JP5409193B2 - Method for producing stress corrosion cracking specimen having residual stress and stress corrosion cracking testing method - Google Patents

Description

  The present invention relates to a method for manufacturing a test body for a stress corrosion cracking (hereinafter referred to as “SCC”) test for a member having residual stress, and a stress corrosion cracking test method.

Conventionally, a CT (compact) specimen as shown in FIG. 10 has been used as a specimen for an SCC test for acquiring the crack propagation characteristics of SCC. Prior to the test, a slit and a fatigue precrack are introduced as an initial crack in this CT test piece. The slit is introduced by wire cutting, electric discharge machining, or the like, and the fatigue precrack is introduced by repeatedly applying a load in a direction perpendicular to the slit surface until a predetermined crack depth is obtained.
On the other hand, since such a CT test piece does not necessarily simulate the shape of a member (for example, the inner surface of a cylindrical pipe) where SCC occurs in an actual machine, it is shown in FIG. 1 in order to evaluate the actual machine with higher accuracy. An SCC test using a test body such as a cylindrical pipe is performed.
Here, since it is considered that the progress of SCC in the actual machine is induced by the tensile component of the residual stress such as welding, a pre-crack should be introduced into the welded part provided on the CT specimen and the actual specimen. Thus, the SCC test is performed in consideration of not only the stress (stress caused by fluid heat and acting pressure) added as actual machine operating conditions but also residual stress. The SCC test is performed without applying any other external force.

  In addition, as a method for introducing a precrack into an SCC specimen, a method is disclosed in which a specimen material to which a load is applied is immersed in an accelerated corrosion solution and a crack is introduced to a predetermined depth (for example, patent document). 1). In this method, a pre-crack is introduced by corrosion simulating actual SCC.

JP 2006-10427 A

  However, in the method according to Patent Document 1, since corrosion is generated by immersing in an accelerated corrosion solution in order to introduce a precrack, the specimen is exposed to an environment different from the actual SCC test conditions. There was a problem of concern about the impact.

  On the other hand, in the method of introducing a precrack due to fatigue, there has been a problem that a method for setting a fatigue precrack introduction condition has not been established in relation to the test condition in producing an SCC specimen. In other words, when a fatigue pre-crack provided in a weld is introduced, stress due to repeated loading is generated in addition to residual stress, and the stress intensity factor given depends on the former stress and the fluctuation caused by the latter stress (stress intensity factor). Range) is added. In this case, if the stress intensity factor given at the start of the SCC test is lower than the maximum value of the stress intensity factor given at the time of fatigue precrack introduction, it is appropriate to be affected by the load history at the time of fatigue precrack introduction. The problem is that the SCC test cannot be performed.

  The present invention has been made to solve the above-described problem, and an SCC specimen manufacturing method and test for carrying out an appropriate SCC test without being affected by a load history at the time of fatigue pre-crack introduction. A method is provided.

In order to solve the above problems, the present invention proposes the following means.
The method of manufacturing the stress corrosion cracking specimen of the present invention is such that the maximum stress intensity factor at the time of fatigue precrack introduction given by residual stress and stress applied at the time of fatigue precrack introduction is stress applied as test conditions. A fatigue precrack is introduced so that the stress intensity factor is less than or equal to the stress intensity factor at the start of the test given by the residual stress, and the stress intensity factor at the start of the test is the stress corrosion crack growth rate and the stress intensity factor determined in advance. This is characterized in that it is calculated from the correlation data of the above and the stress corrosion cracking rate set as the test execution condition .

According to this method, since the stress intensity factor given at the start of the SCC test is higher than the maximum value of the stress intensity factor given at the time of fatigue precrack introduction, it is affected by the load history at the time of fatigue precrack introduction. Therefore, an appropriate SCC test can be performed according to the stress applied as the test condition and the residual stress.
Further, according to this method, the correlation data between the stress corrosion crack growth rate and the stress intensity factor is acquired in advance, so that the stress as a test condition can be determined from the crack growth amount and the required test time planned in the SCC test. If the corrosion cracking rate is determined, the stress intensity factor at the start of the test can be easily set.

  In addition, in the above method for producing a stress corrosion cracking specimen, the maximum stress intensity factor at the time of fatigue pre-crack introduction is the correlation data between the fatigue crack growth rate and the stress intensity factor range obtained in advance and the fatigue pre- It is characterized by the sum of the stress intensity factor range calculated from the fatigue crack growth rate set as the crack introduction condition and the stress intensity factor based on the residual stress after fatigue precrack introduction.

