Method for measuring high-temperature deformation dynamic recrystallization behavior of iron-carbon alloy

Abstract

The invention discloses a method for determining the dynamic recrystallization behavior of a high-temperature solid solution stable structure in an iron-carbon alloy deformation process. The method comprises the following steps: firstly, processing the iron-carbon alloy into a cylindrical sample, then heating to a certain temperature below an alloy melting-solidification line at a stable temperature rising speed, preserving heat, then cooling to different deformation temperature points, carrying out hot compression deformation, and immediately quenching to room temperature after deformation. By collecting stress-strain-temperature data in real time, a stress-strain curve is constructed, characteristic parameters such as epsilon p, epsilon c and epsilon t are extracted, and a plane rectangular coordinate system diagram of dynamic recrystallization at different strain rates is established. The dynamic recrystallization curve graph can provide controlled rolling process parameters of the material, greatly shortens the mass production test period, reduces the product quality control instability, and remarkably improves the comprehensive mechanical properties of the alloy material. According to the method, accurate determination and prediction of the dynamic recrystallization behavior of the iron-carbon alloy are realized through finely controlled experimental steps and a real-time data acquisition and analysis technology, and a scientific basis is provided for optimizing a hot working process and improving material performance.

Description

Technical Field

[0001] The invention belongs to the technical field of hot processing of metal materials, and in particular relates to a method for measuring the high-temperature deformation dynamic recrystallization behavior of an iron-carbon alloy. Background Art

[0002] In the field of hot deformation of iron-carbon alloy materials, a crucial phenomenon is that when recrystallization is carried out under different heating average temperature and hot deformation rate conditions, the uniformity of the internal microstructure size shows significant differences. In order to ensure that the iron-carbon alloy can form a uniform and stable microstructure during hot working, and then achieve excellent comprehensive performance, it is particularly important to deeply explore the dynamic recrystallization behavior mechanism of the high-temperature solid solution stable microstructure during the deformation of the iron-carbon alloy. At present, the determination of the dynamic recrystallization behavior of the high-temperature solid solution stable microstructure during the deformation of the iron-carbon alloy mainly relies on the combination of actual production and laboratory mechanics and metallographic experiments. However, this method not only has a long experimental cycle, but also may interfere with the normal production process, and has not yet formed a highly mature method for studying the dynamic recrystallization behavior of the high-temperature solid solution stable microstructure during the deformation of the iron-carbon alloy based on simulation technology. In view of this, the development of a method for studying the dynamic recrystallization behavior of the high-temperature solid solution stable microstructure during the deformation of the iron-carbon alloy based on simulation technology is of great significance for achieving precise control of the microstructure in the actual production process. Through simulation technology, we can more accurately predict and control the organizational evolution of materials during thermal processing, thereby providing precise technical parameter support for the rolling process in the material production process and promoting the further development of materials science and engineering technology. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a method for measuring the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy.

[0004] The present invention is achieved by a method for measuring the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy, which is characterized by being carried out according to the following steps:

[0005] S1. Process the metal material into a cylindrical specimen of 10×15 mm in diameter;

[0006] S2. Heat the sample to a temperature of 50-150°C below the melting-solidification line of the alloy at a steady heating rate on a thermal simulator, keep the temperature for 5-10 minutes, and then cool the sample to different deformation temperature points within the temperature range above the critical temperature and below the melting-solidification line temperature at the same temperature change rate. Each temperature point is 50°C apart, and the temperature is averaged for 0.5-1 minute at each temperature point. Select the samples averaged at different deformation temperature points and perform hot compression deformation at different strain rates. The deformation amount is controlled to be the same, and the samples are immediately quenched to room temperature after deformation;

[0007] S3. According to the stress-strain-temperature data collected from time to time during the test, a stress-strain curve is formed;

[0008] S4. further extract characteristic parameters of εp, εc and εt from the above stress-strain curve; εp represents the peak strain corresponding to the peak stress, εc represents the critical strain required to start dynamic recrystallization, and there is the following relationship between εp and εc: εc≈0.83εp; εt is the deformation corresponding to the stress reaching the peak value and then dropping to the stable state on the stress-strain curve; the above parameters can be used to establish a plane rectangular coordinate system diagram of dynamic recrystallization of the sample at different strain rates;

[0009] Preferably, the test is performed on a thermal simulator Gleeble-3800, and the sample is fixed. Preferably, a thermocouple is welded on the same cross section of the sample center by a spot welder, and the distance between the weld points is 0.5-2 mm. The active shaft end of the mobile simulator is used to clamp the sample, and before clamping, graphite lubricant is added to both ends of the sample, and then a flat sheet is adhered, and the sample is clamped together at the center of the two anvil heads.

