JP2009216514A - Residual stress evaluation system and residual stress measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evaluate accurately a residual stress, especially an internal residual stress, of a measuring object member. <P>SOLUTION: This system has a strain measuring device 13 for measuring a strain value of a strain gage 12 laminated on the measuring object member 11; a surface residual stress calculation device 14 for calculating a surface residual stress of the measuring object member from the strain value measured by the strain measuring device; a database 15 for storing correlatively data of a surface residual stress and an internal residual stress determined beforehand relative to a sample having a constitution similar to the measuring object member, a welding condition when preparing a sample, a beveling shape of the sample, and a material characteristic of the sample; and an internal residual stress evaluation device 16 for estimating and evaluating the internal residual stress of the measuring object member by being collated with data in the database based on the surface residual stress calculated by the surface residual stress calculation device, the welding condition, the beveling shape and the material characteristic of the measuring object member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a residual stress evaluation system that evaluates residual stress generated in a measurement target member such as a welded structure, and a residual stress measurement method that measures internal residual stress generated in the measurement target member.

  Thermal power and hydraulic power equipment are becoming more cost-effective and more important to procure, and aggressively weld to structures that have conventionally avoided welding as much as possible (for example, rotating bodies such as turbine rotors). Adopting a structure is being considered. However, in examining the reliability of these welded structures, there are problems such as welding defects, welding residual stress / weld deformation, and material characteristics of the heat affected zone. In particular, regarding welding residual stress, although there is a high impact on fatigue and burst, a sufficient evaluation method has not been studied for thermal and hydraulic equipment. It is necessary to ensure reliability.

  Patent Documents 1 and 2 are known examples of known methods for measuring welding residual stress. In Patent Document 1, a triaxial strain gauge is pasted on the surface of a member, and then the surface layer on which the triaxial strain gauge is pasted is peeled thinly by an electric discharge machining stripping device, so that the surface residual from the strain change appearing in the triaxial strain gauge This is a method for obtaining stress.

Patent Document 2 is a method that, in addition to Patent Document 1, obtains an inherent strain from the released strain measured by a strain gauge, obtains an elastic strain / intrinsic strain matrix by a finite element method, and outputs the most probable value of the surface residual stress.
JP 10-48069 A JP 2005-181172 A

  The residual stress measurement method described in Patent Document 1 is a method of releasing the strain by thinly peeling the surface layer of the measurement target member, and is suitable for evaluating the surface residual stress, but evaluating the internal residual stress of the measurement target member. In this case, it is necessary to repeat peeling, and a lot of time is required for measurement. In addition, when peeling away thickly in order to evaluate the internal residual stress, it is necessary to modify the electric discharge machine main body and the electrode.

  Moreover, although the residual stress measuring method described in Patent Document 2 is suitable for the evaluation of surface residual stress as in Patent Document 1, it is difficult to evaluate the internal residual stress.

  An object of the present invention is to provide a residual stress evaluation system capable of accurately evaluating the residual stress of a member to be measured, particularly the internal residual stress.

  Another object of the present invention is to provide a residual stress measurement method capable of measuring the internal residual stress of a member to be measured with high accuracy.

  The residual stress evaluation system according to the present invention measures a strain initial value by attaching a strain gauge to a measurement target member, and then extracts a portion where the strain gauge is attached, calculates the residual stress by releasing the strain. It is a residual stress evaluation system for evaluating, a strain measuring device for measuring a strain value of the strain gauge affixed to the measurement target member, and a surface residue of the measurement target member from the strain value measured by the strain measurement device Surface residual stress calculation device for calculating stress, surface residual stress and internal residual stress obtained in advance for a sample having the same configuration as the measurement target member, welding conditions at the time of sample preparation, groove shape of the sample, and A database that stores data such as material characteristics of a sample in association with each other, a surface residual stress calculated by the surface residual stress calculation device, and the measurement target member An internal residual stress evaluation device that estimates and evaluates internal residual stress of the measurement target member based on welding conditions, groove shape, and material characteristics, and collates with data in the database. Is.

