Method for determining behavior rule of carbon-rich reticular precipitate of hot-rolled wire rod metal material

Abstract

The invention relates to a method for determining a behavior rule of a carbon-rich reticular precipitate of a hot-rolled wire rod metal material, which is characterized by comprising the following steps of: S1, processing the metal material into a cylindrical sample with the diameter of 6 * 80mm, the sample being one of medium-carbon and high-carbon hot-rolled wire rod metal materials; s2, the critical point of the steel is measured according to the black metallurgical industry standard YB / 1527-2018; s3, the sample is heated to the temperature above the complete austenitizing temperature according to the measured critical point temperature, and the temperature is close to actual spinning production; after heat preservation, cooling to room temperature at different cooling speeds; and S4, in combination with a metallographic structure, according to the formation condition of the carbon-rich net-shaped precipitate in the hot-rolled wire rod metal material at different cooling speeds, the precipitation behavior rule of the carbon-rich net-shaped precipitate is found. The carbon-rich network carbide precipitation behavior rule measured by the measurement method is closer to the actual production, so that the production controlled cooling structure can be effectively optimized, and the product quality is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-rolled wire rod production, and in particular relates to a method for determining the behavior law of carbon-rich network precipitates in hot-rolled wire rod metal materials. Background Art

[0002] In hot-rolled iron-carbon alloy wire rod materials, carbon-rich structure, as a metal compound composed of iron and carbon, exhibits the characteristics of low plasticity, low toughness and high brittleness. When this carbon-rich structure precipitates in a network form along the austenite grain boundary, it will pose a serious threat to the overall performance of the metal material. Therefore, in-depth research and analysis of the precipitation behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials is of vital importance to improving product performance. At present, the determination method for the precipitation behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials mainly relies on the traditional heating furnace heating and insulation followed by cooling, combined with metallographic structure observation. However, this method has significant errors in the determination process, and it is difficult to ensure the accuracy of the results. So far, there is no method for such testing using thermal simulation technology. As an advanced testing method, thermal simulation experimental technology can more accurately simulate the temperature, stress and other conditions in the actual hot rolling process, thereby reducing experimental errors and improving the accuracy of the measurement results. Using thermal simulation technology to study the precipitation behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials not only helps to achieve more precise organizational control, but also provides accurate technical parameters and research methods for the controlled cooling organization of the material after deformation, which has far-reaching significance for promoting the development and application of materials science. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a method for determining the behavior law of carbon-rich network precipitates in hot-rolled wire rod metal materials.

[0004] The present invention is achieved by a method for determining the behavior law of carbon-rich network precipitates in hot-rolled wire rod metal materials, which is characterized by: performing the following steps:

[0005] S1. Processing the metal material into a cylindrical specimen of 6×80 mm in diameter, wherein the specimen is a medium-high carbon hot-rolled wire rod metal material;

[0006] S2. Determine the critical point of steel according to the ferrous metallurgy industry standard YB / 1527-2018;

[0007] S3. The sample is heated to a temperature above the complete austenitization temperature according to the determined critical point temperature, which is close to the actual spinning production; after keeping the temperature, the sample is cooled to room temperature at different cooling rates;

[0008] S4. Combined with the metallographic structure, according to the formation of carbon-rich network precipitates in hot-rolled wire rod metal materials at different cooling rates, the precipitation behavior law of carbon-rich network precipitates is found.

[0009] Further preferably, step S2 is performed on a thermal simulator Gleeble-3800, and the sample is fixed. The sample is welded with a thermocouple on the same cross section at the center of the sample using a spot welder, with a welding point spacing of 0.5-2 mm. The sample is fixed by a copper fixture and fixed with a stopper at the back of the sample.

[0010] Further preferably, in step S3, the sample is heated at a rate of 10°C / s on a thermal simulator Gleeble-3800 to a temperature above the fully austenitizing temperature, which is close to the spinning temperature of the hot-rolled wire rod in actual production, and is cooled to room temperature at three different cooling rates of 0.2°C / s, 0.5°C / s, and 1°C / s, respectively.