[0010] Further preferably, on a thermal simulator Gleeble-3800, the sample is heated at a rate of 5°C / S to a temperature of 50-150°C below the melting-solidification line of the alloy, and the sample is cooled at a rate of 5°C / S to different deformation temperature points in the temperature range above the critical temperature and below the melting-solidification line temperature.

[0011] Further preferably, the sample is one of carbon structural steel, low alloy steel, welding wire steel, high carbon steel, and bearing steel.

[0012] Advantages and technical effects of the present invention: Compared with conventional technologies, the method for determining the dynamic recrystallization behavior of high-temperature deformation of an iron-carbon alloy proposed in the present invention exhibits significant technical effects and advantages. The following is a detailed summary of its technical effects: First, in terms of sample preparation, the present invention adopts a standardized sample size (cylindrical sample of Ф10×15mm). This improvement significantly reduces the experimental error caused by differences in sample size and improves the accuracy and reliability of the data. In conventional methods, the diversity of sample sizes often leads to the dispersion of experimental results, making it difficult to form a unified conclusion. The present invention ensures the repeatability of the experiment and the comparability of the data through standardized sample preparation, providing a solid foundation for in-depth research on the dynamic recrystallization behavior of iron-carbon alloys. Secondly, during the heat treatment and deformation process, the present invention adopts finely controlled heating, insulation and cooling steps, as well as hot compression deformation at different deformation temperature points and strain rates. This technical feature enables researchers to fully explore the effects of temperature, strain rate and deformation on dynamic recrystallization behavior and more accurately simulate actual production conditions. In contrast, conventional methods often lack fine control of these parameters, resulting in experimental results that are difficult to accurately reflect the laws of organizational evolution in actual production processes. In addition, the present invention also introduces real-time data acquisition and analysis technology. By constructing stress-strain curves and extracting characteristic parameters (such as εp, εc and εt), a plane rectangular coordinate system diagram of dynamic recrystallization of the sample at different strain rates is established; this graphical representation method is not only intuitive and easy to understand, but also convenient for mathematical processing and model prediction. Compared with traditional methods, this modeling method based on characteristic parameters improves the prediction accuracy and reliability of dynamic recrystallization behavior, and provides a more scientific basis for optimizing thermal processing technology. Furthermore, the application of the present invention on the thermal simulator Gleeble-3800, as well as the refined sample fixation and thermocouple welding process, significantly improves the accuracy and reliability of the experiment. The optimization of the welding position and spacing of the thermocouple ensures the accuracy and sensitivity of the temperature measurement, and provides strong support for real-time monitoring and recording of the temperature changes of the sample during thermal deformation. At the same time, the use of graphite lubricants and flat sheets at both ends of the sample effectively reduces friction and wear, and ensures the stability and uniformity of the sample during the thermal simulation process. In summary, compared with traditional technologies, the present invention has significant technical advantages in reducing experimental errors, improving data accuracy, optimizing process parameters and predicting material properties. These advantages not only improve the understanding and control of the dynamic recrystallization behavior of iron-carbon alloys, but also provide a more scientific basis and strong support for optimizing hot working processes and improving material properties.

