Device for testing hydrogen-induced delayed fracture of high-strength steel

Abstract

The invention relates to a device for testing hydrogen-induced delayed fracture of high-strength steel, and aims to solve the problems that in the prior art, stress on a sample is not uniform, and stress distribution does not conform to reality. The device is composed of a supporting seat, a sliding seat, a supporting guide rod, a hydraulic push rod, an extrusion sub-block, a pressing sheet, a fixing pad and the like. The hydraulic push rod drives the sliding seat to move up and down, the extrusion blocks move towards the center under the action of hydraulic oil, and the pressing pieces are matched with one another to apply uniform pre-bending force to the high-strength steel plate. The relative positions of the pressing pieces on the supporting base and the sliding base are adjustable, and different pre-bending faces can be formed. The fixing pad is made of polyurethane materials and has good elasticity and abrasion resistance, the mounting groove in the fixing pad is used for containing the high-strength steel plate, and the deformation condition of the steel plate can be conveniently observed through the through holes. By optimizing the structural design, the stress of the sample is uniform, the stress distribution is closer to the actual working condition, and the accuracy and reliability of the test result are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel performance testing, in particular to a device for testing hydrogen-induced delayed fracture of high-strength steel. BACKGROUND

[0002] High-strength steel is widely used in the automotive industry due to its high strength and lightweight advantages, but its hydrogen-induced delayed fracture problem limits further application. Hydrogen-induced delayed fracture refers to the phenomenon that steel absorbs hydrogen in a hydrogen environment and then undergoes brittle fracture after a certain time delay. As the strength increases, the hydrogen embrittlement sensitivity of the steel increases, and when the tensile strength exceeds 1000MPa, the risk of hydrogen-induced delayed fracture increases significantly. In order to ensure the safety and reliability of high-strength steel parts, it is necessary to accurately evaluate its hydrogen-induced delayed fracture performance. Therefore, it is of great significance to develop an efficient device for testing hydrogen-induced delayed fracture of high-strength steel. In the prior art, the most commonly used bending type hydrogen-induced delayed fracture evaluation method in the automotive industry mainly includes two-point, three-point and four-point bending methods. These methods have the advantages of simple operation, low cost, low equipment requirement, short cycle, and intuitive and clear quantitative evaluation results. However, the existing bending evaluation methods have the following common technical problems: the stress of the sample is mainly concentrated in the middle part, resulting in uneven stress distribution, which cannot truly simulate the stress distribution under actual working conditions, thereby affecting the accuracy of the test results. In addition, the friction between the sample and the pressing block in the traditional two-point, three-point and four-point bending test methods may cause local stress concentration of the sample, further exacerbating the unevenness of the stress distribution, resulting in a large deviation between the test results and the actual situation.

[0003] In addition, other patent technologies also provide different test methods and devices, such as patent CN111307612A and patent CN222784424U. CN111307612A provides a method for testing the hydrogen-induced delayed fracture performance of ultra-high-strength automobile steel sheets, which includes the steps of quasi-static tensile test, pre-bending and hydrogen-induced delayed fracture performance test, and uses a non-contact optical measurement system DIC to measure the strain to evaluate the performance. CN222784424U describes a device for testing hydrogen-induced delayed fracture of high-strength steel, which adopts an upper pressing cake, a lower pressing cake, an upper pressing block, a lower pressing block and a screw structure, and realizes bending stress loading on the sample by locking and fixing the nut. However, the common defects of the above two patents are that the stress of the sample is concentrated in the middle part and the stress distribution is uneven, and the nylon pressing block has poor corrosion resistance, which affects the accuracy of the test results. SUMMARY

[0004] (I) Technical problems solved In view of the deficiencies of the prior art, the present application provides a device for testing hydrogen-induced delayed fracture of high-strength steel, which solves the problems raised in the background art.

[0005] (II) Technical Solution To achieve the above object, the present application is implemented by the following technical solution: A device for testing hydrogen-induced delayed fracture of high-strength steel, comprising a support seat, a support guide rod fixedly connected to the upper side wall of the support seat, a support frame fixedly connected to the upper end of the support guide rod, a hydraulic push rod fixedly connected to the upper side wall of the support frame, a sliding seat fixedly connected to the output end of the hydraulic push rod, a plurality of sliding inner cavities provided on the upper side wall of the support seat and the lower side wall of the sliding seat, and a transmission piston slidably connected to the inside of each sliding inner cavity. The transmission piston is fixedly connected to an extrusion block through a connecting rod, one end of the extrusion block away from the transmission piston is detachably connected to a rotating seat, the rotating seat is rollingly connected to a rotating ball in the inside thereof, the upper end of the rotating ball is fixedly connected to a pressing plate, and the support seat and the sliding seat are movably connected to a fixed pad.

