Method for accelerating high temperature internal pressure creep test of metal pipe and application thereof

Abstract

The present application belongs to the technical field of high-temperature internal pressure creep test, and relates to a method for accelerating high-temperature internal pressure creep test of metal pipes and application thereof. The method can significantly improve the efficiency of high-temperature internal pressure creep test of zirconium, titanium and alloy pipes and other metal pipes, and can greatly shorten the test period to several times or even dozens of times of the original without additional test cost. At the same time, under the condition of changing the test temperature or reference stress alone, or combining the test temperature and reference stress, the method ensures that the test results are equivalent to the test results under the standard test conditions of YS / T 1463-2021 "Zirconium Alloy Pipe Internal Pressure Creep Test Method", that is, the test temperature is 400 DEG C, the reference stress is 130 MPa, and the test time is 240 h, greatly shortening the test period and effectively breaking through the technical bottleneck that there is no pipe high-temperature internal pressure creep test method for zirconium, titanium and alloy pipes and other metal pipes.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature internal pressure creep testing technology, and relates to a method for accelerating high-temperature internal pressure creep testing of metal pipes and its application. It is applicable to zirconium, titanium and their alloy pipes or other metal pipes that need to be tested for high-temperature internal pressure creep. Background Technology

[0002] Zirconium alloy cladding tubing is a key core material in nuclear reactors, encasing nuclear fuel such as uranium dioxide. Other zirconium alloy tubing is also a critical in-reactor material, encasing various instruments and other components. Zirconium alloy tubing acts as the first line of defense for nuclear reactor safety. Titanium alloy tubing is used in critical oil and gas pipelines within aircraft in the aerospace industry, playing a vital role in aircraft safety as well.

[0003] Zirconium, titanium, and their alloy tubing operate continuously under harsh high-temperature and high-pressure environments in nuclear energy, aviation, and aerospace fields. Due to the mechanical properties of these metallic materials, high-temperature creep is inevitable. When the creep extension reaches a certain level, the zirconium, titanium, and their alloy tubing will undergo creep deformation, ultimately affecting the safety of related components. For example, during the high-temperature and high-pressure operation of cladding tubes in nuclear reactors, if an anomaly occurs, such as the accumulation of large amounts of fission gases inside the cladding tube, or damage to the cladding tube leading to a large accumulation of hydrogen due to a zirconium-water reaction, the gas expansion will significantly increase the internal pressure of the cladding tube. Combined with the high-temperature environment of the nuclear reactor, this will cause internal pressure creep in the cladding tube. Similarly, some titanium alloy tubing used in aviation and aerospace applications, particularly in high-temperature environments like aircraft engines, may experience internal pressure creep. Therefore, the high-temperature internal pressure creep performance of zirconium, titanium, and their alloy tubing is a crucial performance indicator in nuclear energy, aviation, and aerospace fields.

[0004] Currently, the existing technologies for high-temperature internal pressure creep testing of zirconium alloy tubing, such as cladding tubes, in the international nuclear energy field mainly revolve around various methods developed based on the YS / T 1463-2021 standard, "Test Method for Internal Pressure Creep of Zirconium Alloy Tubing." This test method uses a test temperature of 400℃, a reference stress of 130MPa, and a test time of 240 hours. When the test requires continuous measurement of the outer diameter creep elongation, a single test lasting over 10 days can only measure the outer diameter creep elongation of one sample. This test method is inefficient, and the required experimental instruments are complex and costly to manufacture. Currently, only three to four laboratories in China possess such instruments, and only one or two of these laboratories have passed national accreditation and other quality management system requirements. However, in order to reduce my country's heavy reliance on traditional energy sources such as oil and coal, the demand for new energy sources, represented by nuclear energy, has surged in recent years, making it difficult for existing technologies to meet the large-scale high-temperature internal pressure creep testing needs of various research and production units for zirconium alloy tubing. Currently, my country's aerospace and aviation sectors are accelerating research on high-temperature internal pressure creep testing of titanium alloy pipes. However, internationally, there is currently no technology for high-temperature internal pressure creep testing of titanium alloy pipes, and the aerospace and aviation sectors are still drawing on the YS / T 1463-2021 standard for nuclear energy, "Test Method for Internal Pressure Creep of Zirconium Alloy Pipes." Therefore, there is an urgent need to develop a predictive method for accelerating high-temperature internal pressure creep testing models to meet the pressing needs of key sectors such as nuclear energy, aerospace, and aviation in my country. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for accelerating the high-temperature internal pressure creep test of metal pipes and its application. This method can significantly shorten the cycle of high-temperature internal pressure creep test of zirconium, titanium and their alloy pipes, greatly shorten the development cycle of zirconium alloy pipes in the nuclear energy field and titanium alloy pipes in the aerospace field, and improve scientific research efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On the one hand, the present invention provides a method for accelerating the high-temperature internal pressure creep test of metal pipes, specifically including the following steps:

[0008] S1. Set up one standard group and at least one accelerated group to carry out high-temperature internal pressure creep tests under different test conditions; the standard group and the accelerated group both use metal pipes of the same grade and produced by the same process;

[0009] S2. Obtain the specified plastic elongation strength R of the metal tube at a strain of 0.2%. p0.2 and the specified plastic extension burst strength S at a strain of 0.2%. p0.2 ;

[0010] S3, according to the specified plastic elongation strength Rp0.2 The specified plastic extension burst strength S p0.2 The creep test reference stress coefficient α is calculated using the following formula (1):

[0011] α = 77.5% * S p0.2 / R p0.2 Equation (1)

[0012] S4. Based on the creep test reference stress coefficient α and the specified plastic elongation strength R... p0.2 The creep test reference stress σ is calculated using the following formula (2):

[0013] σ=α×R p0.2 Equation (2)

[0014] S5. Measure the outer diameter creep elongation rate of the metal pipes in the standard group and any accelerated group respectively, and obtain the outer diameter creep elongation rate curves at different times; when the outer diameter creep elongation rate of the accelerated group is equal to or greater than the outer diameter creep elongation rate of the standard group at the specified test time, terminate the accelerated group test.

[0015] S6. For each test group, measure 1 to 5 metal pipes in parallel and calculate the average value of the outer diameter creep elongation rate. Repeat S5 to carry out the high temperature internal pressure creep test of the remaining accelerated groups until all accelerated group tests are terminated.

[0016] S7. Plot the outer diameter creep elongation curves of the standard group and the accelerated group to predict the high-temperature internal pressure creep test performance of the corresponding metal pipes.

[0017] Furthermore, the plastic elongation strength R is specified in S2. p0.2 and the specified plastic elongation burst strength S p0.2 The method for obtaining it is as follows:

[0018] S2.1. Conduct a high-temperature tensile test on the metal pipe at a predetermined test temperature according to standard GB / T 228.2, and determine the specified plastic elongation strength R of the metal pipe at a strain of 0.2%. p0.2 ;

[0019] S2.2. The metal pipe is subjected to a high-temperature internal pressure burst test at a predetermined test temperature in accordance with standard YS / T 1474-2021, and the specified plastic elongation burst strength S of the metal pipe at a strain of 0.2% is determined. p0.2 .

[0020] Furthermore, the metal tube is any one of zirconium, titanium and their alloy tubes, and the outer diameter of the metal tube is 5 to 25 mm, and the wall thickness is 0.4 to 2.0 mm.

[0021] Furthermore, when the metal tubing in the standard group is zirconium alloy tubing, the predetermined test temperature range is 350℃~400℃; when the metal tubing in the standard group is titanium alloy tubing, the predetermined test temperature range is 300℃~450℃.