[0013] Figure Description

[0014] Figure 1 : Schematic diagram of sample assembly;

[0015] Figure 2:Gleeble single pass compression deformation process diagram;

[0016] Figure 3 : strain rate 0.01s -1 Stress-strain curves at different deformation temperatures;

[0017] Figure 4 : strain rate 0.1s -1 Stress-strain curves at different deformation temperatures;

[0018] Figure 5 : strain rate 1s -1 Stress-strain curves at different deformation temperatures;

[0019] Figure 6 :strain rate 1 0s -1 Stress-strain curves at different deformation temperatures;

[0020] Figure 7 : strain rate is 0.01s -1 Dynamic recrystallization diagram of

[0021] Figure 8 : strain rate is 0.1s -1 Dynamic recrystallization diagram of

[0022] Fig. 9 : strain rate is 0.01s -1 The metallographic structure diagram after quenching at 1000℃ deformation;

[0023] Fig.10 : strain rate is 0.1s -1 The metallographic structure diagram after quenching at 1000℃ deformation;

[0024] Fig.11 : strain rate is 1s -1 The metallographic structure diagram after quenching at 1000℃ deformation;

[0025] Figure 1 Middle: 1. Sample 2. Flat piece 3. Anvil head 4. Stainless steel base 5. Thermocouple. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the 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.

[0027] See also Figures 1 to 11 , a method for measuring the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy, characterized by being carried out in the following steps:

[0028] S1. Process the metal material into a cylindrical specimen of Ф10×15mm; Processing the metal material into a cylindrical specimen of a specific size (Ф10×15mm) is a basic step in the experiment. This standardized operation ensures the repeatability of the experiment and the comparability of the data; the appropriate specimen size can not only represent the overall performance of the material, but also facilitate precise temperature control and mechanical testing on the thermal simulator. Technical effect: Compared with traditional methods, standardized specimen preparation reduces experimental errors caused by differences in specimen size and improves data accuracy and reliability. In addition, unified specimen size also facilitates data sharing and comparison between different laboratories and research institutions;

[0029] S2. After heating the sample to 150°C below the melting-solidification line of the alloy at a steady heating rate on a thermal simulator and keeping it at that temperature for 5 minutes, the sample was cooled to different deformation temperature points within the temperature range above the critical temperature and below the melting-solidification line temperature at the same temperature change rate. The temperature was averaged for 0.5 minutes at each temperature point every 50°C. The samples with average temperatures at different deformation temperature points were selected to be subjected to hot compression deformation at different strain rates, with the deformation amount being the same. After deformation, the samples were immediately quenched to room temperature. This step simulates the microstructure evolution of the iron-carbon alloy during actual hot working. By steadily heating the sample to a temperature slightly lower than the melting-solidification line of the alloy and keeping it at that temperature, the inhomogeneity of the original microstructure can be eliminated, providing a stable initial state for subsequent hot deformation. Then, short-term average temperatures were performed at different deformation temperature points, and hot compression deformation was performed at different strain rates, so as to comprehensively explore the effects of temperature, strain rate and deformation amount on dynamic recrystallization behavior. Compared with traditional methods, this finely controlled heat treatment and deformation process can more accurately simulate actual production conditions and reveal the microstructure evolution law of materials under different process parameters. By conducting experiments at different temperature points and strain rates, a more comprehensive database of dynamic recrystallization behavior can be established, providing strong support for optimizing controlled rolling process parameters.

[0030] S3. According to the stress-strain-temperature data collected in real time during the test, the stress-strain curve is constructed; through real-time data collection, the stress-strain curve can be constructed, which is an intuitive tool for analyzing the deformation behavior and dynamic recrystallization characteristics of materials. Compared with traditional methods, real-time data collection improves the accuracy and timeliness of data, making the analysis of dynamic recrystallization behavior more accurate and in-depth;

[0031] S4. Further extract the characteristic parameters of εp, εc and εt from the above stress-strain curve; εp represents the peak strain corresponding to the peak stress, εc represents the critical strain required to start dynamic recrystallization, and there is the following relationship between εp and εc: εc≈0.83εp; εt is the deformation corresponding to the stress reaching the peak value and then dropping to the stable state on the stress-strain curve; the above parameters can be used to establish a plane rectangular coordinate system diagram of dynamic recrystallization of the sample at different strain rates; extracting characteristic parameters (such as εp, εc and εt) from the stress-strain curve is a key step in establishing a dynamic recrystallization model. These parameters reflect important physical phenomena of the material during thermal deformation, such as the appearance of peak stress, the start of dynamic recrystallization and the stabilization of stress. By extracting and analyzing these characteristic parameters, a plane rectangular coordinate system diagram of dynamic recrystallization of the sample at different strain rates can be established; this graphical representation method is not only intuitive and easy to understand, but also convenient for mathematical processing and model prediction. Compared with traditional methods, this modeling method based on characteristic parameters improves the prediction accuracy and reliability of dynamic recrystallization behavior and provides a more scientific basis for optimizing hot working technology.

