed in a film shape along the surface of the crystal 21a at the grain boundary of the crystal 21a. Therefore, using the expression “thickness” as the size of the grain boundary carbide 21b, the thickness of the grain boundary carbide 21b is 10 μm or less (about 2 μm to 3 μm in the example of FIG. 2).

According to the study by the present inventors, when the deposit portion 21 is inspected using the ultrasonic flaw detector, ultrasonic reflection occurs at the grain boundary carbide 21b. Therefore, it is possible to prevent ultrasonic reflection from occurring by making the grain boundary carbides 21b minute. That is, the ultrasonic waves are difficult to be reflected by the minute grain boundary carbides 21b. As a result, ultrasonic reflection can be generated only in the internal defects (for example, voids, bubbles, etc., having a size of, for example, about 0.2 mm or more) of the metal deposit 21. An internal defect in the metal deposit 21 can be detected by inspecting the metal deposit 21 using an ultrasonic flaw detector.

FIG. 3 is a photomicrograph of the cross-sectional structure of the metal deposit 21c formed by a conventional arc welding method. The arc welding method is a method in which the amount of heat input is larger than that of the laser additive manufacturing method capable of forming the metal structure shown in FIGS. 2A and 2B. Similar to the arc welding method, a TIG welding method or the like can be mentioned as a method in which the heat input amount is larger than that in the laser additive manufacturing method.

Also in FIG. 3, the white portion is a crystal 21d (metal crystal) having a dendrite structure. The black portion is the grain boundary carbide 21e formed at the grain boundary between the crystals 21d. In the heap metallurgical portion 21c shown in FIG. 3, the crystals 21d and the grain boundary carbides 21e are larger than those of the metal heap metallurgical portion 21 shown in FIGS. 2A and 2B. Specifically, in the heap portion 21c, the crystal 21d and the grain boundary carbide 21e both greatly exceed 10 μm. In particular, grain boundary carbides 21e having a size exceeding 10 μm are precipitated along the grain boundaries of the crystal 21d.

As described above, in the inspection using the ultrasonic flaw detector, the ultrasonic waves are reflected by the grain boundary carbide 21e. Therefore, as a result of a large grain boundary carbide 21e and a large ultrasonic reflection portion, a large number of ultrasonic reflections other than internal defects occur. As a result, the ultrasonic reflection due to the internal defect is also detected, and the internal defect cannot be accurately detected. Therefore, it is impossible to perform an inspection using the harmonic flaw detection device on the metal deposit 21c having the grain boundary carbides 21e having a size exceeding 10 μm. However, according to the present embodiment in which the grain boundary carbide 21b has a thickness of 10 μm or less, ultrasonic reflection due to the grain boundary carbide 21b can be suppressed, and the internal defect of the deposit portion 21 can be appropriately detected.

FIG. 4 is a flowchart showing a method of manufacturing the valve 10 according to this embodiment. The method of manufacturing the valve 10 includes a method of inspecting the metal deposits 21 and 31. The method of inspecting the metal deposits 21 and 31 includes an inspection process (including a defect position determining process) for inspecting the metal deposits 21 and 31 using an ultrasonic flaw detector, and a removal process (sliding together). Process, and optionally a build-up process). In addition, the method of inspecting the metal deposit portions 21 and 31 may include a pre-inspection step performed before the inspection step, if necessary.

The metal deposit 31 of the valve body 3 can be manufactured (formed) and inspected in the same manner as the metal deposit 21 of the valve seat 2 is manufactured (formed) and inspected. Therefore, for simplification of the description, in the following example, the description of the heap portion 31 of the valve body 3 is omitted. Further, as described above, in the description of the method for manufacturing the valve 10, the method for inspecting the metal deposit 21 provided in the valve 10 will be described. However, the method of inspecting the deposit portion 21 does not necessarily have to be performed together with the manufacture of the valve 10.

First, a base material (not shown) that will become the valve seat 2 is manufactured by forming the heap portion 21 (step S1). The base material is made of, for example, carbon steel, stainless steel, or the like, and is processed into, for example, an annular shape. Next, the metal deposit 21 is formed on the surface of the base material by overlaying the base material by laser additive manufacturing (step S2, metal deposit forming step). That is, by melting the metal raw material using the laser beam on the surface of the base material, the metal deposit 21 formed of the metal raw material is formed on the surface of the base material.

