A method for non-destructive temperature monitoring of a specimen for thermal loading tests

Abstract

The present application relates to temperature heating and monitoring method in thermal load test, specifically relates to a kind of sample nondestructive temperature monitoring method for thermal load test, comprising the following steps: the deformation of sample in the set thermal compression operating mode is calculated, the size of open collar made of easy-to-weld material is confirmed accordingly, and open collar is made;After the side surface of sample is polished flat with sandpaper, flexible heat-conducting material is wrapped on the side surface of sample, forming "heat-conducting material-sample integrated structure";The open collar is installed on the side surface of "heat-conducting material-sample integrated structure";After welding thermocouple on the surface of open collar, the sample is installed in test loading equipment, and temperature measurement and control in subsequent test process can be carried out, the temperature of open collar and sample reaches equilibrium after insulation, and the temperature measured by thermocouple is the temperature of sample.The present application can guarantee the smooth development of thermal load test, and then obtain the high-temperature service performance of material, to provide basis for its design selection.

Description

TECHNICAL FIELD

[0001] The application relates to a temperature heating and monitoring method in a thermal load test. BACKGROUND

[0002] The thermal load test is a necessary test in the design and selection of superhigh-temperature materials. For materials with good welding performance, a thermocouple can be directly welded on the surface of the material to carry out the thermal load test. For materials with poor welding performance, a thermocouple needs to be welded after drilling on the surface of the material, but the drilling will cause initial random damage to the sample and affect the mechanical properties of the material measured in the test. In addition, problems such as thermocouple falling off and thermocouple temperature fluctuation often occur during the thermal load process, which causes the test to fail. Therefore, a method for continuously and stably monitoring the temperature of the sample in the thermal load test without damage needs to be developed. SUMMARY

[0003] To solve the above problems, the application provides a sample nondestructive temperature monitoring method for a thermal load test, which can ensure the smooth development of the thermal load test and further obtain the high-temperature service performance of the material, thereby providing a basis for the design and selection of the material.

[0004] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0005] A sample nondestructive temperature monitoring method for a thermal load test, comprising the following steps:

[0006] S1. Calculate the deformation of the sample under the set thermal compression working condition, and confirm the size of the open collar made of easily weldable material according to the deformation, and manufacture the open collar;

[0007] S2. After the side surface of the sample is polished flat with sandpaper, the flexible heat-conducting material is wrapped on the side surface of the sample to form a "heat-conducting material-sample integrated structure";

[0008] S3. The open collar is installed on the side surface of the "heat-conducting material-sample integrated structure";

[0009] S4. After the thermocouple is welded on the surface of the open collar, the sample is installed on the test loading equipment, and then the temperature measurement and control in the subsequent test process can be carried out. After insulation, the temperature of the collar and the sample reaches equilibrium, and the temperature measured by the thermocouple is the temperature of the sample.

[0010] Further, the sample can be in the shape of a cylinder, or other shapes such as a cuboid.

[0011] Further, the open collar is open on one side, and the phase transition temperature of the material should be at least 200 DEG C higher than the test working condition temperature.

[0012] Further, the width of the opening ring is less than 1 / 3 of the sample height, the thickness of the opening ring is much less than the sample diameter, and the opening angle of the opening ring is selected in the range of 270°-350°.

[0013] Further, the flexible heat-conducting material can be one of graphite, silver foil and gold foil, which can be stably used at a set temperature.

[0014] Further, the thermocouple material can be K-type thermocouple, and when the K-type thermocouple is welded on the ring, the diameter of the welding point should be not less than 1 / 2 of the width of the ring.

[0015] The present application has the following advantages:

[0016] 1) The present application uses a ring outside the sample to measure and monitor the temperature, which is a non-destructive temperature measurement and monitoring method compared with the traditional method of directly welding a thermocouple on the surface of the sample or the method of drilling a hole on the side of the sample and then filling the hole with a thermocouple. Since the sample is not damaged during the temperature measurement and monitoring process, the non-destructive temperature measurement and monitoring method can ensure that the complete bearing performance of the sample can be tested under the thermal loading condition.

