Preparation device and method of calibration test block for nondestructive testing of stress corrosion cracks

Abstract

The invention provides a preparation device of a nondestructive testing stress corrosion crack calibration test block, which comprises a base, a corrosion mechanism, a test block, a pressing mechanism, at least two limiting mechanisms and a crack propagation monitoring mechanism, the corrosion mechanism is arranged on the base, and corrosive liquid flows in the corrosion mechanism; the test block abuts against the end face of the corrosion mechanism, a prefabricated crack is formed in the test block, the corrosion mechanism provides a corrosion environment for the prefabricated crack side of the test block, and stress corrosion crack initiation and expansion are accelerated; the pressing mechanism is arranged opposite to the corrosion mechanism and can linearly move towards one side of the corrosion mechanism to apply a load to the position of the prefabricated crack; the at least two limiting mechanisms are arranged on the base and are used for limiting the test block to move along the horizontal direction; the crack propagation monitoring mechanism is arranged on one side of the base and used for monitoring the propagation depth of the stress corrosion crack of the test block applying the load, the device can effectively simulate the crack propagation process of metal in the stress corrosion environment, the accuracy of the position and the size of the stress corrosion crack in a practical engineering welding structure can be ensured, and the working efficiency is improved. Therefore, the detection reliability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of crack defect extension, and in particular to a preparation device and method for a stress corrosion crack calibration test block for nondestructive testing. Background Art

[0002] Large welded structural parts used in nuclear power plants, petrochemicals and other fields are often exposed to liquids such as steam, coolant, and oil. Stress corrosion cracks will inevitably occur in long-term service environments under stress and corrosion, seriously affecting the safe operation of equipment. Currently, non-destructive testing technology is often used to evaluate the quality of materials and detect internal defects. Among them, ultrasonic non-destructive testing technology uses the propagation characteristics of ultrasonic waves in materials to detect various defects inside the materials. As an accurate reference for ultrasonic non-destructive testing calibration, calibration blocks with known defect types, sizes and locations can not only be used for ultrasonic non-destructive testing calibration and process verification, but also for daily training of ultrasonic non-destructive testing personnel.

[0003] A method for measuring Ω weld defect parameters with publication number CN101672829B reveals that the parameters of the measured defects include the position, length, depth from the upper surface and height of the defect on the weld. The Ω weld is a comparison test block made of an Ω weld welding process assessment test block. Three circumferential electric spark grooves with heights of 1 mm, 1.5 mm, and 2 mm, a width of 0.7 mm, and a length of 25 mm are respectively processed on the center lines of the inner and outer surfaces of the Ω weld, namely the comparison test block circumferential inner groove and the comparison test block circumferential outer groove, which are used to simulate linear defects along the weld direction.

[0004] At present, calibration test blocks containing stress corrosion crack defects are often processed by direct electrospark machining, and narrow grooves with a certain width and depth are machined on the test blocks to simulate stress corrosion cracks, or shallow grooves of a certain width are pre-machined on the test blocks by electrospark machining as pre-cracks on the surface of the test blocks, and then the pre-cracks are extended to a certain depth by a fatigue testing machine to simulate stress corrosion cracks. The simulated stress corrosion cracks produced by the existing method are relatively regular and straight, and cannot truly simulate the characteristics of stress corrosion cracks. As a result, during ultrasonic non-destructive testing calibration and process verification, there is a large difference between the signal reflected after the interaction between the ultrasonic wave and the simulated stress corrosion crack and the signal reflected after the interaction between the ultrasonic wave and the real stress corrosion crack, which has a great impact on the accuracy and precision of ultrasonic non-destructive testing stress corrosion crack calibration and process verification, and there is a risk of missed detection, or large errors in the location and size of the detected stress corrosion cracks, thereby reducing the reliability of the detection. Summary of the invention

[0005] In view of this, the present invention proposes a device and method for preparing a stress corrosion crack calibration test block for non-destructive testing, which is used for ultrasonic non-destructive testing calibration and process verification, and can ensure the accuracy of the stress corrosion crack position and size in actual engineering welding structures, thereby improving the detection reliability.

[0006] The technical solution of the present invention is implemented as follows: In a first aspect, the present invention provides a preparation device for a stress corrosion crack calibration test block for non-destructive testing, comprising:

[0007] Base;

[0008] The corrosion mechanism is arranged on the base and has a corrosion liquid flowing inside;

[0009] The test block is in contact with the end face of the corrosion mechanism, and a prefabricated crack is provided on the test block, and the corrosion liquid corrodes the prefabricated crack side of the test block;

[0010] A pressing mechanism is arranged opposite to the corrosion mechanism, and the pressing mechanism can move linearly toward one side of the corrosion mechanism to apply a load to the position of the prefabricated crack;

[0011] At least two limiting mechanisms are arranged on the base and are arranged on both sides of the corrosion mechanism to limit the movement of the test block in the horizontal direction;

[0012] The crack extension monitoring mechanism is arranged on one side of the base, and a detection part is provided on the crack extension monitoring mechanism. The detection part of the crack extension monitoring mechanism is fixedly connected to the test block and is arranged on both sides of the prefabricated crack to monitor the extension depth of the stress corrosion crack of the test block with applied load.

