Metal material high-temperature tensile test device and test method

Abstract

The invention belongs to the field of metal high-temperature performance testing, and relates to a metal material high-temperature tensile testing device and testing method. The device comprises a synchronous control box, the synchronous control box is respectively connected with the electromagnetic valve, the universal testing machine, the infrared thermal imager and the three-dimensional digital image related equipment; the constant current source is respectively connected with the upper and lower parts of the high-temperature clamp; the high-temperature clamp is mounted in the universal testing machine and comprises an upper clamping part and a lower clamping part which are used for clamping a metal sample; the cooling pipeline is connected with the air compressor, and the electromagnetic valve is mounted on the cooling pipeline connected with the air compressor; during testing, speckles are sprayed on one surface, facing three-dimensional digital image related equipment, of a metal sample, and the metal sample is clamped in the middle of a high-temperature clamp; one end of the thermocouple is welded on the surface without speckles of the metal sample, and the other end of the thermocouple is connected to the constant current source and is connected to the synchronous control box. The problems that when a high-temperature extensometer is used for measuring sample deformation, the measuring range is insufficient, damage is prone to occurring, and additional interference is introduced are solved.

Description

Technical Field

[0001] The invention belongs to the field of metal high temperature performance testing, and in particular relates to a metal material high temperature tensile testing device and a testing method. Background Art

[0002] The application of metal components made of high-strength steel, high-strength aluminum alloy, titanium alloy and other materials in the fields of automobile, rail transportation, aerospace and so on is increasing year by year. These metals have high specific strength, but low forming and processing performance at room temperature, so hot stamping has become a common process for processing such thin-walled metal components. The high-temperature tensile test is used to study the strength and plasticity of these materials at high temperatures, which has important guiding significance for the hot stamping process.

[0003] At present, in the high-temperature rapid tensile test of metal materials, the deformation of the specimen is usually measured by approximate calculation of the displacement of the tensile machine beam or by using a high-temperature extensometer. The accuracy of the approximate calculation using the displacement of the tensile machine beam is insufficient, and the ceramic rod of the high-temperature extensometer is in pressure contact with the surface of the specimen and cannot be removed during the rapid tensile test, which makes it easy to damage. In addition, the plasticity of the specimen improves at high temperatures, and the high-temperature extensometer range is difficult to meet the test requirements. Non-contact measurement, such as video extensometers, can solve the above problems, but it is necessary to achieve coordinated synchronization of heating equipment, tensile equipment, and deformation measurement equipment to ensure that the test is carried out according to the preset parameters, so as to ensure that the data obtained by different equipment can be synchronized to ensure the test accuracy.

[0004] Therefore, there is currently no high-temperature rapid tensile testing device that can both quickly heat the specimen and accurately measure the deformation of the specimen. Summary of the invention

[0005] The purpose of the present invention is to provide a high-temperature tensile testing device and a testing method for metal materials, which realizes rapid heating of the sample by self-resistance, measures deformation by digital image correlation technology, collects temperature data by an infrared thermal imager, and realizes multi-device coordination by a synchronous controller, thereby solving the problems of insufficient range, easy damage and introduction of additional interference when measuring the deformation of the sample by a high-temperature extensometer during high-temperature rapid tensile testing, and can also synchronously obtain the temperature field and strain field data of the sample during the experiment.

[0006] The present invention is achieved through the following technical solutions: A high-temperature tensile testing device for metal materials, comprising an air compressor, a thermocouple, a constant current source, a solenoid valve, a high-temperature fixture, a universal testing machine, an infrared thermal imager, a cooling pipeline, a three-dimensional digital image correlation device, a synchronous control box and a workstation; The synchronous control box is connected to the solenoid valve, universal testing machine, infrared thermal imager and three-dimensional digital image related equipment respectively; the synchronous control box is connected to the workstation; The constant current source is connected to the upper and lower parts of the high temperature fixture respectively; The high temperature fixture is installed in the universal testing machine, and the high temperature fixture includes an upper clamping part and a lower clamping part for clamping the metal sample; The cooling pipeline is connected to the air compressor, and the solenoid valve is installed on the cooling pipeline connected to the air compressor; During the test, the metal sample is sprayed with speckle on the side facing the 3D digital image correlation device and clamped in the middle of the high-temperature fixture; One end of the thermocouple is welded to the surface of the metal sample where no speckles are sprayed, and the other end is connected to a constant current source and then to a synchronous control box.