[0011] Advantages and technical effects of the present invention: The method for determining the behavior law of carbon-rich network precipitates in hot-rolled wire rod metal materials described in the present invention is not only efficient and accurate, but also contains many technical advantages, which are specifically expanded as follows:

[0012] Highly simulated actual production conditions: By accurately measuring the critical point of steel and heating the sample to above the complete austenitization temperature, the high temperature state in the actual hot rolling process is simulated, especially the temperature conditions close to the spinning production. This high degree of simulation ensures the consistency between the experimental environment and the actual production, making the measured behavior of carbon-rich network precipitates more practical and valuable.

[0013] Flexible and controllable cooling rate: On the thermal simulator Gleeble-3800, the sample can be heated at a precisely controlled rate and cooled to room temperature at three different cooling rates of 0.2℃ / s, 0.5℃ / s, and 1℃ / s. This flexible cooling rate setting can fully cover and study the precipitation behavior of carbon-rich network precipitates under different cooling conditions, providing a scientific basis for optimizing the cooling strategy in the production process.

[0014] Accurate temperature and structure monitoring: By welding a thermocouple at the center of the sample and using the precise temperature control system of the thermal simulator, the temperature changes of the sample during heating and cooling can be monitored and recorded in real time. Combined with metallographic structure observation, the formation of carbon-rich network precipitates can be accurately captured, thereby improving the reliability and accuracy of the experiment.

[0015] Reduce experimental errors and improve repeatability: The high-precision temperature and speed control capabilities of the thermal simulator Gleeble-3800, as well as the stability design of the sample fixation, effectively reduce random errors in the experimental process, improve the repeatability and reproducibility of the experiment, and make the measured behavior of carbon-rich network precipitates more reliable and stable. Optimize production control cooling organization and improve product quality: The precipitation behavior of carbon-rich network carbides measured by the present invention can directly guide the optimization of control cooling organization in production practice. By adjusting parameters such as cooling rate and temperature, the formation of carbon-rich network precipitates can be effectively controlled and reduced, thereby significantly improving the plasticity and toughness of hot-rolled wire rod metal materials, reducing brittleness, and improving the overall quality and performance of the product.

[0016] In summary, the present invention not only provides an efficient and accurate determination method for the study of the behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials, but also provides powerful technical support and scientific basis for optimizing production control cooling structure and improving product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attached Figure 1 : Schematic diagram of sample assembly.

[0018] Attached Figure 2 : Schematic diagram of heating and cooling process.

[0019] Attached Figure 3 : Critical point expansion curve of 82B steel.

[0020] Attached Figure 4 : Metallographic structure diagram of 82B steel is heated at 900℃ for 5 minutes and cooled to room temperature at a rate of 0.2℃ / s.

[0021] Attached Figure 5 : Metallographic structure diagram of 82B steel is heated at 900℃ for 5 minutes and cooled to room temperature at a rate of 0.5℃ / s.

[0022] Attached Figure 6 : Metallographic structure diagram of 82B steel is heated at 900℃ for 5 minutes and cooled to room temperature at a rate of 1℃ / s.

[0023] In Figure 1: 1. Sample 2. Thermocouple 3. Copper fixture 4. Stopper. DETAILED DESCRIPTION

[0024] 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.

[0025] A method for determining the behavior law of carbon-rich network precipitates in hot-rolled wire rod metal materials is characterized by: performing the following steps:

[0026] S1. Processing a metal material into a cylindrical sample 1 of Ф6×80mm, wherein the sample is a medium-high carbon hot-rolled wire rod metal material;

[0027] S2. Determine the critical point of steel according to the ferrous metallurgy industry standard YB / 1527-2018;

[0028] S3. The sample is heated to a temperature above the complete austenitization temperature according to the determined critical point temperature, which is close to the actual spinning production; after keeping the temperature, the sample is cooled to room temperature at different cooling rates;

[0029] S4. Combined with the metallographic structure, according to the formation of carbon-rich network precipitates in hot-rolled wire rod metal materials at different cooling rates, the precipitation behavior law of carbon-rich network precipitates is found.

[0030] Further preferably, step S2 performed on the thermal simulator Gleeble-3800, by accurately fixing the sample and welding a thermocouple 2 on the same cross section of the sample center, the solder joint spacing is controlled at 0.5-2mm, ensuring the accuracy and stability of temperature measurement. The firm fixation of the copper fixture 3 and the limiting effect of the stopper 4 jointly ensure the stability and consistency of the sample during heating and cooling, and effectively avoid the experimental error caused by sample movement or deformation. The specific technical effect of this step is to improve the accuracy and reliability of the experiment, lay a solid foundation for subsequent research on the precipitation behavior law of carbon-rich network precipitates, and ensure the accuracy and repeatability of experimental data.

