Thermal simulation testing machine sample clamp, cooling device and annealing test method

Abstract

The invention relates to a thermal simulation testing machine sample clamp, a cooling device and an annealing test method, and belongs to the technical field of metal material plate strip annealing tests in the metallurgical industry. According to the technical scheme, the method comprises the following steps: firstly, clamping a sample on a sample clamp, and then putting the sample clamp into a cavity of a thermal simulation testing machine; vacuumizing the cavity of the thermal simulation testing machine, and forming a protective atmosphere in the cavity; heating the sample to 950-1050 DEG C at the speed of 10-50 DEG C / s, keeping the temperature for 3-5 minutes, then quickly cooling the sample to room temperature by blowing, and recording a temperature curve; and stretching the sample subjected to annealing simulation at room temperature, analyzing test data, and observing a metallographic structure through an optical phase microscope. The device has the beneficial effects that on one hand, the problems of short soaking area and low cooling speed in the existing plate and strip annealing test are solved, the processing requirements of a standard tensile sample are met, on the other hand, tedious Jaw module mounting and dismounting operations are avoided, and the test period is shortened.

Description

Technical Field

[0001] The invention relates to a thermal simulation test machine sample fixture, a cooling device and an annealing test method, and belongs to the technical field of annealing tests for metal material plates and strips in the metallurgical industry. Background Art

[0002] The Gleeble3800 thermal simulation testing machine can be used to simulate processes such as rolling and phase change of metal materials, providing an important support means for metal material performance testing.

[0003] Continuous annealing is a heat treatment process used to improve material properties. By heating to the annealing temperature, holding at that temperature for the required time, and controlling the cooling rate, it can eliminate work hardening and internal stresses caused by cold working or heat treatment, thereby improving the material's mechanical properties. Therefore, it is widely used in the steel industry. However, when conducting annealing tests on traditional continuous annealing testing machines, due to their large specimen size and poor temperature control capabilities, they can lead to significant variations in microstructure and properties, seriously affecting material performance.

[0004] For this reason, the industry typically uses the gleeble series thermal simulation testing machines for plate and strip annealing simulations. These machines are widely used due to their high temperature control accuracy, small size, and reduced test material requirements. However, due to cavity limitations, the gleeble series thermal simulation testing machines require the removal of the jaw modules at both ends during plate and strip annealing simulations. This process is complex, time-consuming, and labor-intensive. Furthermore, the cooling device configured in the original mill can only cool one side of the specimen, resulting in a low cooling rate and uneven cooling, which limits their application. Furthermore, if the jaw modules are not removed, the specimen's uniform heat zone is relatively short during annealing simulations, at only about 25 to 30 mm, making it impossible to process them into standard tensile test specimens, which in turn affects the results of subsequent mechanical properties tests. Summary of the Invention

[0005] The purpose of the present invention is to provide a thermal simulation test machine sample fixture, cooling device and annealing test method. On the one hand, it solves the problems of short soaking zone and low cooling rate in the existing plate and strip annealing test, and meets the processing requirements of standard tensile specimens. On the other hand, it avoids the tedious Jaw module installation and disassembly operations, shortens the test cycle, and solves the problems existing in the background technology.

[0006] The technical solution of the present invention is: The utility model relates to a sample fixture of a thermal simulation test machine. The fixture is composed of four identical wedge-shaped stainless steel plates, two of which form a pair and are respectively clamped at both ends of the sample.

[0007] The wedge-shaped stainless steel plate is provided with a groove.

[0008] A thermal simulation test machine sample cooling device includes a cooling plate, an air path right-angle adapter, an air inlet pipe, a connecting pipe, an air hole solenoid valve and an air pipe. The cooling plates are arranged in parallel in an upper and lower direction. Both cooling plates are provided with air injection holes that are evenly arranged and face the sample. One end of the air inlet pipe is connected to the cooling plate, and the other end is connected to the connecting pipe through the air path right-angle adapter. The connecting pipe is connected to the air pipe through the air hole solenoid valve, and the air pipe is connected to a high-pressure inert gas source.

[0009] The air inlet pipe is fixed to the support rod through a locking block and bolts, and the support rod is fixed to the cavity of the thermal simulation test machine through a fixing plate, a fixing rod and bolts.

