Tensile sample for thin-wall pipe and mounting method of tensile sample

Abstract

The invention discloses a tensile sample for a thin-wall pipe and an installation method of the tensile sample, and belongs to the technical field of metal embrittlement, the tensile sample comprises a ring-column-shaped pipe, two open grooves are oppositely formed in the middle area of the ring-column-shaped pipe, a scale distance section is formed between the two open grooves, clamping ends are formed at the two ends of the ring-column-shaped pipe, and two force bearing holes are oppositely formed in the clamping ends. Through the arrangement of the boat-shaped scale distance section and the circular tube-shaped clamping end, the effective circular arc circumference of the scale distance section is far smaller than that of the clamping end, in the slow tensile test process, it can be guaranteed that the clamping end does not deform obviously when plastic stretching happens to the scale distance section, the problem that the clamping end deforms seriously is solved, and the service life of the clamping end is prolonged. The influence of the deformation of the clamping end on the elongation data can be reduced, the accuracy of measuring the elongation of the sample is obviously improved, and the reliability of the embrittlement test data of the liquid lead-bismuth alloy of the thin-wall pipe is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of metal embrittlement, and in particular to a tensile test specimen for a thin-walled pipe and a mounting method thereof. Background Art

[0002] When materials are used in a lead-bismuth fast reactor environment, they face the problem of liquid lead-bismuth embrittlement. At present, candidate materials are usually stretched at a slow strain rate in a test kettle filled with a high-temperature lead-bismuth alloy to obtain the elongation data of the materials and study the liquid lead-bismuth embrittlement behavior of the materials in a lead-bismuth reactor environment. The reliability of the elongation data is not only affected by the displacement measurement accuracy of the stretching system, but also related to the geometric configuration of the specimen. For pipes, slow strain rate tensile tests usually use boat-shaped specimens. The clamping end and gauge section of the specimen are both boat-shaped. The elongation is obtained by converting the total elongation of the measured specimen, that is, the sum of the elongation of the clamping end and the gauge section. When the deformation of the clamping end can be ignored relative to the deformation of the gauge section, the elongation calculated by the total elongation can well reflect the true elongation of the gauge section.

[0003] However, for thin-walled tubes, especially small-diameter thin-walled tubes, when processed into the above-mentioned slow strain rate tensile test specimens, the effective arc circumference of the boat-shaped clamping end is close to the effective arc circumference of the boat-shaped gauge section, resulting in serious deformation of the clamping end during slow strain rate stretching. Therefore, the elongation calculated from the total elongation is significantly greater than the actual elongation of the gauge section, and there is a large error. The present invention proposes a new solution to the above problem. Summary of the invention

[0004] In order to overcome at least one of the above disadvantages, the present invention provides a tensile test specimen for thin-walled pipes and a method for installing the same. The purpose of the present invention can be achieved by adopting the following technical solutions:

[0005] According to a first aspect of the present invention, there is provided a tensile test specimen for thin-walled pipes, comprising a cylindrical pipe having two grooves disposed in a middle region thereof, a gauge section being formed between the two grooves, and clamping ends formed at both ends of the cylindrical pipe, with two load-bearing holes disposed in a relative manner on the clamping ends.

[0006] In one possible implementation manner, the gauge section is connected to the clamping end via a transition arc.

[0007] In one possible implementation manner, the clamping end is in a circular tube shape, and the gauge section is in a boat shape.

[0008] In one possible implementation, the gauge section includes a pipe wall portion between two of the slots, and the gauge section includes a first pipe wall and a second pipe wall, wherein the first pipe wall and the second pipe wall have the same size and are arranged opposite to each other.

[0009] In one possible implementation, the arc lengths of the first tube wall and the second tube wall are the same and are both less than 1 / 8 of a circular arc.

[0010] In one embodiment, the effective arc circumference of the gauge section is smaller than the effective arc circumference of the clamping end; and / or,

[0011] The ratio of the effective arc circumference of the gauge section to the effective arc circumference of the clamping end is smaller than the ratio of the yield strength to the tensile strength of the annular columnar tubular material.

