Aluminum alloy material bending stress corrosion testing device and experimental method thereof

Abstract

According to the aluminum alloy material bending stress corrosion testing device and the experimental method thereof, a corrosion solution is loaded in an experimental bin cavity, a bottom supporting base is fixedly installed at the bottom of the experimental bin and supports the middle of the lower surface of a test piece, a top cover is arranged at the top of the experimental bin, and two guide rings A are arranged at two through holes of the top cover; a pressing rod penetrates through the through hole and a middle hole of the guide ring A, the lower end of the pressing rod is pressed on the edge of the upper surface of the test piece, a shoulder is arranged on the upper portion of the pressing rod, and a plurality of weights are supported on the shoulder. A comprehensive force application structure of the servo motor, the pressurization lead screw and the force sensor is used for carrying out constant or variable bending stress loading on an aluminum alloy sample in a corrosion state, and the device has the advantages that the loading pressure precision is high, and the pressure adjusting range is wide; and the control feedback is sensitive.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material experiments, and particularly relates to a bending stress corrosion test device for aluminum alloy materials and an experimental method thereof. Background Art

[0002] The damage caused by the combined action of stress and corrosion environment on materials is called stress corrosion. The factors affecting stress corrosion mainly include environmental factors, mechanical factors, and metallurgical factors. Bending stress corrosion test is to check whether the indicators such as stress corrosion cracking (SCC) sensitivity, crack propagation rate, and corrosion depth meet the requirements under the stress bending state of the specimen in a corrosive atmosphere. After the actual metal workpiece is produced, in order to verify the stress corrosion resistance of the metal workpiece, test pieces with the same metallurgical treatment are commonly used for laboratory stress corrosion tests to indirectly verify whether the metal workpiece meets the usage requirements.

[0003] Usually, when performing a constant load bending stress corrosion test on an aluminum alloy material test piece, a constant pressure pressurization method can be used to apply bending stress to the test piece. For example, in the prior art, a weight or a hydraulic pressure device is used to pressurize the specimen. However, the existing pressurization devices and methods still have the following deficiencies: 1. For bending stress corrosion, especially for the experimental device of four-point bending aluminum alloy test piece stress corrosion, there is less public content and no suitable experimental equipment to choose from. For example, Chinese Patent 1: A specimen tensile stress corrosion testing machine; Publication Number: CN103091235A, uses a specimen tensile stress weight loading form; Chinese Patent 2: A constant load stress corrosion torsion test device; Publication Number: CN201909742U, uses a specimen torsional stress weight loading form; 2. After adding weights to the device, the overall weight is relatively large. In order to bear the weight of the weights, the overall rods and beams are thick, not concise, and not convenient for transportation; 3. For some irregular specimens, such as bending specimens that need to test butt welding, it cannot be satisfied; 4. For a hydraulic pressure loading device, such as Chinese Patent 3: An automatic hydraulic pressure loading device for a stress corrosion testing machine; Publication Number: CN201311381Y, which uses a hydraulic pressure loading form, but during the long-term pressure maintaining process, the hydraulic system needs to continuously consume electricity, with high energy consumption. When the equipment breaks down, the pressure will also be lost, affecting the accuracy of the experimental results. Summary of the Invention

[0004] In view of the above problems, the present invention provides a bending stress corrosion test device for aluminum alloy materials and an experimental method thereof, which uses a comprehensive force application structure of a servo motor, a pressurizing screw rod, and a force sensor to apply constant or variable bending stress to an aluminum alloy specimen in a corrosive state, and has the advantages of high loading pressure accuracy, wide pressure adjustment range, and sensitive control feedback.

[0005] The present invention is achieved through the following solutions: An aluminum alloy material bending stress corrosion test device, in which a corrosion solution is loaded in the experimental chamber cavity, a bottom support seat is fixedly installed at the bottom of the experimental chamber, the bottom support seat supports the middle part of the lower surface of the specimen, a top cover is arranged at the top of the experimental chamber, and the joint between the experimental chamber and the top cover is tightly connected through a flange edge and bolts; a support frame is fixedly arranged on the upper part of the top cover, a pressure rod passes through two through holes of the top cover, the lower end of the pressure rod presses on the edge of the upper surface of the specimen, a column type pressure sensor is installed at the upper end of the pressure rod, the upper part of the column type pressure sensor contacts the lower end of a lead screw, the lead screw is installed on a lead screw lift and is driven to lift and lower, and the drive shaft of the lead screw lift is connected to a motor.