[0022] Furthermore, when the metal tubing of the acceleration group is a zirconium alloy tubing, the predetermined test temperature range is 400℃~430℃; when the metal tubing of the acceleration group is a titanium alloy tubing, the predetermined test temperature range is 350℃~480℃.

[0023] Furthermore, the creep test reference stress coefficient of the standard group ranges from 80% to 100%; when the metal pipe of the standard group is a zirconium alloy pipe, the creep test reference stress ranges from 100 MPa to 140 MPa; when the metal pipe of the standard group is a titanium alloy pipe, the creep test reference stress ranges from 460 MPa to 580 MPa.

[0024] Furthermore, the creep test reference stress coefficient of the accelerated group ranges from 100% to 135%; when the metal tube of the accelerated group is a zirconium alloy tube, the creep test reference stress ranges from 130MPa to 190MPa; when the metal tube of the accelerated group is a titanium alloy tube, the creep test reference stress ranges from 570MPa to 800MPa.

[0025] Furthermore, the data rounding interval for the creep test reference stress coefficient α is 5%, and the data rounding interval for the creep test reference stress σ is 5 MPa.

[0026] Furthermore, the test time range for the standard group is 100h to 360h, and the test time range for the accelerated group is 3h to 70h.

[0027] On the other hand, the present invention also provides an application based on some or all of the methods described above, which can be used for zirconium, titanium and their alloy pipes or other metal pipes that require high-temperature internal pressure creep testing. Without increasing the testing cost significantly, the testing cycle can be greatly shortened to several times or even tens of times the original.

[0028] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0029] 1. This invention can significantly improve the efficiency of high-temperature internal pressure creep testing of zirconium, titanium and their alloy tubes and other metal tubes. Without increasing the test cost significantly, the test cycle can be shortened to several times or even tens of times the original time. For example, the test time recommended by YS / T 1463-2021 "Internal Pressure Creep Test Method for Zirconium Alloy Tubes" is 240 hours, while the fastest test time obtained by the accelerated test model provided by this invention under equivalent conditions is about 3 hours.

[0030] 2. This invention, through extensive scientific research experiments, systematically studies the boundary conditions for high-temperature internal pressure creep tests on metal pipes (especially zirconium, titanium, and their alloy pipes), eliminating many invalid conditions and models that lead to irregular expansion and deformation of samples after high-temperature internal pressure creep tests under harsh conditions. Referring to zirconium alloy phase diagrams and titanium alloy phase diagrams, and through extensive high-temperature microstructure studies, the upper limit of the predetermined test temperature for the accelerated group was determined, avoiding model failure caused by differences in creep mechanisms between the accelerated group and the standard group when the predetermined test temperature is too high. Referring to YS / T 1474 "High-Temperature Internal Pressure Burst Test Method for Zirconium Alloy Pipes," extensive research was conducted to determine the upper limit of the reference stress coefficient for creep tests in the accelerated group, avoiding deformation of the metal material due to non-creep mechanisms when the reference stress is too high. Finally, scientifically rigorous boundary conditions and accelerated models were obtained, ensuring the accuracy and effectiveness of the experimental results obtained from the accelerated model.

[0031] 3. The accelerated model for high-temperature internal pressure creep testing of zirconium, titanium, and their alloy tubes obtained by this invention ensures that the test results are equivalent to those under the standard test conditions of YS / T 1463-2021 "Internal Pressure Creep Test Method for Zirconium Alloy Tubes" (test temperature 400℃, reference stress 130MPa, test time 240h), by changing the test temperature or reference stress alone or in combination. This significantly shortens the test cycle and effectively overcomes the technical bottleneck of not having a high-temperature internal pressure creep test method for titanium alloy tubes. Attached Figure Description

[0032] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A flowchart of a method for accelerating high-temperature internal pressure creep testing of metal pipes provided by the present invention;

[0035] Figure 2(a) shows the complete test curves of the standard group and accelerated group of the Φ9.5mm×0.57mm zirconium alloy clad tube provided in Example 1 of the present invention;