[0012] In one possible implementation manner, the distance between the load-bearing hole and the end face of the annular cylindrical tube is greater than twice the circumference of the outer arc of the gauge length segment.

[0013] In one possible implementation manner, a pin is provided on the load-bearing hole, and the hardness of the pin is not less than the hardness of the annular columnar tube.

[0014] In one possible implementation manner, the wall thickness of the annular cylindrical tube is less than 1.5 mm.

[0015] A second aspect of the present invention provides a method for installing a tensile specimen for a thin-walled pipe, which is applied to the tensile specimen for a thin-walled pipe as described in any one of the first aspects, and the installation method includes inserting a pin into a load-bearing hole at the clamping end and placing the specimen on a fixture of a slow tensile test device.

[0016] Beneficial technical effects of the present invention: According to the content of the present disclosure, the tensile specimen for thin-walled pipes includes an annular columnar pipe, both ends of the annular columnar pipe are circular tubular clamping ends, the middle area of ​​the annular columnar pipe is a boat-shaped gauge section, the effective arc circumference of the gauge section is much smaller than the effective arc circumference of the clamping end, and during the slow tensile test, it can be ensured that when plastic stretching occurs in the gauge section, the clamping end does not undergo obvious deformation, which solves the problem of severe deformation of the clamping end, can reduce the influence of the deformation of the clamping end on the elongation data, significantly improves the accuracy of the specimen elongation measurement, and ensures the reliability of the thin-walled pipe liquid lead-bismuth alloy embrittlement test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the accompanying drawings, the following are given by way of example and not limitation:

[0018] Figure 1 A schematic diagram of the overall structure of the present invention from one angle is shown;

[0019] Figure 2 A schematic diagram showing the overall structure of the present invention from another angle is shown;

[0020] Figure 3 A schematic diagram of the overall structure of the present invention from another angle is shown.

[0021] In the figure: 1. Gauge length section; 2. Clamping end; 3. Load-bearing hole; 4. Transition arc. DETAILED DESCRIPTION

[0022] In the following detailed disclosure, these embodiments are fully described with reference to the accompanying drawings. In order to make the technical scheme of the present invention more clear and specific to those skilled in the art, the implementation methods described below are not limited to this. The present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings.

[0023] In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0025] During the test of the traditional boat-shaped specimen of a thin-walled pipe slow tensile specimen, the specimen clamping end 2 will undergo obvious plastic deformation. At this time, if the elongation is calculated by the total elongation, the calculated elongation is significantly greater than the actual elongation of the gauge section 1, which greatly affects the accuracy of the elongation measurement.

[0026] The first aspect of the present invention, as Figure 1-Figure 3 As shown, a tensile test specimen for thin-walled pipes is provided, including a cylindrical pipe, wherein two slots are relatively opened in the middle area of ​​the cylindrical pipe, a gauge section 1 is formed between the two slots, and clamping ends 2 are formed at both ends of the cylindrical pipe, and two load-bearing holes 3 are relatively opened on the clamping ends 2.

[0027] The tensile test specimen for thin-walled pipes comprises an annular cylindrical pipe, both ends of the annular cylindrical pipe are circular tubular clamping ends 2, the middle area of ​​the annular cylindrical pipe is a boat-shaped gauge section 1, the effective arc circumference of the gauge section 1 is much smaller than the effective arc circumference of the clamping end 2, and during the slow tensile test, it can be ensured that when the gauge section 1 undergoes plastic stretching, the clamping end 2 does not undergo obvious deformation, thereby solving the problem of severe deformation of the clamping end 2, reducing the influence of the deformation of the clamping end 2 on the elongation data, significantly improving the accuracy of the elongation measurement of the specimen, and ensuring the reliability of the liquid lead-bismuth alloy embrittlement test data of the thin-walled pipe.

[0028] In one possible implementation, Figure 2 As shown, the gauge section 1 is connected to the clamping end 2 via a transition arc 4.

[0029] Among them, one end of the annular columnar tube is the first clamping end 2, and the other end of the annular columnar tube is the second clamping end 2. The first clamping end 2 is connected to the gauge section 1 through the first transition arc 4, and the second clamping end 2 is connected to the gauge section 1 through the second transition arc 4.