In the overlaying on the base material by the laser additive manufacturing, the deposit portion 21 to be formed has a crystal 21a having a dendrite structure and a grain boundary carbide 21b having a size of 10 μm or less at the grain boundary between the crystals 21a. Perform under high conditions. In general, in laser overlay manufacturing, unlike welding such as TIG welding and gas welding, local heat input can be performed at a target position where overlaying is performed. As a result, the base material temperature other than the target position remains low, and after the build-up to the target position, the build-up portion is rapidly cooled by heat dissipation to the surrounding low temperature portion. The excessive cooling of the crystal 21a having the dendrite structure is suppressed by the rapid cooling of the buildup portion, and the crystal 21a becomes dense. Therefore, the grain boundary carbides 21b formed at the grain boundaries of the crystal 21a also become dense. As a result, the metal deposit 21 formed by laser additive manufacturing has crystals 21a of dendride structure and grain boundary carbides 21b of 10 μm or less at grain boundaries between the crystals 21a.

The composition of the metal raw material (the constituent material of the metal deposit part 21) used for overlaying is not particularly limited. For example, a cobalt-based alloy can be used as the metal raw material. As the cobalt-based alloy, for example, chromium 10 mass% or more and 35 mass% or less, carbon 0.1 mass% or more and 3 mass% or less, tungsten 0 mass% or more and 15 mass% or less, and the balance cobalt and unavoidable impurities Mixtures can be used. Specific examples of such a mixture include Stellite (registered trademark). By configuring the metal deposit 21 with the metal raw materials having these compositions, the corrosion resistance and wear resistance of the metal deposit 21 can be improved. Therefore, even if the valve body 3 slides on the valve seat 2, it is possible to obtain the valve seat 2 and the valve body 3 that are not easily worn.

The shape of the metal raw material used for overlaying is not particularly limited, and can be, for example, a wire or powder. Moreover, the laser additive manufacturing can be performed using an arbitrary laser additive manufacturing apparatus, and for example, a 3D printer can be used.

The laser output may be set such that the metal raw material is completely melted and the temperature does not rise excessively during melting, and it depends on the composition of the metal raw material. The laser output may be set so that the heat input amount per 1 cm of the distance is, for example, about 1 kJ to 20 kJ. However, from the viewpoint of increasing the bonding strength to the base material 22, it is preferable that the heat input amount is the largest immediately after the start of overlaying and the heat amount is reduced as the distance from the base material increases. As a result, the grain boundary carbide 21b on the surface (the surface on the side opposite to the base material) of the metal deposit 21 can be 10 μm or less, and the ultrasonic reflection at the grain boundary carbide 21b can be sufficiently suppressed. Further, the grain boundary carbide 21b having a grain size of 10 μm or less suppresses continuous corrosion in the grain boundary carbide 21b, and the corrosion resistance of the metal deposit 21 can be enhanced.

After forming the base metal portion 21 on the base material, the base metal portion 21 is planarized by appropriately sliding the metal base portion 21 to complete the valve seat 2 (see FIG. 1) (step S3). The sliding can be performed using, for example, a jig such as a sliding surface plate. The valve 10 (see FIG. 1) including the valve seat 2 is assembled using the completed valve seat 2 (step S4). Assembly can be done in any way. However, an inspection step (described later) of the valve seat 2 may be performed before assembly.

The valve 10 is assembled in a factory, for example, and the assembled valve 10 is inspected before shipping from the factory. Specifically, the valve 10 is once disassembled so that the valve seat 2 can be inspected by an ultrasonic flaw detector (not shown), and the metal deposit 21 of the valve seat 2 is exposed to the outside. Then, in order to detect the internal defect of the metal deposit 21 using the ultrasonic flaw detector, the ultrasonic flaw inspection of the valve seat 2 is performed (step S5, inspection step). An internal flaw in the valve seat 2 can be detected by ultrasonic flaw detection. In particular, when the presence or absence of an internal defect in the base material is inspected before the formation of the metal deposit 21, the internal defect of the metal deposit 21 can be detected in this step.

The inspection conditions by the ultrasonic flaw detector are not particularly limited. As the inspection condition, for example, the method defined in JIS Z2344-1993 (the general rule of ultrasonic flaw detection test method by pulse reflection method for metal material) can be applied.

As a result of the inspection, if there is no internal defect (step S6, No), it is confirmed that the valve element 3 hits the valve seat 2 (step S7). The hit confirmation is performed by using a paint such as Komeitan. When the hit is good (step S8, Yes), the valve 10 is reassembled, and the valve 10 including the deposit portion 21 that has undergone the inspection process is manufactured (step S9, manufacturing process). The manufactured valve 10 is shipped from the factory. On the other hand, when the hit is not good (No in step S8), the metal deposit portion 21 is flattened by sliding (step S10). Then, the valve 10 including the flattened metal deposit 21 is assembled and shipped from the factory.

