Room-temperature tensile test method of stainless steel pipe for aviation high-pressure hydraulic system

Abstract

The invention provides a room-temperature tensile test method of a stainless steel pipe for an aviation high-pressure hydraulic system, which comprises the following steps: plugging two ends of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested into chock plugs, then mounting the stainless steel pipe on a clamp of a tensile test device, and clamping; the stainless steel pipe for the aviation high-pressure hydraulic system to be tested is subjected to a room-temperature tensile test, the displacement rate of the cross beam before yield strength is controlled to be 0.45-0.55 mm / min, and the displacement rate of the cross beam after yield strength is controlled to be 4.5-5.5 mm / min. By establishing a unified measurement method, data obtained when the stainless steel pipe for the aviation high-pressure hydraulic system is measured in different units are ensured to have consistency and comparability, and a solid foundation is provided for application of the high-strength cold-working hardened stainless steel pipe in actual engineering; and a technical support is provided for further research on the high-strength cold-working hardened stainless steel pipe and similar materials.

Description

Technical Field

[0001] The invention belongs to the technical field of room temperature tensile testing of austenitic stainless steel pipe metal materials, and relates to a room temperature tensile testing method of a stainless steel pipe for an aviation high-pressure hydraulic system. Background Art

[0002] With the development of science and technology, the aerospace field has higher and higher requirements for high-pressure hydraulic pipes, and the current pipes on aircraft engines can no longer meet these requirements. 03Cr21Ni6Mn9N stainless steel seamless pipe is an austenitic stainless steel that uses Mn and N to replace part of Ni to stabilize austenite. Nitrogen has a strengthening effect, making the steel have higher toughness, extremely low magnetic permeability and more stable austenite structure. The room temperature tensile yield strength of this stainless steel is greater than 890MPa, and the tensile strength is greater than 980MPa, which can meet the requirements of high-pressure hydraulic pipes on aircraft engines.

[0003] Yield strength is one of the important mechanical properties of high-strength cold-worked hardened stainless steel pipes. It is directly used to measure the bearing capacity of stainless steel pipe components during engineering design and material selection. At the same time, the yield strength ratio (the ratio of the yield strength to the tensile strength of the material) is also often used as an important mechanical property index of stainless steel pipes in engineering to measure their toughness and brittleness. In addition, elongation is one of the important parameters for measuring the plastic properties of stainless steel pipes. The higher the elongation, the better the plasticity of the material, that is, it is easier to deform and not easy to break under the action of external forces. Therefore, the accurate measurement of yield strength, tensile strength and elongation is of great significance to the practical application and structural design of high-strength cold-worked hardened stainless steel pipes.

[0004] According to the national standard GB / T228 "Metal Tensile Test Method", when the testers measured the yield strength of 03Cr21Ni6Mn9N stainless steel pipe according to this national standard, they found that the yield strength, tensile strength and elongation could not be accurately measured; and different testing units measured different data according to the national standard method, resulting in different judgments on the same material.

[0005] As important mechanical and plastic performance indicators of high-strength cold-worked hardened stainless steel pipes, the inconsistency in the test results of yield strength, tensile strength and elongation directly affects the application of stainless steel pipes in actual engineering, and even causes trouble for the design ideas of stainless steel pipe R&D personnel.

[0006] In summary, a unified room temperature tensile test method is provided to accurately measure the yield strength, tensile strength and elongation of high-strength cold-work hardened stainless steel pipes, thereby providing a solid foundation for the application of stainless steel pipes in practical engineering and providing technical support for further research on stainless steel pipes and similar materials. Summary of the invention

[0007] The purpose of the present invention is to provide a room temperature tensile test method for stainless steel pipes for aviation high-pressure hydraulic systems. By establishing a unified measurement method, it is ensured that the data obtained when the stainless steel pipes for aviation high-pressure hydraulic systems are measured in different units are consistent and comparable, providing a solid foundation for the application of high-strength cold-work hardened stainless steel pipes in practical engineering, and providing technical support for further research on high-strength cold-work hardened stainless steel pipes and similar materials.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides a room temperature tensile test method for a stainless steel pipe for an aviation high pressure hydraulic system, the room temperature tensile test method comprising the following steps:

[0010] (1) Insert plugs into both ends of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested, and then install it on the fixture of the tensile test device and clamp it;

[0011] (2) A room temperature tensile test is performed on a stainless steel tube for an aviation high-pressure hydraulic system to be tested, and the crossbeam displacement rate is controlled to be 0.45-0.55 mm / min before the yield strength and 4.5-5.5 mm / min after the yield strength.