[0010] The locking block is a rectangular block, and two circular holes are respectively provided on the side and top of the locking block, which penetrate through the width and thickness directions of the locking block.

[0011] A thermal simulation test machine annealing test method is performed according to the following steps: 1) Process the specimen into a rectangle and set two circular holes with a diameter of 6 to 8 mm at both ends; 2) Weld the positive and negative thermocouple wires to the center of the specimen; 3) Mount the sample on the sample fixture and place it in the cavity of the thermal simulation test machine; 4) Install the cooling device and adjust the locking block so that the two parallel cooling plates are parallel to the specimen, and secure the fixing rod. 5) The cavity of the thermal simulation test machine is evacuated to 2×10-1 torr or below, and then filled with argon gas to form a protective atmosphere in the cavity; 6) Raise the temperature of the sample to 950-1050°C at a rate of 10-50°C / s, keep it at that temperature for 3-5 minutes, then quickly cool it to room temperature by blowing air, and record the temperature curve; 7) The sample after the annealing simulation is stretched at room temperature, the test data is analyzed, and the metallographic structure is observed using an optical phase microscope.

[0012] In the step 1), the sample size is 140-170 mm in length, 25-30 mm in width, 1-2.5 mm in thickness, and the surface roughness Ra is ≤ 3.2 μm.

[0013] In the step 2), the two welding points are spaced 1 to 2 mm apart, and the exposed galvanic wires at the welding points are covered with quartz tubes.

[0014] In step 6), after the sample is kept warm, high-purity inert gas is blown into the cavity of the thermal simulation test machine toward the sample to quickly cool the sample to room temperature.

[0015] In step 6), when the sample temperature is above 750°C, the cooling rate is greater than 150°C / s; when the sample temperature is between 750°C and 350°C, the cooling rate is greater than 100°C / s; when the sample temperature is between 350°C and room temperature, the cooling rate is greater than 70°C / s.

[0016] The beneficial effects of the present invention are as follows: the sample fixture of the present invention can reduce heat conduction and even out the temperature at the center and both ends of the sample; the cooling device is provided with a large-area cooling plate and is equipped with a dual-path dual-spray air blowing cooling mode, which greatly improves the cooling rate while increasing the heat equalization area, meets the standard tensile sample processing requirements, and obtains ideal test results; in addition, compared with the traditional plate and strip annealing method, the present invention avoids the tedious jaw module installation and disassembly operations, saves test materials, shortens the test cycle, and greatly improves the test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the installation structure of the present invention in the testing machine cavity; Figure 2 It is a side view of the present invention; Figure 3 A top view of the present invention; Figure 4 is a cross-sectional view of the sample fixture of the present invention; Figure 5 It is the temperature curve diagram of the sample of the present invention; Figure 6 is a tensile curve diagram of the sample of the present invention; Figure 7 The metallographic organization diagrams of different positions of the sample of the present invention are shown; In the figure: fixed end 1, top block 2, stainless steel splint 3, specimen 4, support rod 5, locking block 6, cooling plate 7, simulation testing machine motion axis 8, air path right-angle adapter 9, air inlet pipe 10, fixing plate 11, fixing rod 12, connecting pipe 13, air hole solenoid valve 14, air pipe 15. DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to the accompanying drawings and through examples.

[0019] Refer to the attached Figure 1-7 A thermal simulation test machine sample fixture is composed of four identical wedge-shaped stainless steel plates, two in a pair, which are clamped at both ends of the sample.

[0020] A thermal simulation test machine sample cooling device includes a cooling plate 7, an air path right-angle adapter 9, an air inlet pipe 10, a connecting pipe 13, an air hole solenoid valve 14 and an air pipe 15. The cooling plates 7 are arranged in parallel in an upper and lower manner. Both cooling plates 7 are provided with air injection holes facing the sample 4 and evenly arranged. One end of the air inlet pipe 10 is connected to the cooling plate 7, and the other end is connected to the connecting pipe 13 through the air path right-angle adapter 9. The connecting pipe 13 is connected to the air hole solenoid valve 14 and the air pipe 15. The air pipe 15 is connected to a high-pressure inert gas source.