  In this method, correlation data between the fatigue crack growth rate and the stress intensity factor range is acquired in advance. For this reason, if the fatigue crack growth rate is determined from the fatigue precrack introduction conditions (target crack depth, target introduction amount, target time required for introduction, frequency of repeated load, etc.) of the SCC specimen, fatigue It is possible to easily obtain a stress intensity factor range due to repeated loading at the time of fatigue precrack introduction according to precrack introduction conditions. The sum of the stress intensity factor range and the stress intensity factor based on the residual stress after the fatigue precrack introduction can be obtained as the maximum stress intensity factor at the time of fatigue precrack introduction. Furthermore, since the time required for introducing the fatigue precrack can be arbitrarily set, the SCC specimen can be manufactured systematically in the target time.

  In the method of manufacturing the stress corrosion cracking specimen described above, the stress intensity factor based on the residual stress after fatigue precracking is calculated as the correlation data between the crack depth and the stress intensity factor for the residual stress obtained in advance. It is characterized in that it is calculated from the crack depth planned after the fatigue precrack introduction.

  According to this method, since the correlation data between the crack depth and the stress intensity factor with respect to the residual stress is acquired in advance, the fatigue prediction is performed from the introduced crack depth set as the fatigue precrack introduction condition of the SCC specimen. A stress intensity factor based on the residual stress after crack introduction can be easily obtained.

  Further, in the above method for producing a stress corrosion cracking specimen, the crack depth planned after the fatigue precrack introduction is the crack depth with respect to the stress and residual stress added as the test conditions determined in advance. It is calculated from the correlation data with the stress intensity factor and the stress intensity factor at the start of the test.

  According to this method, since the correlation data between the crack depth and the stress intensity factor for the stress and residual stress applied as test conditions are acquired in advance, the fatigue precrack introduction is determined from the stress intensity factor at the start of the test. The crack depth planned later can be obtained easily.

  Further, in the above-described method for producing the stress corrosion cracking specimen, the fatigue crack growth rate is determined from the crack depth expected after the fatigue precrack introduction to the depth of the crack introduced before the fatigue precrack introduction. It is characterized in that it is obtained from the fatigue precrack introduction amount obtained by subtracting and the number of vibrations set as the fatigue precrack introduction condition.

  According to this method, the fatigue precrack introduction amount can be determined from the crack depth planned after the fatigue precrack introduction and the crack depth provided in advance before the introduction. Then, the fatigue crack growth rate corresponding to the desired test time can be obtained from the determined fatigue precrack introduction amount and the preset number of vibrations.

  Further, the stress corrosion cracking specimen is provided with a slit as a crack provided in advance before the introduction of the fatigue precrack, and the sectional width of the slit decreases as the slit depth increases.

  According to this configuration, since the introduction of the fatigue precrack can be easily induced, the repeated load can be reduced.

  According to the manufacturing method of the stress corrosion cracking test body of the present invention, it becomes possible to manufacture an SCC test body for carrying out an appropriate SCC test without being affected by the load history at the time of fatigue precrack introduction, It can be manufactured in a short time.

It is a perspective view which shows an example of the initial stage crack introduced into the pipe inner surface of the welding part of cylindrical piping which is embodiment of this invention. It is a top view which shows an example of the initial stage crack introduced into the pipe inner surface of the welding part of cylindrical piping which is embodiment of this invention. It is process drawing which shows the procedure of the manufacturing method of the SCC test body which is embodiment of this invention. Correlation diagram showing an example of the correlation between the tensile stress (pipe circumferential stress) in the direction perpendicular to the SCC crack plane assumed in the welded part of the cylindrical pipe and the distance from the pipe inner surface for each of the actual machine operating conditions and non-operating conditions It is. It is a correlation diagram which shows an example of transition of a stress intensity factor and a crack depth from the introduction of a fatigue precrack to the end of an SCC test and the correlation between the stress intensity factor and the crack depth for each of actual machine operating conditions and non-operating conditions. It is a correlation diagram which shows an example of the correlation with the stress intensity | strength coefficient assumed by a SCC test, and the stress corrosion crack progress rate. It is a correlation diagram which shows an example of the correlation with the fatigue crack growth rate assumed at the time of fatigue | exhaustion precrack introduction | transduction, and the stress intensity factor range. It is a top view of the slit introduce | transduced as an initial stage crack which is embodiment of this invention. It is sectional drawing of the slit introduce | transduced as an initial stage crack which is embodiment of this invention. It is explanatory drawing of the CT (compact) test piece conventionally used as a SCC test body.

