Thermal-mechanical coupling test method for measuring zero-intensity temperature of metal material

Abstract

The invention provides a thermal-mechanical coupling test method for measuring the zero-intensity temperature of a metal material, and belongs to the technical field of material mechanics and thermodynamic experiments. In the zero-strength test process, the air cylinder is used for restraining the sample, and the response rate is increased. According to the method, the sample size, the overshoot temperature and the heating rate are considered, the zero-intensity temperature NST and the overshoot temperature delta T of the same material under different conditions are recorded through an orthogonal test, and then through comprehensive evaluation, the finally obtained NST is closer to the reality.

Description

Technical Field

[0001] The invention belongs to the technical field of material mechanics and thermodynamics experiments, and in particular relates to a thermomechanical coupling test method for measuring the zero-intensity temperature of a metal material. Background Art

[0002] With the continuous development of industrial technology, the demand for the application of metal materials in high temperature, low temperature and complex stress states is increasing. Under these environments, the mechanical properties of metal materials may change significantly, especially when approaching their zero strength temperature. Zero strength temperature refers to the critical temperature at which a material loses its load-bearing capacity at a certain temperature, which is crucial to ensure the safety and reliability of materials in extreme environments. Therefore, accurately determining the zero strength temperature of metal materials has become an important topic in material research and engineering applications.

[0003] The thermomechanical coupling test method is an advanced experimental technique that combines thermal and mechanical loading to simulate the complex conditions in actual applications. This method can monitor and analyze the stress-strain behavior of materials at different temperatures in real time by gradually changing the temperature and applying mechanical loads in a controlled test environment. This not only helps to determine the zero-strength temperature of the material, but also reveals its microstructural changes and failure mechanisms under the action of thermomechanical coupling. Summary of the invention

[0004] In view of this, in order to solve the technical problems mentioned in the above background technology, the present invention proposes a thermomechanical coupling test method for measuring the zero-intensity temperature of metal materials, which can comprehensively and accurately measure the zero-intensity temperature of metal materials.

[0005] To achieve the above object, the present invention adopts the following technical solution: a thermomechanical coupling test method for measuring the zero-intensity temperature of a metal material, specifically comprising the following steps:

[0006] Step 1: Prepare the sample size as follows: prepare several round bar samples;

[0007] Step 2: Spot weld the R-type thermocouple to the center of the sample, clamp the two ends of the sample with a thermal simulation test machine, and after the R-type thermocouple is connected, use a cylinder to constrain the sample with a tensile load of 0.1kN, and heat it at a heating rate of 100℃ / s until the sample breaks. Record the temperature at this time as NST MAX ℃;

[0008] Step 3: After obtaining NSTMAX℃, repeat the experimental part of step 2, but divide the heating process into two steps:

[0009] 1. Heat up at a heating rate of 100℃ / s to the inflection point temperature of the heating rate. The inflection point temperature is NST. MAX -X℃, keep warm for 2s~5s;

[0010] 2. Starting from the inflection point temperature of the heating rate, increase the temperature at a rate of 2℃ / s to 5℃ / s until the sample breaks. The temperature at this time is recorded as NST. i ℃; Due to the response speed and inertia of the control system, the heating system of the GLEEBLE thermal simulation test machine will experience temperature overshoot. The overshoot temperature after reaching the inflection point of the heating rate is recorded as ΔT i ℃;

[0011] Step 4: Determine the inflection point of the heating rate, repeat the test part of step 3, and stop the test when the result meets the requirement that the sample breaks at the heating stage of 2℃ / s to 5℃ / s, the thermocouple breaks normally, and there is no necking at the fracture. Record the X value at this time, the inflection point of the heating rate NST MAX -X℃, and record the temperature at fracture as NST℃;

[0012] Step 5: After completing the test part of the round bar specimens, the overshoot temperature ΔT of the specimens of each size is i ℃ and inflection point temperature NST MAX -X℃ are added, and the size of the sample with the value closest to NST℃ is screened out, and the NST℃ obtained according to this sample size is recorded as the final NST℃.

[0013] Furthermore, the size of the round rod sample is Φ6.00±0.01mm×(80, 85, 90, 95, 100, 105, 110)±1mm.