[0012] In the present invention, the test object is a stainless steel pipe for aviation high-pressure hydraulic system (cold-hardened stainless steel), which has an obvious elastic straight line segment (its internal stress is proportional to the strain), so the room temperature tensile test method can be carried out, and the existence of the elastic straight line segment also helps to determine the yield point of the material. The tensile test rate is controlled by the displacement rate of the crossbeam of the tensile test device; the tensile strength is measured after the yield strength.

[0013] The present invention provides a room temperature tensile test method, plugs are inserted into both ends of a cold-work hardened stainless steel pipe, and then a room temperature tensile test is performed, and a unified measurement method is established by combining the range of crossbeam displacement rates when controlling the yield strength measurement and the range of crossbeam displacement rates when controlling the tensile strength measurement, thereby ensuring the accuracy and reliability of the yield strength, tensile strength and elongation measurement results, ensuring that the data obtained when high-strength cold-work hardened stainless steel is measured in different units are consistent and comparable, providing a solid foundation for the application of cold-work hardened stainless steel pipes in practical engineering, and providing technical support for further research on cold-work hardened stainless steel pipes and similar materials.

[0014] It is worth noting that when conducting room temperature tensile tests on high-strength cold-work hardened stainless steel pipes, based on the beam displacement rate = strain rate × parallel length, the beam displacement rate before yield strength is determined to be 0.45-0.55mm / min and the beam displacement rate after yield strength (i.e. measuring tensile strength) is determined to be 4.5-5.5mm / min, and then a unified measurement method is established to accurately measure the yield strength, tensile strength and elongation of high-strength cold-work hardened stainless steel pipes.

[0015] As a preferred technical solution of the present invention, the stainless steel pipe for aviation high-pressure hydraulic system includes 03Cr21Ni6Mn9N stainless steel pipe.

[0016] In the present invention, since the 03Cr21Ni6Mn9N stainless steel pipe is a cold-worked hardened stainless steel pipe, the tensile test rate recommended by the metal tensile test method provided by the national standard GB / T228 cannot accurately measure the yield strength, tensile strength and elongation of the material.

[0017] As a preferred technical solution of the present invention, the length of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested in step (1) is 210-230 mm, for example, it can be 212 mm, 214 mm, 215 mm, 216 mm, 218 mm, 220 mm, 222 mm, 224 mm, 225 mm, 226 mm or 228 mm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0018] As a preferred technical solution of the present invention, the outer surface roughness Ra of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested in step (1) is ≤ 0.2 μm, for example, it can be 0.18 μm, 0.16 μm, 0.15 μm, 0.14 μm, 0.13 μm, 0.12 μm or 0.1 μm, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0019] In the present invention, by controlling the outer surface roughness range of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested, the contact between the sample and the fixture can be made closer when clamped, reducing stress concentration on the sample surface and ensuring the reliability and accuracy of the test data.

[0020] As a preferred technical solution of the present invention, the plug in step (1) includes a round plug.

[0021] Preferably, the length of the plug in step (1) is 55-65 mm, for example, it can be 56 mm, 57 mm, 58 mm, 59 mm, 60 mm, 61 mm, 62 mm, 63 mm or 64 mm, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0022] In the present invention, by controlling the size of the plug, it is not only helpful to reduce the stress concentration of the sample in the clamping area, but also possible to control the length of the deformation zone of the high-strength cold-work hardened stainless steel pipe, ensuring that the high-strength cold-work hardened stainless steel pipe is uniformly deformed in the gauge length area, thereby more accurately measuring the elongation of the material.

[0023] As a preferred technical solution of the present invention, the outer diameter of the plug in step (1) is smaller than the inner diameter of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested, and the difference is 0.02-0.04 mm, for example, it can be 0.022 mm, 0.024 mm, 0.025 mm, 0.026 mm, 0.028 mm, 0.03 mm, 0.032 mm, 0.034 mm, 0.036 mm or 0.038 mm, etc., but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0024] As a preferred technical solution of the present invention, the temperature of the room temperature tensile test in step (2) is 10-35°C, for example, it can be 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C or 32°C, but is not limited to the listed values, and other values ​​within the numerical range are also applicable.

[0025] In the present invention, the original gauge length in the room temperature tensile test in step (2) is 50 mm.