  Hereinafter, a flow of a manufacturing method of a test body for a stress corrosion cracking (hereinafter referred to as “SCC”) test as an embodiment according to the present invention will be described with reference to FIGS. 1 to 9. The present invention relates to a method for introducing an initial crack of a specimen for acquiring SCC crack growth characteristics of a member having residual stress such as a welded portion by fatigue precracking. In particular, when using an actual machine, in addition to residual welding stress, SCC cracks under stress conditions in which stress constantly acts on the member, such as stress due to thermal expansion and internal pressure, self-weight and deformation of the entire structural system, etc. The present invention relates to a method of manufacturing a test body for acquiring progress characteristics.

  In the present embodiment, as an example, a method for producing a test body for acquiring SCC crack propagation characteristics generated in a welded portion of a pipe in which a fluid having a temperature higher than that of the external environment flows with a predetermined pressure will be described. Specifically, a method for introducing a fatigue precrack as an initial crack in a welded portion of a pipe as shown in FIG. 1 will be described.

  FIG. 1 is an example in which a crack 1 having a crack surface 1 a parallel to the axial direction L and the radial direction R of the cylindrical pipe 2 is introduced as an initial crack into the pipe inner surface 2 a of the welded portion 3. Here, as shown in FIG. 2, the crack surface 1a has a shape simulating an actual SCC, for example, a semi-elliptical shape, but it is not realistic to introduce all of the initial cracks by fatigue cracks. This is because it is difficult to accurately control the introduction of a crack so as to obtain an assumed shape, and it takes a long time to introduce the crack. Therefore, after preliminarily providing a small elliptical crack with a slit by electric discharge machining or the like, by introducing a fatigue pre-crack until a crack surface with a predetermined shape is induced by the slit, The initial crack is introduced.

  In addition, as the target pipe and the initial crack introduction location, the piping and location where the occurrence of SCC is a concern in the actual machine are selected. For example, in pipes made of materials that are easily affected by material changes due to heat from welding (austenitic stainless steel, etc.), locations affected by heat from welding, etc., internal fluid is high at high pressure and high temperature, and high at high temperature and high pressure. It is a surface part etc. exposed to the said environment in piping exposed to the environment of ph.

  As shown in FIG. 3, the manufacturing method of the SCC specimen of this embodiment is broadly divided into a preparation step S1 for preparing data necessary for introducing a fatigue crack in advance and a preparation step S1. Based on the data, a fatigue precrack introduction condition determining step S2 for determining a precondition for introducing a fatigue precrack, and a determination step S3 for determining the validity of the introduction condition obtained in the fatigue precrack introduction condition determining step S2; And a fatigue precrack introduction step S4 for actually introducing a fatigue precrack. Below, the detail of each process is demonstrated.

  Preparatory step S1: As pre-preparation in this step, the first correlation data indicating the correlation between the tensile stress in the direction orthogonal to the crack surface and the distance from the member surface, the stress intensity factor and the crack for the SCC specimen Second correlation data indicating a correlation with the depth is acquired in advance. Further, the third correlation data showing the correlation between the stress intensity factor and the stress corrosion crack growth rate in the material forming the SCC specimen, and the correlation between the fatigue crack growth rate and the stress intensity factor range are shown. 4 correlation data is acquired in advance. By acquiring these in advance, it becomes easy to determine conditions in a fatigue precrack introduction condition determining step S2 described later.

  The preparation process S1 includes four steps from a first step S11 to a fourth step S14, and correlation data is acquired at each step. Each step of acquiring each correlation data will be described below.