[0036] Figure 2(b) shows the test curves of the standard group and the accelerated group provided in Example 1 of the present invention after 11 hours;

[0037] Figure 3(a) shows the complete test curves of the standard group and accelerated group of the Φ12.5mm×0.7mm zirconium alloy tube provided in Example 2 of the present invention;

[0038] Figure 3(b) shows the test curves of the standard group and the accelerated group provided in Example 2 of the present invention after 6 hours;

[0039] Figure 4(a) shows the complete test curves of the standard group and accelerated group of the Φ14mm×1.0mm titanium alloy tube provided in Example 3 of the present invention;

[0040] Figure 4(b) shows the test curves of the standard group and the accelerated group provided in Example 3 of the present invention when both were carried out for 7.7 hours. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods consistent with some aspects of the invention as detailed in the appended claims.

[0042] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0043] Example 1

[0044] See Figure 1 As shown, this embodiment provides a method for accelerating the high-temperature internal pressure creep test of metal pipes, specifically including the following steps:

[0045] Step 1: Set up 4 test groups, including 1 standard group and 3 accelerated groups. The standard group and accelerated groups are zirconium alloy clad tubes of the same grade and produced by the same process. In this embodiment, the zirconium alloy clad tubes have an outer diameter of 9.5 mm and a wall thickness of 0.57 mm. High temperature internal pressure creep tests are carried out under different test conditions. In this embodiment, the predetermined test temperature for the standard group and accelerated group 1 is 400℃, and the predetermined test temperature for accelerated groups 2 and 3 is 420℃.

[0046] Step 2: Conduct a high-temperature tensile test on the selected zirconium alloy clad tube at a predetermined test temperature of 400℃, referring to standard GB / T 228.2, and determine its specified plastic elongation strength (R) at 0.2% strain. p0.2 =132MPa); In this embodiment, the creep test reference stress coefficient of the standard group is selected as 100%. The specified plastic elongation strength is multiplied by the creep test reference stress coefficient, and then the obtained strength value is rounded to a 5MPa interval to be specified as the creep test reference stress (σ) of the standard group. s =130MPa);

[0047] Step 3: Select the reference stress for the creep test of the three accelerated groups:

[0048] Step 301: Conduct a high-temperature internal pressure burst test on the selected zirconium alloy clad tube at a predetermined test temperature of 400℃, referring to YS / T 1474, and determine its specified plastic extension burst strength (S) at a strain of 0.2%. p0.2 =228MPa), the specified plastic extension burst strength (S p0.2 =228MPa) divided by the specified plastic elongation strength (R) obtained in step 2 p0.2 =132MPa) The quotient is 172.73%, and after multiplying by 77.5%, the coefficient obtained is 133.87%. The data is rounded at 5% intervals, and it is specified that the upper limit of the reference stress coefficient for creep test of accelerated group is 135%. In this embodiment, the reference stress coefficient for creep test of accelerated group 1 and accelerated group 3 is selected as 120%, and the reference stress coefficient for creep test of accelerated group 2 is 100%.

[0049] Step 302: The zirconium alloy clad tubes selected by acceleration group 1 and acceleration group 3 will have the specified plastic elongation strength (R) obtained in step 2. p0.2 =132MPa) multiplied by the creep test reference stress coefficient of 120%, and then the obtained strength value rounded to a 5MPa interval, is defined as the creep test reference stress (σ) for accelerated group 1 and accelerated group 3. a =160MPa);

[0050] Step 303: The zirconium alloy clad tube selected in Acceleration Group 2 will be subjected to the specified plastic elongation strength (R) obtained in Step 2. p0.2 =132MPa) multiplied by the creep test reference stress coefficient of 100%, and then the obtained strength value rounded to a 5MPa interval, is defined as the creep test reference stress (σ) for accelerated group 2. a =130MPa);

[0051] Step 4: Measure the outer diameter creep elongation of the zirconium alloy clad tube according to the standard group and the accelerated group, and obtain the outer diameter creep elongation curve at different times. When the outer diameter creep elongation of the accelerated group is equal to the outer diameter creep elongation of the standard group at the specified test time of 240h, the accelerated group test is terminated.

