Metal superplasticity testing device and testing method

Abstract

The present invention discloses a metal superplasticity testing device and testing method, which relates to the technical field of metal property detection. The device comprises two clamps, each comprising a clamping component and a sample loading component, wherein the sample loading component comprises a connecting body, a base and a fixing plate. The clamping component is fixed to the connecting body, a base is provided on one side of the connecting body, a fixing plate is provided on the side of the base away from the connecting body, a fixing groove is formed between the fixing plate and the connecting body, a sample loading hole is provided on the fixing plate that passes through the upper and lower end faces and the front end face, a positioning hole is provided on the base that passes through the upper and lower end faces, and the sample loading hole is connected to the positioning hole. By adopting an I-shaped specimen, processing cost and efficiency are saved. A clamp is connected to each of the two high-temperature connecting rods, so that a smaller-sized specimen can be used to perform a high-temperature tensile test on a high-temperature tensile testing machine, thereby avoiding affecting the accuracy of the test. Therefore, the research test of metal superplasticity can be smoothly carried out using a traditional high-temperature tensile testing machine.

Description

Technical Field

[0001] The present invention relates to the technical field of metal property detection, in particular to a metal superplasticity testing device and a testing method. Background Art

[0002] Plasticity is one of the most important properties of metals. It refers to the ability of metals to permanently change shape without damage under external forces. Superplasticity refers to the phenomenon in which a material exhibits exceptionally low flow resistance and exceptionally high rheological properties under certain internal and external conditions. Characteristics of superplasticity include high elongation, no necking, low stress, and easy forming.

[0003] Superplasticity is a key property of metals. In the era of lightweight manufacturing, superplastic metal forming processes have gained widespread application in aerospace, automotive, and equipment manufacturing. High-temperature tensile testing is the most commonly used test method for measuring the superplastic mechanical properties of metals.

[0004] Currently, the fixtures of conventional high-temperature tensile equipment generally require a total specimen length of 150 to 200 mm. The internal dimensions of a conventional high-temperature furnace are generally around 300 mm. The tensile components of a conventional high-temperature tensile testing machine are two upper and lower high-temperature connecting rods with threaded holes at the ends. Conventional high-temperature tensile specimens need to be made into 150 to 200 mm threaded rods to be connected to the high-temperature connecting rods through threaded fit. If a 150 to 200 mm metal threaded rod is used for a high-temperature tensile test, the specimen size will usually be stretched to a size larger than the furnace body when superplasticity occurs. The tensile specimen is likely to be pulled out of the furnace body, affecting the accuracy of the test and causing great trouble for the study of metal superplasticity. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a metal superplasticity testing device and testing method, which saves processing costs and efficiency, enables the use of smaller-sized specimens for testing, and avoids affecting the accuracy of the test.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a metal superplasticity testing device, comprising two clamps, wherein the clamps include a clamping component and a sample loading component, wherein the sample loading component includes a connecting body, a base and a fixing plate, wherein the clamping component is fixed to the connecting body, the base is provided on one side of the connecting body, and a fixing plate is provided on a side of the base away from the connecting body, wherein a fixing groove is formed between the fixing plate and the connecting body, wherein a sample loading hole penetrating the upper and lower end faces and the front end face is provided on the fixing plate, wherein a positioning hole penetrating the upper and lower end faces is provided on the base, wherein the sample loading hole is connected to the positioning hole, wherein the sample loading hole is used for allowing the middle parallel test section of an I-shaped specimen to pass through, wherein the fixing groove is used for accommodating the clamping section of the I-shaped specimen, and wherein the positioning hole is used for positioning the I-shaped specimen.

[0008] Preferably, the connecting body includes a top plate and a side plate fixed to one side of the top plate, the clamping component is fixed to the top plate, the base is fixed to an end of the side plate away from the top plate, the fixing plate is provided at an end of the base away from the side plate, and the fixing groove is formed between the fixing plate and the side plate.

[0009] Preferably, the base is parallel to the top plate, and the fixing plate is parallel to the side plate.

[0010] Preferably, the positioning hole is a first rectangular hole, and first rounded corner structures are formed on both sides of the upper portion of the first rectangular hole.

[0011] Preferably, the sample loading hole includes a second rectangular hole and a third rectangular hole connected to each other, the second rectangular hole passes through the upper end surface of the fixing plate, the third rectangular hole passes through the lower end surface of the fixing plate, and a second chamfered structure is formed on both sides of the connection between the second rectangular hole and the third rectangular hole.

[0012] Preferably, the length of the second rectangular hole is greater than the length of the third rectangular hole, and the length of the third rectangular hole is equal to the length of the first rectangular hole.