  First step S11: For each of the actual machine operating condition and the non-operating condition, the stress distribution inside the piping member, which is the actual machine member targeted in the SCC test, is obtained by analysis, and orthogonal to the assumed SCC crack surface as shown in FIG. The first correlation data D1 indicating the correlation between the tensile stress in the direction of the pipe (the stress in the pipe circumferential direction in the case of the crack shown in FIG. 1) and the distance from the pipe inner surface is acquired. Here, the actual machine operating condition means a stress condition that the pipe to be tested as the SCC specimen is subjected to during actual machine operation. In other words, in the present embodiment, the residual stress in the welded portion 3 and the stress conditions in which the fluid flows through the pipe 2 cause stress due to internal pressure acting from the fluid and thermal stress due to heat transmitted from the fluid. . Further, the non-operating condition means a stress condition that the pipe to be tested as the SCC specimen is subjected to during non-operating. That is, in the present embodiment, the stress condition is a state in which no fluid flows in the pipe 2 and only the residual stress in the welded portion 3 is generated. As an analysis method, a known method such as a finite element method is applied. In the first correlation data D1, a curve D11 shows the correlation between the pipe circumferential stress and the distance X from the pipe inner surface 2a under the actual machine operating conditions, that is, the conditions under which residual stress, stress due to thermal expansion or internal pressure is generated. It represents. A curve D12 represents the correlation between the pipe circumferential stress and the distance X from the pipe inner surface 2a under the non-operating condition, that is, the condition where only the residual stress is generated.

  Second step S12: Second correlation data indicating the correlation between the stress intensity factor and the crack depth for each of the actual machine operating condition and the non-operating condition from the tensile stress obtained from the first correlation data D1 as shown in FIG. D2 is acquired. The second correlation data D2 is used for managing the transition of the stress intensity factor and the crack depth from the stage of producing the SCC specimen in which residual stress is generated to the end of the SCC test. In the second correlation data D2, a curve D21 represents the correlation between the stress intensity factor and the crack depth under actual machine operating conditions. Curve D22 represents the correlation between the stress intensity factor and the crack depth under non-operating conditions.

σ：き裂部位の公称（引張り）応力
ａ：き裂深さ
ｃ：き裂半長
Ｆ：き裂・構造物の形状、加重による定数 Here, in the case of a semi-elliptical crack, the stress intensity factor K is generally given by the following equation.

σ: Nominal (tensile) stress at the crack site
a: Crack depth c: Half length of crack F: Shape of crack / structure, constant by weight

  Then, from the first correlation data D1 shown in FIG. 4, the stress state at the crack tip at each crack depth (distance from the inner surface) is specified, and from the stress state and the crack depth, based on <Equation 1>. The second correlation data D2 can be obtained by calculating the stress intensity factor and relating it to the crack depth.

  Third Step S13: As shown in FIG. 6, the third correlation data D3 indicating the correlation between the stress intensity factor and the stress corrosion crack growth rate is acquired. The third correlation data D3 is data for temporarily determining the stress intensity factor assumed at the start of the test by setting the stress corrosion crack growth rate (da / dt) at the start of the SCC test.

  Specifically, the third correlation data D3 is made of the same material as that of the SCC specimen, for example, a CT specimen as shown in FIG. 9 is manufactured in advance under the same corrosive environment as the actual SCC test. It can be obtained by conducting an SCC test. As shown in FIG. 1, a test piece corresponding to an actual machine may be used as in the actual SCC test, and further, it may be obtained by analysis without depending on the test.

  Fourth Step S14: As shown in FIG. 7, fourth correlation data D4 indicating the correlation between the fatigue crack growth rate and the stress intensity factor range is acquired. The fourth correlation data D4 shows the maximum and minimum values of the stress intensity factor corresponding to the set fatigue crack growth rate when introducing the fatigue precrack that is performed by applying a repeated load in the production of the SCC specimen. It is the data for acquiring the stress intensity factor range which is the difference of. Here, the fatigue precrack growth rate may be a crack growth amount per unit time (da / dt) in addition to a crack growth amount per vibration (da / dN).

  Specifically, the fourth correlation data D4 is the same as that at the time of fatigue pre-crack introduction using a CT test piece of the same material as the SCC specimen and a test piece equivalent to the actual machine, like the third correlation data D3. It can be obtained in advance by a fatigue test or analysis under a condition where only residual stress is generated.

  Thus, the preparation step S1 is completed, and the process proceeds to the fatigue pre-crack introduction condition determination step S2, which is the next step.

  Fatigue pre-crack introduction condition determination step S2: This step is to determine the pre-fatigue crack introduction conditions when the SCC specimen is manufactured. The fatigue precrack introduction condition determining step S2 is composed of six steps from the fifth step S21 to the tenth step S26, and the stress intensity factor range at the time of fatigue precrack introduction serving as a fatigue precrack introduction condition. And obtain the maximum stress intensity factor. Each step will be described below.