[0013] On the basis of the above technical solution, preferably, the corrosion mechanism includes a liquid storage member, a pump body, a liquid storage tank and a valve body, wherein:

[0014] The liquid storage part is fixed on the base, and the liquid storage part is hollow inside, and an opening is provided on a side away from the base. The liquid storage part is filled with a corrosive liquid, and the test block is abutted against the opening, and a prefabricated crack is in contact with the corrosive liquid;

[0015] The liquid storage member is provided with symmetrically arranged through holes;

[0016] The pump body and the liquid storage tank are both arranged on one side of the base, the liquid outlet end of the pump body penetrates and extends into the liquid storage tank and is above the liquid level, the liquid extraction end of the pump body is connected with the through hole on one side, and the through hole on the other side is connected with the inside of the liquid storage tank, so that the corrosive liquid circulates in the liquid storage member;

[0017] The valve body is arranged between the through hole on the other side and the liquid storage tank, and is used for selectively disconnecting the communication between the liquid storage tank and the liquid storage member.

[0018] On the basis of the above technical solution, preferably, both sides of the opening of the liquid storage member abutting against the test block are provided with arc chamfers.

[0019] On the basis of the above technical solution, preferably, when the pressing mechanism moves to apply the load, the pressing mechanism abuts against the side of the test block away from the liquid storage member, and the abutment position corresponds to the position of the prefabricated crack, and the applied load is not greater than the yield strength of the test block.

[0020] On the basis of the above technical solution, preferably, the at least two limiting mechanisms each include a fixing seat, a plurality of sleeves, a plurality of guide members, a plurality of limiting members, a plurality of elastic members and a plurality of blocking members, wherein:

[0021] The fixing seat is fixed on the base and is arranged corresponding to the position of the liquid storage member, and a groove is provided on a side of the fixing seat close to the liquid storage member;

[0022] The plurality of sleeves are all fixed on a side of the fixing seat away from the base, and one side of the sleeve passes through and extends into the groove, and the plurality of sleeves on the same side are arranged at intervals;

[0023] The plurality of guide members are slidably connected in the respective sleeves, and one end of the guide member passes through the sleeve and extends into the groove, and the guide member is perpendicular to the base;

[0024] The plurality of stoppers are respectively fixed on one end of each guide member extending into the groove, and the side of the stopper away from the guide member abuts against the surface of the test block;

[0025] The plurality of elastic members are respectively sleeved on the outer sides of the guide member and the sleeve, and the two sides of the elastic members are respectively in contact with the inner wall of the groove and the limiting member;

[0026] The plurality of blocking members are respectively arranged on the outer sides of the guide members, and the blocking members are located at a side of the fixing seat away from the base.

[0027] On the basis of the above technical solution, preferably, the end of the test block is located in the groove, and the width of the groove is equal to the width of the test block, and the side walls of the test block are respectively abutted against the corresponding inner walls of the groove.

[0028] On the basis of the above technical solution, preferably, the crack extension monitoring mechanism includes a current probe, a voltage probe and a crack extension monitor, wherein the current probe and the voltage probe are both arranged on the test block and located on one side of the prefabricated crack, the current probe and the voltage probe each have two contact portions, and the two contact portions of the current probe and the voltage probe are symmetrically arranged on both sides of the prefabricated crack, and the current probe and the voltage probe are both electrically connected to the crack extension monitor.

[0029] On the basis of the above technical solution, preferably, it further comprises a plurality of coating layers, wherein the plurality of coating layers are all arranged on the test block, and the plurality of coating layers are arranged on both sides of the prefabricated crack and the vertical projection position of the pressing mechanism on the test block.

[0030] On the basis of the above technical solution, preferably, the material of the coating layer is epoxy resin, and the spacing between the coating layer adjacent to the prefabricated crack and the prefabricated crack is 1-3 mm.

[0031] In a second aspect, the present invention further provides a method for preparing a stress corrosion crack calibration test block for non-destructive testing, using the above-mentioned preparation device for the stress corrosion crack calibration test block for non-destructive testing, comprising the following steps:

[0032] S1, by using the EDM method to process a prefabricated crack of a certain length and a depth of 0.1-0.5mm on the weld, heat-affected zone or parent material surface of the test block;

[0033] S2, fix the current probe and the voltage probe on the test block by spot welding, so that the two contact parts of the current probe and the voltage probe are symmetrically arranged on both sides of the prefabricated crack;

[0034] S3, the surface of the test block is coated with a coating layer except for 1-3 mm on both sides of the prefabricated crack and the contact position between the pressing mechanism and the surface of the test block;