[0026] As a preferred technical solution of the present invention, the displacement rate of the beam before yield strength in step (2) is 0.48-0.52 mm / min, for example, it can be 0.485 mm / min, 0.49 mm / min, 0.495 mm / min, 0.5 mm / min, 0.505 mm / min or 0.51 mm / min, but is not limited to the listed values. Other values ​​within the numerical range are also applicable, preferably 0.5 mm / min.

[0027] Preferably, the displacement rate of the beam after the yield strength in step (2) is 4.8-5.2 mm / min, for example, it can be 4.85 mm / min, 4.9 mm / min, 4.95 mm / min, 5 mm / min, 5.05 mm / min or 5.1 mm / min, but is not limited to the listed values. Other values ​​within the numerical range are also applicable, preferably 5 mm / min.

[0028] As a preferred technical solution of the present invention, step (2) further includes performing a qualification evaluation on the room temperature tensile test results after performing the room temperature tensile test.

[0029] Preferably, the qualification criteria for the room temperature tensile test results are tensile strength ≥ 980 MPa, yield strength ≥ 825 MPa, and elongation ≥ 18%.

[0030] In the present invention, the tensile strength of the stainless steel pipe for aviation high pressure hydraulic system is preferably 980-1120Mpa, the yield strength is ≥825Mpa, and the elongation is ≥18%. When the nominal outer diameter of the stainless steel pipe for aviation high pressure hydraulic system is <12mm and the nominal wall thickness is ≤0.5mm, the elongation of the stainless steel pipe is ≥18%, and the elongation of the stainless steel pipe under other conditions is ≥20%.

[0031] As a preferred technical solution of the present invention, the room temperature tensile test method comprises the following steps:

[0032] (1) A stainless steel pipe for an aviation high-pressure hydraulic system to be tested with a length of 210-230 mm and an outer surface roughness of Ra ≤ 0.2 μm is plugged with plugs with a length of 55-65 mm at both ends, and then installed on the fixture of the tensile test device and clamped;

[0033] The stainless steel pipe for aviation high-pressure hydraulic system comprises a 03Cr21Ni6Mn9N stainless steel pipe; the outer diameter of the plug is smaller than the inner diameter of the stainless steel pipe for aviation high-pressure hydraulic system to be tested, and the difference is 0.02-0.04 mm;

[0034] (2) Conduct a room temperature tensile test on the stainless steel pipe for the aviation high-pressure hydraulic system to be tested at a temperature of 10-35°C, and control the crossbeam displacement rate before yield strength to 0.45-0.55 mm / min and the crossbeam displacement rate after yield strength to 4.5-5.5 mm / min;

[0035] (3) performing a qualification evaluation on the room temperature tensile test results obtained in step (2); the qualification criteria for the room temperature tensile test results are tensile strength ≥ 980 MPa, yield strength ≥ 825 MPa, and elongation ≥ 18%.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Plugs are inserted into both ends of the stainless steel pipe, and then a room temperature tensile test is performed. A unified measurement method is established by combining the range of crossbeam displacement rates when controlling the yield strength measurement with the range of crossbeam displacement rates when controlling the tensile strength measurement. The accuracy and reliability of the yield strength, tensile strength and elongation measurement results are ensured, and the consistency and comparability of the data obtained when the high-strength cold-work hardened stainless steel is measured in different units are ensured. A solid foundation is provided for the application of the high-strength cold-work hardened stainless steel pipe in practical engineering, and technical support is provided for further research on the high-strength cold-work hardened stainless steel pipe and similar materials. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0039] When the room temperature tensile test method is performed in the following examples and comparative examples, the displacement rate of the beam is kept uniform when the yield strength and tensile strength are measured.

[0040] Example 1

[0041] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high pressure hydraulic system, the room temperature tensile test method comprising the following steps:

[0042] (1) A 60 mm long round plug was inserted into both ends of a 220 mm long stainless steel tube for an aviation high pressure hydraulic system to be tested with an outer surface roughness Ra of 0.1 μm, and then installed on the fixture of the tensile test device and clamped;

[0043] The stainless steel pipe for the aviation high-pressure hydraulic system is a 03Cr21Ni6Mn9N stainless steel pipe with an outer diameter of 6 mm and a wall thickness of 0.5 mm; the outer diameter of the circular plug is smaller than the inner diameter of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested, and the difference is 0.03 mm;

[0044] (2) A room temperature tensile test is performed on the stainless steel pipe for the aviation high pressure hydraulic system to be tested at a temperature of 25°C until it breaks; and the crossbeam displacement rate is controlled to be 0.5 mm / min before the yield strength and 5 mm / min after the yield strength;

[0045] The gauge length in the room temperature tensile test is 50 mm;

[0046] (3) Repeat the room temperature tensile test 4 times and conduct a qualification evaluation on the obtained room temperature tensile test results.