  Fifth step S21: The stress corrosion crack growth rate C1 at the start of the SCC test is determined. First, the target time required for the SCC test and the target progress amount of the SCC introduced from the start to the end in the SCC test are set. The target time is set by the operating time of the testing machine that performs the SCC test, and the target progress amount is set by the dimensions of the specimen. Then, the stress corrosion crack growth rate is obtained by dividing the target progress amount by the target time, and this is set as the stress corrosion crack growth rate C1 at the start of the SCC test.

  Sixth step S22: Next, a stress intensity factor K1 introduced at the start of the SCC test is provisionally determined. Specifically, the stress corrosion coefficient K1 at the start of the corresponding SCC test is obtained by inputting the stress corrosion crack growth rate C1 at the start of the SCC test into the third correlation data D3 shown in FIG. Thereby, by introducing the stress intensity factor K1 into the SCC specimen at the start of the SCC test, the SCC can be roughly advanced by the target progress amount at the target time.

  Seventh step S23: Crack depth at the start of the SCC test corresponding to the stress intensity factor K1 at the start of the SCC test obtained in the sixth step S22 based on the curve D21 of the second correlation data D2 shown in FIG. Get A1.

  Thereby, in the SCC specimen, the crack depth at the start of the SCC test, that is, the initial crack is set to the crack depth A1, so that the residual stress of the SCC specimen and the fluid added as the test condition are The stress intensity factor at the start of the SCC test can be set to the stress intensity factor K1 obtained in the sixth step S22 by the stress caused by the heat and the acting pressure.

  Eighth step S24: In the manufacture of the SCC specimen, the fatigue crack growth rate Cf0 when the fatigue precrack is introduced as the initial crack is determined. First, target crack depth, target introduction amount, target time required for introduction, frequency of repeated load, etc. are set as the fatigue precrack introduction conditions of the SCC specimen. The target time is set by the operating time of the fatigue pre-crack introduction device, and the target introduction amount is set by the dimensions of the specimen. Then, the crack propagation amount per vibration (da / dN) obtained by dividing the target introduction amount by the number of vibrations from the introduction start to the end obtained from the frequency of the cyclic load and the target time is used as the fatigue precrack introduction. The fatigue crack growth rate at the time is Cf0. Alternatively, the amount of crack growth per unit time (da / dt) may be set as the fatigue crack growth rate Cf0 at the time of fatigue precrack introduction by dividing the target introduction amount by the target time.

  Ninth step S25: Next, from the initial crack depth A1 obtained in the seventh step S23, a corresponding stress intensity factor is obtained in the curve D22 of the second correlation data D2 shown in FIG. That is, since the initial crack depth A1 is the crack depth after the fatigue precrack introduction of the SCC specimen, the fatigue in the state where only the residual stress is generated from the curve D22 of the second correlation data D2. The stress intensity factor K0 with respect to the crack depth A1 after the introduction of the precrack can be obtained.

  Tenth Step S26: Next, a stress intensity factor range ΔK with respect to the fatigue crack growth rate set at the time of introducing the fatigue precrack is obtained. That is, the corresponding stress intensity factor range ΔK0 in the fourth correlation data D4 is obtained from the fatigue crack growth rate Cf0 obtained in the eighth step S24.

  As a result, the sum of the stress intensity factor K0 with respect to the crack depth A1 after introduction of the fatigue precrack and the stress intensity factor range ΔK0 with respect to the fatigue crack growth rate Cf0 in the state where only the residual stress is generated is the maximum stress intensity. It can be obtained as a coefficient K0max.

  Determination step S3: Next, the validity of the target crack depth A1 and the fatigue crack growth rate Cf0 at the time of fatigue precrack introduction determined in the fatigue precrack introduction condition determination step S2 is determined. Specifically, it is determined whether the maximum stress intensity factor K0max at the time of fatigue precrack introduction is greater than the stress intensity factor K1 at the start of the SCC test.

  That is, the maximum stress intensity factor K0max and the stress intensity factor K1 at the start of the SCC test are compared. If the maximum stress intensity factor K0max is equal to or less than the stress intensity factor K1 at the start of the SCC test, the fatigue prediction of the SCC specimen is predicted. The target crack depth at the time of crack introduction is fixed to the crack depth A1 obtained in the seventh step S23. This is because an appropriate SCC test can be performed without being affected by the load history at the time of fatigue precrack introduction.

  On the other hand, when the maximum stress intensity factor K0max exceeds the stress intensity factor K1 at the start of the SCC test, the target crack depth at the time of introducing the precrack of the SCC specimen is set to a value larger than A1, or the fatigue crack The fatigue precrack introduction condition determination step S2 and the determination step S3 until the growth rate is set to a value smaller than Cf0 or the combination thereof makes the maximum stress intensity factor K0max equal to or less than the stress intensity factor K1 at the start of the SCC test. Repeat.