[0035] S4, placing the test block at the top opening of the liquid storage member, with the side with the prefabricated crack facing the inside of the liquid storage member, and with the prefabricated crack position of the test block corresponding to the middle position of the liquid storage member, the test block abuts in the groove, and the elastic members on both sides squeeze the limit members to abut against the upper surface of the test block;

[0036] S5, after the test block is limited by the limiting mechanism, the pressing mechanism is driven to move toward the side of the test block to squeeze the back side of the prefabricated crack of the test block, and the load applied is not greater than the yield strength of the test block;

[0037] S6, the contact part between the test block and the liquid storage part is sealed, and the pump body injects the corrosive liquid in the liquid storage tank into the liquid storage part, and makes the corrosive liquid circulate in the liquid storage part;

[0038] S7, the crack depth is analyzed by the crack extension monitor. When the crack extends to the required depth, the corrosive liquid in the liquid storage part is pumped back to the discharge storage tank through the pump body, the pressing mechanism is returned to the initial position, and the test block is separated from the liquid storage part and taken out, and the coating layer on the surface of the test block is removed. The test block is cleaned with anhydrous ethanol and blown dry, and the test block production is completed.

[0039] The device and method for preparing a stress corrosion crack calibration test block for nondestructive testing of the present invention have the following beneficial effects compared with the prior art:

[0040] (1) The corrosion mechanism is set to provide a corrosion environment for the prefabricated crack side of the test block, the pressing mechanism applies a load to the crack position to simulate the stress conditions in the actual working environment, the limit mechanism ensures that the test block does not move in the horizontal direction during the test, and the crack extension monitoring mechanism monitors the extension depth of the stress corrosion crack of the test block to which the load is applied. The device can effectively simulate the crack extension process of metals in a stress corrosion environment, ensure the accuracy of the stress corrosion crack position and size in the actual engineering welding structure, and thus improve the detection reliability;

[0041] (2) The corrosive liquid in the liquid storage tank is kept flowing by means of a pump body, thereby increasing the number of times the corrosive solution flushes the prefabricated cracks of the test block, accelerating the removal of corrosion products generated after the expansion of stress corrosion cracks, and thus increasing the expansion rate of stress corrosion cracks;

[0042] (3) The liquid storage member is used to support the test block when the downward pressure mechanism applies a load. The two sides of the liquid storage member in contact with the test block are rounded, which is conducive to the test block to generate bending stress. The downward pressure mechanism applies a certain load to the upper side of the test block. The applied load does not exceed the yield strength of the test block material itself, so that the test block produces a certain degree of elastic deformation, thereby accelerating the propagation of cracks;

[0043] (4) The limit mechanism can ensure that the test block can stably abut against the end face of the corrosion mechanism during the corrosion process, and prevent the test block from moving or tilting horizontally when subjected to the corrosion liquid, thereby ensuring the accuracy of the stress corrosion crack initiation position of the test block; BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A three-dimensional diagram of a preparation device for a stress corrosion crack calibration test block for nondestructive testing of the present invention;

[0046] Figure 2 It is a side view of a preparation device for a stress corrosion crack calibration test block for nondestructive testing of the present invention;

[0047] Figure 3 The invention provides a preparation device for the stress corrosion crack calibration test block for nondestructive testing Figure 3 Sectional view at AA;

[0048] Figure 4The invention provides a preparation device for the stress corrosion crack calibration test block for nondestructive testing Figure 4 A partial enlarged schematic diagram of point B in the middle;

[0049] Figure 5 It is a structural stereogram of a liquid storage part of a preparation device for a stress corrosion crack calibration test block for nondestructive testing of the present invention;

[0050] Figure 6 A three-dimensional diagram of the position of the prefabricated cracks on the test piece structure of the preparation device for the stress corrosion crack calibration test block for non-destructive testing of the present invention;

[0051] Figure 7 The invention provides a preparation device for the stress corrosion crack calibration test block for nondestructive testing Figure 6 A partial enlarged schematic diagram of point C in the middle;

[0052] Figure 8 The present invention is a structural block diagram of a crack propagation monitoring mechanism of a device for preparing a stress corrosion crack calibration test block for nondestructive testing. DETAILED DESCRIPTION

[0053] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] like Figure 1-8 As shown, the present invention provides a device for preparing a stress corrosion crack calibration test block for non-destructive testing, including a base 1, a corrosion mechanism 2, a test block 3, a pressing mechanism 4, at least two limiting mechanisms 5 and a crack extension monitoring mechanism 6.

[0055] In this embodiment, the base 1 is used to support other structural parts. The base 1 is provided with mounting holes evenly distributed in a rectangular array. The corrosion mechanism 2 and the limiting mechanism 5 are threadedly connected to the corresponding mounting holes by bolts to fix the corrosion mechanism 2 and the limiting mechanism 5 on the base 1.