When the internal defect is detected in the above step S5 (inspection step) (step S6, No), the detected internal defect is removed by the sliding of the metal deposit 21 as follows. That is, the removal step of removing the internal defect includes a sliding step of removing the internal defect by sliding the metal deposit 21 together. By removing the internal defect, it is possible to prevent the internal defect from being newly detected during maintenance of the valve 10. Further, by removing the internal defect by sliding, it is possible to easily remove the internal defect.

First, the height direction position (the thickness direction position of the metal deposit part 21) of the internal defect in the metal deposit part 21 is determined (step S11, defect position determination step, inspection step). The position of the internal defect in the height direction can be determined based on the intensity of the reflected ultrasonic wave, which will be described later in detail with reference to FIG. 7. Then, the built-up portion 21 is rubbed on the basis of the position of the internal defect in the height direction, whereby the internal defect is removed. That is, the internal defect is removed by cutting (cutting) the surface of the metal deposit portion 21 to a position deeper than the position of the internal defect in the height direction (step S12, sliding step, removing step). It is possible to suppress the excessive scraping of the metal deposit 21 by the sliding based on the position in the height direction. As a result, it is possible to suppress the deterioration of the function of the valve seat 2 due to the excessive shaving of the metal deposit 21 and to ensure the function of the valve seat 2. Further, the internal defect can be surely removed by performing the sliding to scrape the surface of the metal-plated portion to a position deeper than the position of the internal defect in the height direction.

However, in order to remove the internal defect, the removal process may include a build-up process performed by overlaying the exposed internal defect by shaving the surface of the metal deposit portion 21. Although details will be described later with reference to FIG. 5C, internal defects (corresponding to the internal defects 23 in FIG. 5C) are exposed by the sliding. Then, the exposed internal defect may be subjected to a build-up to fill the internal defect by the same method as the method of forming the metal deposit 21 to remove the internal defect. By removing the internal defects by overlaying the exposed internal defects, it is possible to reduce the scraping amount (cutting thickness) of the metal deposit 21.

After removing the internal defect, the above steps S7 to S10 are performed to manufacture the valve 10.

In addition to the above-described steps, the method for inspecting the metal deposits 21 and 31 may include a pre-inspection step for detecting surface defects of the metal deposits 21 by the penetrant inspection device before step S5 (inspection step). By including the pre-inspection step, it is possible to find the surface defect of the deposit 21 before the ultrasonic flaw detection test. Thus, the deposit portion 21 after the surface defects are removed can be inspected using the ultrasonic flaw detector (step S5, inspection step). As a result, only the internal defect can be efficiently detected using the ultrasonic flaw detector.

5A to 5C are process drawings performed in the method of manufacturing the valve 10 according to the present embodiment. FIG. 5A shows the valve seat 2 having a length (thickness) L in the height direction. In the valve seat 2, the thickness of the metal deposit 21 is L1 and the thickness of the base material 22 is L2. In some cases, the bonding interface between the metal deposit 21 and the base material 22 is not clear in some cases, but the snow image interface is explicitly shown in FIG. 5 for simplification of the drawing. An internal defect 23 formed of, for example, a void is present in the metal deposit 21. The position of the internal defect 23 in the height direction is L3 as a distance from the outer surface (surface on the side to be irradiated with ultrasonic waves) of the metal deposit 21 as shown in FIG. 5B. The height direction position of the internal defect 23 can be determined by ultrasonic flaw detection as described above.

As shown in FIG. 5C, the internal defects 23 are exposed on the surface of the metal-plated portion 21 due to the sliding of the metal-plated portion 21. By repeating the sliding operation once or twice or more, the internal defect 23 can be exposed by shaving by the thickness L3. Further, in the above example, the sliding is performed based on the position of the internal defect 23 in the height direction, but the sliding is performed not based on the position of the internal defect 23 in the height direction, and the exposed internal portion happens to occur during the sliding. It may be a defect 23.

Then, when the internal defects 23 are exposed and the sliding is performed again in the state shown in FIG. 5C, the metal deposit 21 is scraped by the thickness L4. As a result, the valve seat 2 shown in FIG. 5(d) from which the internal defect 23 is removed is obtained.

According to the inspection method of the present embodiment, it is possible to provide a method for inspecting the built-up portion 21 that can detect an internal defect in the built-up portion 21. In particular, in the metal deposit portion 21, the grain boundary carbides 21b that cause ultrasonic reflection in the ultrasonic flaw detection inspection are dense (10 μm or less). Therefore, when ultrasonic waves are applied to the metal-filled portion 21 having the dense grain boundary carbide 21b, ultrasonic reflection by the grain-boundary carbide 21b is less likely to occur inside the metal-filled portion 21. Thereby, ultrasonic reflection can be generated only in the internal defect of the metal deposit 21. As a result, the internal flaw can be detected by the ultrasonic flaw detector without destroying the metal deposit 21.