[0030] In one possible implementation, Figure 1 and Figure 2 As shown, the clamping end 2 is in the shape of a circular tube, and the gauge section 1 is in the shape of a boat.

[0031] The clamping end 2 is closed along the circumferential direction except the bearing hole 3. The gauge section 1 is boat-shaped and has a small width. The effective arc circumference of the gauge section 1 is much smaller than the effective arc circumference of the circular tube end. When performing a slow tensile test, the deformation of the clamping end 2 can be ignored, and the measured elongation is true and reliable.

[0032] In one embodiment, the gauge section 1 includes a pipe wall portion between two slots, and the gauge section 1 includes a first pipe wall and a second pipe wall, wherein the first pipe wall and the second pipe wall have the same size and are arranged opposite to each other.

[0033] Among them, the first tube wall and the second tube wall are also connected through a transition arc 4, the first end of the first tube wall is connected to the first end of the first transition arc 4, the second end of the first transition arc 4 is connected to the first end of the second tube wall, the second end of the first tube wall is connected to the first end of the second transition arc 4, and the second end of the second transition arc 4 is connected to the second end of the second tube wall.

[0034] The first tube wall and the second tube wall are arranged opposite to each other, and the first transition arc 4 and the second transition arc 4 are arranged opposite to each other.

[0035] In one possible implementation, the arc lengths of the first tube wall and the second tube wall are the same and are both less than 1 / 8 of a circular arc.

[0036] The gauge section includes a first tube wall and a second tube wall that are relatively arranged. The first tube wall and the second tube wall are approximately parallel. In the tensile test, the first tube wall and the second tube wall cooperate to bear force evenly. The elongation calculated by the total elongation can well reflect the actual elongation of the gauge section.

[0037] The clamping end 2 is in the shape of a circular tube, and the gauge section 1 is in the shape of a boat. The clamping end 2 and the gauge section 1 are connected by a transition arc 4. The boat-shaped gauge section 1 is composed of two symmetrical tube walls, namely, a first tube wall and a second tube wall. The length of the boat-shaped arc is as small as possible, preferably less than 1 / 8 of the arc, so that the effective arc circumference of the gauge section 1 is much smaller than the effective arc circumference of the clamping end 2.

[0038] In one embodiment, the effective arc circumference of the gauge section 1 is smaller than the effective arc circumference of the clamping end 2; and / or the ratio of the effective arc circumference of the gauge section 1 to the effective arc circumference of the clamping end 2 is smaller than the ratio of the yield strength to the tensile strength of the annular cylindrical tubing material.

[0039] Among them, the effective arc circumference of the gauge segment 1 is the outer arc circumference of the gauge segment 1, that is, along the circumference of the annular cylindrical tube, the effective arc circumference of the gauge segment is the sum of the outer arc length of the first tube wall and the outer arc length of the second tube wall.

[0040] Among them, along the circumference of the annular columnar tube, the effective arc circumference of the clamping end 2 is smaller than the outer arc length of the clamping end 2 tube minus the load-bearing hole 3. Since the two ends of the arc are unconstrained, the deformation is small during actual stretching, and the deformation position is mainly concentrated in the area around the load-bearing hole 3.

[0041] The effective arc circumference of gauge section 1 is much smaller than the effective arc circumference of the tube end, and the ratio of the two should be smaller than the ratio of the yield strength to the tensile strength of the sample material to ensure that when plastic stretching occurs in gauge section 1, no obvious deformation occurs in the clamping section.

[0042] In one possible implementation manner, the distance between the load-bearing hole 3 and the end face of the annular cylindrical pipe is greater than twice the circumference of the outer arc of the gauge section 1 .

[0043] Among them, a load-bearing hole 3 is opened in the circular tube section of the clamping end 2, and the opening position is located in the middle position of the clamping end 2. The clamping end 2 is connected to the stretching fixture through a pin.

[0044] Among them, the pin can be made of high-strength alloy, and the strength of the pin material is usually not lower than that of the sample material. While maintaining sufficient rigidity, the pin diameter is minimized.