[0047] The test results and evaluation results in this embodiment are shown in Table 1.

[0048] Table 1

[0049]

[0050] Example 2

[0051] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Except that the outer diameter of the stainless steel pipe for an aviation high-pressure hydraulic system is 16 mm and the wall thickness is 1.2 mm, other conditions are the same as those in Embodiment 1.

[0052] The test results and evaluation results in this embodiment are shown in Table 2.

[0053] Table 2

[0054]

[0055]

[0056] Example 3

[0057] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Except that the outer diameter of the stainless steel pipe for an aviation high-pressure hydraulic system is 8 mm and the wall thickness is 0.6 mm, other conditions are the same as those in Embodiment 1.

[0058] The test results and evaluation results in this embodiment are shown in Table 3.

[0059] Table 3

[0060]

[0061] Example 4

[0062] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Except that the outer diameter of the stainless steel pipe for an aviation high-pressure hydraulic system is 10 mm and the wall thickness is 0.7 mm, other conditions are the same as those in Embodiment 1.

[0063] The test results and evaluation results in this embodiment are shown in Table 4.

[0064] Table 4

[0065]

[0066] Example 5

[0067] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Except that the outer diameter of the stainless steel pipe for an aviation high-pressure hydraulic system is 18 mm and the wall thickness is 1.3 mm, other conditions are the same as those in Embodiment 1.

[0068] The test results and evaluation results in this embodiment are shown in Table 5.

[0069] Table 5

[0070]

[0071] It can be seen from Tables 1 to 5 that the room temperature tensile test method provided by the present invention is suitable for tensile tests of cold-work hardened 03Cr21Ni6Mn9N stainless steel pipes of different specifications. By establishing a unified measurement method, the accuracy and reliability of the yield strength, tensile strength and elongation measurement results are ensured, thereby ensuring that the data obtained when high-strength cold-work hardened stainless steel is measured in different units are consistent and comparable.

[0072] Example 6

[0073] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high pressure hydraulic system. Except that the outer surface roughness Ra of the stainless steel pipe for an aviation high pressure hydraulic system to be tested is 0.5 μm, other conditions are the same as those in Embodiment 1.

[0074] The test results and evaluation results in this embodiment are shown in Table 6.

[0075] Table 6

[0076]

[0077] From the comparison between Table 1 and Table 6, it can be seen that when the roughness of the outer surface of the stainless steel pipe to be tested is too large, the surface of the sample is rough due to polishing, which is caused by the sand grains on the sand belt used for polishing on the surface of the sample, and fine cracks will be generated. Stress concentration is likely to occur in these places, resulting in a decrease in the yield strength measurement result of the 03Cr21Ni6Mn9N stainless steel pipe and an unqualified elongation. The tensile strength of the 03Cr21Ni6Mn9N stainless steel pipe actually selected meets the qualified standard, resulting in an incorrect judgment result for the 03Cr21Ni6Mn9N stainless steel pipe, which not only affects its application in actual engineering, but also causes trouble to the design ideas of the 03Cr21Ni6Mn9N stainless steel pipe R&D personnel.

[0078] Example 7

[0079] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Except that the length of the plug is 30 mm, other conditions are the same as those in Embodiment 1.

[0080] The test results and evaluation results in this embodiment are shown in Table 7.

[0081] Table 7

[0082]

[0083] Example 8

[0084] This embodiment provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system. Except that the length of the plug is 80 mm, other conditions are the same as those in Embodiment 1.

[0085] The test results and evaluation results in this embodiment are shown in Table 8.

[0086] Table 8

[0087]

[0088]

[0089] From the comparison between Table 1 and Table 7-8, it can be seen that when the length of the plug is too short, there is a section of the pipe without a plug in the clamping section, resulting in unqualified elongation measurement results of the 03Cr21Ni6Mn9N stainless steel pipe; when the length of the plug is too long, the plug exceeds the clamping section, and the exceeding plug will affect the deformation of the pipe during the stretching process, resulting in unqualified elongation measurement results of the 03Cr21Ni6Mn9N stainless steel pipe. However, the tensile strength of the 03Cr21Ni6Mn9N stainless steel pipe actually selected meets the qualified standard, resulting in incorrect judgment results for the 03Cr21Ni6Mn9N stainless steel pipe, which not only affects its application in actual engineering, but also causes troubles for the design ideas of the 03Cr21Ni6Mn9N stainless steel pipe R&D personnel.