[0006] The experimental chamber can be made of tempered organic glass for convenient observation of the situation inside the chamber. By driving the lead screw of the lead screw lift to descend through the motor, the lead screw presses down on the column type pressure sensor on the pressure rod, and then the pressure of the pressure rod is transmitted to the specimen to achieve the effect of ballast. At any stage of the experiment, the bending stress received by the specimen can be obtained from the reading of the column type pressure sensor, the data of the pressure sensor is fed back to the PLC, and the PLC selects whether to start the motor to drive the lead screw to press down to increase the downward pressure by comparing with the preset pressure value; the upper end of the pressure rod is a shoulder and can be treated with rubber coating to prevent the pressure rod from falling and the shoulder from impacting the top cover.

[0007] Guide rings A are arranged at the two through holes of the top cover through which the pressure rod passes, through holes matching them are arranged on the fixing plate at the middle beam of the support frame, guide rings B are arranged on the through holes, and the upper end of the pressure rod sequentially passes through guide rings A and guide rings B.

[0008] Guide rings A and guide rings B cooperate with each other for two-point guidance to prevent the pressure rod from tilting and keep it in a vertical state. The lower end part of the pressure rod is set as a horizontal cross bar to apply force evenly to the edge of the test piece.

[0009] There is one motor, which drives the lead screw lifts on both sides simultaneously to achieve synchronous lifting and lowering of the lead screws. When the specimen is a test piece with uniform thickness, the form of single-motor lead screw synchronous downward pressure can be adopted.

[0010] There are two motors, which separately drive the lead screw lifts on both sides to achieve asynchronous lifting and lowering of the lead screws. The motor can be connected to the drive shaft of the lead screw lift through a coupling or directly; when the specimen is a specimen with uneven heights at both ends, the form of unequal heights of the motor lead screws pressing down simultaneously can be adopted to achieve stress corrosion testing of more specimens and have stronger adaptability.

[0011] Several heaters are also arranged in the experimental chamber, and the wiring terminals of the heaters are arranged on the top cover. The heaters heat the corrosion liquid in the test chamber to meet the temperature requirements of the experiment; multiple heaters can be arranged to achieve heating uniformity and heating efficiency. The heaters can select the stainless steel single-head electric heating tubes produced by Dongguan Jinyie Electric Heating Materials Co., Ltd.

[0012] A temperature sensor is also provided inside the experimental chamber, and the wiring terminal of the temperature sensor is arranged on the top cover. The temperature sensor is located in the middle, and the temperature measuring end is close to the specimen position to obtain a more effective corrosion liquid temperature area. The temperature sensor can be connected to the heater signal through the PLC. After setting the heating temperature, the heater automatically and intermittently heats the corrosion liquid to maintain the temperature range of the corrosion liquid. The temperature sensor can be a corrosion-resistant platinum resistance temperature sensor manufactured by Xingyi Sensor Manufacturing Co., Ltd. in Sanhe City, Langfang City, Hebei Province.

[0013] An inlet is arranged at the upper part of one side of the experimental chamber, and a drain is arranged at the upper part. The inlet is used to inject the treated corrosion liquid; the drain is used to drain the corrosion liquid after the experiment is completed.

[0014] The experimental method includes the following steps: A. With the top cover open, place the specimen flat on the support frame inside the experimental chamber; B. Place a cushion block at the upper shoulder of the upper end of the pressure rod, support the pressure rod, and then carefully place the top cover on the top of the experimental chamber C. Remove the cushion blocks at the upper shoulders of the upper ends of the two pressure rods at the same time, so that the lower ends of the pressure rods freely contact the surface of the specimen; D. Manually control the screw of the screw jack to press down simultaneously until the lower end of the screw contacts the columnar pressure sensor, and slightly load the sensor to start displaying readings, and then tighten the bolts on the flange one by one; E. Manually or automatically control the screw to press down simultaneously according to the preset pressure value. After completing the ballast, inject the treated corrosion liquid into the experimental chamber; F. Turn on the heater and the temperature sensor, and conduct a bending stress corrosion experiment according to the preset pressure value; G. After the experiment is completed, drain the corrosion liquid, raise the screw to relieve the pressure, loosen the bolts on the flange, remove the top cover, and take out the specimen, that is, complete the experimental process.

[0015] Advantages of the present invention

[0016] 1. The present invention is specifically used for the constant load bending stress corrosion test of aluminum alloy specimens, and can apply arbitrary program bending stresses to the aluminum alloy specimens. Through the program control of the PLC, different pressures are set to be loaded at different time periods, making the simulated stress conditions more complex and accurate.