[0006] Preferably, the sliding seat and the support guide rod are slidably connected, which improves the stability of the sliding seat in sliding up and down, the pressing plate on each sliding seat is matched with the pressing plate on the support seat, and the two pressing plates are matched with each other to pre-bend the high-strength steel plate therebetween.

[0007] Preferably, the inside of the support seat and the sliding seat is provided with an oil cylinder, the inside of the oil cylinder is provided with an oil pump, the output end of the oil pump is fixedly connected to a plurality of oil inlet pipes, each oil inlet pipe is in communication with the sliding inner cavity, and the inside of the oil inlet pipe is provided with a control valve. The oil pump can introduce hydraulic oil into the inside of the sliding inner cavity through the oil inlet pipe, thereby pushing the transmission piston to move upward, adjusting the position of the extrusion block, and controlling the communication of the oil inlet pipe. The control valve is connected with a master controller in the outside, the master controller is responsible for controlling the operation of the hydraulic system, adjusting the position of the pressing plate, monitoring the state of the device, collecting and processing data, realizing automatic test process control, and having a safety protection function. It controls the flow and pressure of hydraulic oil in real time, drives the sliding seat and the extrusion block to move, and ensures the accuracy of pre-bending operation. In addition, the master controller collects sensor data, analyzes the deformation and crack of the sample, draws a performance curve, realizes the automation and accurate control of the whole test process, and guarantees the safety and reliability of the test. In addition, the device is also provided with an overflow valve, a throttle valve and a filter commonly used in the hydraulic cylinder.

[0008] Preferably, the oil cylinder and the sliding inner cavity are connected through an oil outlet pipe, one end of the oil outlet pipe is located between the transmission piston and the extrusion block, and a reversing valve is fixedly connected between the oil outlet pipe and the oil inlet pipe for controlling the flow direction of the hydraulic oil. After the hydraulic oil enters the sliding inner cavity through the oil outlet pipe, the transmission piston can be pushed to move, thereby adjusting the position of the extrusion block.

[0009] Preferably, the upper end of each sliding inner cavity is internally provided with a cleaning sleeve, which is in sliding connection with the extrusion block, and is used for cleaning the dust on the outer sidewall of the extrusion block.

[0010] Preferably, the upper sidewall of the tablet pressing piece at the four corners of the support seat and the lower sidewall of the tablet pressing piece at the four corners of the sliding seat are fixedly connected with fixing holes, and the upper sidewall and the lower sidewall of the fixing pad are fixedly connected with four limiting protrusions. The fixing holes are matched with the limiting grooves, so that the tablet pressing piece can effectively fix the fixing pad, and the fixing pad will not slip during the pre-bending process, which affects the pre-bending effect.

[0011] Preferably, the inside of the fixing pad is provided with a mounting groove, one side of the mounting groove penetrates through the fixing pad, the mounting groove is used for placing the high-strength steel plate, and the inside of the fixing pad is uniformly provided with a plurality of through holes, which is convenient for observing the high-strength steel plate. The fixing pad is made of polyurethane material, has good elasticity, high mechanical strength, excellent oil resistance, wear resistance and aging resistance, and can maintain stable performance within a wide temperature range.

[0012] Preferably, the outer sidewall of the extrusion block is fixedly connected with a sealing sleeve, which is matched with the sliding inner cavity, improves the sealing effect between the extrusion block and the sliding inner cavity, and can effectively prevent the hydraulic oil from overflowing.