  The residual stress measurement method according to the present invention is a residual stress measurement method for measuring internal residual stress of a measurement target member. A plurality of holes having different depths are drilled in a measurement target member, and Each strain gauge is attached to the bottom surface to measure the initial strain value of the bottom surface of this processed hole, and then the portion where the strain gauge is attached is collected, from the release strain measured by the strain gauge at this time, The internal residual stress at an arbitrary depth of the measurement target member is obtained.

  According to the residual stress evaluation system according to the present invention, the internal residual stress evaluation apparatus estimates and evaluates the internal residual stress of the measurement target member from the surface residual stress calculated for the measurement target member. Residual stress, especially internal residual stress, can be evaluated with high accuracy.

  Further, according to the residual stress measuring method according to the present invention, the internal residual stress is obtained from the strain of the bottom surface of the processed hole drilled in the measurement target member, so that the internal residual stress of the measurement target member can be measured with high accuracy.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1A is a system configuration diagram illustrating a configuration of an embodiment of a residual stress evaluation system according to the present invention, FIG. 1B is an explanatory diagram illustrating a measurement state of an initial strain value in a measurement target member, and FIG. FIG. 6 is an explanatory diagram showing a repair situation of a peeling sampling portion in a measurement target member.

  The residual stress evaluation system 10 shown in FIG. 1 releases a strain by attaching a strain gauge 12 to a measurement target member 11 and measuring an initial strain value, then collecting the portion to which the strain gauge 12 is attached and releasing the strain. Is measured with a strain gauge 12, surface residual stress is determined from the released strain, and internal residual stress is determined based on the surface residual stress. The residual stress evaluation system 10 includes a strain gauge 12, a strain measuring device 13 as a strain measuring device, a surface residual stress calculating device 14, a database 15, an internal residual stress evaluating device 16, a quality determining device 17, an output device 18, and It has a welding torch 19 and a cutting cutter 20 which are welding devices as smoothing means.

  The measurement target member 11 is a welded structure, for example, a welded product such as a welded rotor of a turbine. The strain measuring device 13 is connected to the strain gauge 12 attached to the measurement target member 11 by an electric wire 21 and measures the strain value of the strain gauge 12. First, the strain measuring device 13 measures the initial strain value of the measurement target member 11 to which the strain gauge 12 is attached.

The surface residual stress calculation device 14 calculates and measures the surface residual stress of the measurement target member 11 from the strain values measured by the strain gauge 12 and the strain measuring device 13. That is, the surface residual stress calculation device 14 is configured such that after the initial strain value of the measurement target member 11 is measured by the strain gauge 12 and the strain measuring device 13, the surface layer 11A to which the strain gauge 12 is attached is subjected to electric discharge machining and wire cutting. Alternatively, the surface residual stress of the member 11 to be measured is calculated from the strain change (that is, the release strain) measured by the strain gauge 12 and the strain measuring instrument 13 when it is peeled off and collected by electric discharge polishing. The following equation (1) is used for calculating the surface residual stress. Moreover, the measuring method of the surface residual stress at this time is the below-mentioned cutting method.
[Equation 1]
σ0 = E · ε (1)
σ0: surface residual stress, E: elastic modulus, ε: release strain

  The database 15 includes data such as surface residual stress and internal residual stress obtained in advance for the sample 22 (see FIGS. 2 to 5), welding conditions at the time of preparing the sample 22, groove shape of the sample 22, and material characteristics of the sample 22. Are stored in association with each other. Here, the sample 22 is manufactured by the same configuration as the measurement target member 11, that is, by the same material and welding method as the measurement target member 11.