[0056] In this embodiment, the corrosion mechanism 2 is arranged on the base 1 , and a corrosion liquid flows inside the corrosion mechanism 2 to provide a corrosion environment for the test block 3 .

[0057] As a preferred embodiment, the corrosion mechanism 2 in this embodiment includes a liquid storage member 21, a pump body 22, a liquid storage tank 23 and a valve body 24, wherein the liquid storage member 21 is fixed on the base 1, and the liquid storage member 21 is hollow inside, and an opening is provided on the side away from the base 1, the liquid storage member 21 is filled with corrosion liquid, the test block 3 abuts on the opening, and the prefabricated crack 300 is in contact with the corrosion liquid; the liquid storage member 21 is provided with symmetrically arranged through holes 210; the pump body 22 and the liquid storage tank 23 are both arranged on one side of the base 1, the liquid outlet end of the pump body 22 penetrates and extends into the liquid storage tank 23, and is above the liquid level, the liquid extraction end of the pump body 22 is connected with the through hole 210 on one side, and the through hole 210 on the other side is connected with the inside of the liquid storage tank 23, so that the corrosion liquid circulates in the liquid storage member 21; the valve body 24 is arranged between the through hole 210 on the other side and the liquid storage tank 23, and is used to selectively disconnect the connection between the liquid storage tank 23 and the liquid storage member 21.

[0058] It should be noted that the liquid storage part 21 is fixed to the base 1 by bolts and is used to contain the corrosive liquid. The liquid storage part 21 is made of corrosion-resistant material to resist the erosion of the corrosive liquid. Due to the different materials of the test block 3, by changing the composition and concentration ratio of the corrosive liquid in the liquid storage tank 21, the stress corrosion cracks of the welding joints of different metal materials can be preset.

[0059] In addition, the liquid storage part 21 is provided with symmetrical through holes 210. When it is necessary to inject liquid into the liquid storage part 21, the test block 3 and the liquid storage part 21 are in a sealed state. The valve body 24 is opened to connect the liquid storage tank 23 with the liquid storage part 21, and the pump body 22 on the other side is started. At this time, the pump body 22 can draw the corrosive liquid in the liquid storage tank 23 into the liquid storage part 21, and discharge the corrosive liquid into the liquid storage tank 23 for recycling. When it is necessary to discharge the liquid storage part 21, the valve body 24 is closed to disconnect the connection between the liquid storage tank 23 and the liquid storage part 21, and the pump body 22 is started to draw the corrosive liquid in the liquid storage part 21 into the liquid storage tank 23 for storage, which is convenient for recycling. At the same time, the pump body 22 is used to provide a flowing corrosion environment, so that the surface of the test block 3 can fully contact the corrosive liquid, accelerate the corrosion efficiency and accuracy, and at the same time, through the control of the valve body 24, the circulation of the corrosive liquid can be conveniently controlled to meet different test requirements.

[0060] In addition, both sides of the opening of the liquid storage member 21 in this embodiment that abut against the test block 3 are provided with arc chamfers.

[0061] It should be noted that the liquid storage member 21 is used to support the test block 3 when the downward pressing mechanism 4 applies a load, and both sides of the liquid storage member 21 in contact with the test block 3 are rounded, which is beneficial for the test block 3 to generate bending stress.

[0062] The test block 3 in this embodiment is in contact with the end surface of the corrosion mechanism 2 , and a prefabricated crack 300 is provided on the test block 3 . The corrosion mechanism 2 provides a corrosion environment for the prefabricated crack 300 side of the test block 3 .

[0063] It should be noted that the test block 3 is used to simulate the behavior of the material in a stress corrosion environment. The prefabricated crack 300 on the test block 3 is used to simulate cracks or defects that may exist in actual materials. The corrosion mechanism 2 allows the corrosion liquid to directly contact the prefabricated crack 300 on the test block 3 through the opening on its end face to simulate and accelerate the crack expansion process in a stress corrosion environment.

[0064] The pressing mechanism 4 in this embodiment is arranged opposite to the corrosion mechanism 2 , and the pressing mechanism 4 can move linearly toward one side of the corrosion mechanism 2 to apply a load to the position of the prefabricated crack 300 .

[0065] In this embodiment, when the pressing mechanism 4 moves to apply a load, the pressing mechanism 4 abuts against the side of the test block 3 away from the liquid storage member 21 , and the abutting position corresponds to the position of the prefabricated crack 300 , and the applied load is not greater than the yield strength of the test block 3 .

[0066] It should be noted that the pressing mechanism 4 adopts the three-point bending principle to apply a load to the test block 3. When applying the load to the test block 3, the test block 3 is first placed above the liquid storage member 21, and then the pressing mechanism 4 is controlled to apply a certain load to the upper side of the test block 3. The applied load does not exceed the yield strength of the test block material itself, so that the test block 3 produces a certain degree of elastic deformation, thereby accelerating the expansion of the crack.