[0090] Comparative Example 1

[0091] This comparative example provides a room temperature tensile test method for stainless steel pipes for aviation high-pressure hydraulic systems, except that the crossbeam displacement rate before the yield strength is 1.5 mm / min and the crossbeam displacement rate after the yield strength is 40.2 mm / min; other conditions are the same as those in Example 1.

[0092] The test results and evaluation results in this comparative example are shown in Table 9.

[0093] Table 9

[0094]

[0095] Comparative Example 2

[0096] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 33 mm / min; other conditions are the same as those in Example 1.

[0097] The test results and evaluation results in this comparative example are shown in Table 10.

[0098] Table 10

[0099]

[0100] Comparative Example 3

[0101] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 30 mm / min; other conditions are the same as those in Example 1.

[0102] The test results and evaluation results in this comparative example are shown in Table 11.

[0103] Table 11

[0104]

[0105] Comparative Example 4

[0106] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 25 mm / min; other conditions are the same as those in Example 1.

[0107] The test results and evaluation results in this comparative example are shown in Table 12.

[0108] Table 12

[0109]

[0110]

[0111] Comparative Example 5

[0112] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 20 mm / min; other conditions are the same as those in Example 1.

[0113] The test results and evaluation results in this comparative example are shown in Table 13.

[0114] Table 13

[0115]

[0116] Comparative Example 6

[0117] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 15 mm / min; other conditions are the same as those in Example 1.

[0118] The test results and evaluation results in this comparative example are shown in Table 14.

[0119] Table 14

[0120]

[0121] Comparative Example 7

[0122] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 10 mm / min; other conditions are the same as those in Example 1.

[0123] The test results and evaluation results in this comparative example are shown in Table 15.

[0124] Table 15

[0125]

[0126] From the comparison between Table 1 and Tables 9-15, it can be seen that when the beam displacement rate before and after the yield strength is not within the preferred range, the measured elongation of the 03Cr21Ni6Mn9N stainless steel pipe does not meet the corresponding qualified standards partially or completely, and the greater the beam displacement rate after the yield strength, the lower the measured elongation; and the elongation of the selected 03Cr21Ni6Mn9N stainless steel pipe meets the qualified standards, resulting in incorrect judgment results for the 03Cr21Ni6Mn9N stainless steel pipe, which not only affects its application in actual engineering, but also causes troubles for the design ideas of the 03Cr21Ni6Mn9N stainless steel pipe R&D personnel.

[0127] Comparative Example 8

[0128] This comparative example provides a room temperature tensile test method for a stainless steel pipe for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 2 mm / min; other conditions are the same as those in Example 1.

[0129] The test results and evaluation results in this comparative example are shown in Table 16.

[0130] Table 16

[0131]

[0132] Comparative Example 9

[0133] This comparative example provides a room temperature tensile test method for stainless steel pipes for aviation high-pressure hydraulic systems, except that the crossbeam displacement rate before the yield strength is 1.5 mm / min and the crossbeam displacement rate after the yield strength is 40.2 mm / min; other conditions are the same as those in Example 2.

[0134] The test results and evaluation results in this comparative example are shown in Table 17.

[0135] Table 17

[0136]

[0137] Comparative Example 10

[0138] This comparative example provides a room temperature tensile test method for a stainless steel tube for an aviation high-pressure hydraulic system, except that the crossbeam displacement rate after the yield strength is 2 mm / min; other conditions are the same as those in Example 2.

[0139] The test results and evaluation results in this comparative example are shown in Table 18.

[0140] Table 18

[0141]

[0142] From the comparison between Table 1-2 and Table 16 and Table 18, it can be seen that when the displacement rate of the beam after the yield strength is too low, although when the outer diameter of the stainless steel pipe is less than 12mm, the measured performance indicators of the 03Cr21Ni6Mn9N stainless steel pipe meet the qualified standards, but when the outer diameter of the stainless steel pipe is greater than 12mm, due to the larger specifications and the wall thickness above 1mm, which is related to the hardening characteristics of the material itself, the measured tensile strength of the 03Cr21Ni6Mn9N stainless steel pipe does not meet the qualified standards, while the tensile strength of the 03Cr21Ni6Mn9N stainless steel pipe actually selected meets the qualified standards, resulting in inconsistent judgment results for 03Cr21Ni6Mn9N stainless steel pipes of different specifications and the existence of erroneous judgments.