  Moreover, the welding conditions at the time of preparation of the sample 22 are welding heat input, welding speed, number of welding passes, welding rod material, welding specifications, and the like. The material properties of the sample 22 include the linear expansion coefficient, specific heat, melting point temperature, phase transformation characteristics, structure, elastic modulus, and the like of the sample 22. A method for measuring the surface residual stress and the internal residual stress of the sample 22 stored in the database 15 will be described in detail later.

  The internal residual stress evaluation device 16 collates with data in the database 15 based on the surface residual stress of the measurement target member 11 calculated by the surface residual stress calculation device 14, the welding conditions, the groove shape, and the material characteristics of the measurement target member 11. Then, the internal residual stress of the measurement target member 11 is estimated and evaluated. That is, the internal residual stress evaluation device 16 includes the surface residual stress of the measurement target member 11 calculated by the surface residual stress calculation device 14, the welding conditions, the groove shape, and the material characteristics of the measurement target member 11, and the data in the database 15. The surface residual stress of the sample 22 in the database 15 that matches the surface residual stress of the measurement target member 11 calculated by the surface residual stress calculation device 14, the welding conditions, the groove shape, and the material characteristics of the measurement target member 11. The internal residual stress of the sample 22 associated with the welding condition, groove shape, and material property data is extracted from the database 15 and is used as the estimated value of the internal residual stress of the measurement target member 11.

  The quality judgment device 17 is the internal residual stress of the measurement target member 11 estimated or evaluated by the internal residual stress evaluation device 16 (or the internal residual stress and the surface residual stress of the measurement target member 11 calculated by the surface residual stress calculation device 14). The quality of the measurement target member 11 is determined based on the above. This quality pass / fail judgment is made when the residual stress (internal residual stress, or internal residual stress and surface residual stress) is equal to or low with respect to the design residual stress (pass), and when it is high (fail). And It is also possible to reject the case where the design residual stress and the measured residual stress are equal depending on the setting. The design residual stress value is arbitrarily set because it varies depending on welding conditions and materials used.

  The output device 18 includes the surface residual stress of the measurement target member 11 calculated by the surface residual stress calculation device 14, the internal residual stress of the measurement target member 11 evaluated by the internal residual stress evaluation device 16, and the quality determined by the quality determination device 17. Output the judgment result.

  The welding torch 19 and the cutting cutter 20 are for finishing the peeling sampling part 11B of the measurement target member 11 from which the surface layer 11A has been peeled off smoothly. The welding torch 19 welds and repairs the peeling sampling portion 11B to form the build-up welded portion 11C, and the cutting cutter 20 cuts the surface of the measurement target member 11 to the depth of the peeling sampling portion 11B. Further, welding repair by the welding torch 19 and cutting by the cutting cutter 20 may be combined, and for example, the built-up welded part 11C repaired by the welding torch 19 may be cut by the cutting cutter 20 to be processed smoothly. By the repair process of the welding torch 19 and the cutting cutter 20, the measurement target member 11 can be used as a product even after the residual stress measurement.

  Next, a method for measuring the surface residual stress stored in the database 15 will be described with reference to FIGS. The surface residual stress stored in the database 15 is calculated by using the sample 22 and at least one of the cutting method (FIG. 2), the drilling method (FIG. 3), and the Sachs method (FIG. 4).

  As shown in FIG. 2, the cutting method is performed by attaching a strain gauge 23 on the surface of the weld line 29 of the sample 22 and measuring the initial strain value (FIG. 2A). As shown in FIG. 2B, the strain is released by cutting (cutting out) by electric discharge machining or electrolytic polishing, or the sample 22 is cut by wire cutting or the like as shown in FIG. The strain is released by cutting with a strain gauge, and the strain change (that is, the release strain) at this time is measured by a strain gauge 23 and a strain measuring instrument (not shown), and the surface residual stress is calculated from the released strain using the equation (1). It is a method of calculating and measuring.

  In the drilling method, as shown in FIG. 3, after a strain gauge 23 is attached to the surface of the sample 22 on the weld line 29 and the initial strain value is measured, a hole 24 is drilled in the sample 22 using a drill or the like. Then, the strain is released, the strain change (that is, the release strain) at this time is measured by the strain gauge 23 and a strain measuring device (not shown), and the surface residual stress is calculated from the released strain using the equation (1). It is a method of measuring.