[0067] Specifically, the pressing mechanism 4 in this embodiment includes a bracket, a pushing member and a pressing head, wherein the bracket is mounted on the base 1, the pushing member is fixed on the bracket, and the telescopic end of the pushing member is arranged opposite to the liquid storage member 21, the pressing head is fixed on the telescopic end of the pushing member, and the position of the pressing head corresponds to the back position of the prefabricated crack 300 on the specimen 3. The pushing member pushes the pressing head toward the liquid storage member 21 to apply a load to the specimen 3.

[0068] It can be understood that the pushing member in this embodiment can be an oil cylinder, an air cylinder or a linear module.

[0069] In this embodiment, at least two limiting mechanisms 5 are disposed on the base 1 and are disposed on both sides of the corrosion mechanism 2 to limit the movement of the test block 3 in the horizontal direction.

[0070] As a preferred embodiment, at least two limiting mechanisms 5 in this embodiment include a fixed seat 51, a plurality of sleeves 52, a plurality of guide members 53, a plurality of limiting members 54, a plurality of elastic members 55 and a plurality of blocking members 56, wherein the fixed seat 51 is fixed on the base 1 and is arranged corresponding to the position of the liquid storage member 21, and a groove 500 is provided on a side of the fixed seat 51 close to the liquid storage member 21; the plurality of sleeves 52 are fixed on a side of the fixed seat 51 away from the base 1, and one side of the sleeves 52 penetrates and extends into the groove 500, and the plurality of sleeves 52 on the same side are arranged at intervals; the plurality of guide members 53 are respectively connected to the fixed seat 51 corresponding to the sliding connection In each sleeve 52, one end of the guide member 53 passes through the sleeve 52 and extends into the groove 500, and the guide member 53 is perpendicular to the base 1; a plurality of limit members 54 are respectively fixed on one end of each guide member 53 extending into the groove 500, and the side of the limit member 54 away from the guide member 53 abuts against the surface of the test block 3; a plurality of elastic members 55 are respectively sleeved on the outside of the guide member 53 and the sleeve 52, and the two sides of the elastic member 55 abut against the inner wall of the groove 500 and the limit member 54; a plurality of blocking members 56 are respectively arranged on the outside of each guide member 53, and the blocking member 56 is located on the side of the fixed seat 51 away from the base 1.

[0071] It should be noted that the limiting mechanism 5 is used to ensure that the test block 3 can stably abut against the end face of the corrosion mechanism 2 during the corrosion process, and prevent the test block 3 from moving or tilting horizontally when subjected to the load applied by the pressing mechanism 4. The guide member 53 slides in the sleeve 52, and the elastic member 55 can push the limiting member 54 to abut against the surface of the test block 3 through the stable guiding effect to limit its position. The blocking member 56 prevents the guide member 53 from completely sliding out of the sleeve 52, thereby ensuring the stability and safety of the limiting mechanism 5.

[0072] In addition, the end of the test block 3 in this embodiment is located in the groove 500 , and the width of the groove 500 is equal to the width of the test block 3 , and the side walls of the test block 3 are respectively in contact with the corresponding inner walls of the groove 500 .

[0073] It should be noted that when the pressing mechanism 4 starts to squeeze the test block 3, it can prevent the test block 3 from sliding horizontally and causing the test block 3 to deviate during the pressurization process, thereby ensuring the accuracy of the stress corrosion crack initiation position of the test block 3.

[0074] The crack extension monitoring mechanism 6 in this embodiment is arranged on one side of the base 1, and a detection part is provided on the crack extension monitoring mechanism 6. The detection part of the crack extension monitoring mechanism 6 is fixedly connected to the test block 3 and is arranged on both sides of the prefabricated crack 300, so as to monitor the extension depth of the stress corrosion crack of the test block 3 to which the load is applied.

[0075] It should be noted that the crack extension monitoring mechanism 6 is used to monitor the extension of stress corrosion cracks generated on the inner surface of the test block 3 located on the liquid storage member 21 based on the direct current potential drop method DCPD.

[0076] Among them, the DCPD method monitors the crack expansion by applying a small DC current to the test block and measuring the potential change caused by the crack expansion. When the crack expands, it changes the distribution of the current on the test block, resulting in a change in potential. By measuring these potential changes, the crack expansion speed and direction can be monitored in real time. This technology is an existing technology and will not be described in detail here.

[0077] As a preferred embodiment, the crack extension monitoring mechanism 6 in this embodiment includes a current probe 61, a voltage probe 62 and a crack extension monitor 63, wherein the current probe 61 and the voltage probe 62 are both arranged on the test block 3 and are located on one side of the prefabricated crack 300, and the current probe 61 and the voltage probe 62 each have two contact portions, and the two contact portions of the current probe 61 and the voltage probe 62 are symmetrically arranged on both sides of the prefabricated crack 300, and the current probe 61 and the voltage probe 62 are both electrically connected to the crack extension monitor 63.