[0045] The distance between the center of the load-bearing hole 3 and the top of the specimen is as large as possible. Generally, the hole end distance is greater than twice the circumference of the arc of the gauge length segment 1, which is approximately C>B*2 to ensure that no obvious deformation occurs to the top of the specimen during the stretching process.

[0046] In one possible implementation, a pin is provided on the load-bearing hole 3, and the hardness of the pin is not less than the hardness of the annular columnar pipe.

[0047] In one possible implementation, the wall thickness of the annular cylindrical tube is less than 1.5 mm.

[0048] The tensile specimen is suitable for thin-walled tubes with a wall thickness of less than 1.5 mm. When slow strain rate stretching is performed in a high-temperature lead-bismuth environment, the clamping end 2 of the specimen does not undergo obvious deformation, thereby significantly improving the accuracy of the specimen elongation measurement.

[0049] like Figure 3 As shown, the length of the annular columnar tube is L, the radius of the annular columnar tube is R, the length of the gauge end is A, the width of the gauge section 1 is approximately B, the hole end distance of the load-bearing hole 3 is C, the radius of the load-bearing hole 3 is r, and the length of the clamping end 2 is D.

[0050] Among them, the effective arc circumference of gauge segment 1 ≈ B*2.

[0051] This embodiment provides a first tensile specimen for thin-walled pipes. The specific data of the tensile specimen size are: the radius R of the cylindrical pipe is 6 mm, the wall thickness is 0.6 mm, the 12Cr-ferrite / martensitic steel has a room temperature yield strength of 700 MPa, a tensile strength of 900 MPa, and a yield strength to tensile strength ratio of 0.78.

[0052] Among them, the length of the gauge section 1 is A=12mm, the arc length is 1 / 16 arc, that is, the sum of the outer arc lengths of the first tube wall and the second tube wall is 1 / 16*2*π*3, the gauge end length is D=15mm, the radius of the load-bearing hole 3 is r=1.5mm, and the simulation calculation shows that the ratio of the effective arc circumference of the gauge section 1 to the effective arc circumference of the clamping end 2 is approximately 0.15, which is much smaller than the ratio of yield strength to tensile strength.

[0053] Among them, the load-bearing hole 3 has a diameter of 3mm and is located in the middle of the clamping end 2. The distance between the center of the load-bearing hole 3 and the upper end of the clamping end 2 is 6mm, that is, the hole end distance C=6mm, and the ratio of the hole end distance to the circumference of the arc of the gauge section 1 is greater than 2.

[0054] The pin can be made of the same 12Cr-ferrite / martensitic steel with a diameter of 3 mm. The pin is inserted into two circular holes at the clamping end of the sample, and the sample is mounted on the sample mounting fixture of the slow tensile testing machine.

[0055] This embodiment provides a second tensile test specimen for thin-walled pipes, wherein the length of the annular columnar pipe is L=40 mm, the radius of the annular columnar pipe is R=6 mm, the length of the gauge end is A=12 mm, the width of the gauge section 1 is approximately B=2 mm, the hole end distance of the load-bearing hole 3 is C=5 mm, the radius of the load-bearing hole 3 is r=1.5 mm, the length of the clamping end 2 is D=8.55 mm, and the radius of the transition arc 4 is 6 mm.

[0056] This embodiment provides a third tensile test specimen for thin-walled pipes, wherein the length of the annular columnar pipe is L=40 mm, the radius of the annular columnar pipe is R=6 mm, the length of the gauge end is A=12 mm, the width of the gauge section 1 is approximately B=3 mm, the hole end distance of the load-bearing hole 3 is C=5 mm, the radius of the load-bearing hole 3 is r=1.55 mm, the length of the clamping end 2 is D=8.55 mm, and the radius of the transition arc 4 is 6 mm.

[0057] The specific size data of the tensile test specimen are not limited to the above-mentioned ones, and can satisfy that the effective arc circumference of the gauge section 1 is smaller than the effective arc circumference of the clamping end 2, or the ratio of the effective arc circumference of the gauge section 1 to the effective arc circumference of the clamping end 2 is smaller than the ratio of the yield strength to the tensile strength of the annular cylindrical pipe material.