When an internal defect is detected by inspection before factory shipment, the internal defect can be removed by, for example, sliding. This makes it possible to reduce the number of internal defects that do not exist or have a large effect on the performance, and improve the reliability of the valve 10. Further, the valve 10 can be shipped in a state in which the possibility of an internal defect existing in the fill-up portion 21 is sufficiently reduced by the inspection before shipment from the factory. Therefore, the valve 10 with improved quality can be shipped.

Further, since the valve 10 having the internal defects sufficiently removed is installed, it is unlikely that a new internal defect will be exposed due to the sliding operation performed on the metal deposit 21 during maintenance. Therefore, it is not necessary to perform an internal defect removal operation due to the exposure of a new internal defect (for example, removal by repeating sliding ((rough finishing, intermediate finishing and main finishing)). As a result, maintenance can be simplified and the time required for maintenance can be shortened. In particular, when the valve 10 is installed in a nuclear facility, the time required for maintenance can be shortened, and thus the exposure can be reduced.

Further, since the internal defects are sufficiently removed, the maintenance performed after the installation can be performed by rubbing the surface of the metal deposit part 21 according to the stroke of the valve 10. Therefore, the thickness of the metal deposit 21 can be ensured for a long period of time, and the period of use of the valve 10 can be extended.

Moreover, according to the manufacturing method of the valve 10 including the inspection method of the present embodiment, it is possible to detect the internal defect of the metal deposit 21 during the manufacturing of the valve 10 and provide the user with the highly reliable valve 10. In particular, since the grain boundary carbide 21b in the heap portion 21 is dense, continuous corrosion and wear originating from the grain boundary carbide 21b due to contact of fluid (water, gas, etc.) with the grain boundary carbide 21b is prevented. Can be suppressed. As a result, in the valve 10, the corrosion resistance and wear resistance of the deposit portion 21 are improved. Therefore, the reliability of the valve 10 can be sufficiently enhanced in combination with the high durability resulting from the reduction of internal defects.

The effect of the grain boundary carbide 21b on the ultrasonic flaw detection test was examined by preparing a test body shown in FIG.

FIG. 6A is a perspective view of the test body 101 used for studying the influence on the ultrasonic flaw detection test. The ultrasonic flaw detector 110, the probe 111, and the opening 123 will be described later with reference to FIG. 6B. The test body 101 (corresponding to the valve seat 2) has a cylindrical base material 122 and an annular heap portion 121 (equivalent to the heap portion 21) formed concentrically with the upper surface of the base material 122. It was made by that. In the manufactured test body 101, the thickness (height direction length) of the metal deposit 121 was 6 mm, and the thickness of the base material 122 was 80 mm. The metal deposit 121 was formed by overlaying by laser additive manufacturing using Stellite (registered trademark). The metallographic structure of the metal deposit 121 in the test body 101 is the metallographic structure shown in FIG. Therefore, the size of the grain boundary carbide 21b in the test body 101 is several μm (10 μm or less).

6B is a cross-sectional view taken along the line BB of FIG. 6A. A hole 124 extending in the radial direction of the base material 122 is formed on the side surface of the base material 122 below the metal deposit portion 21. The hole 124 communicates with the outside through the opening 123, and has a circular cross section (diameter 3 mm) in the radial direction of the base material 122. The hole 124 is formed horizontally so that the upper end of the hole 124 is located at a position approximately 6.5 mm from the upper surface of the base material 122. Therefore, the hole 124 is formed at a position approximately 14.5 mm from the upper surface of the metal deposit 121. Then, ultrasonic waves were radiated from the upper surface of the metal deposit 121 toward the base material 122, and it was evaluated whether or not ultrasonic reflection caused by the hole 124 could be detected without being affected by the metal deposit 121.

The ultrasonic flaw detection was performed by irradiating ultrasonic waves to the upper surface of the metal deposit 121 from above the hole 124 using the probe 111 connected to the ultrasonic flaw detector 110. For convenience of illustration, the probe 111 is illustrated as being separated from the metal deposit part 121, but it is arranged as close to the metal component 121 as possible. The ultrasonic irradiation conditions were a gain of 15.0 dB, a pulse position of 0 mm, a measurement range of 100.0 mm, a test frequency of 5 MHz narrow, a sound velocity of 5900 m/sec, and a refraction angle vertical.