[0021] In this embodiment, refer to the attached Figure 1-4 The model of the thermal simulation test machine is Gleeble3800. Its sample fixture consists of four identical wedge-shaped stainless steel clamps 3, two in a pair, clamped at both ends of the sample respectively. The stainless steel clamps 3 are provided with grooves to reduce heat conduction.

[0022] The cooling device includes two upper and lower cooling plates 7, a locking block 6, a fixing plate 11, a support rod 5, an air inlet pipe 10, a right-angle air adapter 9, and a fixing rod 12. An air inlet that connects the inside and outside of the thermal simulation tester is located at the top of the thermal simulation tester cavity, which is the original structure of the thermal simulation tester. The upper and lower cooling plates 7 are each connected to the right-angle air adapter 9 via an air inlet pipe 10. The right-angle air adapter 9 is connected to the outlet port inside the thermal simulation tester's air inlet via a connecting pipe 13. A pneumatic solenoid valve 14 is installed above the outlet port. The air inlet port outside the air inlet is connected to a high-pressure inert gas source via an air pipe 15.

[0023] There are two locking blocks 6, both of which are rectangular blocks. Two circular holes are provided on the sides and top of the blocks, respectively, running through the width and thickness of the blocks. They connect the support rod 5 with a diameter of 12mm and the intake pipe 10 with a diameter of 16mm. The support rod 5 and the intake pipe 10 are fixed by tightening the screws on the locking blocks 6. The locking blocks 6 can be adjusted up and down according to actual needs. A fixing plate 11 is provided at each end of the fixing rod 12. It is connected to the screw hole under the cavity by a nut to fix the fixing rod 12. The left and right distance can be adjusted according to actual needs to ensure that the cooling plate 7 is accurately aligned with the sample 4 to achieve a better cooling effect.

[0024] The strip annealing test method includes the following steps: 1) Process specimen 4 into a rectangular specimen with dimensions of 140-170 mm in length, 25-30 mm in width, and 1-2.5 mm in thickness. Two circular holes with a diameter of 6-8 mm are provided at both ends of the specimen. The surface of the specimen must be smooth and clean, with a surface roughness Ra ≤ 3.2 μm. The steel type of the specimen is galvanized hot-formed steel. 2) Weld the positive and negative thermocouple wires to the center of sample 4, with a distance of 1 to 2 mm between the two welding points, and cover the exposed thermocouple wires at the welding points with a quartz tube; 3) Install the sample 4 on the matching sample fixture as required and place it in the cavity of the thermal simulation test machine. Adjust the moving axis 8 of the thermal simulation test machine and clamp the two ends of the stainless steel clamping plate 3 with the matching top blocks 2 to prevent the sample 4 from sliding, so as to ensure good contact between the sample 4 and the stainless steel clamping plate 3 and ensure uniform heating. 4) Install the cooling device. Adjust the vertical and horizontal distances of the locking block 6 so that the upper and lower layers of the cooling plate 7 are parallel to the specimen. Secure the fixing rod 12 by tightening the nut with the screw hole under the cavity. 5) The chamber of the thermal simulation test machine is evacuated to 2×10-1 torr or below, and then filled with argon gas to form a protective atmosphere in the chamber to prevent oxidation of the sample; 6) Conduct plate and strip annealing test on the sample: heat the sample to 950-1050℃ at a rate of 10-50℃ / s and keep it at that temperature for 3-5min; 7) Rapidly cool the sample after heat preservation to room temperature and record the temperature curve; during the sample cooling process, blow high-purity inert gas into the chamber towards the sample for 5-10 seconds to rapidly cool the sample; the high-purity inert gas is high-purity argon with a purity of 99.99%; the cooling rate of the sample in the medium-high temperature section above 750°C is greater than 150°C / s, the cooling rate in the medium temperature section between 750°C and 350°C is greater than 100°C / s, and the cooling rate in the low temperature section between 350°C and room temperature is greater than 70°C / s; 8) Process the sample after annealing simulation into a standard tensile specimen, perform room temperature stretching, and analyze the stress-strain and other test data; 9) Metallographic sampling was performed on the specimens after annealing simulation: samples were taken at the center of the specimen, 20 mm, 40 mm, 60 mm, and 80 mm from the center. After mounting, grinding and polishing, the specimens were etched with 4% nitric acid alcohol by volume, and the metallographic structure was observed using an optical phase microscope.