[0013] Preferably, when the high-strength steel hydrogen-induced delayed fracture test is carried out, first, the high-strength steel plate to be tested is placed in the mounting groove of the fixing pad, and the fixing pad is installed on the pressing piece on the support seat through the cooperation of the fixing hole and the limiting convex. Then, according to the required pre-bending curvature and shape, a model is designed by using professional three-dimensional modeling software, and then the model is imported into numerical control programming software for path planning and process parameter setting to generate numerical control codes for controlling the oil pump, control valve and reversing valve. The sliding seat is driven to move downward by the hydraulic push rod, and the main control unit controls the extrusion blocks to press the fixing pad in turn according to the preset program through the numerical control system. The pressing piece gradually forms multiple indentations on the surface of the plate. With the continuous movement of the punch and the gradual increase of the pressure, the plate gradually deforms into the required shape. The extrusion blocks move to the center under the action of hydraulic oil, and the pressing piece applies uniform pre-bending force to the steel plate. After pre-bending, the sliding seat is raised for resetting for the next hydrogen-induced delayed fracture test: the pre-bent high-strength steel plate together with the fixing pad is carefully placed in the hydrogen-induced delayed fracture performance test solution for static treatment. The test solution is 0.1 mol / L HCL aqueous solution to ensure the stability of the solution concentration. A video monitoring device with continuous recording and storage function is used to observe the test sample continuously, and the generation of surface cracks of the test sample is monitored in real time. The time of surface cracking of each group of test samples is recorded, and the stress change of the test sample in the solution is measured. The recorded time of surface cracking of the corresponding test sample and the pre-bending stress of the test sample are taken as the hydrogen-induced delayed fracture performance test data of the test sample. According to the hydrogen-induced delayed fracture performance test data of each group of test samples, combined with the fracture time-bending stress curve, the hydrogen-induced delayed fracture sensitivity of the ultra-high strength steel plate is effectively evaluated. This process verifies the effectiveness and accuracy of the device in simulating the actual working condition of the high-strength steel hydrogen-induced delayed fracture performance evaluation, and provides key data support for subsequent material selection and process optimization.

[0014] (Three) beneficial effects The present application provides a high-strength steel hydrogen-induced delayed fracture testing device, which has the following beneficial effects: The present application optimizes the layout of the pressing piece and the extrusion block, and uses a corrosion-resistant polyurethane material fixing pad in cooperation with a special installation method, so that the stress of the test sample is uniform, and the stress distribution is closer to the actual working condition, solving the problem of stress concentration in the middle part and uneven stress distribution in the prior art. The design of the hydraulic system can provide stable pressure to ensure smooth pre-bending process, further improving the uniformity of the stress of the test sample.

[0015] The present application can form different pre-bending surfaces by optimizing the relative position of the pressing plate of the support seat and the sliding seat, and meet diversified requirements under different test standards and material properties. The adjustable design makes the device more flexible, and can adapt to the pre-bending requirements of high-strength steel plates of various shapes and thicknesses, effectively solves the problem that the sample stress mode in the prior art does not match the actual situation, and improves the accuracy and reliability of the test results. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the present application; Figure 2 is a support seat schematic diagram of the present application; Figure 3 is a fixed pad cross-sectional schematic diagram of the present application; Figure 4 is an extrusion block schematic diagram of the present application; Figure 5 is a support seat internal schematic diagram of the present application; Figure 6 is a pre-bending schematic diagram of the present application.

[0017] Among them, 1, support seat; 101, support guide rod; 2, sliding seat; 3, support frame; 301, hydraulic push rod; 4, fixed pad; 401, mounting groove; 402, through hole; 5, extrusion block; 501, rotating seat; 502, pressing plate; 5021, fixed hole; 5022, rotating ball; 503, sealing sleeve; 504, transmission piston; 6, oil cylinder; 601, oil pump; 602, oil inlet pipe; 603, sliding inner cavity; 604, oil outlet pipe; 605, control valve; 606, cleaning sleeve; 607, reversing valve. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0019] Example one: As Figures 1-6As shown, the embodiment of the application provides a device for testing hydrogen-induced delayed fracture of high-strength steel, which comprises a support seat 1 placed on a solid horizontal ground to ensure its stability, and the support seat 1 serves as the foundation of the entire device, and four support guide rods 101 are fixedly connected to the upper side wall thereof, which are uniformly distributed for guiding the up-and-down movement of a sliding seat 2 to ensure the linearity and stability of the movement. The upper ends of the support guide rods 101 are fixedly connected to a support frame 3, a hydraulic push rod 301 is installed on the upper side wall of the support frame 3, and the output end of the hydraulic push rod 301 is connected to the sliding seat 2. By adjusting the pressure and stroke of the hydraulic push rod 301, the up-and-down position of the sliding seat 2 can be accurately controlled to provide a stable power source for subsequent pre-bending operation.

[0020] The lower side wall of the sliding seat 2 and the upper side wall of the support seat 1 are both provided with a plurality of sliding inner cavities 603, and a transmission piston 504 is installed in each sliding inner cavity 603, and the transmission piston 504 is connected to an extrusion block 5 through a connecting rod. When the hydraulic system is working, the hydraulic oil enters the sliding inner cavities 603 through the oil inlet pipe 602 to push the transmission piston 504 to move up and down, thereby driving the extrusion block 5 to approach or move away from the center position. The sliding seat 2 is in sliding connection with the support guide rods 101. This design not only improves the stability of the sliding seat 2, but also allows it to move freely in the vertical direction, ensuring that the extrusion block 5 can uniformly apply pressure to the high-strength steel plate.