[0013] Preferably, the sample loading hole is provided in the middle of the fixing plate, and the positioning hole is provided in the middle of the base.

[0014] Preferably, the clamping component is a threaded cylinder.

[0015] Preferably, the clamping component and the sample loading component are both made of cast high-temperature alloy.

[0016] The present invention also provides a testing method based on the metal superplasticity testing device, comprising the following steps:

[0017] Step 1: Fix the clamping component of one of the clamps to the upper end of the high-temperature tensile testing machine through a high-temperature connecting rod, place the I-shaped specimen into the fixing groove through the sample loading hole and the positioning hole, until the clamping section of the upper part of the I-shaped specimen contacts the base; connect the clamping component of another clamp to another high-temperature connecting rod, so that the clamping section of the lower part of the I-shaped specimen is located in the fixing groove of the other clamp, and then suspend the other clamp and the other high-temperature connecting rod at the lower part of the I-shaped specimen, perform load calibration on the high-temperature tensile testing machine, and then fix the other high-temperature connecting rod to the lower end of the high-temperature tensile testing machine;

[0018] Step 2: Open the high-temperature furnace and adjust the height of the high-temperature furnace so that the I-shaped specimen is located in the center of the high-temperature furnace and the thermocouple in the high-temperature furnace touches the I-shaped specimen. Close the high-temperature furnace, set the test temperature, holding time, and tensile test rate, hold the specimen at the set test temperature, and perform the tensile test after the set holding time is reached, and pull the I-shaped specimen until it breaks.

[0019] Step 3: After the stretching is completed, the stress-stroke curve is obtained, the material elongation is calculated using the obtained test data, the stress-stroke curve is converted into a true stress-true strain curve, and the strain rate sensitivity index is calculated.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] The metal superplasticity testing device of the present invention includes two clamps, each of which includes a clamping component and a sample loading component. The sample loading component includes a connecting body, a base, and a fixed plate. The clamping component is fixed to the connecting body. A base is provided on one side of the connecting body, and a fixed plate is provided on the side of the base away from the connecting body. A fixing groove is formed between the fixed plate and the connecting body. A sample loading hole is provided on the fixed plate that passes through the upper and lower end faces and the front end face. A positioning hole is provided on the base that passes through the upper and lower end faces, and the sample loading hole is connected to the positioning hole. The clamp first changes the processing method of the required sample. The sample only needs to be made into an "I-shaped" shape to be tested, without being processed into a threaded pull rod, which saves processing cost and efficiency. A clamp is connected to each of the two high-temperature connecting rods. The length of the clamp itself is used to increase the distance of the end of the high-temperature connecting rod, which means that the minimum required size of the sample is reduced, so that a smaller sample can be used to perform a high-temperature tensile test on a high-temperature tensile testing machine. This metal superplasticity testing device is suitable for stretching micro specimens of all types of metal materials with a total length of 32 to 50 mm. When superplasticity occurs, the size of metal specimens with a total length of 32 to 50 mm will not exceed the furnace size of the high-temperature furnace, avoiding affecting the accuracy of the test. Therefore, the research and test of metal superplasticity can be carried out smoothly through traditional high-temperature tensile testing machines. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic diagram of the three-dimensional structure of the fixture in the metal superplasticity testing device provided by the present invention;

[0024] Figure 2 A front view of a fixture in the metal superplasticity testing device provided by the present invention;

[0025] Figure 3 A left side view of the fixture in the metal superplasticity testing device provided by the present invention;

[0026] Figure 4 A schematic structural diagram of an I-shaped specimen corresponding to the metal superplasticity testing device provided by the present invention;

[0027] Figure 5 A schematic diagram of the use of the metal superplasticity testing device provided by the present invention;

[0028] Figure 6 is a stress-stroke curve obtained in Example 1 of the present invention;

[0029] Figure 7 This is a stress-stroke curve obtained in Example 2 of the present invention;

[0030] Figure 8 This is a stress-stroke curve diagram obtained in Example 3 of the present invention.