[0017] 2) The flexible heat-conducting material is tightly filled between the sample and the ring, which makes the continuous and uniform heat conduction among the sample, the heat-conducting material and the ring, so that the temperature stability monitoring during the whole thermal experiment process such as heating, temperature maintaining and loading can be realized.

[0018] 3) In the size design of the ring, the thermal expansion and deformation of the sample are considered, and in addition, the ring is designed to be open, so that the radial deformation of the sample under the action of thermal load is not limited, and the accuracy of the test results is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0019] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings:

[0020] Figure 1 Temperature data graph obtained by using the monitoring method of the embodiment of the present application.

[0021] Figure 2 Temperature data graph obtained by using the conventional surface welding thermocouple method.

[0022] Figure 3 Temperature data graph obtained by using the conventional surface welding thermocouple method.

[0023] Figure 4 Structure schematic diagram of one specific embodiment of the present application. DETAILED DESCRIPTION

[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0025] like Figure 4 As shown, the present invention provides a non-destructive temperature monitoring method for specimens used in thermal load tests, comprising the following steps:

[0026] S1. Calculate the deformation of the sample under the set thermo-compression conditions, and confirm the size of the open collar 3 made of easy-to-weld material accordingly.

[0027] S2. After smoothing the side surface of sample 1 with sandpaper, wrap the flexible thermal conductive material 2 around the side surface of the sample to form an "integrated structure of thermal conductive material-sample".

[0028] S3. Install an open collar 3 made of easily weldable material on the side of the "thermal conductive material-sample integrated structure (1&2)";

[0029] S4. After welding the thermocouple onto the surface of the open collar 3, install the sample on the test loading device. Temperature measurement and control can then be performed during subsequent tests. After heat preservation, the temperatures of the collar and the sample reach equilibrium, and the temperature measured by the thermocouple is the sample temperature. Specifically, the deformation D is determined based on the sample's material properties and thermal load conditions. The total deformation calculation formula is: D=α×T×Ds+δ×μ, where α is the coefficient of linear expansion, T is the temperature, Ds is the sample diameter, δ is the axial deformation, and μ is Poisson's ratio.

[0030] Specifically, the formula for determining the inner diameter Dt of the collar is: Dt=Ds+D, where D is the calculated deformation of the sample under the set thermo-compression condition.

[0031] Specifically, the width of the open collar should be less than 1 / 3 of the sample height, the thickness of the open collar should be much smaller than the sample diameter, and the opening angle can be selected within the range of 270° to 350°.

[0032] Specifically, the material for making the collar is selected based on the temperature required for the thermal loading conditions of the sample. The phase transition temperature of the material of the open collar should be at least 200°C higher than the test temperature to prevent unstable temperature measurement of the collar during the test.

[0033] Specifically, based on the thermal test conditions, flexible thermal conductive materials that can stably operate at the test temperature are selected.

[0034] Specifically, when welding the thermocouple to the collar, the diameter of the weld point should be no less than 1 / 2 of the collar width.

[0035] In this embodiment, the flexible heat-conducting material makes the sample temperature close to the collar wall temperature, and the open collar does not limit the radial deformation of the sample under the action of thermal load. At the same time, the open collar can continuously and stably measure the temperature after being welded with the thermocouple at the temperature of the test.

[0036] Embodiment:

[0037] The sample subjected to thermal loading is a ceramic material which is difficult to weld, has a diameter Ds of 10 mm, a height H of 12 mm, and is intended to carry out a thermal loading test at 828°C, with an axial deformation of 1 mm.