[0052] Step 5: In this embodiment, three zirconium alloy clad tubes are measured in parallel for each test group and their average value is calculated. All high-temperature internal pressure creep tests in Step 4 are repeated until all tests are terminated.

[0053] Step 6: Based on the obtained outer diameter creep elongation rates of the standard group and the accelerated group, plot the corresponding test curves, as shown in Figures 2(a) and 2(b). This can further predict the high-temperature internal pressure creep test performance of the zirconium alloy clad tube. The characteristic values ​​of the outer diameter creep elongation rates of the standard group, accelerated group 1, accelerated group 2, and accelerated group 3 are detailed in Table 1.

[0054] Table 1. Characteristic values ​​of outer diameter creep elongation in the high-temperature internal pressure creep test of the zirconium alloy clad tube provided in Example 1.

[0055]

[0056]

[0057] In this embodiment, the testing speed of accelerated group 1 is 5.87 times that of the standard group. When the standard group's testing time is 240 hours, accelerated group 1 can achieve the equivalent result in only 41 hours. The testing speed of accelerated group 2 is 9.2 times that of the standard group. When the standard group's testing time is 240 hours, accelerated group 2 can achieve the equivalent result in only 26 hours. The testing speed of accelerated group 3 is 35.5 times that of the standard group. When the standard group's testing time is 240 hours, accelerated group 3 can achieve the equivalent result in only 6.75 hours.

[0058] Example 2

[0059] This embodiment provides yet another method for accelerating the high-temperature internal pressure creep test of metal pipes, specifically including the following steps:

[0060] Step 1: Set up 4 test groups, including 1 standard group and 3 accelerated groups. The standard group and accelerated groups are zirconium alloy tubes of the same grade and produced by the same process. In this embodiment, the zirconium alloy tubes have an outer diameter of 12.5 mm and a wall thickness of 0.7 mm. High temperature internal pressure creep tests are carried out under different test conditions. In this embodiment, the predetermined test temperature for the standard group and accelerated group 1 is 400℃, and the predetermined test temperature for accelerated groups 2 and 3 is 430℃.

[0061] Step 2: Conduct a high-temperature tensile test on the selected zirconium alloy tube at a predetermined test temperature of 400℃, referring to GB / T228.2, and determine its specified plastic elongation strength (R) at 0.2% strain. p0.2 =128MPa); In this embodiment, the creep test reference stress coefficient of the standard group is selected as 100%. The specified plastic elongation strength is multiplied by the creep test reference stress coefficient, and then the obtained strength value is rounded to a 5MPa interval to be specified as the creep test reference stress (σ) of the standard group. s =130MPa);

[0062] Step 3: Select the reference stress for the creep test of the three accelerated groups:

[0063] Step 301: Conduct a high-temperature internal pressure burst test on the selected zirconium alloy tube at a predetermined test temperature of 400℃, referring to YS / T 1474, and determine its specified plastic elongation burst strength (S) at a strain of 0.2%. p0.2 =226MPa), the specified plastic extension burst strength (S p0.2 =226MPa) divided by the specified plastic elongation strength (R) obtained in step 2 p0.2 =128MPa) The quotient is 176.56%, and after multiplying by 77.5%, the coefficient obtained is 136.84%. The data is rounded at 5% intervals, and it is specified that the upper limit of the reference stress coefficient for creep test of accelerated group is 135%. In this embodiment, the reference stress coefficient for creep test of accelerated group 1 and accelerated group 3 is selected as 135%, and the reference stress coefficient for creep test of accelerated group 2 is 100%.