[0031] Explanation of the accompanying reference numerals: 100, fixture; 101, clamping component; 102, top plate; 103, side plate; 104, base; 105, fixing plate; 106, positioning hole; 107, sample loading hole; 108, fixing groove; 109, sample loading groove; 200, I-shaped specimen; 201, clamping section; 202, middle parallel test section. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The purpose of the present invention is to provide a metal superplasticity testing device and testing method, which saves processing cost and efficiency, enables the use of smaller-sized specimens for testing, and avoids affecting the accuracy of the test.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1:

[0036] like Figure 1-3 As shown, this embodiment provides a metal superplasticity testing device, including two clamps 100, the clamps 100 include a clamping component 101 and a sample loading component, the sample loading component includes a connecting body, a base 104 and a fixing plate 105, the clamping component 101 is fixed to the connecting body, the clamping component 101 is used to connect with the high-temperature connecting rod and is fixed to the high-temperature tensile testing machine through the high-temperature connecting rod, a base 104 is provided on one side of the connecting body, and a fixing plate 105 is provided on the side of the base 104 away from the connecting body. A fixing groove 108 is formed between the fixed plate 105 and the connecting body. The fixing plate 105 is provided with a sample loading hole 107 that passes through the upper and lower end surfaces and the front end surface. The base 104 is provided with a positioning hole 106 that passes through the upper and lower end surfaces. The sample loading hole 107 is connected to the positioning hole 106. The sample loading hole 107 is used for allowing the middle parallel test section 202 of the I-shaped specimen 200 to pass through. The fixing groove 108 is used to accommodate the clamping section 201 of the I-shaped specimen 200. The positioning hole 106 is used to position the I-shaped specimen 200.

[0037] The fixture 100 in this embodiment first changes the processing method of the required sample. The sample only needs to be made into an "I-shaped" shape for testing, without having to be processed into a threaded pull rod, which saves processing costs and efficiency. A fixture 100 is connected to each of the two high-temperature connecting rods. The length of the fixture 100 itself is used to increase the end of the high-temperature connecting rod by a certain distance, which means that the minimum required size of the sample is reduced, so that a smaller sample can be used to perform a high-temperature tensile test on a high-temperature tensile testing machine. This metal superplasticity testing device is suitable for stretching all types of metal material micro-samples with a total length of 32 to 50 mm. When superplasticity occurs, the size of the metal sample with a total length of 32 to 50 mm will not exceed the size of the high-temperature furnace, avoiding affecting the accuracy of the test. Therefore, the research test of metal superplasticity can be carried out smoothly through the traditional high-temperature tensile testing machine.

[0038] In this embodiment, an I-shaped specimen 200 is mounted on a fixture 100 and subjected to a tensile test in a high-temperature furnace of a high-temperature tensile testing machine. According to a proposed test plan, a high-temperature tensile test is performed on the I-shaped specimen 200 at different tensile test rates and different test temperatures to obtain a stress-stroke curve. Finally, the superplasticity of the material is evaluated by measuring superplastic performance indicators such as superplastic elongation, flow stress, and strain rate sensitivity index.

[0039] Specifically, the connecting body includes a top plate 102 and a side plate 103 fixed to one side of the top plate 102. The clamping member 101 is fixed to the top plate 102, and the base 104 is fixed to the end of the side plate 103 away from the top plate 102. A fixing plate 105 is provided at the end of the base 104 away from the side plate 103, and a fixing groove 108 is formed between the fixing plate 105 and the side plate 103. A sample loading groove 109 is formed between the lower portion of the top plate 102, the upper portion of the fixing plate 105, and the front portion of the side plate 103. The provision of the sample loading groove 109 and the sample loading hole 107 facilitates the placement of the clamping section 201 of the I-shaped specimen 200 into the fixing groove 108.

[0040] In this embodiment, the base 104 is parallel to the top plate 102, and the fixing plate 105 is parallel to the side plate 103. The top plate 102 and the base 104 are vertically disposed at the upper and lower ends of the side plate 103 respectively.

[0041] Specifically, the positioning hole 106 is a first rectangular hole, with first rounded corners formed on both sides of the upper portion of the first rectangular hole. When manufacturing the I-shaped specimen 200, the connection between the clamping section 201 and the middle parallel test section 202 of the I-shaped specimen 200 forms a curved surface structure that matches the first rounded corner structure. At the same time, the width of the middle parallel test section 202 of the I-shaped specimen 200 matches the length of the first rectangular hole. This allows the positioning hole 106 to accurately position the I-shaped specimen 200 after it is installed in the fixing slot 108. It should be noted that the length direction of the first rectangular hole is consistent with the length direction of the base 104.

[0042] Specifically, the sample loading hole 107 includes a second rectangular hole and a third rectangular hole connected to each other. The second rectangular hole extends through the upper end surface of the fixing plate 105, and the third rectangular hole extends through the lower end surface of the fixing plate 105. A second rounded corner structure is formed on both sides of the connection between the second and third rectangular holes. Specifically, the second rounded corner structure has the same shape as the first rounded corner structure.