[0078] It should be noted that there are two current probes 61 symmetrically arranged on both sides of the prefabricated crack 300, and there are also two voltage probes 62 arranged on both sides of the prefabricated crack 300. The current probe 61 is used to apply a constant current to the plane where the prefabricated crack 300 is located, and the voltage probe 62 is used to detect the potential difference on both sides of the prefabricated crack 300.

[0079] Among them, the current probe 61 and the voltage probe 62 located inside the liquid storage part 21 need to be connected to the crack extension monitor 63 through wires, and part of the wires need to be immersed in the corrosive liquid. Therefore, the wires are preferably wires with a corrosion-resistant outer layer to prevent the corrosive liquid from corroding the wires. The crack extension monitor 63 is used to monitor the depth of the crack. When the crack depth reaches the expected value, the stress corrosion crack preparation is stopped, and the production of the required artificial stress corrosion crack calibration test block for ultrasonic non-destructive testing training, calibration and process verification is completed.

[0080] The present embodiment further includes a plurality of coating layers 7 , wherein the plurality of coating layers 7 are all disposed on the test block 3 , and the plurality of coating layers 7 are disposed on both sides of the prefabricated crack 300 and the vertical projection position of the pressing mechanism 4 on the test block 3 .

[0081] It should be noted that the coating protection of the test block 3 by the coating layer 7 is used to prevent corrosion from occurring in other areas of the test block to form corrosion pits, which may lead to poor probe coupling during ultrasonic testing.

[0082] The material of the coating layer 7 in this embodiment is epoxy resin, and the distance between the coating layer 7 adjacent to the prefabricated crack 300 and the prefabricated crack 300 is 1-3 mm.

[0083] It should be noted that epoxy resin has good corrosion resistance and can effectively resist the erosion of corrosive liquid, thereby protecting other parts of the test block 3 from corrosion. In addition, epoxy resin has good insulation and will not have a significant impact on the current distribution on the test block 3, thereby ensuring the accuracy of crack extension monitoring based on the direct current potential drop method DCPD. At the same time, epoxy resin has a certain mechanical strength and can remain intact during the test and is not easily damaged.

[0084] The present invention also provides a method for preparing a stress corrosion crack calibration test block for non-destructive testing, comprising the following steps:

[0085] S1, by using the electric spark machining method, a prefabricated crack 300 with a certain length and a depth of 0.1-0.5mm is machined on the weld, heat-affected zone or parent material surface of the test block 3;

[0086] The material of the test block 3 can be replaced, and can be stainless steel such as 304, 316L, etc., or a welded joint of other metal materials.

[0087] S2, fix the current probe 61 and the voltage probe 62 on the test block 3 by spot welding, so that the two contact parts of the current probe 61 and the voltage probe 62 are symmetrically arranged on both sides of the prefabricated crack 300;

[0088] The current probe 61 is used to apply current to the plane where the prefabricated crack 300 is located, and the voltage probe 62 is used to monitor the potential difference between the two sides of the prefabricated crack 300 .

[0089] S3, coating the surface of the test block 3 with a coating layer 7 except for the 1-3 mm positions on both sides of the prefabricated crack 300 and the contact position between the pressing mechanism 4 and the surface of the test block 3;

[0090] Among them, except for 1-3mm near the prefabricated crack 300 and the position where the downward pressure mechanism 4 applies the load, the remaining front and back surfaces of the test block 3 are coated with epoxy resin for protection to prevent corrosion in other areas of the test block 3 and the formation of corrosion pits, which will cause poor probe coupling during ultrasonic testing.

[0091] S4, place the test block 3 at the top opening of the liquid storage member 21, with the side with the prefabricated crack 300 facing the inside of the liquid storage member 21, and make the position of the prefabricated crack 300 of the test block 3 correspond to the middle position of the liquid storage member 21, the test block 3 abuts in the groove 500, and the elastic members 55 on both sides squeeze the limit members 54 to abut against the upper surface of the test block 3;

[0092] Among them, the positions of the fixing seats 51 on both sides of the limit device 5 are adjusted in advance according to the length of the test block 3, so that the position of the prefabricated crack 300 of the test block 3 corresponds to the middle position of the liquid storage member 21, and the grooves 500 of the two fixing seats 51 are respectively abutted against the two ends of the test block 6, which can prevent the test block 3 from sliding sideways when the load is applied.