[0031] Further preferably, the implementation of step S3 on the thermal simulator Gleeble-3800 simulates the spinning temperature of the hot-rolled wire rod in actual production by rapidly heating to above the fully austenitizing temperature at a rate of 10°C 1S, ensuring that the experimental conditions are highly consistent with the actual production. Subsequently, the sample was cooled to room temperature at three different cooling rates of 0.2°C 10, 0.5°C 10, and 1°C 10, respectively. This design can fully cover and accurately study the precipitation behavior of carbon-rich network precipitates at different cooling rates. The specific technical effect of this step is that it provides rich experimental data, which helps to deeply reveal the influence mechanism of cooling rate on the formation of carbon-rich network precipitates, and provides a scientific basis for optimizing the cooling strategy in the production process, thereby effectively controlling the generation of carbon-rich network precipitates and improving product quality.

[0032] The test samples were made from 82B high-carbon high-speed wire produced by the applicant, and the test method of the present invention was applied on a Gleeble-3800 thermal simulation test machine to study the precipitation behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials. Figures 1 to 4 , follow the steps below:

[0033] S1. Take a cylindrical sample with a specification of 6×80mm, and the chemical composition is shown in Table 1. Use a spot welder to weld a thermocouple 2 on the same section at the center of the sample 1, with a welding point spacing of 0.5-2mm. Use a copper clamp 3, and block the back with a block 4. When measuring the critical point, clamp the dilatometer at the center of the sample.

[0034] Table 1 Chemical composition of the test steel / %

[0035]

[0036] S2. Determine the critical point of steel according to the ferrous metallurgical industry standard YB / 1527-2018.

[0037] S3.82B is a hypereutectoid steel. It is heated at 10°C / S to above the austenitizing temperature, close to the spinning temperature of 900°C in actual production. It is kept at this temperature for 5 minutes and then cooled to room temperature at three different cooling rates of 0.2°C / s, 0.5°C / s, and 1°C / s, respectively.

[0038] S4. Combined with the metallographic structure, according to the formation of carbon-rich network precipitates in the hot-rolled wire rod metal material at different cooling rates, the precipitation behavior law of carbon-rich network precipitates was found: at a slow cooling rate of 0.2℃ / s, there are more network cementite in the core of the wire rod, and the network carbon reaches level 4; at a cooling rate of 0.5℃ / s, the network carbon in the core of the wire rod is not obvious, it is semi-network, and the network carbon reaches level 1; at a cooling rate of 1℃ / s, there is no network carbon in the core of the wire rod.

[0039] 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 behavior law of carbon-rich network precipitates in hot-rolled wire rod metal materials, characterized in that: Follow these steps: S1. Processing the metal material into a cylindrical specimen of 6×80 mm in diameter, wherein the specimen is a medium-high carbon hot-rolled wire rod metal material; S2. Determine the critical point of steel according to the ferrous metallurgy industry standard YB / 1527-2018; S3. The sample is heated to a temperature above the complete austenitization temperature according to the determined critical point temperature, which is close to the actual spinning production; after keeping the temperature, the sample is cooled to room temperature at different cooling rates; S4. Combined with the metallographic structure, according to the formation of carbon-rich network precipitates in hot-rolled wire rod metal materials at different cooling rates, the precipitation behavior law of carbon-rich network precipitates is found.

2. A method for determining the precipitation behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials according to claim 1, characterized in that: Step S2 is performed on a thermal simulator Gleeble-3800, and the sample is fixed. A thermocouple is welded on the same cross section at the center of the sample using a spot welder, with a welding point spacing of 0.5-2 mm. The sample is fixed by a copper fixture and fixed with a stopper at the back of the sample.

3. A method for determining the precipitation behavior of carbon-rich network precipitates in hot-rolled wire rod metal materials according to claim 2, characterized in that: In step 3, the sample is heated at a rate of 10°C / s on a thermal simulator Gleeble-3800 to a temperature above the fully austenitizing temperature, which is close to the spinning temperature of the hot-rolled wire rod in actual production, and then cooled to room temperature at three different cooling rates of 0.2°C / s, 0.5°C / s, and 1°C / s, respectively.

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