[0032] In summary, the method for determining the dynamic recrystallization behavior of iron-carbon alloys under high temperature deformation proposed in the present invention significantly improves the ability to understand and control the dynamic recrystallization behavior of materials through finely controlled experimental steps and real-time data acquisition and analysis technology. Compared with traditional methods, the present invention has shown significant technical advantages in reducing experimental errors, improving data accuracy, optimizing process parameters and predicting material properties.

[0033] Further preferably, the experiment is performed on a thermal simulator Gleeble-3800 and the sample is fixed. Its refined sample fixing and thermocouple welding process significantly improve the accuracy and reliability of the experiment.

[0034] Further preferably, a thermocouple is welded on the same cross section of the center of the sample with a spot welder, with a welding spot spacing of 0.5-2mm, and the active shaft end of the mobile simulator clamps the sample, ensuring the accuracy and sensitivity of the temperature measurement, and providing strong support for real-time monitoring and recording of the temperature changes of the sample during thermal deformation. At the same time, before clamping, graphite lubricant is added to both ends of the sample and then glued to the flat sheet, which is clamped together in the center of the two anvil heads. This operation not only effectively reduces the friction and wear of the sample during the clamping process, but also ensures the stability and uniformity of the sample during the thermal simulation process. The application of this technical feature greatly improves the accuracy and repeatability of the experimental data, and provides a solid technical foundation for in-depth research on the dynamic recrystallization behavior of high-temperature solid solution stable organization in the deformation process of iron-carbon alloys.

[0035] Further preferred, the sample is heated to a slightly lower temperature near the melting-solidification line of the alloy at a rate of 5°C / S on the thermal simulator Gleeble-3800. This technical feature ensures that the sample can quickly and evenly reach the required heat treatment state, laying a solid foundation for subsequent thermal deformation experiments; then, the sample is cooled to different deformation temperature points in the temperature range above the critical temperature and below the melting-solidification line temperature at a rate of 5°C / S; this operation not only achieves fine control of the sample temperature, but also enables researchers to explore the deformation behavior of iron-carbon alloys under different temperature conditions. The application of this technical feature greatly improves the accuracy and flexibility of the experiment, provides strong support for in-depth research on the dynamic recrystallization behavior and mechanism of iron-carbon alloys at different temperatures, and helps to reveal the organizational evolution law of alloy materials at high temperatures.

[0036] Further preferably, the sample is one of carbon structural steel, low alloy steel, welding wire steel, high carbon steel, and bearing steel.

[0037] The test specimens were made of Q355B iron-carbon alloy material produced by the applicant, and the test method of the present invention was applied on the Gleeble-3800 thermal simulation test machine to conduct a study on the dynamic recrystallization behavior of the high-temperature solid solution stable structure of the iron-carbon alloy during the deformation process. Figures 1 to 11 , follow the steps below:

[0038] S1. Process the iron-carbon alloy material into a cylindrical sample of 10×15 mm in diameter. The chemical composition is shown in Table 1.

[0039] Table 1 Chemical composition of the test steel / %

[0040]

[0041] Thermocouple 2 is welded on the same cross section of the center of sample 1 by a spot welder, and the distance between the welding points is 0.5-2mm. The active shaft end of the mobile simulator clamps the sample, and before clamping, graphite lubricant is added to both ends of the sample, and then flat sheets are glued and clamped together in the center of the two anvil heads.

[0042] S2. The sample was heated to 1200℃ at a rate of 5℃ / s on a thermal simulator Gleeble-3800, kept at that temperature for 5min, and then cooled to deformation temperatures of 1150, 1100, 1050, 1000, 950, 900, 850, and 800℃ at a rate of 5℃ / s. After a short-term average temperature of 0.5min, each temperature was heated at a rate of 0.01s -1 , 0.1s -1 , 1s -1 , 10s -1 The steel sheets were hot compressed and deformed at a strain rate of 60%, and then quenched to room temperature immediately after deformation.