[0017] 2. The device of the present invention is small in size, compact in structure, has low requirements for laboratory facilities, and during the experiment, the device can also be freely moved and transferred without affecting the experimental results.

[0018] 3. The operation process of the device of the present invention is convenient, and all operations are realized at the top cover, which is convenient for maintenance.

[0019] 4. The present invention can not only apply constant pressure loading to regular metal test pieces, but also perform ballast on irregular metal specimens. For example, for lap-welded specimens with different thicknesses at both ends, different control of the lifting height can be achieved by separately controlling the unilateral screw lift, with a wider application range and stronger expansion ability.

[0020] 5. The device of the present invention does not require continuous power supply during the maintenance stage, and the constant position of the pressure rod can be achieved only by the self-locking effect of the screw and nut. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the elevation structure diagram of Embodiment 1; Figure 2 It is the middle cross-sectional structure diagram of Embodiment 1; Figure 3 It is the elevation structure diagram of Embodiment 2; Figure 4 It is the middle cross-sectional structure diagram of Embodiment 2; Figure 5 It is the control logic block diagram of Embodiment 2; Figure 6 It is the schematic diagram of the positional relationship among the pressure rod, screw rod and columnar pressure sensor; Figure 7 It is the elevation structure diagram of the bottom support base; Each serial number in the figure is marked as: 1 - experimental chamber; 11 - liquid injection port; 12 - liquid discharge port; 2 - top cover; 3 - bottom support base; 4 - support frame; 5 - pressure rod; 51 - guide ring A; 52 - guide ring B; 54 - shoulder; 61 - temperature sensor; 62 - heater; 71 - screw lift; 711 - screw rod; 72 - motor; 8 - specimen; 9 - columnar pressure sensor. DETAILED DESCRIPTION OF THE INVENTION

[0022] Embodiment 1

[0023] For the bending stress corrosion test device of aluminum alloy material, the corrosion solution is loaded in the cavity of the experimental chamber 1. The bottom support base 3 is fixedly installed at the bottom of the experimental chamber 1, and the bottom support base 3 supports the middle part of the lower surface of the specimen 8. The top cover 2 is arranged at the top of the experimental chamber 1, and the joint between the experimental chamber 1 and the top cover 2 is tightly connected by a flange edge and bolts; the support frame 4 is fixedly arranged on the upper part of the top cover 2, and the pressure rod 5 passes through two through holes of the top cover 2. The lower end of the pressure rod 5 presses on the edge of the upper surface of the specimen 8. The columnar pressure sensor 9 is installed at the upper end of the pressure rod 5, and the lower end of the screw rod 711 contacts the upper part of the columnar pressure sensor 9. The screw rod 711 is installed on the screw lift 71 and is driven to lift and lower, and the drive shaft of the screw lift 71 is connected to the motor 72.

[0024] A guide ring A51 is provided at the two through holes of the top cover 2 through which the pressure rod 5 passes. A through hole matching it is provided on the fixing plate at the middle beam of the support frame 4, and a guide ring B52 is provided on the through hole. The upper end of the pressure rod 5 passes through the guide ring A51 and the guide ring B52 in sequence.

[0025] The specimen is a symmetric aluminum alloy test piece. There is one motor 72, which drives the screw jacks 71 on both sides simultaneously to realize the synchronous lifting of the screw rods 711.

[0026] A number of heaters 7 are also provided in the test chamber 1, and the wiring terminals of the heaters 7 are arranged on the top cover 2.

[0027] A temperature sensor 6 is also provided in the test chamber 1, and the wiring terminals of the temperature sensor 6 are arranged on the top cover 2.

[0028] A liquid inlet 11 is provided at the upper part of one side of the test chamber 1, and a liquid outlet 12 is provided at the upper part.

[0029] The experimental method includes the following steps: A. With the top cover open, place the specimen flat on the support frame in the test chamber. B. Place a spacer at the upper end shoulder of the pressure rod to support the pressure rod, and then carefully place the top cover on the top of the test chamber. C. Remove the spacers at the upper end shoulders of the two pressure rods simultaneously, so that the lower ends of the pressure rods freely contact the surface of the specimen. D. Manually control the screws of the screw jacks to press down simultaneously until the lower ends of the screws contact the columnar pressure sensor, and slightly load the sensor until it starts to display readings, and then tighten the bolts on the flange one by one. E. Manually or automatically control the screws to press down simultaneously according to the preset pressure value. After the ballast is completed, inject the treated corrosion liquid into the test chamber. F. Turn on the heater and the temperature sensor, and conduct a bending stress corrosion experiment according to the preset pressure value. G. After the experiment is completed, drain the corrosion liquid, raise the screws to relieve the pressure, loosen the bolts on the flange, remove the top cover, and take out the specimen, thus completing the experimental process.