[0007] Furthermore, the synchronous control box is provided with a programmable logic controller, a temperature acquisition module, an intermediate relay, a touch screen, a switching power supply and a control power supply; The control power supply controls the start and stop of the synchronous control box by controlling the on and off of the 220V input circuit; The switching power supply converts 220V AC into 24V DC to provide the required power for the programmable logic controller, temperature acquisition module, intermediate relay and solenoid valve; The temperature acquisition module is used to convert the voltage signal of the thermocouple test into a digital temperature value; the control parameters of the equipment connected to the synchronous control box are set on the touch screen; The programmable logic controller is used to process and analyze the temperature data obtained by the temperature acquisition module, send out pulse voltage signals according to the program setting parameters to control the start and stop of the universal testing machine, infrared thermal imager and three-dimensional digital image related equipment, and control the on-off control of the solenoid valve through the intermediate relay.

[0008] Furthermore, the type of the thermocouple is K type, and the temperature measurement range is from room temperature to 1200°C.

[0009] Furthermore, the output of the constant current source is alternating current.

[0010] Furthermore, the maximum load of the universal testing machine is 100 kN, and the crossbar adjustment speed is 0.001-1500 mm / min.

[0011] Furthermore, the temperature measurement range of the infrared thermal imager is from room temperature to 1200°C, and the shooting frame rate is 1-50fps.

[0012] Furthermore, the 3D digital image correlation device has two 5-megapixel industrial cameras with a shooting frame rate of 1-70fps.

[0013] The present invention also discloses a testing method based on the metal material high temperature tensile testing device, which is characterized by comprising the following steps: S1, start the synchronous control box and initialize the program; S2. Set the control parameters related to the solenoid valve, universal testing machine, infrared thermal imager and three-dimensional digital image related equipment on the synchronous control box; S3, start the solenoid valve to open the cooling pipeline to cool the metal sample, automatically collect and analyze the thermocouple temperature signal, and if the surface temperature of the metal sample is lower than the required temperature for starting the experiment, close the solenoid valve and cut off the gas line; If the surface temperature of the metal sample is higher than the temperature required to start the experiment, continue to open the solenoid valve until the surface temperature of the metal sample is lower than the temperature required to start the experiment, then close the solenoid valve and cut off the gas path; S4, synchronously start the constant current source, infrared thermal imager, and three-dimensional digital image related equipment; S5, controlling the output current of the constant current source to heat the metal sample, and synchronously starting the infrared thermal imager and the three-dimensional digital image related equipment to start shooting; S6, the synchronous control box automatically collects and analyzes the thermocouple temperature signal, and stops the constant current source current output when the surface temperature of the metal sample reaches the target experimental temperature; S7, start the universal testing machine to carry out a tensile test; S8. When it is detected that the universal testing machine stops stretching, the signal collection of the infrared thermal imager and the three-dimensional digital image related equipment is stopped synchronously; S9, start the solenoid valve, open the cooling pipeline to cool down the metal sample, automatically collect and analyze the thermocouple temperature signal, and close the solenoid valve and cut off the gas line when the surface temperature of the metal sample is lower than the required temperature for unloading the sample.

[0014] Furthermore, before testing, make preparations for the test, as follows: Connect the high temperature fixture to the universal testing machine; Connect and fix the two cables of the constant current source to the upper and lower parts of the high temperature fixture respectively; Spray the metal sample with speckle on the side facing the 3D digital image correlation device and clamp it on the high temperature fixture; Weld one end of the thermocouple to the surface of the metal sample without spraying spots, and connect the other end of the thermocouple to a constant current source and then to a synchronous control box; Use communication lines to connect the synchronous control box with the solenoid valve, the universal testing machine, the infrared thermal imager and the three-dimensional digital image related equipment.

[0015] Furthermore, after the experiment, the constant current source is turned off first, and then the metal sample is removed and the rest of the equipment is turned off.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a high-temperature tensile testing device for metal materials, comprising a universal testing machine, a constant current source, a cable, a thermocouple, a high-temperature fixture, an air compressor, a cooling pipeline, an electromagnetic valve, a three-dimensional digital image related device, an infrared thermal imager, a synchronous control box and a workstation; the metal sample is heated by the constant current source, the thermocouple and the high-temperature fixture; the temperature field data of the sample is collected by the infrared thermal imager; the deformation data of the sample is collected contactlessly by the three-dimensional digital image related device; the metal sample is cooled by the air compressor, the cooling pipeline and the electromagnetic valve; the start and stop of the universal testing machine, the infrared thermal imager, the electromagnetic valve and the three-dimensional digital image related device are controlled by the synchronous control box, and the start and end of the experiment are automatically controlled according to preset parameters.