FIG. 7 is a graph showing the evaluation results of the ultrasonic flaw detection test. The horizontal axis of the graph shown in FIG. 7 is the distance from the lower end (irradiation end of ultrasonic waves) of the probe 111, and the vertical axis represents the intensity of the ultrasonic waves reflected and returned to the probe 111. As shown in FIG. 7, mainly three peaks C, D, and E were observed. Of the three observed peaks C, D, and E, the intensity of peak C detected at the position of 6 mm is 8%, the intensity of peak D detected at the position of 12.8 mm is 22%, and that of 86.1 mm. The intensity of the peak E detected at the position was 32%. Based on the distance on the horizontal axis corresponding to each peak, peak C is caused by reflection at the bonding interface between the metal deposit 121 and the base material 122, peak D is caused by reflection at the hole 124, and peak is It is considered that E is caused by the reflection on the lower end surface of the base material 122.

In the graph shown in FIG. 7, the peak was not disturbed in the distance from 0 mm to 6 mm (the position of the peak C) corresponding to the height direction of the metal deposit 121. Then, the peak D was not disturbed between these distances, and the peak D caused by the ultrasonic reflection at the hole 124 of the base material 122 and the peak E caused by the reflection at the lower end surface of the base material 122 could be detected. .. As described above, the size of the grain boundary carbide 21b in the heap portion 121 is 10 μm or less. Therefore, by setting the size of the grain boundary carbides 21b to 10 μm or less, it is possible to suppress the reflection disturbance of ultrasonic waves and to detect the position of the hole 124 in the height direction. Therefore, since the disturbance of the ultrasonic waves is suppressed in the heap metallurgical portion 21 having the grain boundary carbide 21b having a size of 10 μm or less, the internal defect 23 of the metal heap metal portion 21 can be detected. In addition, the ultrasonic flaw inspection can also determine the position of the internal defect 23 in the height portion 21 in the height direction. Furthermore, the thickness of the metal deposit 21 can be determined.

1 Valve Box 10 Valve Body 101 Specimen 110 Ultrasonic Flaw Detector 111 Probe 121 Plated Part 122 Base Metal 123 Opening 124 Hole 2 Valve Seat (Valve Member)
21 heap metal portion 21a crystal 21b grain boundary carbide 21c metal heap portion 21d crystal 21e grain boundary carbide 22 base metal 23 internal defect 3 valve body (valve member)
31 heap portion 4 valve rod 5 handle S2 step (heather portion forming step)
S5 step (inspection process)
S9 step (manufacturing process)
S11 step (defect position determination step, inspection step)
S12 step (sliding process, removing process)

Claims (11)

A metallurgical deposit comprising an inspection step of detecting, by an ultrasonic flaw detector, an internal defect of a metal deposit having a dendride structure crystal and a grain boundary carbide having a size of 10 μm or less at a grain boundary between the crystals. Inspection method. The method of inspecting a metal deposit part according to claim 1, further comprising a removing step of removing the internal defect detected in the inspecting step. The method of inspecting the metal-filled portion according to claim 2, wherein the removing step includes a rubbing step of sliding the metal-coated portion together. The depositing process according to claim 2 or 3, wherein the removing process includes a build-up process performed by overlaying the internal defects exposed by shaving the surface of the deposit. Method. The inspecting step includes a defect position determining step of determining a height direction position of the internal defect in the fill-up portion,
5. The removing step removes the internal defect by sliding the metal-plated portion on the basis of the position of the internal defect in the height direction. Inspection method for the listed metal deposit. The method for inspecting a metal deposit part according to claim 5, wherein the removing step is performed by shaving the surface of the metal deposit part to a position deeper than the position of the internal defect in the height direction. Before the inspecting step, a pre-inspecting step of detecting a surface defect of the bank portion by a penetrant inspection device is included. The method for inspecting the bank portion according to any one of claims 1 to 6, further comprising: .. The metal deposit part according to any one of claims 1 to 7, wherein the metal deposit part is formed on a surface of at least one valve member of the valve seat and the valve body. Inspection method. The said valve member includes the valve member which comprises the valve installed in the nuclear power facility. The inspection method of the metal deposit part of Claim 8 characterized by the above-mentioned. An inspection step of detecting, by an ultrasonic flaw detection device, an internal defect in the metal-filled portion having a crystal of dendride structure and a grain boundary carbide having a size of 10 μm or less at a grain boundary between the crystals;
And a manufacturing step of manufacturing a valve including the fill-up portion that has undergone the inspection step. The method for manufacturing a valve according to claim 10, further comprising: a build-up portion forming step of forming the build-up portion by overlaying a base material by laser additive manufacturing.