[0014] Furthermore, the surface roughness of the round rod sample is not higher than 0.8.

[0015] Furthermore, the inflection point temperature NST MAX In -X°C, X=5-50°, and the interval is 5°.

[0016] Compared with the prior art, the thermomechanical coupling test method for measuring the zero-intensity temperature of metal materials described in the present invention has the following beneficial effects:

[0017] 1. In the zero-intensity test process, the present invention uses a cylinder to constrain the sample to increase the response rate.

[0018] 2. The present invention takes into account the sample size, overshoot temperature and heating rate. Through orthogonal experiments, the zero-strength temperature NST and overshoot temperature ΔT obtained under different conditions for the same material are recorded. Then, through comprehensive evaluation, the final NST obtained is closer to reality. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of them.

[0020] A thermomechanical coupling test method for measuring the zero-intensity temperature of a metal material comprises the following steps:

[0021] (1) Prepare a number of round bar specimens with dimensions of Φ6.00±0.01mm×(80, 85, …, 105, 110)±1mm and a surface roughness not higher than 0.8;

[0022] (2) Select a round bar specimen with the size of Φ6.00±0.01mm×(80, 85, ..., 105, 110)±1mm and perform the test in accordance with steps (3) to (5) in sequence;

[0023] (3) Spot weld the R-type thermocouple to the center of the sample, clamp the two ends of the sample using the GLEEBLE thermal simulation tester, and after the thermocouple is connected, use a cylinder to constrain the sample with a tensile load of 0.1 kN and heat it at a heating rate of 100 °C / s until the sample breaks. The temperature at this time is recorded as NST MAX ℃;

[0024] (4) After obtaining NSTMAX℃, repeat the experimental part of step (3), but the heating process needs to be divided into two steps:

[0025] 1. Heat up at a heating rate of 100°C / s to the inflection point temperature (NST MAX -X)℃(X=5, 10, ...45, 50), keep warm for 2s~5s.

[0026] 2. Temperature of the heating rate inflection point (NST MAX -X)℃ as the starting point, and increase the temperature at a rate of 2℃ / s to 5℃ / s until the sample breaks. The temperature at this time is recorded as NST i ℃; Due to the response speed and inertia of the control system, the heating system of the GLEEBLE thermal simulation test machine will experience temperature overshoot. The overshoot temperature after reaching the inflection point of the heating rate is recorded as ΔT i ℃.

[0027] (5) Determine the inflection point of the heating rate (NST MAX-X)℃, set X = 5℃, 10℃, ..., 45℃, 50℃ in sequence, and repeat the test part of step (4) at 5℃ intervals. When the result meets the requirement that the sample breaks in the "2℃ / s~5℃ / s heating stage", the thermocouple breaks normally, and there is no necking at the fracture, the test can be stopped, and the X value at this time is recorded. The inflection point of the heating rate (NST MAX -X)℃, and record the temperature at fracture as NST℃.

[0028] (6) After completing the test part of the round bar specimens of Φ6.00±0.01mm×(80, 85, ..., 105, 110)±1mm, the overshoot temperature ΔTi℃ and the inflection point temperature (NST) of the specimens of each size are compared. MAX -X)℃, screen out the size of the sample with the value closest to NST℃, and record the NST℃ obtained according to this sample size as the final NST℃.

[0029] Embodiment 1:

[0030] A certain metal was selected for testing. Several round bar specimens with dimensions of Φ6.00±0.01mm×(80, 85, …, 105, 110)±1mm and surface roughness not higher than 0.8 were prepared for zero-intensity temperature testing. The R-type thermocouple was spot welded to the center of the specimen. The two ends of the specimen were clamped and fixed using a GLEEBLE thermal simulation tester. After the thermocouple was connected, the specimen was constrained with a tensile load of 0.1kN using a cylinder. The temperature was raised at a heating rate of 100℃ / s until the specimen broke. The average NST of the specimens of each size was MAX ℃ are: 1448℃, 1445℃, 1446℃, 1444℃, 1450℃, 1449℃, 1445℃ respectively.