[0017] Fast, accurate and safe heating: The metal sample is heated by a constant current source, thermocouple and high temperature fixture. The heating method is self-resistance heating. Adjusting the current can quickly heat the target area of ​​the sample to the set temperature. The temperature of the target area is measured by thermocouples, and the current is adjusted in real time to ensure temperature control accuracy. The self-designed high temperature fixture can achieve insulation between the power circuit and the universal testing machine.

[0018] Non-contact synchronous deformation measurement: The universal testing machine, 3D digital image correlation equipment and synchronous control box are used to perform non-contact synchronous deformation measurement of the specimen. The 3D digital image correlation equipment realizes non-contact deformation measurement of the specimen through optical measurement system and image processing; the synchronous control box controls the synchronous start and stop of the universal testing machine and the 3D digital image correlation equipment to realize synchronous matching of stress and strain data.

[0019] Synchronization of temperature field and strain field: The temperature field and strain field data of the sample are obtained synchronously through the infrared thermal imager, three-dimensional digital image correlation equipment and synchronous control box. The infrared thermal imager records the temperature field data of the sample during the entire experiment; the three-dimensional digital image correlation equipment measures the strain field data during the deformation of the sample; the synchronous control box controls the synchronous start and stop of the infrared thermal imager and the three-dimensional digital image correlation equipment to achieve synchronization of temperature field and strain field.

[0020] The present invention also discloses a test method based on the high-temperature tensile test device for metal materials, wherein the high-temperature fixture is connected to the universal testing machine, and the constant current source is respectively connected and fixed to the upper and lower parts of the high-temperature fixture; the side of the sample facing the three-dimensional digital image correlation device is sprayed with speckles, and clamped between the high-temperature fixtures; one end of the thermocouple is welded to the surface of the metal sample that is not sprayed with speckles, and the other end of the thermocouple is connected to the constant current source, so as to facilitate the non-contact optical strain field measurement of the three-dimensional digital image correlation device; the air compressor, the constant current source, the universal testing machine, the infrared thermal imager, the three-dimensional digital image correlation device and the synchronous control box are started to enter the standby state; the parameters related to the electromagnetic valve, the universal testing machine, the infrared thermal imager and the three-dimensional digital image correlation device on the synchronous control box are set. When starting the test, the electromagnetic valve should be started to open the cooling pipeline to cool the metal sample, because the fixture will have residual temperature after the continuous use of the equipment, which will affect the sample, and the initial temperature of the sample should be ensured to be as consistent as possible, such as not exceeding 5°C from room temperature. The present invention is different from the traditional tensile testing device. It also uses an infrared thermal imager and a three-dimensional digital image correlation device, which can not only measure stress and displacement data, but also obtain temperature field and strain field. The infrared thermal imager records the temperature field data of the sample during the entire experiment; the three-dimensional digital image correlation device measures the strain field data of the sample during deformation; the synchronous control box controls the synchronous start and stop of the infrared thermal imager and the three-dimensional digital image correlation device to achieve synchronization of temperature field and strain field. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of an assembly of an embodiment of the present invention; In the figure: 1. air compressor; 2. cable; 3. thermocouple; 4. constant current source; 5. solenoid valve; 6. metal sample; 7. high temperature fixture; 8. universal testing machine; 9. infrared thermal imager; 10. cooling pipeline; 11. 3D digital image related equipment; 12. synchronous control box; 13. communication line; 14. workstation; Figure 2 This is a test flow chart of the automatic control system of the synchronous control box of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clear, the following is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, not all embodiments.

[0023] The components described and shown in the drawings and embodiments of the present invention may be arranged and designed in various configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. Based on the drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0024] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, element, method, article or equipment that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to the process, element, method, article or equipment.

[0025] The features and performances of the present invention are further described in detail below in conjunction with the embodiments.

[0026] Reference Figure 1 The present invention discloses a high-temperature tensile testing device for metal materials, including a universal testing machine 8, a constant current source 4, a thermocouple 3, a high-temperature fixture 7, an air compressor 1, a cooling pipeline 10, a solenoid valve 5, a three-dimensional digital image correlation device 11, an infrared thermal imager 9, a synchronous control box 12 and a workstation 14.