[0093] S5, after the test block 3 is limited by the limiting mechanism 5, the pressing mechanism 4 is driven to move toward the side of the test block 3 to squeeze the back side of the prefabricated crack 300 of the test block 3, and the applied load is not greater than the yield strength of the test block 3;

[0094] S6, the contact portion between the test block 3 and the liquid storage member 21 is sealed, and the pump body 22 injects the corrosive liquid in the liquid storage tank 23 into the liquid storage member 21, and the corrosive liquid circulates in the liquid storage member 21;

[0095] Among them, after the position of the test block 3 is fixed, the contact position between the test block 3 and the liquid storage part 21 is sealed by using a sealing colloid, etc. to avoid problems such as leakage of the corrosive liquid during the stress corrosion process, and the corrosive liquid is prepared, wherein the concentration of the components of the corrosive liquid can be configured according to actual needs, such as 3-5mol / L NaCl+0.01-0.03mol / LNaHSO3, and the valve body 24 is opened to connect the liquid storage tank 23 with the liquid storage part 21, and the pump body 22 on the other side is started. At this time, the pump body 22 can draw the corrosive liquid in the liquid storage tank 23 into the liquid storage part 21, and discharge the corrosive liquid into the liquid storage tank 23 for recycling, and the corrosive liquid in the liquid storage part 21 is in a flowing state.

[0096] S7, analyze the crack depth through the crack extension monitor 63. When the crack extends to the required depth, the corrosive liquid in the liquid storage part 21 is pumped back to the discharge liquid storage tank 23 through the pump body 22, and the pressing mechanism 4 is returned to the initial position. The test block 3 is separated from the liquid storage part 21 and taken out, and the coating layer 7 on the surface of the test block 3 is removed. The test block 3 is cleaned with anhydrous ethanol and then blown dry, and the production of the test block 3 is completed.

[0097] The valve body 24 is closed to disconnect the connection between the liquid storage tank 23 and the liquid storage member 21 , and the pump body 22 is started to pump the corrosive liquid in the liquid storage member 21 back into the liquid storage tank 23 for storage.

[0098] 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, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation device for non-destructive testing stress corrosion crack calibration test block, characterized in that: include: Base (1); The corrosion mechanism (2) is arranged on the base (1) and has corrosion liquid flowing inside; The test block (3) is in contact with the end surface of the corrosion mechanism (2), and a prefabricated crack (300) is provided on the test block (3), and the corrosion liquid corrodes the prefabricated crack (300) side of the test block (3); A pressing mechanism (4) is arranged opposite to the corrosion mechanism (2), and the pressing mechanism (4) can move linearly toward one side of the corrosion mechanism (2) to apply a load to the position of the prefabricated crack (300); At least two limiting mechanisms (5) are both arranged on the base (1) and are respectively arranged on both sides of the corrosion mechanism (2) and are used to limit the movement of the test block (3) in the horizontal direction; The crack extension monitoring mechanism (6) is arranged on one side of the base (1), and a detection part is provided on the crack extension monitoring mechanism (6). The detection part of the crack extension monitoring mechanism (6) is fixedly connected to the test block (3) and is arranged on both sides of the prefabricated crack (300) to monitor the extension depth of the stress corrosion crack of the test block (3) to which a load is applied.

2. The preparation device for the stress corrosion crack calibration test block for nondestructive testing according to claim 1, characterized in that: The corrosion mechanism (2) comprises a liquid storage member (21), a pump body (22), a liquid storage tank (23) and a valve body (24), wherein: The liquid storage member (21) is fixed on the base (1), and the liquid storage member (21) is hollow inside and has an opening on a side away from the base (1). The liquid storage member (21) is filled with a corrosive liquid, and the test block (3) is abutted against the opening, and a prefabricated crack (300) is in contact with the corrosive liquid. The liquid storage member (21) is provided with symmetrically arranged through holes (210); The pump body (22) and the liquid storage tank (23) are both arranged on one side of the base (1); the liquid outlet end of the pump body (22) penetrates and extends into the liquid storage tank (23) and is above the liquid level; the liquid extraction end of the pump body (22) is connected to a through hole (210) on one side, and the through hole (210) on the other side is connected to the inside of the liquid storage tank (23), so that the corrosive liquid circulates in the liquid storage member (21); The valve body (24) is arranged between the through hole (210) on the other side and the liquid storage tank (23), and is used to selectively disconnect the communication between the liquid storage tank (23) and the liquid storage member (21).

3. The preparation device for the stress corrosion crack calibration test block for non-destructive testing according to claim 2, characterized in that: Arc chamfers are provided on both sides of the opening of the liquid storage member (21) that abut against the test block (3).

4. The preparation device for non-destructive testing stress corrosion crack calibration test block according to claim 3, characterized in that: When the pressing mechanism (4) moves to apply a load, the pressing mechanism (4) abuts against a side of the test block (3) away from the liquid storage member (21), and the abutting position corresponds to the position of the prefabricated crack (300), and the magnitude of the applied load is not greater than the yield strength of the test block (3).