[0021] The fixed pad 4 is made of polyurethane material and has good elasticity, wear resistance and oil resistance. An installation groove 401 is arranged in the fixed pad 4 for placing the high-strength steel plate to be tested. One side of the installation groove 401 penetrates through the fixed pad 4, facilitating the installation and removal of the steel plate. The upper and lower side walls of the fixed pad 4 are both provided with four limiting protrusions which cooperate with the fixed holes 5021 on the support seat 1 and the sliding seat 2 to ensure that the fixed pad 4 will not displace during the pre-bending process. In addition, the uniformly distributed through holes 402 in the fixed pad 4 facilitate the observation of the deformation of the steel plate during the pre-bending process.

[0022] The extrusion blocks 5 are uniformly distributed in a rectangular shape between the support seat 1 and the sliding seat 2, and a sealing sleeve 503 is arranged on the outer side wall of the extrusion blocks 5 to tightly cooperate with the sliding inner cavities 603 to prevent leakage of hydraulic oil. One end of the extrusion block 5 is connected to a rotating ball 5022 through a rotating seat 501, and the upper end of the rotating ball 5022 is fixedly connected to a pressing piece 502. When the sliding seat 2 moves downward, the extrusion blocks 5 move toward the center under the action of the hydraulic oil, and the pressing pieces 502 cooperate with each other to apply uniform pre-bending force to the high-strength steel plate in the fixed pad 4. The special design of the pressing pieces 502 enables them to pre-bend steel plates with different curvatures, ensuring the smooth progress of the pre-bending process.

[0023] The support base 1 and the sliding base 2 are internally integrated with an oil cylinder 6, the oil cylinder 6 is internally installed with an oil pump 601, the oil pump 601 delivers hydraulic oil to a sliding inner cavity 603 through an oil inlet pipe 602, a control valve 605 is used for adjusting the flow and pressure of the hydraulic oil, ensuring the smooth movement of the transmission piston 504, an oil outlet pipe 604 connects the oil cylinder 6 and the sliding inner cavity 603, and the backflow direction of the hydraulic oil is controlled through a reversing valve 607. The closed-loop hydraulic system design not only improves the energy utilization efficiency, but also enhances the stability and reliability of the system.

[0024] The upper end of each sliding inner cavity 603 is internally installed with a cleaning sleeve 606, and the cleaning sleeve 606 is in sliding connection with the extrusion block 5. During the up-and-down movement of the extrusion block 5, the cleaning sleeve 606 can effectively remove dust and impurities from the outer sidewall, reduce hydraulic system failures caused by impurities, and prolong the service life of the device.

[0025] Before the hydrogen-induced delayed fracture test of high-strength steel, first place the high-strength steel plate to be tested in the installation groove 401 of the fixing pad 4, install the fixing pad 4 on the pressing piece 5 on the support base 1 through the cooperation of the fixing hole 5021 and the limiting convex, then according to the required pre-bending curvature and shape, use professional three-dimensional modeling software to design the model, then import the model into the numerical control programming software, plan the path and set the process parameters, generate numerical control code to control the oil pump 601, the control valve 605 and the reversing valve 607, drive the sliding base 2 to descend through the hydraulic push rod 301, and the host controller controls the extrusion block to press the fixing pad in turn according to the preset program through the numerical control system, the pressing piece 502 gradually forms multiple indentations on the surface of the plate, and as the punch continuously moves and the pressure gradually increases, the plate gradually deforms into the required shape. The extrusion block 5 moves to the center under the action of the hydraulic oil, and the pressing piece 502 applies uniform pre-bending force to the steel plate. After pre-bending, the sliding base 2 is reset to prepare for the next hydrogen-induced delayed fracture test.

[0026] The pre-bent high-strength steel plate is carefully placed in the hydrogen-induced delayed fracture performance test solution along with the fixing pad 4 for static treatment. The test solution uses 0.1 mol / L HCL aqueous solution to ensure the stability of the solution concentration. A video monitoring device with continuous recording and storage function is used to observe the sample continuously, and the generation of cracks on the surface of the sample is monitored in real time. The time of surface cracking of each group of samples is recorded, and the stress change of the sample in the solution is measured. The recorded time of surface cracking of the corresponding sample and the pre-bending stress of the sample are taken as the hydrogen-induced delayed fracture performance test data of the sample. According to the hydrogen-induced delayed fracture performance test data of each group of samples, combined with the fracture time-bending stress curve, the effective evaluation of the hydrogen-induced delayed fracture sensitivity of the ultra-high strength steel plate is realized. This process verifies the effectiveness and accuracy of the device in simulating the actual working conditions for evaluating the hydrogen-induced delayed fracture performance of high-strength steel, and provides key data support for subsequent material selection and process optimization.