[0027] The two cables 2 of the constant current source 4 are respectively connected and fixed to the upper and lower parts of the high temperature fixture 7 .

[0028] The high temperature fixture 7 is a self-designed and processed special insulating fixture suitable for a universal testing machine 8, and includes an upper and lower part.

[0029] One end of the thermocouple 3 is welded to the side of the metal sample 6 where no speckle is sprayed, and the other end is connected to the constant current source 4 and then to the synchronous control box 12 .

[0030] The three-dimensional digital image correlation device 11 also includes a software part loaded on the workstation 14 .

[0031] The infrared thermal imager 9 also includes a software part loaded on the workstation 14 .

[0032] The solenoid valve 10 is installed on the cooling pipeline 10 between the air compressor 1 and the nozzle.

[0033] The synchronous control box 12 is connected to the electromagnetic valve 5, the universal testing machine 8, the infrared thermal imager 9 and the three-dimensional digital image related device 11 through the communication line 13; before the experiment, the acquisition frequency of each device is set to be the same. After the experiment starts, the synchronous control box 12 sends a pulse signal to the connected devices at the same time according to the program setting to trigger the synchronous start and stop of each device. For example, the thermal imaging and three-dimensional digital image related devices 11 are started and stopped synchronously, which can ensure that the obtained temperature field and strain field are synchronized.

[0034] Preferably, the synchronous control box 12 is provided with a programmable logic controller, a temperature acquisition module, an intermediate relay, a touch screen, a switching power supply and a control power supply; The control power supply controls the start and stop of the synchronous control box 12 by controlling the on and off of the 220V input circuit; The switching power supply converts 220V AC power into 24V DC power to provide the required power for the programmable logic controller, temperature acquisition module, intermediate relay and solenoid valve 5; The temperature acquisition module is used to convert the voltage signal tested by the thermocouple 3 into a temperature value in digital form; the control parameters of the equipment connected to the synchronous control box 12 are set on the touch screen; The programmable logic controller is used to process and analyze the temperature data obtained by the temperature acquisition module, send out pulse voltage signals according to the program setting parameters to control the start and stop of the universal testing machine 8, infrared thermal imager 9 and three-dimensional digital image related equipment 11, and control the on-off control of the solenoid valve 5 through the intermediate relay.

[0035] Specifically, the capacity of the air compressor 1 is 60 L, and the exhaust volume is 360 L / min.

[0036] Specifically, the type of thermocouple 3 is K type, and the temperature measurement range is from room temperature to 1200°C.

[0037] Specifically, the output of the constant current source 4 is alternating current with a voltage of 0-3 volts and a current of 0-2000 amperes.

[0038] Specifically, the high temperature fixture 7 is a dedicated insulating fixture designed and processed independently and suitable for the universal testing machine 8 , and includes an upper and lower part.

[0039] Specifically, the maximum load of the universal testing machine 8 is 100 kN, and the crossbeam adjustment speed is 0.001-1500 mm / min.

[0040] Specifically, the temperature measurement range of the infrared thermal imager 9 is from room temperature to 1200° C., and the shooting frame rate is 1-50fps.

[0041] The installation process of the present invention: Figure 1As shown, the high temperature fixture 7 is connected to the universal testing machine 8 through a pin; the two cables 2 of the constant current source 4 are respectively connected and fixed to the upper and lower parts of the high temperature fixture 7; the side of the metal sample 6 facing the three-dimensional digital image correlation device 11 is sprayed with speckles and clamped to the high temperature fixture 7 to facilitate the subsequent acquisition of images; one end of the thermocouple 3 is welded to the surface of the sample 6 without the speckle spray, and the other end is connected to the constant current source 4; the synchronous control box 12 is connected to the solenoid valve 5, the universal testing machine 8, the infrared thermal imager 9 and the three-dimensional digital image correlation device 11 by a communication line 13. The use process of the present invention after installation: Connect the high temperature fixture 7 to the universal testing machine 8, connect and fix the two cables 2 of the constant current source 4 to the upper and lower parts of the high temperature fixture 7 respectively; spray the speckle on the side of the metal sample 6 facing the three-dimensional digital image correlation device 11, and clamp it between the high temperature fixtures 7; weld one end of the thermocouple 3 to the surface of the metal sample 6 that is not sprayed with speckle, and connect the other end of the thermocouple to the constant current source 4; connect the synchronous control box 12 with the electromagnetic valve 5, the universal testing machine 8, the infrared thermal imager 9 and the three-dimensional digital image correlation device 11 through the communication line 13; start the air compressor 1, the constant current source 4, the universal testing machine 8, the infrared thermal imager 9, the three-dimensional digital image correlation device 11 and the synchronous control box 12, and enter the standby state; set the parameters related to the electromagnetic valve 5, the universal testing machine 8, the infrared thermal imager 9 and the three-dimensional digital image correlation device 11 on the synchronous control box 12 according to the experimental working conditions. The synchronous control box 12 automatically controls the start and end of the experiment according to the preset parameters. After the experiment is finished, first turn off the constant current source 4, then remove the metal sample 6 and turn off the rest of the equipment.