[0043] In this embodiment, the length of the second rectangular hole is greater than that of the third rectangular hole, and the length of the third rectangular hole is equal to that of the first rectangular hole. It should be noted that the length direction of the second rectangular hole and the third rectangular hole is consistent with the length direction of the fixing plate 105.

[0044] In this embodiment, the sample loading hole 107 is disposed in the middle of the fixing plate 105 , and the positioning hole 106 is disposed in the middle of the base 104 .

[0045] In this specific embodiment, the clamping component 101 is a threaded cylinder, which is convenient for mating and connecting with the threaded hole of the high-temperature connecting rod.

[0046] Specifically, the clamping component 101 and the sample loading component are both made of cast high-temperature alloy. In this embodiment, the clamping component 101 and the sample loading component are made of K465 cast high-temperature alloy. The clamping component 101 and the sample loading component are an integrated structure.

[0047] Before the test, the fixture 100 and the I-shaped specimen 200 were prepared. Specifically, two fixtures 100 of the same size were processed using K465 cast high-temperature alloy; the test material was 5083 aluminum alloy, which was processed into the I-shaped specimen 200 using a rolled plate machine. The dimensions of the I-shaped specimen 200 were as follows: Figure 4 As shown, the dimensions of the I-shaped specimen 200 are designed and processed according to the dimensions of the base 104 , the positioning hole 106 , the fixing plate 105 , the sample loading hole 107 and the fixing groove 108 of the fixture 100 .

[0048] This embodiment also provides a testing method based on a metal superplasticity testing device, comprising the following steps:

[0049] Step 1: Figure 5 As shown, the clamping component 101 of one clamp 100 is fixed to the upper end of the high-temperature tensile testing machine through a high-temperature connecting rod, and the I-shaped specimen 200 is placed into the fixing groove 108 through the sample loading hole 107 and the positioning hole 106 until the upper clamping section 201 of the I-shaped specimen 200 contacts the base 104. Specifically, tweezers are used to place the upper clamping section 201 of the I-shaped specimen 200 into the fixing groove 108; the clamping component 101 of another clamp 100 is connected to another high-temperature connecting rod, so that the lower clamping section 201 of the I-shaped specimen 200 is in contact with the base 104. Located in the fixing groove 108 of another clamp 100, the other clamp 100 and the other high-temperature connecting rod are suspended at the lower part of the I-shaped specimen 200, the high-temperature tensile testing machine is load calibrated, and then the other high-temperature connecting rod is fixed to the lower end of the high-temperature tensile testing machine; due to the presence of the positioning hole 106 in the clamp 100, and the base 104 of the upper clamp 100 is kept parallel to the base 104 of the lower clamp 100, the I-shaped specimen 200 can be subjected to only axial force but no tangential force when there is no error in the assembly, thereby ensuring the accuracy of the test.

[0050] Step 2: Open the high-temperature furnace and adjust the height of the high-temperature furnace so that the I-shaped specimen 200 is located in the center of the high-temperature furnace, and the thermocouple in the high-temperature furnace touches the I-shaped specimen 200. Close the high-temperature furnace, set the test temperature, holding time and tensile test rate, and hold the specimen until the set test temperature is reached. After the set holding time is reached, perform the tensile test and pull the I-shaped specimen 200 to fracture. Specifically, after setting the test temperature and holding time, click the load zero point to hold and start heating at the same time. Pay attention to prevent temperature overshoot during the heating process. The holding time should be more than 15 minutes.

[0051] Step 3: After the stretching is completed, the required data is measured and recorded, and the data is analyzed to evaluate the superplasticity of the material. Specifically, a stress-stroke curve is obtained, and the material elongation is calculated using the obtained test data. The stress-stroke curve is converted into a true stress-true strain curve, and the strain rate sensitivity index is calculated. Specifically, the strain rate sensitivity index m is calculated using the formula as follows:

[0052]

[0053] Where m is the strain rate sensitivity index, σ is the flow stress, is the true strain rate.

[0054] The high-temperature tensile testing machine used in this embodiment is a 100 kN high-temperature electronic tensile testing machine produced by Shimadzu Corporation (AG-IS) of Japan, and the furnace temperature can reach up to 1100°C.

[0055] In this specific embodiment, in step 2, the test temperature and holding time are set to 375°C and 20 minutes respectively. For tests without tensile test rate requirements, the tensile test rate calculation formula v in GB / T228.2 can be used. c =e Lc ×L c Calculate the tensile test rate, where v c is the tensile test rate, e Lc The strain rate estimated for the length of the middle parallel test section 202 of the I-shaped specimen 200, L c is the length of the middle parallel test section 202 of the I-shaped specimen 200. The test rate is not specified in this embodiment. The tensile test rate is calculated to be 0.225 mm / min, and the I-shaped specimen 200 is pulled to fracture at this rate. The stress-stroke curve obtained in this embodiment is shown in FIG. Figure 6 shown.