  In the Sachs method, as shown in FIG. 4, after the strain gauge 23 is attached to the surface of the sample 22 on the weld line 29 and the initial strain value is measured, the sample 22 is subjected to electric discharge machining, electropolishing, lathe machining, or the like. For example, the inner peripheral surface 22A of the sample 22 is cut to release strain, and the strain change (that is, release strain) at this time is measured by a strain gauge 23 and a strain measuring instrument (not shown). From this, the surface residual stress is calculated and measured using equation (1).

  Next, a method for measuring the internal residual stress stored in the database 15 will be described with reference to FIGS.

  The internal residual stress stored in the database 15 is obtained by drilling a plurality of holes (processed holes 25) having different depths in the sample 22 and attaching strain gauges 27 to the bottom surfaces 26 of these processed holes 25, respectively. After the initial strain value of the bottom surface 26 of the hole 25 is measured using the strain gauge 27 and the strain measuring device 28, the portion to which the strain gauge 27 is attached is sampled and measured with the strain gauge 27 and the strain measuring device 28 at this time. This is data obtained by calculating the internal residual stress at an arbitrary depth of the sample 22 from the strain change (that is, the release strain).

  The sample 22 is an axially symmetric weld joint having a weld line 29 perpendicular to the axial direction, for example, a cylindrical butt weld joint shown in FIG. The sample 22 may be a welded joint composed of a plurality of flat plates. A plurality of processed holes 25 are drilled in the sample 22 in parallel or perpendicular to the weld line 29. The machining holes 25 arranged parallel to the welding line 29 are suitable for measuring the stress distribution of the heat-affected zone along the welding line 29, and the machining holes 25 arranged perpendicular to the welding line 29 are It is suitable for measuring the stress distribution in the vicinity of the welding line 29 and the position away from the welding line 29.

  Further, the processed hole 25 has a circular or rectangular cross section, and the bottom surface 26 is smoothly perforated. The cross sectional shape of the processed hole 25 is selected according to the shape of the strain gauge 27. Further, the processing hole 25 is formed in the thickness direction of the sample 22, for example, in the case of the cylindrical butt weld joint shown in FIG. 5, in the radial direction as shown in FIG. By drilling the hole 22 in the radial direction in the sample 22, the residual stress in the same direction (radial direction) is released, but the residual stress in the axial direction and the circumferential direction, which are the measurement targets, is lightly released. Therefore, the influence on the measurement result of the residual stress can be ignored even by drilling the processed hole 25.

  For attaching the strain gauge 27 to the bottom surface 26 of the processing hole 25, a strain gauge attaching device 30 shown in FIGS. 6 and 7 is used. This strain gauge affixing device 30 comprises a tip 31 covered with a plastic film 32, and a strain gauge 27 having an adhesive applied to a sticking surface 33 is attached to the tip 31. The tip 31 of the strain gauge affixing device 30 is made of a metal material or a non-metal material, preferably elastic silicon rubber or the like. The plastic film 32 is a film that is not bonded even by the adhesive for bonding the strain gauge 27.

  In this state, the tip 31 of the strain gauge affixing device 30 is inserted into the machining hole 25 of the sample 22 (FIG. 7A), and the affixing surface of the strain gauge 27 is positioned on the bottom surface 26 of the machining hole 25. The tip 31 of the strain gauge affixing device 30 is pressed and brought into close contact with the bottom surface 26 of the processing hole 25 (FIG. 7B), and then the strain gage affixing device 30 is pulled out from the processing hole 25 (FIG. 7C). )), A strain gauge 27 is attached to the bottom surface 26 of the processing hole 25. As shown in FIG. 6, the strain gauge 27 is connected to a strain measuring device 28 via an electric wire 34. With the strain gauge 27 attached to the bottom surface 26 of the machining hole 25, the initial strain value of the bottom surface 26 is measured by the strain gauge 27 and the strain measuring device 28.