[0031] To obtain a more accurate NST℃, get NST MAX After ℃, repeat the zero-intensity test, but the heating process needs to be divided into: 1. Inflection point temperature (NST MAX -X)℃ before heating at a heating rate of 100℃ / s, 2. heating at the inflection point temperature (NST MAX -X)℃ as the starting point, the temperature is increased at a rate of 2℃ / s to 5℃ / s until the sample breaks. To determine the inflection point of the heating rate (NST MAX -X)℃, set X = 5℃, 10℃, ..., 45℃, 50℃ in sequence, when the result is consistent with the sample breaking in the "2℃ / s ~ 5℃ / s heating stage", record the average value of X, the heating rate inflection point (NST MAX -X)℃, and the average value of the fracture temperature NST℃. The results are shown in Table 1.

[0032] Table 1 Related parameters of double-stage heating zero-intensity test for specimens of various sizes

[0033]

[0034] Due to the response speed and inertia of the control system, the heating system of the GLEEBLE thermal simulation test machine will experience temperature overshoot. The overshoot temperature after reaching the inflection point of the heating rate is recorded as ΔT i The average values ​​of ℃ are: 16℃, 16℃, 20℃, 19℃, 19℃, 22℃, 24℃. The overshoot temperature ΔT of the samples of each size i ℃ and inflection point temperature (NST MAX -X)℃ are: 1424℃, 1421, 1426, 1423, 1429, 1431, 1429. Since the overshoot temperature ΔT of the sample with a size of Φ6.00±0.01mm×110±1mm i ℃ and inflection point temperature (NST MAX -X)℃ is closest to its NST℃, so this size is determined to be selected, and the temperature is raised to 1405℃ at a heating rate of 100℃ / s. After keeping warm for 2s to 5s, the temperature is raised to the test fracture at a heating rate of 2℃ / s to 5℃ / s. The obtained NST=1439℃ is closest to the true NST℃ of a certain metal.

[0035] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A thermomechanical coupling test method for measuring the zero-intensity temperature of a metal material, characterized in that: The specific steps include: Step 1: Prepare the sample size as follows: prepare several round bar samples; Step 2: Spot weld the R-type thermocouple to the center of the sample, clamp the two ends of the sample with a thermal simulation test machine, and after the R-type thermocouple is connected, use a cylinder to constrain the sample with a tensile load of 0.1kN, and heat it at a heating rate of 100℃ / s until the sample breaks. Record the temperature at this time as NST MAX ℃; Step 3: After obtaining NSTMAX℃, repeat the experimental part of step 2, but divide the heating process into two steps:

301. The temperature is raised at a heating rate of 100°C / s to the inflection point temperature of the heating rate. The inflection point temperature is NST. MAX -X℃, keep warm for 2s~5s; 302. Starting from the inflection point temperature of the heating rate, heat at a rate of 2℃ / s to 5℃ / s until the sample breaks. The temperature at this time is recorded as NST. i ℃; Due to the response speed and inertia of the control system, the heating system of the GLEEBLE thermal simulation test machine will experience temperature overshoot. The overshoot temperature after reaching the inflection point of the heating rate is recorded as ΔT i ℃; Step 4: Determine the inflection point of the heating rate, repeat the test part of step 3, and stop the test when the result meets the requirement that the sample breaks at the heating stage of 2℃ / s to 5℃ / s, the thermocouple breaks normally, and there is no necking at the fracture. Record the X value at this time, the inflection point of the heating rate NST MAX -X℃, and record the temperature at fracture as NST℃; Step 5: After completing the test part of the round bar specimens, the overshoot temperature ΔT of the specimens of each size is i ℃ and inflection point temperature NST MAX -X℃ are added, and the size of the sample with the value closest to NST℃ is screened out, and the NST℃ obtained according to this sample size is recorded as the final NST℃.

2. The thermomechanical coupling test method for measuring the zero-intensity temperature of metal materials according to claim 1, characterized in that: The size of the round rod sample is Φ6.00±0.01mm×(80, 85, 90, 95, 100, 105, 110)±1mm.

3. The thermomechanical coupling test method for measuring the zero-intensity temperature of metal materials according to claim 1, characterized in that: The surface roughness of the round rod sample is not higher than 0.

8.

4. The thermomechanical coupling test method for measuring the zero-intensity temperature of metal materials according to claim 1, characterized in that: Inflection point temperature NST MAX In -X°C, X=5-50°, and the interval is 5°.

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