[0064] Step 302: The zirconium alloy tubing selected by Acceleration Group 1 and Acceleration Group 3 will be subjected to the specified plastic elongation strength (R) obtained in Step 2. p0.2 =128MPa) multiplied by the creep test reference stress coefficient of 135%, and then the obtained strength value rounded to a 5MPa interval, is defined as the creep test reference stress (σ) for accelerated group 1 and accelerated group 3. a =175MPa);

[0065] Step 303: The zirconium alloy tube selected by Acceleration Group 2 will have the specified plastic elongation strength (R) obtained in Step 2. p0.2 =128MPa) multiplied by the creep test reference stress coefficient of 100%, and then the obtained strength value rounded to the nearest 5MPa interval, is defined as the creep test reference stress (σ) for accelerated group 2. a =130MPa);

[0066] Step 4: Measure the outer diameter creep elongation of the zirconium alloy tube according to the standard group and the accelerated group, and obtain the outer diameter creep elongation curve at different times. When the outer diameter creep elongation of the accelerated group is equal to the outer diameter creep elongation of the standard group at the specified test time of 240h, the accelerated group test is terminated.

[0067] Step 5: In this embodiment, three zirconium alloy tubes are measured in parallel for each experimental group and their average value is calculated. All high-temperature internal pressure creep tests in Step 4 are repeated until all tests are terminated.

[0068] Step 6: Based on the obtained outer diameter creep elongation rates of the standard group and the accelerated group, plot the corresponding test curves, as shown in Figures 3(a) and 3(b). This can further predict the high-temperature internal pressure creep test performance of zirconium alloy tubes. The characteristic values ​​of the outer diameter creep elongation rates of the standard group, accelerated group 1, accelerated group 2, and accelerated group 3 are detailed in Table 2.

[0069] Table 2 shows the characteristic values ​​of the outer diameter creep elongation in the high-temperature internal pressure creep test of the zirconium alloy tubes provided in Example 2.

[0070]

[0071] In this embodiment, the testing speed of accelerated group 1 is 15.35 times that of the standard group. When the standard group test time is 240 hours, accelerated group 1 only needs 15.63 hours to achieve the equivalent result. The testing speed of accelerated group 2 is 8.75 times that of the standard group. When the standard group test time is 240 hours, accelerated group 2 only needs 27.43 hours to achieve the equivalent result. The testing speed of accelerated group 3 is 69.56 times that of the standard group. When the standard group test time is 240 hours, accelerated group 3 only needs 3.45 hours to achieve the equivalent result.

[0072] Example 3

[0073] This embodiment provides another method for accelerating the high-temperature internal pressure creep test of metal pipes, specifically including the following steps:

[0074] Step 1: Set up 4 test groups, including 1 standard group and 3 accelerated groups. The standard group and accelerated groups are titanium alloy pipes of the same grade and produced by the same process. In this embodiment, the titanium alloy pipes have an outer diameter of 14 mm and a wall thickness of 1.0 mm. High temperature internal pressure creep tests are carried out under different test conditions. In this embodiment, the predetermined test temperature for the standard group and accelerated group 1 is 450℃, and the predetermined test temperature for accelerated groups 2 and 3 is 480℃.

[0075] Step 2: Conduct a high-temperature tensile test on the selected titanium alloy pipe at a predetermined test temperature of 450℃, referring to GB / T228.2, and determine its specified plastic elongation strength (R) at 0.2% strain. p0.2=552MPa); In this embodiment, the creep test reference stress coefficient of the standard group is selected as 100%. The specified plastic elongation strength is multiplied by the creep test reference stress coefficient, and then the obtained strength value is rounded to a 5MPa interval to be specified as the creep test reference stress (σ) of the standard group. s =550MPa);

[0076] Step 3: Select the reference stress for the creep test of the three accelerated groups:

[0077] Step 301: Conduct a high-temperature internal pressure burst test on the selected titanium alloy pipe at a predetermined test temperature of 400℃, referring to YS / T 1474, and determine its specified plastic elongation burst strength (S) at a strain of 0.2%. p0.2 =895MPa), the specified plastic extension burst strength (S p0.2 =895MPa) divided by the specified plastic elongation strength (R) obtained in step 2 p0.2 =552MPa) The quotient is 162.14%, and after multiplying by 77.5%, the obtained coefficient is 125.66%. The data is rounded at 5% intervals, and it is specified that the upper limit of the reference stress coefficient for creep test of accelerated group is 125%. In this embodiment, the reference stress coefficient for creep test of accelerated group 1 and accelerated group 3 is selected as 125%, and the reference stress coefficient for creep test of accelerated group 2 is 100%.

[0078] Step 302: The titanium alloy tubing selected by Acceleration Group 1 and Acceleration Group 3 will have the specified plastic elongation strength (R) obtained in Step 2. p0.2 =552MPa) multiplied by the creep test reference stress coefficient of 125%, and then the obtained strength value rounded to the nearest 5MPa interval, is defined as the creep test reference stress (σ) for accelerated group 1 and accelerated group 3. a =690MPa);

[0079] Step 303: The titanium alloy tubing selected by Acceleration Group 2 will have the specified plastic elongation strength (R) obtained in Step 2. p0.2 =552MPa) multiplied by the creep test reference stress coefficient of 100%, and then the obtained strength value rounded to the nearest 5MPa interval, is defined as the creep test reference stress (σ) for accelerated group 2. a =550MPa);

[0080] Step 4: Measure the outer diameter creep elongation rate of the titanium alloy pipe according to the standard group and the accelerated group, and obtain the outer diameter creep elongation rate curve at different times. When the outer diameter creep elongation rate of the accelerated group is equal to the outer diameter creep elongation rate of the standard group at the specified test time of 100h, the accelerated group test is terminated.

[0081] Step 5: In this embodiment, three titanium alloy tubes are measured in parallel for each experimental group and their average value is calculated. All high-temperature internal pressure creep tests in Step 4 are repeated until all tests are terminated.

[0082] Step 6: Based on the obtained outer diameter creep elongation rates of the standard group and the accelerated group, plot the corresponding test curves, as shown in Figures 4(a) and 4(b). This can further predict the high-temperature internal pressure creep test performance of titanium alloy pipes. The characteristic values ​​of the outer diameter creep elongation rates of the standard group, accelerated group 1, accelerated group 2, and accelerated group 3 are detailed in Table 3.

[0083] Table 3. Characteristic values ​​of outer diameter creep elongation in high-temperature internal pressure creep test of titanium alloy tubing in Example 3.

[0084]

[0085] In this embodiment, the testing speed of accelerated group 1 is 1.62 times that of the standard group. When the standard group's testing time is 100 hours, accelerated group 1 only needs 61.78 hours to achieve the equivalent result. The testing speed of accelerated group 2 is 7.37 times that of the standard group. When the standard group's testing time is 100 hours, accelerated group 2 only needs 13.57 hours to achieve the equivalent result. The testing speed of accelerated group 3 is 10.78 times that of the standard group. When the standard group's testing time is 100 hours, accelerated group 3 only needs 9.27 hours to achieve the equivalent result.

[0086] In summary, the prediction method for the accelerated high-temperature internal pressure creep test model provided by this invention can be widely applied to the field of internal pressure creep testing of zirconium alloy pipes and titanium alloy pipes, effectively breaking through the technical bottleneck that there is no high-temperature internal pressure creep test method for other metal pipes such as zirconium, titanium and their alloy pipes.