5. The preparation device for the stress corrosion crack calibration test block for nondestructive testing according to claim 2, characterized in that: The at least two limiting mechanisms (5) each comprise a fixing seat (51), a plurality of sleeves (52), a plurality of guide members (53), a plurality of limiting members (54), a plurality of elastic members (55) and a plurality of blocking members (56), wherein: The fixing seat (51) is fixed on the base (1) and is arranged corresponding to the position of the liquid storage member (21), and a groove (500) is provided on a side of the fixing seat (51) close to the liquid storage member (21); The plurality of sleeves (52) are all fixed on a side of the fixing seat (51) away from the base (1), and one side of the sleeve (52) penetrates and extends into the groove (500), and the plurality of sleeves (52) on the same side are arranged at intervals; The plurality of guide members (53) are slidably connected in the respective sleeves (52), and one end of the guide member (53) passes through the sleeve (52) and extends into the groove (500), and the guide member (53) is perpendicular to the base (1); The plurality of stoppers (54) are respectively fixed on one end of each guide member (53) extending into the groove (500), and the side of the stopper (54) away from the guide member (53) is in contact with the surface of the test block (3); The plurality of elastic members (55) are respectively sleeved on the outer sides of the guide member (53) and the sleeve (52), and two sides of the elastic members (55) are respectively in contact with the inner wall of the groove (500) and the stop member (54); The plurality of blocking members (56) are respectively arranged on the outside of each guide member (53), and the blocking members (56) are located on a side of the fixing seat (51) away from the base (1).

6. The preparation device for the stress corrosion crack calibration test block for nondestructive testing according to claim 5, characterized in that: The end of the test block (3) is located in the groove (500), and the width of the groove (500) is equal to the width of the test block (3), and the side walls of the test block (3) are respectively in contact with the corresponding inner walls of the groove (500).

7. The preparation device for non-destructive testing stress corrosion crack calibration test block according to claim 1, characterized in that: The crack extension monitoring mechanism (6) comprises a current probe (61), a voltage probe (62) and a crack extension monitor (63), wherein the current probe (61) and the voltage probe (62) are both arranged on the test block (3) and located on one side of the prefabricated crack (300), the current probe (61) and the voltage probe (62) each have two contact portions, and the two contact portions of the current probe (61) and the voltage probe (62) are symmetrically arranged on both sides of the prefabricated crack (300), and the current probe (61) and the voltage probe (62) are both electrically connected to the crack extension monitor (63).

8. The preparation device for non-destructive testing stress corrosion crack calibration test block according to claim 1, characterized in that: It also comprises a plurality of coating layers (7), wherein the plurality of coating layers (7) are all arranged on the test block (3), and the plurality of coating layers (7) are arranged on both sides of the prefabricated crack (300) and the vertical projection position of the pressing mechanism (4) on the test block (3).

9. The preparation device for the stress corrosion crack calibration test block for nondestructive testing according to claim 8, characterized in that: The material of the coating layer (7) is epoxy resin, and the spacing between the coating layer (7) adjacent to the prefabricated crack (300) and the prefabricated crack (300) is 1-3 mm.

10. A method for preparing a stress corrosion crack calibration test block for non-destructive testing, using the device for preparing a stress corrosion crack calibration test block for non-destructive testing as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: S1, using an electrospark machining method to machine a prefabricated crack (300) of a certain length and a depth of 0.1-0.5 mm on the weld, heat-affected zone or the surface of the base material of the test block (3); S2, spot welding the current probe (61) and the voltage probe (62) to the test block (3), so that the two contact parts of the current probe (61) and the voltage probe (62) are symmetrically arranged on both sides of the prefabricated crack (300); S3, coating the remaining area of ​​the surface of the test block (3) with a coating layer (7) except for 1-3 mm on both sides of the prefabricated crack (300) and the contact position between the pressing mechanism (4) and the surface of the test block (3); S4, placing the test block (3) at the top opening of the liquid storage member (21), with the side having the prefabricated crack (300) facing the inside of the liquid storage member (21), and with the position of the prefabricated crack (300) of the test block (3) corresponding to the middle position of the liquid storage member (21), the test block (3) abutting against the groove (500), and the elastic members (55) on both sides pressing the limit members (54) abutting against the upper surface of the test block (3); S5, after the test block (3) is limited by the limiting mechanism (5), the pressing mechanism (4) is driven to move toward the side of the test block (3) to press the back side of the prefabricated crack (300) of the test block (3), and the load applied is not greater than the yield strength of the test block (3); S6, the contact portion between the test block (3) and the liquid storage member (21) is sealed, and the pump body (22) injects the corrosive liquid in the liquid storage tank (23) into the liquid storage member (21), and causes the corrosive liquid to circulate in the liquid storage member (21); S7, the crack depth is analyzed by a crack extension monitor (63). When the crack extends to a desired depth, the corrosive liquid in the liquid storage member (21) is pumped back into the discharge liquid storage tank (23) by the pump body (22), the pressing mechanism (4) is returned to the initial position, and the test block (3) is separated from the liquid storage member (21) and taken out, and the coating layer (7) on the surface of the test block (3) is removed. The test block (3) is cleaned with anhydrous ethanol and then blown dry, and the preparation of the test block (3) is completed.

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