[0027] Example Two: On the basis of Example One, this embodiment optimizes and upgrades the fixing pad 4, using a layered composite structure to improve its durability and adaptability.

[0028] The base layer of the fixing pad 4 uses polyurethane material, and a metal mesh reinforcing layer is added on top. The polyurethane layer provides good elasticity, corrosion resistance, wear resistance and oil resistance, while the metal mesh reinforcing layer significantly improves the mechanical strength and impact resistance of the fixing pad 4, making it less likely to deform and damage under high pressure and frequent use. The metal mesh reinforcing layer uses stainless steel material, which has good corrosion resistance and can adapt to acidic test environment, prolonging the service life of the fixing pad 4.

[0029] As an alternative, the fixing pad 4 can also use hydrogenated nitrile rubber, a high-pressure resistant elastomer material. Hydrogenated nitrile rubber has excellent oil resistance, wear resistance, high temperature resistance and ozone resistance, while also having high elasticity and strength, allowing it to withstand higher pressure and more severe environmental conditions while maintaining good elasticity, meeting the stringent requirements of high-strength steel hydrogen-induced delayed fracture testing.

[0030] Through the above optimization, the fixing pad 4 further improves its durability and adaptability on the basis of maintaining its original performance, better meeting the needs of different test conditions.

[0031] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for testing hydrogen induced delayed fracture of high strength steel, comprising a support base (1), characterized in that: The upper side wall of the support seat (1) is fixedly connected with a support guide rod (101), the upper end of the support guide rod (101) is fixedly connected with a support frame (3), the upper side wall of the support frame (3) is fixedly connected with a hydraulic push rod (301), the output end of the hydraulic push rod (301) is fixedly connected with a sliding seat (2), the upper side wall of the support seat (1) and the lower side wall of the sliding seat (2) are provided with a plurality of sliding inner cavities (603), and the inside of each sliding inner cavity (603) is slidably connected with a transmission piston (504). The transmission piston (504) is fixedly connected with an extrusion block (5) through a connecting rod, one end of the extrusion block (5) away from the transmission piston (504) is detachably connected with a rotating seat (501), the inside of the rotating seat (501) is rollingly connected with a rotating ball (5022), the upper end of the rotating ball (5022) is fixedly connected with a pressing piece (502), and the support seat (1) and the sliding seat (2) are movably connected with a fixed pad (4).

2. The device for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, characterized in that: The sliding seat (2) and the support guide rod (101) are slidably connected, and the pressing piece (502) on each sliding seat (2) is matched with the pressing piece (502) on the support seat (1).

3. The device for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, characterized in that: The inside of the support seat (1) and the sliding seat (2) is provided with an oil cylinder (6), the inside of the oil cylinder (6) is provided with an oil pump (601), the output end of the oil pump (601) is fixedly connected with a plurality of oil inlet pipes (602), each oil inlet pipe (602) is communicated with the sliding inner cavity (603), and the inside of the oil inlet pipe (602) is provided with a control valve (605).

4. The apparatus for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, characterized in that: The oil cylinder (6) and the sliding inner cavity (603) are connected through an oil outlet pipe (604), one end of the oil outlet pipe (604) is located between the transmission piston (504) and the extrusion block (5), and the oil outlet pipe (604) and the oil inlet pipe (602) are fixedly connected with a reversing valve (607).

5. The apparatus for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, characterized in that: The upper end inside of each sliding inner cavity (603) is provided with a cleaning sleeve (606), and the cleaning sleeve (606) is slidably connected with the extrusion block (5).

6. The apparatus for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, wherein: The upper side wall of the pressing piece (502) at the four corners of the support seat (1) and the lower side wall of the pressing piece (502) at the four corners of the sliding seat (2) are fixedly connected with fixed holes (5021), and the upper side wall and the lower side wall of the fixed pad (4) are fixedly connected with four limiting protrusions.

7. The apparatus for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, characterized in that: The inside of the fixed pad (4) is provided with a mounting groove (401), one side of the mounting groove (401) penetrates the fixed pad (4), the mounting groove (401) is used for placing a high-strength steel plate, a plurality of through holes (402) are uniformly arranged in the inside of the fixed pad (4), and the fixed pad (4) is made of polyurethane material.

8. The apparatus for testing hydrogen induced delayed fracture of high-strength steel according to claim 1, wherein: The outer side wall of the extrusion block (5) is fixedly connected with a sealing sleeve (503), and the sealing sleeve (503) is matched with the sliding inner cavity (603).

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