[0030] Embodiment 2

[0031] The difference from Embodiment 1 is that the specimen is a lap joint plate with asymmetric thicknesses at both ends, and there are two motors 72, which separately drive the screw jacks 71 on both sides to realize the synchronous lifting of the screw rods 711 at different heights.

Claims

1. A servo variable load bending stress corrosion test device for aluminum alloy materials, characterized in that The cavity of the test chamber (1) is loaded with a corrosion solution. A bottom support base (3) is fixedly installed at the bottom of the test chamber (1), and the bottom support base (3) supports the middle of the lower surface of the specimen (8). A top cover (2) is arranged at the top of the test chamber (1), and the joint between the test chamber (1) and the top cover (2) is tightly connected by a flange edge and bolts; a support frame (4) is fixedly arranged on the upper part of the top cover (2). Pressure rods (5) pass through two through holes of the top cover (2). The lower ends of the pressure rods (5) press on the edge of the upper surface of the specimen (8), and a columnar pressure sensor (9) is installed at the upper end of the pressure rod (5). The upper part of the columnar pressure sensor (9) contacts the lower end of a lead screw (711). The lead screw (711) is installed on a lead screw lift (71) and is driven to lift and lower. The drive shaft of the lead screw lift (71) is connected to a motor (72).

2. The servo variable load bending stress corrosion test device for the aluminum alloy material according to claim 1, wherein, Guide rings A (51) are arranged at the two through holes of the top cover (2) through which the pressure rods (5) pass. Through holes matching them are arranged on the fixing plate at the middle beam of the support frame (4), and guide rings B (52) are arranged on the through holes. The upper ends of the pressure rods (5) sequentially pass through the guide rings A (51) and the guide rings B (52).

3. The servo variable load bending stress corrosion test device for the aluminum alloy material according to claim 1, wherein There is one motor (72), which simultaneously drives the lead screw lifts (71) on both sides to realize the synchronous lifting and lowering of the lead screws (711).

4. The servo variable load bending stress corrosion test device for the aluminum alloy material according to claim 1, wherein There are two motors (72), which separately drive the lead screw lifts (71) on both sides to realize the synchronous lifting and lowering of the lead screws (711) at different heights.

5. The bending stress corrosion test device for aluminum alloy materials according to claim 1, characterized in that, A number of heaters (7) are also arranged in the test chamber (1), and the wiring terminals of the heaters (7) are arranged on the top cover (2).

6. The bending stress corrosion test device for aluminum alloy materials according to claim 1, wherein A temperature sensor (6) is also arranged in the test chamber (1), and the wiring terminals of the temperature sensor (6) are arranged on the top cover (2).

7. The bending stress corrosion test device for aluminum alloy materials according to claim 1, wherein, An inlet (11) is arranged at the upper part of one side of the test chamber (1), and a drain outlet (12) is arranged at the upper part.

8. The bending stress corrosion test device for aluminum alloy materials according to claim 3, wherein, The test method includes the following steps: A. With the top cover open, place the specimen flat on the support frame in the test chamber. B. Place pads at the shoulder of the upper end of the pressure rod to support the pressure rod, and then carefully place the top cover on the top of the test chamber. C. Remove the pads at the shoulder of the upper ends of the two pressure rods at the same time, so that the lower ends of the pressure rods freely contact the surface of the specimen. D. Manually control the lead screws of the lead screw lifts to press down simultaneously until the lower ends of the lead screws contact the columnar pressure sensor and slightly load the sensor to start displaying readings, and then tighten the bolts on the flange one by one. E. Manually or automatically control the lead screws to press down simultaneously according to the preset pressure value. After the pressure loading is completed, inject the treated corrosion liquid into the test chamber. F. Turn on the heater and the temperature sensor, and conduct a bending stress corrosion test according to the preset pressure value. G. After the test is completed, drain the corrosion liquid, raise the lead screws to relieve the pressure, loosen the bolts on the flange, remove the top cover, and take out the specimen, thus completing the test process.

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