[0042] like Figure 2 As shown, the synchronous control box 12 automatically controls the start and end of the experiment according to the preset parameters. The specific process is: Start the solenoid valve 5 to open the cooling pipeline 10 to cool the metal sample 6, and automatically collect and analyze the temperature signal of the thermocouple 3. If the surface temperature of the metal sample 6 is lower than the required temperature for starting the experiment, close the solenoid valve 5 and cut off the gas path; If the surface temperature of the metal sample 6 is higher than the temperature required for starting the experiment, the solenoid valve 5 continues to be opened until the surface temperature of the metal sample 6 is lower than the temperature required for starting the experiment, and then the solenoid valve 5 is closed to cut off the gas path; Synchronously start the constant current source 4, the infrared thermal imager 9, and the three-dimensional digital image related equipment 11; Control the constant current source 4 to output current to heat the metal sample 6, and synchronously start the infrared thermal imager 9 and the three-dimensional digital image correlation device 11 to start shooting; The synchronous control box 12 automatically collects and analyzes the temperature signal of the thermocouple 3, and stops the current output of the constant current source 4 when the surface temperature of the metal sample 6 reaches the target experimental temperature; Start the universal testing machine 8 to carry out a tensile test; When it is detected that the universal testing machine 8 stops stretching, the signal collection of the infrared thermal imager 9 and the three-dimensional digital image correlation device 11 is stopped synchronously; Start the solenoid valve 5, open the cooling pipeline 10 to cool the metal sample 6, automatically collect and analyze the temperature signal of the thermocouple 3, and close the solenoid valve 5 and cut off the gas path when the surface temperature of the metal sample 6 is lower than the required temperature of the unloading sample.

[0043] In summary, the present invention provides a high-temperature tensile testing device and method for metal materials, which quickly heats the sample by self-resistance, optically measures the deformation of the sample by digital image correlation technology, measures the temperature distribution of the sample by infrared technology, and uses a synchronous controller to coordinate multiple devices, thereby realizing rapid and accurate heating of the metal sample, contactless synchronous deformation measurement, and synchronous acquisition of the temperature field and strain field data of the sample during the experiment.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A high temperature tensile testing device for metal materials, characterized in that: It includes an air compressor (1), a thermocouple (3), a constant current source (4), a solenoid valve (5), a high temperature fixture (7), a universal testing machine (8), an infrared thermal imager (9), a cooling pipeline (10), a three-dimensional digital image correlation device (11), a synchronous control box (12) and a workstation (14); The synchronous control box (12) is respectively connected to the electromagnetic valve (5), the universal testing machine (8), the infrared thermal imager (9) and the three-dimensional digital image related equipment (11); the synchronous control box (12) is connected to the workstation (14); The constant current source (4) is respectively connected to the upper and lower parts of the high temperature fixture (7); The high temperature fixture (7) is installed in the universal testing machine (8), and the high temperature fixture (7) comprises an upper clamping part and a lower clamping part for clamping the metal sample (6); The cooling pipeline (10) is connected to the air compressor (1), and the solenoid valve (5) is installed on the cooling pipeline (10) connected to the air compressor (1); During the test, the metal sample (6) is sprayed with speckles on the side facing the three-dimensional digital image correlation device (11) and is clamped in the middle of a high-temperature fixture (7); One end of the thermocouple (3) is welded to the surface of the metal sample (6) that is not sprayed with spots, and the other end is connected to a constant current source (4) and then to a synchronous control box (12).