  Here, the affixing of the strain gauge 27 by the strain gage affixing device 30 is similarly applied to the later-described strain gauge 27A. The strain gauge 27 </ b> A is also connected to the strain measuring device 28 via the electric wire 34.

After the above-described initial strain value is measured, the surface layer 35 of the bottom surface 26, which is the portion to which the strain gauge 27 is attached, in a state where the strain gauge 27 is attached to the bottom surface 26 of the machining hole 25, for example, electric discharge machining or the like. And isolated by Then, the strain gauge 27 and the strain measuring device 28 measure the release strain from the change of the strain value at this time. From this released strain, the internal residual stress at an arbitrary depth of the sample 22 is calculated and measured using the following equation (2).
[Equation 2]
σd = E · ε (2)
σd: internal residual stress, E: elastic modulus, ε: release strain

  After measurement of the initial strain value, the sample 22 is cut by wire cutting or the like with the strain gauge 27 attached to the bottom surface 26 of the processed hole 25, and the bottom surface 26, which is the portion to which the strain gauge 27 is attached. A portion of block 36 is taken. Then, the strain change at this time is measured as a release strain by the strain gauge 27 and the strain measuring instrument 28, and the internal residual stress at an arbitrary depth of the sample 22 may be calculated and measured using the equation (2). .

  Further, when measuring the internal residual stress at a deeper position based on the drilled hole 25, the surface layer of the bottom surface 26 of the hole 25 drilled in the sample 22 is attached with a strain gauge 27. The other strain gauge 27A is attached to the peeling bottom surface 37 after peeling 35, and the initial strain value of the peeling bottom surface 37 is measured by the strain gauge 27A and the strain measuring device 28. Thereafter, the surface layer 38 of the peeling bottom surface 37 is peeled off by, for example, electric discharge machining with the strain gauge 27A attached. The strain gauge 27A and the strain measuring instrument 28 measure the release strain from the strain change at this time, and the internal residual stress is calculated from the release strain using the equation (2) and measured.

  As another method for measuring the internal residual stress at a deeper position based on the drilled hole 25, a surface layer 35 on which a strain gauge 27 is attached to the bottom surface 26 of the hole 25 drilled in the sample 22. After peeling off, a deeper processed hole 39 is further drilled using a drill or the like, and another strain gauge 27A is attached to the bottom surface (deep bottom surface) 40 of the processed hole 39. The initial strain value of the bottom surface 40 is measured by the measuring device 28. Thereafter, the surface layer 41 of the bottom surface 40 is peeled off by electric discharge machining or the like with the strain gauge 27A attached. The strain gauge 27A and the strain measuring device 28 measure the release strain from the change in strain value at this time, and the internal residual stress is calculated from the release strain using the equation (2) and measured.

  Since the residual stress evaluation system 10 of the present embodiment is configured as described above, the following effects (1) and (2) are achieved.

  (1) The internal residual stress evaluation device 16 stores in the database 15 based on the surface residual stress calculated by the surface residual stress calculation device 14 for the measurement target member 11, the welding conditions, the groove shape, and the material characteristics of the measurement target member 11. Data (that is, surface residual stress and internal residual stress obtained in advance for the sample 22 having the same configuration as the measurement target member 11, welding conditions at the time of preparing the sample 22, groove shape of the sample 22, and material characteristics of the sample 22) The internal residual stress of the measurement target member 11 is estimated and evaluated. For this reason, according to this residual stress evaluation system 10, the residual stress of the measurement object member 11, especially the internal residual stress can be evaluated with high accuracy. As a result, the structural reliability of the welded structure can be ensured, and for example, a turbine having a high-quality and highly reliable welded rotor can be manufactured.