[0143] From the comparison between Table 2 and Tables 17-18, it can be seen that when the beam displacement rate before and after the yield strength is not in the preferred range, the measured elongation or tensile strength of the 03Cr21Ni6Mn9N stainless steel pipe does not meet the corresponding qualified standards, while the elongation or tensile strength of the selected 03Cr21Ni6Mn9N stainless steel pipe meets the qualified standards, resulting in incorrect judgment results for the 03Cr21Ni6Mn9N stainless steel pipe, which not only affects its application in actual engineering, but also causes troubles for the design ideas of the 03Cr21Ni6Mn9N stainless steel pipe R&D personnel.

[0144] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A room temperature tensile test method for stainless steel pipes for aviation high pressure hydraulic systems, characterized in that: The room temperature tensile test method comprises the following steps: (1) Insert plugs into both ends of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested, and then install it on the fixture of the tensile test device and clamp it; (2) A room temperature tensile test is performed on a stainless steel tube for an aviation high-pressure hydraulic system to be tested, and the crossbeam displacement rate is controlled to be 0.45-0.55 mm / min before the yield strength and 4.5-5.5 mm / min after the yield strength.

2. The room temperature tensile test method according to claim 1, characterized in that: The stainless steel pipe for aviation high pressure hydraulic system comprises 03Cr21Ni6Mn9N stainless steel pipe.

3. The room temperature tensile test method according to claim 1 or 2, characterized in that: The length of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested in step (1) is 210-230 mm.

4. The room temperature tensile test method according to any one of claims 1 to 3, characterized in that: The outer surface roughness of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested in step (1) is Ra≤0.2 μm.

5. The room temperature tensile test method according to any one of claims 1 to 4, characterized in that: The plug in step (1) comprises a round plug; Preferably, the length of the plug in step (1) is 55-65 mm.

6. The room temperature tensile test method according to any one of claims 1 to 5, characterized in that: In step (1), the outer diameter of the plug is smaller than the inner diameter of the stainless steel pipe for the aviation high-pressure hydraulic system to be tested, and the difference is 0.02-0.04 mm.

7. The room temperature tensile test method according to any one of claims 1 to 6, characterized in that: The temperature of the room temperature tensile test in step (2) is 10-35°C.

8. The room temperature tensile test method according to any one of claims 1 to 7, characterized in that: The displacement rate of the crossbeam before yield strength in step (2) is 0.48-0.52 mm / min, preferably 0.5 mm / min; Preferably, the displacement rate of the beam after yield strength in step (2) is 4.8-5.2 mm / min, preferably 5 mm / min.

9. The room temperature tensile test method according to any one of claims 1 to 8, characterized in that: Step (2) further includes performing a qualification evaluation on the room temperature tensile test results after performing the room temperature tensile test; Preferably, the qualification criteria for the room temperature tensile test results are tensile strength ≥ 980 MPa, yield strength ≥ 825 MPa, and elongation ≥ 18%.

10. The room temperature tensile test method according to any one of claims 1 to 9, characterized in that: The room temperature tensile test method comprises the following steps: (1) A stainless steel pipe for an aviation high-pressure hydraulic system to be tested with a length of 210-230 mm and an outer surface roughness of Ra ≤ 0.2 μm is plugged with plugs with a length of 55-65 mm at both ends, and then installed on the fixture of the tensile test device and clamped; The stainless steel pipe for aviation high-pressure hydraulic system comprises a 03Cr21Ni6Mn9N stainless steel pipe; the outer diameter of the plug is smaller than the inner diameter of the stainless steel pipe for aviation high-pressure hydraulic system to be tested, and the difference is 0.02-0.04 mm; (2) Conduct a room temperature tensile test on the stainless steel pipe for the aviation high-pressure hydraulic system to be tested at a temperature of 10-35°C, and control the crossbeam displacement rate before yield strength to 0.45-0.55 mm / min and the crossbeam displacement rate after yield strength to 4.5-5.5 mm / min; (3) performing a qualification evaluation on the room temperature tensile test results obtained in step (2); the qualification criteria for the room temperature tensile test results are tensile strength ≥ 980 MPa, yield strength ≥ 825 MPa, and elongation ≥ 18%.

Images