2. A metal material high temperature tensile testing device according to claim 1, characterized in that: The synchronous control box (12) is provided with a programmable logic controller, a temperature acquisition module, an intermediate relay, a touch screen, a switching power supply and a control power supply; The control power supply controls the start and stop of the synchronous control box (12) by controlling the on and off of the 220V input circuit; The switching power supply converts 220V AC power into 24V DC power to provide the required power for the programmable logic controller, the temperature acquisition module, the intermediate relay and the solenoid valve (5); A temperature acquisition module, used for converting the voltage signal tested by the thermocouple (3) into a temperature value in digital form; The control parameters of the equipment connected to the synchronous control box (12) are set on the touch screen; The programmable logic controller is used to process and analyze the temperature data obtained by the temperature acquisition module, send out pulse voltage signals according to program setting parameters to control the start and stop of the universal testing machine (8), the infrared thermal imager (9) and the three-dimensional digital image related equipment (11), and control the on and off of the electromagnetic valve (5) through the intermediate relay to control the gas path.

3. A metal material high temperature tensile testing device according to claim 1, characterized in that: The thermocouple (3) is of type K, and has a temperature measurement range from room temperature to 1200°C.

4. A metal material high temperature tensile testing device according to claim 1, characterized in that: The output of the constant current source (4) is alternating current.

5. A metal material high temperature tensile testing device according to claim 1, characterized in that: The maximum load of the universal testing machine (8) is 100 kN, and the crossbeam adjustment speed is 0.001-1500 mm / min.

6. A metal material high temperature tensile testing device according to claim 1, characterized in that: The temperature measurement range of the infrared thermal imager (9) is from room temperature to 1200°C, and the shooting frame rate is 1-50fps.

7. A metal material high temperature tensile testing device according to claim 1, characterized in that: The three-dimensional digital image correlation device (11) has two industrial cameras with 5 million pixels and a shooting frame rate of 1-70fps.

8. A testing method based on the metal material high temperature tensile testing device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, start the synchronous control box (12), and initialize the program; S2, setting control parameters related to the solenoid valve (5), the universal testing machine (8), the infrared thermal imager (9) and the three-dimensional digital image related equipment (11) on the synchronous control box (12); S3, starting the solenoid valve (5) to open the cooling pipeline (10) to cool the metal sample (6), automatically collecting and analyzing the temperature signal of the thermocouple (3), and if the surface temperature of the metal sample (6) is lower than the temperature required to start the experiment, closing the solenoid valve (5) to cut off the gas path; If the surface temperature of the metal sample (6) is higher than the temperature required for starting the experiment, the solenoid valve (5) continues to be opened until the surface temperature of the metal sample (6) is lower than the temperature required for starting the experiment, and the solenoid valve (5) is closed to cut off the gas path; S4, synchronously starting a constant current source (4), an infrared thermal imager (9), and a three-dimensional digital image correlation device (11); S5, controlling the constant current source (4) to output current to heat the metal sample (6), and synchronously starting the infrared thermal imager (9) and the three-dimensional digital image correlation device (11) to start shooting; S6, the synchronous control box (12) automatically collects and analyzes the temperature signal of the thermocouple (3), and stops the current output of the constant current source (4) when the surface temperature of the metal sample (6) reaches the target experimental temperature; S7, starting the universal testing machine (8) to perform a tensile test; S8, when it is detected that the universal testing machine (8) stops stretching, synchronously stopping the signal collection of the infrared thermal imager (9) and the three-dimensional digital image correlation device (11); S9, start the solenoid valve (5), open the cooling pipeline (10) to cool the metal sample (6), automatically collect and analyze the temperature signal of the thermocouple (3), and close the solenoid valve (5) and cut off the gas path when the surface temperature of the metal sample (6) is lower than the required temperature for unloading the sample.

9. The testing method according to claim 8, characterized in that: Before testing, please prepare for the test as follows: Connecting the high temperature fixture (7) to the universal testing machine (8); The two cables (2) of the constant current source (4) are respectively connected and fixed to the upper and lower parts of the high temperature fixture (7); The metal sample (6) is sprayed with speckle on the side facing the three-dimensional digital image correlation device (11), and is clamped on a high-temperature fixture (7); Weld one end of the thermocouple (3) to the surface of the metal sample (6) without the sprayed speckle, and connect the other end of the thermocouple to the constant current source (4) and then to the synchronous control box (12); The synchronous control box (12) is connected to the electromagnetic valve (5), the universal testing machine (8), the infrared thermal imager (9) and the three-dimensional digital image correlation device (11) by a communication line (13).

10. The testing method according to claim 8, characterized in that: After the experiment is over, first turn off the constant current source (4), then remove the metal sample (6) and turn off the remaining equipment.

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