  (2) The internal residual stress at an arbitrary depth of the sample 22 is formed by drilling a plurality of processed holes 25 having different depths in the sample 22 and attaching strain gauges 27 to the bottom surfaces 26 of these processed holes 25. 26, an initial strain value is measured, and then a portion (surface layer 35 or block 36) to which the strain gauge 27 is attached is collected and calculated from the released strain measured by the strain gauge 27 and the strain measuring instrument 28 at this time. And measured. The internal residual stress at a deeper position based on the processed hole 25 is calculated and measured in the same manner. As a result, the internal residual stress of the sample 22 can be measured with high accuracy.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this. For example, in the present embodiment, the measurement of the surface residual stress of the measurement target member 11 by the surface residual stress calculation device 14 is performed by peeling the surface layer 11A of the measurement target member 11 to which the strain gauge 12 is attached and releasing it at this time. Although what was calculated from distortion was described, you may measure the surface residual stress of the measuring object member 11 by the nondestructive method which does not peel the surface of the measuring object member 11. FIG.

(A) is a system block diagram which shows the structure of one Embodiment of the residual stress evaluation system based on this invention, (B) is explanatory drawing explaining the measurement condition of the distortion initial value in a measuring object member, (C) is a measuring object. Explanatory drawing explaining the repair condition of the peeling sampling part in a member. (A), (B), and (C) are explanatory drawings which show the condition which measures the surface residual stress each stored in the database of FIG. 1 by a cutting method. Explanatory drawing which shows the condition which measures the surface residual stress stored in the database of FIG. 1 by the drilling method. Explanatory drawing which shows the condition which measures the surface residual stress processed into the database of FIG. 1 by the Sachs method. The sample which measures the internal residual stress stored in the database of FIG. 1 is shown, (A) is a front view, (B) is a side view. Sectional drawing which shows the condition which measures an internal residual stress using the sample of FIG. 5, and follows the VI-VI line of FIG. (A), (B) and (C) are explanatory drawings which show the condition which affixes a strain gauge to the processing hole of the sample of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Residual stress evaluation system 11 Measurement object member 11A Surface layer 11B Peeling sampling part 12 Strain gauge 13 Strain measuring device (strain measuring device)
14 Surface residual stress calculation device 15 Database 16 Internal residual stress evaluation device 17 Quality judgment device 19 Welding torch (smoothing means)
20 Cutting cutter (smoothing means)
22 Sample 25 Processed hole 26 Bottom surface 27, 27A Strain gauge 29 Weld line 30 Strain gauge application device 31 Tip 32 Plastic film 33 Application surface 35 Surface layer 36 Block 37 Peeling surface 38 Surface layer 39 Processing hole 40 Bottom surface (deep bottom surface)
41 Surface

Claims (14)