[0043] S3. According to the stress-strain-temperature data collected from time to time during the test, a stress-strain curve is formed;

[0044] S4. Characteristic parameters such as εp, εc and εt can be further extracted from the above stress-strain curve. εp represents the peak strain corresponding to the peak stress, εc represents the critical strain required to start dynamic recrystallization, and there is the following relationship between εp and εc: εc≈0.83εp; εt is the deformation corresponding to the stress reaching the peak value and then dropping to the stable state on the stress-strain curve. Strain rate 0.01s -1 and 0.1s -1 The test data are shown in Table 2. The above parameters can be used to establish a plane rectangular coordinate system diagram of dynamic recrystallization of the test material at different strain rates;

[0045] Table 2 Strain rate 0.01s -1 and 0.1s -1 Test value

[0046]

[0047] Dynamic recrystallization is easy to occur when the deformation temperature is high, the deformation rate is low, and the deformation amount is large. It can be seen from the dynamic recrystallization diagram that with the increase of deformation temperature and the decrease of deformation rate, the critical deformation amount of dynamic recrystallization gradually decreases, and dynamic recrystallization is easy to complete. The strain rate of this test is 0.01s -1 Dynamic recrystallization occurred at each strain temperature, and the strain rate was 0.1s -1 Dynamic recrystallization occurs at strain temperatures of 900-1150°C, while only dynamic recovery occurs at strain temperatures of 800-850°C. The strain rate is 1s -1 and 10s -1 Only dynamic recovery occurs at each strain temperature.

[0048] The dynamic recrystallization behavior of high-temperature solid solution stable structure in the deformation process of iron-carbon alloy measured by this measurement method is closer to actual production, and can effectively optimize the production controlled rolling structure control and effectively improve product quality.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy, characterized in that Follow these steps: S1. Process the metal material into a cylindrical specimen of 10×15 mm in diameter; S2. Heat the sample to a temperature of 50-150°C below the melting-solidification line of the alloy at a steady heating rate on a thermal simulator, keep the temperature for 5-10 minutes, and then cool the sample to different deformation temperature points within the temperature range above the critical temperature and below the melting-solidification line temperature at the same temperature change rate. Each temperature point is 50°C apart, and the temperature is averaged for 0.5-1 minute at each temperature point. Select the samples averaged at different deformation temperature points and perform hot compression deformation at different strain rates. The deformation amount is controlled to be the same, and the samples are immediately quenched to room temperature after deformation; S3. According to the stress-strain-temperature data collected from time to time during the test, a stress-strain curve is formed; S4. further extracting characteristic parameters of εp, εc and εt from the above stress-strain curve; εp represents the peak strain corresponding to the peak stress, εc represents the critical strain required to start dynamic recrystallization, and there is the following relationship between εp and εc: εc≈0.83εp; εt is the deformation corresponding to the stress reaching the peak value and then dropping to the stable state on the stress-strain curve; the above parameters can be used to establish a plane rectangular coordinate system diagram of dynamic recrystallization of the sample at different strain rates.

2. The method for determining the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy according to claim 1, characterized in that: The test was carried out on a thermal simulator Gleeble-3800, and the specimen was fixed.

3. The method for determining the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy according to claim 2, characterized in that: Thermocouples are welded on the same cross section at the center of the sample using a spot welder, with a weld spot spacing of 0.5-2mm. The active shaft end of the mobile simulator is used to clamp the sample. Before clamping, graphite lubricant is added to both ends of the sample and then flat sheets are glued and clamped together in the center of the two anvil heads.

4. The method for determining the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy according to claim 2, characterized in that: On the thermal simulator Gleeble-3800, the sample was heated at a rate of 5°C / S to a temperature of 50-150°C below the alloy melting-solidification line, and then cooled at a rate of 5°C / S to different deformation temperature points in the temperature range above the critical temperature and below the melting-solidification line temperature.

5. The method for determining the high temperature deformation dynamic recrystallization behavior of an iron-carbon alloy according to claim 1, characterized in that: The sample is one of carbon structural steel, low alloy steel, welding wire steel, high carbon steel and bearing steel.

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