[0025] Figure 5 is the temperature curve of the sample during cooling, Figure 6 is the tensile curve obtained by stretching the sample at room temperature, Figure 7 is the metallographic structure at different positions of the sample; Figure 5-Figure 7 It can be seen that by adopting the plate and strip annealing test method of the present invention, the length of the soaking zone can meet the processing of the standard tensile specimen, and the tensile curve obtained is good. It can be clearly seen that the cooling rate in the low-temperature section is greater than 70°C / s, and the metallographic structure at different positions is all martensite. It can be seen that the cooling method adopted by this method is more effective and can meet the requirements of cooling rate and soaking zone at the same time.

Claims

1. A thermal simulation test machine specimen fixture, characterized by: The fixture is composed of four identical wedge-shaped stainless steel plates, two in a pair, clamped at both ends of the specimen.

2. The thermal simulation test machine sample fixture according to claim 1, characterized in that: The wedge-shaped stainless steel plate is provided with a groove.

3. A thermal simulation test machine sample cooling device, characterized by: The invention comprises a cooling plate (7), an air path right-angle adapter (9), an air inlet pipe (10), a connecting pipe (13), an air hole solenoid valve (14) and an air pipe (15), wherein the cooling plates (7) are arranged in parallel in an upper and lower direction, and both cooling plates (7) are provided with air injection holes evenly arranged toward the sample (4), one end of the air inlet pipe (10) is connected to the cooling plate (7), and the other end is connected to the connecting pipe (13) through the air path right-angle adapter (9), the connecting pipe (13) is connected to the air pipe (15) through the air hole solenoid valve (14), and the air pipe (15) is connected to a high-pressure inert gas source.

4. A thermal simulation test machine sample cooling device according to claim 3, characterized in that: The air inlet pipe (10) is fixed to the support rod (5) via a locking block (6) and bolts, and the support rod (5) is fixed to the cavity of the thermal simulation test machine via a fixing plate (11), a fixing rod (12) and bolts.

5. The thermal simulation test machine sample cooling device according to claim 4, characterized in that: The locking block (6) is a rectangular block, and two circular holes are provided on its side and top respectively, penetrating its width and thickness directions.

6. A thermal simulation test machine annealing test method, characterized in that: Follow these steps: 1) Process the specimen into a rectangle and set two circular holes with a diameter of 6 to 8 mm at both ends; 2) Weld the positive and negative thermocouple wires to the center of the specimen; 3) Mount the sample on the sample fixture and place it in the cavity of the thermal simulation test machine; 4) Install the cooling device and adjust the locking block (6) so that the two cooling plates (7) arranged in parallel above and below are parallel to the specimen, and fix the fixing rod (12); 5) The cavity of the thermal simulation test machine is evacuated to 2×10-1 torr or below, and then filled with argon gas to form a protective atmosphere in the cavity; 6) Raise the temperature of the sample to 950-1050°C at a rate of 10-50°C / s, keep it at that temperature for 3-5 minutes, then quickly cool it to room temperature by blowing air, and record the temperature curve; 7) The sample after the annealing simulation is stretched at room temperature, the test data is analyzed, and the metallographic structure is observed using an optical phase microscope.

7. The annealing test method using a thermal simulation test machine according to claim 6, characterized in that: In the step 1), the sample size is 140-170 mm in length, 25-30 mm in width, 1-2.5 mm in thickness, and the surface roughness Ra is ≤ 3.2 μm.

8. The annealing test method using a thermal simulation test machine according to claim 6, characterized in that: In the step 2), the two welding points are spaced 1 to 2 mm apart, and the exposed galvanic wires at the welding points are covered with quartz tubes.

9. The annealing test method using a thermal simulation test machine according to claim 6, wherein: In step 6), after the sample is kept warm, high-purity inert gas is blown into the cavity of the thermal simulation test machine toward the sample to quickly cool the sample to room temperature.

10. The annealing test method using a thermal simulation test machine according to claim 9, characterized in that: In step 6), when the sample temperature is above 750°C, the cooling rate is greater than 150°C / s; when the sample temperature is between 750°C and 350°C, the cooling rate is greater than 100°C / s; when the sample temperature is between 350°C and room temperature, the cooling rate is greater than 70°C / s.

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