  If the maximum stress intensity factor K0max is less than or equal to the stress intensity factor K1 at the start of the SCC test in the determination step S3, the process proceeds to the introduction step S4 and the desired target crack depth at the time of introducing the fatigue precrack. Up to A1, a fatigue precrack is introduced with a stress intensity factor range K0 and a maximum stress intensity factor K0max.

  Thus, by setting the conditions at the time of fatigue precrack introduction, the stress intensity factor given at the start of the SCC test can be set higher than the maximum value of the stress intensity factor given at the time of fatigue precrack introduction. This makes it possible to produce a test body for performing an appropriate SCC test without being affected by the load history at the time of fatigue precrack introduction. In addition, since a precrack is introduced due to fatigue, an SCC specimen can be manufactured in a short time.

  Next, a description will be given of the shape of the slit provided in the specimen in advance before introducing the fatigue precrack. Since it is not realistic to introduce all of the initial cracks by fatigue cracks, a small elliptical crack is provided in advance by a slit by electric discharge machining or the like, and then the crack is induced by the slit. A fatigue precrack is introduced until a crack surface with a predetermined shape is obtained. Therefore, it is desirable to provide a slit that easily induces a fatigue crack. For example, a slit having a sectional shape as shown in FIGS. 9A to 9C is used. Of these, the slit shape as shown in FIG. 9B where the crack tip is most sharp is ideal, but considering the ease of manufacturing, it is formed in a step shape as shown in FIG. 9C. Then, the one that is sharpened toward the tip is preferable.

DESCRIPTION OF SYMBOLS 1 Crack 1a Crack surface 2 Cylindrical piping 2b Pipe inner surface 3 Welding part 11 Slit surface 50 CT (compact) test piece 51 Slit 52 Fatigue crack L Cylindrical piping axial direction R Cylindrical piping radial direction P Repeated overload

Claims (7)

In the method of manufacturing a stress corrosion cracking specimen having residual stress,
The maximum stress intensity factor at the time of fatigue precrack introduction given by the residual stress and the stress applied at the time of fatigue precrack introduction is the stress applied as test conditions and the stress expansion at the start of the test given by the residual stress. introduced a fatigue pre-crack so that the coefficient below,
The stress intensity factor at the start of the test is calculated from correlation data between a stress corrosion crack growth rate and a stress intensity factor obtained in advance and a stress corrosion crack growth rate set as a test execution condition. , Manufacturing method of stress corrosion cracking specimen. The maximum stress intensity factor at the time of fatigue pre-crack introduction depends on the correlation data between the fatigue crack growth rate and stress intensity factor range obtained in advance and the fatigue crack growth rate set as the fatigue pre-crack introduction condition. 2. The method for producing a stress corrosion cracking specimen according to claim 1, wherein the stress corrosion coefficient range is a sum of a calculated stress intensity factor range and a stress intensity factor based on residual stress after fatigue precrack introduction. The stress intensity factor based on the residual stress after the fatigue precrack is introduced is the correlation data between the crack depth and the stress intensity factor for the residual stress obtained in advance and the crack expected after the fatigue precrack is introduced. The method for producing a stress corrosion cracking specimen according to claim 2, wherein the stress corrosion cracking specimen is calculated from a depth. The crack depth planned after the fatigue pre-crack introduction is the correlation data of the crack depth and the stress intensity factor with respect to the stress and residual stress added as the test conditions determined in advance, and at the start of the test. The method for producing a stress corrosion cracking specimen according to claim 3, wherein the stress corrosion cracking specimen is calculated from a stress intensity factor. The fatigue crack growth rate is the amount of fatigue precrack introduction obtained by subtracting the crack depth previously set before fatigue precrack introduction from the crack depth planned after the fatigue precrack introduction. The stress corrosion cracking specimen manufacturing method according to claim 4, wherein the stress corrosion cracking specimen is obtained from the number of vibrations set as a fatigue precrack introduction condition. The test specimen is provided with a slit as a crack provided in advance before the introduction of a fatigue precrack, and the cross-sectional width of the slit decreases as the slit depth increases . The manufacturing method of the stress corrosion cracking test body as described in any one of Claims . The stress corrosion cracking test method which has a residual stress using the test body manufactured by the method as described in any one of Claims 1-6 .

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