[0058] A second aspect of the present invention provides a method for installing a tensile specimen for a thin-walled pipe, which is applied to the tensile specimen for a thin-walled pipe of any one of the first aspects, and the installation method includes inserting a pin into the load-bearing hole 3 of the clamping end 2 and placing the specimen on the fixture of the slow tensile test device.

[0059] After adopting the above-mentioned installation method of the sample mechanism, when slow strain rate stretching is performed in a high-temperature lead-bismuth environment, the sample clamping end 2 hardly deforms, thereby significantly improving the accuracy of the sample elongation measurement.

[0060] The present invention proposes a liquid lead-bismuth alloy embrittlement test specimen and installation method for a small-diameter thin-walled tube. The clamping end 2 of the specimen is a round tube connected to a fixture by a pin, and the gauge section 1 is boat-shaped. The clamping end 2 and the gauge section 1 are connected by a transition arc 4. The effective arc circumference of the gauge section 1 is much smaller than the effective arc circumference of the clamping end 2, ensuring that the clamping end 2 has sufficient strength during the stretching process to avoid significant deformation. By using the above-mentioned specimen and installation method to carry out slow strain rate tensile specimens, the influence of the deformation of the clamping end 2 on the elongation data can be avoided, ensuring the reliability of the liquid lead-bismuth alloy embrittlement test data of small-diameter thin-walled tubes.

[0061] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0062] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0063] In view of the above detailed description, these and other changes can be made to these embodiments, and this written description includes the best mode embodiments to disclose the present invention. The scope of the patent obtained by the present invention is defined by the claims, which are not limited by the present disclosure, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field within the scope disclosed by the present invention, according to the technical solution and its conception of the present invention, is equivalent to or changes, and all are within the protection scope of the present invention.

Claims

1. A tensile test specimen for thin-walled pipes, characterized in that: The invention comprises an annular columnar tube, wherein two slots are provided in a middle region thereof, a gauge section (1) is formed between the two slots, and clamping ends (2) are formed at two ends of the annular columnar tube, and two load-bearing holes (3) are provided in a relative manner on the clamping ends (2).

2. The tensile test specimen for thin-walled pipe according to claim 1, characterized in that: The gauge section (1) is connected to the clamping end (2) via a transition arc (4).

3. The tensile test specimen for thin-walled pipe according to claim 1, characterized in that: The clamping end (2) is in the shape of a circular tube, and the gauge section (1) is in the shape of a boat.

4. The tensile test specimen for thin-walled pipe according to claim 1, characterized in that: The gauge section (1) comprises a pipe wall portion between two of the slots, and the gauge section (1) comprises a first pipe wall and a second pipe wall, wherein the first pipe wall and the second pipe wall have the same size and are arranged opposite to each other.

5. The tensile test specimen for thin-walled pipe according to claim 4, characterized in that: The arc lengths of the first tube wall and the second tube wall are the same and are both less than 1 / 8 of a circular arc.

6. The tensile test specimen for thin-walled pipe according to claim 1, characterized in that: The effective arc circumference of the gauge section (1) is smaller than the effective arc circumference of the clamping end (2); and / or, The ratio of the effective arc circumference of the gauge section (1) to the effective arc circumference of the clamping end (2) is smaller than the ratio of the yield strength to the tensile strength of the annular columnar tubular material.

7. The tensile test specimen for thin-walled pipe according to claim 1, characterized in that: The distance between the load-bearing hole (3) and the end surface of the annular columnar pipe is greater than twice the circumference of the outer arc of the gauge section (1).

8. The tensile test specimen for thin-walled pipe according to claim 1, characterized in that: The load-bearing hole (3) is provided with a pin, and the hardness of the pin is not less than the hardness of the annular columnar pipe.

9. The tensile test specimen for thin-walled pipe according to any one of claims 1 to 8, characterized in that: The wall thickness of the annular columnar tube is less than 1.5 mm.

10. A method for installing a tensile test specimen for a thin-walled pipe, characterized in that: Applied to the tensile test specimen for thin-walled pipes as claimed in any one of claims 1 to 9, the installation method comprises inserting a pin into a load-bearing hole (3) of a clamping end (2) and placing the specimen on a fixture of a slow tensile test device.

Images