[0056] Example 2:

[0057] The difference between this embodiment and the first embodiment is that in step 2, the tensile test rate is set to 1.5 mm / min, and the I-shaped specimen 200 is pulled to fracture using this rate. The stress-stroke curve obtained in this embodiment is shown in FIG. Figure 7 shown.

[0058] Example 3:

[0059] The difference between this embodiment and the first embodiment is that in step 2, the test temperature and holding time are set to 425°C and 20 minutes respectively. The tensile test rate is set to 1.5 mm / min, and the I-shaped specimen 200 is pulled to fracture at this rate. The stress-stroke curve obtained in this embodiment is shown in FIG. Figure 8 shown.

[0060] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A metal superplasticity testing device, characterized in that: The fixing plate is fixed to the fixing body, and the fixing plate is fixed to the fixing body, wherein the fixing plate is fixed to the fixing body, and a fixing groove is formed between the fixing plate and the connecting body, and the fixing plate is provided with a loading hole passing through the upper and lower end surfaces and the front end surface, and a positioning hole passing through the upper and lower end surfaces is provided on the base, the loading hole is connected with the positioning hole, and the loading hole is used for allowing the middle parallel test section of the I-shaped sample to pass through, the fixing groove is used to accommodate the clamping section of the I-shaped sample, and the positioning hole is used to position the I-shaped sample; the connecting body comprises a top plate and a side plate fixed to one side of the top plate, the clamping part is fixed to the top plate, the base is fixed to one end of the side plate away from the top plate, the fixing plate is provided at one end of the base away from the side plate, and the fixing groove is formed between the fixing plate and the side plate.

2. The metal superplasticity testing device according to claim 1, characterized in that: The base is parallel to the top plate, and the fixing plate is parallel to the side plate.

3. The metal superplasticity testing device according to claim 1, characterized in that: The positioning hole is a first rectangular hole, and first rounded corner structures are formed on both sides of the upper portion of the first rectangular hole.

4. The metal superplasticity testing device according to claim 3, characterized in that: The sample loading hole includes a second rectangular hole and a third rectangular hole connected to each other, the second rectangular hole passes through the upper end surface of the fixing plate, and the third rectangular hole passes through the lower end surface of the fixing plate, and a second chamfered structure is formed on both sides of the connection between the second rectangular hole and the third rectangular hole.

5. The metal superplasticity testing device according to claim 4, characterized in that: The length of the second rectangular hole is greater than that of the third rectangular hole, and the length of the third rectangular hole is equal to that of the first rectangular hole.

6. The metal superplasticity testing device according to claim 1, characterized in that: The sample loading hole is arranged in the middle of the fixing plate, and the positioning hole is arranged in the middle of the base.

7. The metal superplasticity testing device according to claim 1, characterized in that: The clamping component is a threaded cylinder.

8. The metal superplasticity testing device according to claim 1, characterized in that: The clamping component and the sample loading component are both made of cast high-temperature alloy.

9. A testing method based on the metal superplasticity testing device according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Fix the clamping component of one of the clamps to the upper end of the high-temperature tensile testing machine through a high-temperature connecting rod, place the I-shaped specimen into the fixing groove through the sample loading hole and the positioning hole, until the clamping section of the upper part of the I-shaped specimen contacts the base; connect the clamping component of another clamp to another high-temperature connecting rod, so that the clamping section of the lower part of the I-shaped specimen is located in the fixing groove of the other clamp, and then suspend the other clamp and the other high-temperature connecting rod at the lower part of the I-shaped specimen, perform load calibration on the high-temperature tensile testing machine, and then fix the other high-temperature connecting rod to the lower end of the high-temperature tensile testing machine; Step 2: Open the high-temperature furnace and adjust the height of the high-temperature furnace so that the I-shaped specimen is located in the center of the high-temperature furnace and the thermocouple in the high-temperature furnace touches the I-shaped specimen. Close the high-temperature furnace, set the test temperature, holding time, and tensile test rate, hold the specimen at the set test temperature, and perform the tensile test after the set holding time is reached, and pull the I-shaped specimen until it breaks. Step 3: After the stretching is completed, the stress-stroke curve is obtained, the material elongation is calculated using the obtained test data, the stress-stroke curve is converted into a true stress-true strain curve, and the strain rate sensitivity index is calculated.

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