[0087] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0088] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for accelerating the high-temperature internal pressure creep test of metal pipes, characterized in that, Specifically, the steps include the following: S1. Set up one standard group and at least one accelerated group to carry out high-temperature internal pressure creep tests under different test conditions; the standard group and the accelerated group both use metal pipes of the same grade and produced by the same process; S2. Obtain the specified plastic elongation strength R of the metal tube at a strain of 0.2%. p0.2 and the specified plastic extension burst strength S at a strain of 0.2%. p0.2 ; S3, according to the specified plastic elongation strength R p0.2 The specified plastic extension burst strength S p0.2 The creep test reference stress coefficient α is calculated using the following formula (1): α = 77.5% * S p0.2 / R p0.2 Equation (1) S4. Based on the creep test reference stress coefficient α and the specified plastic elongation strength R p0.2 The creep test reference stress σ is calculated using the following formula (2): σ=α×R p0.2 expression(2) S5. Measure the outer diameter creep elongation rate of the metal pipes in the standard group and any accelerated group respectively, and obtain the outer diameter creep elongation rate curves at different times; when the outer diameter creep elongation rate of the accelerated group is equal to or greater than the outer diameter creep elongation rate of the standard group at the specified test time, terminate the accelerated group test. S6. For each test group, measure 1 to 5 metal pipes in parallel and calculate the average value of the outer diameter creep elongation rate. Repeat S5 to carry out the high temperature internal pressure creep test of the remaining accelerated groups until all accelerated group tests are terminated. S7. Plot the outer diameter creep elongation curves of the standard group and the accelerated group to predict the high-temperature internal pressure creep test performance of the corresponding metal pipes.

2. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 1, characterized in that, The plastic elongation strength R specified in S2 is... p0.2 and the specified plastic elongation burst strength S p0.2 The method for obtaining it is as follows: S2.

1. Conduct a high-temperature tensile test on the metal pipe at a predetermined test temperature according to standard GB / T 228.2, and determine the specified plastic elongation strength R of the metal pipe at a strain of 0.2%. p0.2 ; S2.

2. The metal pipe is subjected to a high-temperature internal pressure burst test at a predetermined test temperature in accordance with standard YS / T 1474-2021, and the specified plastic elongation burst strength S of the metal pipe at a strain of 0.2% is determined. p0.2 .

3. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 1 or 2, characterized in that, The metal tube is any one of zirconium, titanium and their alloy tubes, and the outer diameter of the metal tube is 5 to 25 mm and the wall thickness is 0.4 to 2.0 mm.

4. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 3, characterized in that, When the metal tubing in the standard group is zirconium alloy tubing, the predetermined test temperature range is 350℃~400℃; when the metal tubing in the standard group is titanium alloy tubing, the predetermined test temperature range is 300℃~450℃.

5. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 3, characterized in that, When the metal tubing of the acceleration group is a zirconium alloy tubing, the predetermined test temperature range is 400℃~430℃; when the metal tubing of the acceleration group is a titanium alloy tubing, the predetermined test temperature range is 350℃~480℃.

6. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 3, characterized in that, The creep test reference stress coefficient range for the standard group is 80% to 100%; when the metal pipe of the standard group is a zirconium alloy pipe, the creep test reference stress range is 100MPa to 140MPa; when the metal pipe of the standard group is a titanium alloy pipe, the creep test reference stress range is 460MPa to 580MPa.

7. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 3, characterized in that, The creep test reference stress coefficient range for the accelerated group is 100% to 135%; when the metal tube of the accelerated group is a zirconium alloy tube, the creep test reference stress range is 130MPa to 190MPa; when the metal tube of the accelerated group is a titanium alloy tube, the creep test reference stress range is 570MPa to 800MPa.

8. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 1, characterized in that, The data rounding interval for the creep test reference stress coefficient α is 5%, and the data rounding interval for the creep test reference stress σ is 5 MPa.

9. The method for accelerating the high-temperature internal pressure creep test of metal pipes according to claim 1, characterized in that, The test time range for the standard group is 100h to 360h, and the test time range for the accelerated group is 3h to 70h.

10. Application of the method according to any one of claims 1-9 in high-temperature internal pressure creep tests of zirconium, titanium and their alloy tubes.

Images