After measuring the initial strain value by affixing a strain gauge to the measurement target member, the portion where the strain gauge is affixed is collected, the strain is released and the residual stress is calculated and evaluated,
A strain measuring device for measuring a strain value of the strain gauge attached to the measurement target member;
A surface residual stress calculating device for calculating the surface residual stress of the measurement target member from the strain value measured by the strain measuring device;
Data relating to surface residual stress and internal residual stress determined in advance for a sample having the same configuration as the measurement target member, welding conditions at the time of sample preparation, groove shape of the sample, and material characteristics of the sample are stored in association with each other. Database and
Based on the surface residual stress calculated by the surface residual stress calculation device, the welding conditions of the measurement target member, the groove shape, and the material characteristics, the internal residual stress of the measurement target member is determined by collating with the data in the database. An internal residual stress evaluation device for estimating and evaluating the residual stress evaluation system. The residual stress evaluation system according to claim 1, further comprising a quality determination device that determines the quality of the measurement target member based on the internal residual stress evaluated by the internal residual stress evaluation device. In the surface residual stress calculation device, after the initial strain value of the measurement target member is measured by a strain gauge and a strain measurement device, the surface layer to which the strain gauge is attached is peeled off by electrical discharge machining, wire cutting, or electrolytic polishing. The residual stress evaluation system according to claim 1, wherein a surface residual stress of the measurement target member is calculated from a release strain measured when the sample is collected. The residual stress evaluation system according to claim 1, further comprising a smoothing unit that smoothes a portion of the measurement object peeled and collected by welding repair, cutting, or a combination thereof. The residual stress evaluation system according to claim 1, wherein the surface residual stress data stored in the database is data calculated by at least one of a cutting method, a drilling method, and a Sachs method. The internal residual stress data stored in the database is obtained by drilling a plurality of holes with different depths in the sample to be measured, and attaching strain gauges to the bottom surfaces of these processed holes. After measuring the initial value, the portion to which the strain gauge is attached is collected, and the internal residual stress at an arbitrary depth of the sample is calculated from the release strain measured by the strain gauge at this time. The residual stress evaluation system according to claim 1. The internal residual stress data stored in the database is obtained by measuring the initial strain of the bottom surface of the processed hole drilled in the sample and then applying a strain gauge to the bottom surface of the processed hole. The data calculated from the release strain measured by the strain gauge at this time,
Alternatively, after measuring the initial strain of the bottom surface of the processed hole drilled in the sample, the sample is cut in a state where the strain gauge is applied to the bottom surface of the processed hole, and the bottom surface is attached with the strain gauge. The residual stress evaluation system according to claim 6, wherein the residual stress evaluation system is data calculated from a release strain measured by the strain gauge at the time when a block of a portion is collected. The internal residual stress data stored in the database is obtained by attaching another strain gauge to the bottom surface of the processed hole drilled in the sample after peeling the surface layer to which the strain gauge is attached. After measuring the initial strain value of the peeling bottom surface with another strain gauge, the surface layer of the peeling bottom surface is peeled off with the other strain gauge attached, and the release measured by the other strain gauge at this time The residual stress evaluation system according to claim 6, wherein the residual stress evaluation system is data calculated from strain. The internal residual stress data stored in the database is drilled by adding deeper drilled holes after peeling off the surface layer with the strain gauge attached to the bottom of the drilled holes in the sample. After attaching another strain gauge to the deep bottom surface of the added processing hole and measuring the initial strain value of the deep bottom surface with this other strain gauge, the surface layer of the deep bottom surface with this other strain gauge attached. The residual stress evaluation system according to claim 6, wherein the residual stress evaluation system is data calculated from a release strain measured by the other strain gauge at this time. The strain gauge is attached to the tip of the strain gauge attaching device having a tip covered with a film that is not bonded with an adhesive, and an adhesive is applied to the application surface of the strain gauge. Insert the tip of the strain gauge attaching device into the drilled processing hole, and press the tip of the strain gauge attaching device against the bottom of the processing hole in a state where the strain gauge is positioned at the bottom of the processing hole. The residual stress evaluation system according to claim 6, wherein the residual stress evaluation system is attached. The residual stress evaluation according to claim 6, wherein the processed hole has a circular or rectangular cross section in the sample and has a bottom surface smoothly drilled, and a strain gauge is attached to the bottom surface. system. 7. The sample according to claim 6, wherein the sample is an axially symmetric weld joint having a weld line perpendicular to the axial direction, and a plurality of machining holes are drilled parallel or perpendicular to the weld line. Residual stress evaluation system. The residual stress evaluation system according to claim 6, wherein the sample is a welded joint made of a plurality of flat plates, and a plurality of processed holes are drilled parallel or perpendicular to the weld line. A residual stress measurement method for measuring internal residual stress of a measurement target member,
Drill a number of holes with different depths in the measurement target member, and attach a strain gauge to the bottom of these holes to measure the initial strain value on the bottom of these holes.
Thereafter, the portion where the strain gauge is attached is collected, and the internal residual stress at an arbitrary depth of the measurement target member is obtained from the release strain measured by the strain gauge at this time. Measuring method.

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