[0038] The process steps are as follows:

[0039] 1) Calculate the deformation of the sample under the set thermal compression working condition, and according to this, confirm the size of the open collar 3 made of easy-to-weld material:

[0040] a) The total deformation is:

[0041] D = a x T x Ds + d x m = 7.6E-6 x (828 + 273) x 10 + 1 x 0.23 = 0.31 mm;

[0042] b) The inner diameter of the collar is Dt = Ds + D = 10.31 mm;

[0043] c) The width of the open collar is 2 mm, the thickness of the open collar is 0.5 mm, and the opening angle is 300°;

[0044] d) The collar material is selected to be 314 stainless steel;

[0045] 2) After the sample 1 side and surface are ground flat with sandpaper, the flexible graphite heat-conducting material 2 is wrapped on the side of the sample, and the thickness of the graphite layer is 0.3 mm;

[0046] 3) On the side of the "heat-conducting material-sample integrated structure (1 & 2)", further install the collar 3 made of 314 stainless steel;

[0047] 4) Weld a K-type thermocouple on the surface of the collar 3, and ensure that the diameter of the welding point is greater than 1 mm. After the sample is installed on the conventional thermal test loading equipment, the temperature during the test can be stably monitored.

[0048] Temperature measurement stability and discussion:

[0049] The temperature data monitored by the above method is as follows: Figure 1shown. And for the sample, the conventional surface welding thermocouple method is adopted: the thermocouple wire is clamped on the thermocouple welding machine, the welding voltage is between 18-20V, the sample side is polished bright with sandpaper, then the thermocouple wire is welded on the middle of the sample side, the distance between the two welding points is kept at about 1-2mm. The temperature data obtained by the method is shown in Figure 2 、 Figure 3 .

[0050] It can be found intuitively from Figure 1 that the temperature monitored by the application is continuously and smoothly determined during the heating and holding processes. Based on this smooth temperature monitoring, the smooth progress of the thermal loading test can be ensured. The test method of the application avoids the large temperature fluctuation ( Figure 2 ) that occurs when the temperature of the conventional sample surface is measured, which leads to severe thermal oscillation and termination of the test. It also avoids the thermocouple falling off ( Figure 3 ) around 500s, which leads to failure of temperature measurement and termination of the test.

[0051] As shown in Figure 2 , the temperature fluctuation of the thermocouple is large when the conventional sample surface welding thermocouple method is used for testing. As shown in Figure 3 , the thermocouple will fall off when the conventional sample surface welding thermocouple method is used for testing, which leads to the failure of temperature monitoring.

[0052] The specific embodiments of the application have been described above. It should be understood that the application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the application.

Claims

1. A method for non-destructive temperature monitoring of a test sample for thermal loading tests, characterized in that It comprises the following steps: S1, calculating the deformation of the sample under the set thermal compression condition, and confirming the size of the open collar made of the easy-to-weld material and making the open collar; S2, after smoothing the side surface of the sample with sandpaper, wrapping the flexible heat-conducting material on the side surface of the sample to form an "integrated structure of heat-conducting material-sample"; S3, installing the open collar on the side surface of the "integrated structure of heat-conducting material-sample"; S4, after welding the thermocouple on the surface of the open collar, installing the sample on the test loading equipment, and then carrying out the temperature measurement and control in the subsequent test process, the temperature of the sample and the collar reaches equilibrium after insulation, and the temperature measured by the thermocouple is the temperature of the sample.

2. The method for non-destructive temperature monitoring of a test sample for thermal loading tests according to claim 1, characterized in that The sample is in a cylindrical shape.

3. The method for non-destructive temperature monitoring of a test sample for thermal loading tests according to claim 1, characterized in that The open collar is open on one side, and the phase change temperature of the material should be at least 200℃ higher than the test condition temperature.

4. The method for non-destructive temperature monitoring of a test sample for thermal loading testing of claim 1, wherein, The flexible heat-conducting material can stably serve at the set test temperature, and is one of graphite, silver foil and gold foil.

5. The method for non-destructive temperature monitoring of a test sample for thermal loading testing of claim 1, wherein, The thermocouple material is selected as K-type thermocouple, and when it is welded on the collar, the diameter of the welding point should be not less than 1 / 2 of the width of the collar.

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