阅读说明：本技术 一种超声检测试块及其制备方法 (Ultrasonic detection test block and preparation method thereof ) 是由 熊江涛 尹小康 张昊 李京龙 孙静茹 宋慧 宋文清 于 2021-01-20 设计创作，主要内容包括：本发明公开了一种超声检测试块及其制备方法,涉及超声检测用试块技术领域。该超声检测试块包括经扩散焊连接的盖板和缺陷板,缺陷板的扩散焊界面位置处在扩散焊之前铣削加工有多个宽度不同的线槽状缺陷,线槽状缺陷的宽度范围为80-1200μm,深度范围为2-6mm。本申请的超声检测试块的线槽状缺陷可以保持在扩散焊界面位置处,试块的缺陷范围广,尤其是相较于传统机械加工的方式获得的试块而言,本申请可以获得具有精准且微米级尺寸的缺陷的超声检测试块,且可以将缺陷精准控制在任意深度位置。本申请中采用线槽状缺陷可以获得形状均匀的试块,有利于提升试块的检测精度,提升扩散焊缺陷检测的检测效果。(The invention discloses an ultrasonic detection test block and a preparation method thereof, and relates to the technical field of test blocks for ultrasonic detection. The ultrasonic detection test block comprises a cover plate and a defect plate which are connected through diffusion welding, wherein a plurality of line groove-shaped defects with different widths are milled at the position of a diffusion welding interface of the defect plate before the diffusion welding, the width range of the line groove-shaped defects is 80-1200 mu m, and the depth range of the line groove-shaped defects is 2-6 mm. The utility model provides a wire casing form defect of ultrasonic testing test block can keep in diffusion welding interface position department, and the defect range of test block is wide, especially compares in the test block that traditional machining's mode obtained, and this application can obtain the ultrasonic testing test block that has the defect of accurate and micron order size, and can be with the accurate control of defect in arbitrary depth position. Adopt the line groove form defect can obtain the even test block of shape in this application, be favorable to promoting the detection precision of test block, promote the detection effect that the diffusion welding defect detected.)

1. The ultrasonic testing test block is characterized by comprising a cover plate and a defect plate which are connected through diffusion welding, wherein a plurality of line groove-shaped defects with different widths are milled and processed at the position of a diffusion welding interface of the defect plate before the diffusion welding, the width range of the line groove-shaped defects is 80-1200 mu m, and the depth range of the line groove-shaped defects is 2-6 mm.

2. The ultrasonic testing test block of claim 1, wherein the linear groove defects are arranged in at least one row in parallel, and the distance between any two adjacent linear groove defects in any one row is 8-12 mm.

3. The ultrasonic detection test block of claim 1, wherein the widths of the line-groove-shaped defects are at least two of 90-110 μm, 140-.

4. The ultrasonic testing block of claim 3, wherein the widths of the plurality of line-groove-shaped defects increase sequentially from left to right.

5. The ultrasonic testing block of any one of claims 1 to 4, wherein the groove depth of the linear groove-like defect is the same as the width of the linear groove-like defect.

6. The ultrasonic testing block of any one of claims 1 to 4, wherein one side of the cover plate away from the defect plate is stepped, and the defect plate corresponding to each step is provided with the linear groove-shaped defect.

7. A preparation method of an ultrasonic detection test block is characterized in that a plurality of line groove-shaped defects with different widths are milled on the surface to be welded of a defect plate, a cover plate, the defect plate and the surface to be welded are assembled and then diffusion welding is carried out, and the width range of the line groove-shaped defects is 80-1200 mu m.

8. The method for preparing an ultrasonic testing block according to claim 7, further comprising cleaning the surface of the cover plate and the to-be-welded surface of the non-defective position of the defective plate before welding;

preferably, the cover plate and the defect plate are ground and polished;

preferably, the surfaces of the cover plate and the defect plate are polished by a polishing liquid;

preferably, the polishing solution is silica sol and hydrogen peroxide in a volume ratio of 8-12: 1;

preferably, after cleaning, the method also comprises the steps of carrying out acid cleaning on the sample to be welded for 1-2min, carrying out ultrasonic cleaning for 8-12min, carrying out water cleaning for 20-40min, and then drying;

preferably, the sample to be welded is acid-washed with a Keller reagent until surface atomization occurs.

9. The method of manufacturing an ultrasonic testing block according to claim 7, wherein assembling the cover plate and the defect plate includes: attaching and centering to-be-welded surfaces of the cover plate and the defect plate, and adding a solder mask for preventing diffusion bonding at a position where the cover plate and the defect plate are in contact with a welding pressure head;

preferably, the solder resist layer comprises a mica sheet.

10. The method of manufacturing an ultrasonic testing block according to claim 7, wherein welding the assembled cap plate and the defect plate includes: keeping the temperature for 50-70min under the conditions that the welding temperature is 800-; and cooling after the heat preservation is finished.

Technical Field

The invention relates to the technical field of test blocks for ultrasonic detection, in particular to an ultrasonic detection test block and a preparation method thereof.

Background

In order to ensure the accuracy, repeatability and comparability of the detection results in ultrasonic detection, the detection system must be calibrated with a sample having known fixed characteristics. Such purpose-designed specimens with simple geometric artificial reflectors or simulated defects are commonly referred to as test blocks. The test block for ultrasonic testing is generally divided into a standard test block, a reference test block and a simulation test block. The artificial reflectors in the test block are selected according to the purpose and should be as close as possible to the defect features to be detected. Usually, the required shape and size are machined inside or on the surface of the material by a mechanical machining method, and the commonly used artificial reflectors mainly comprise long transverse holes, short transverse holes, transverse through holes, flat-bottom holes, V-shaped grooves, other wire-cut grooves and the like.

The transverse through hole and the long transverse hole have the characteristics of axial symmetry, stable reflection amplitude and linear defect characteristics, and generally represent that the inside of a workpiece has cracks, incomplete penetration, incomplete fusion and strip-shaped slag inclusion with certain length. It is commonly used in ultrasonic testing of butt joints, weld overlays, and also in bolt pieces and castings.

The short transverse holes appear as linear reflector features in the inbound field region and as point reflector features in the far field region. The method is mainly used for detecting the butt welding joint.

The flat bottom hole generally has the characteristic of a point-shaped area type reflector, and is mainly used for ultrasonic detection of forgings, steel plates, butt-joint welding joints, composite plates and surfacing layers. The method is generally suitable for calibration and detection of a straight probe and a bimorph probe.

V-grooves and other cut grooves feature linear defects with open surfaces. The device is suitable for transverse wave detection of workpieces such as steel plates, steel pipes, forgings and the like, and can also simulate the defects on the surfaces or near surfaces of other workpieces or butt joints to adjust the detection sensitivity.

FIG. 1 is a test block for ultrasonic testing of defects in welds of aluminum alloy sheets manufactured in patent CN207650160U, wherein the length, width and height of the test block are 250mm, 30mm and 10mm, 1 is a series of transverse holes with phi 1mm, the axes of the transverse holes are perpendicular to the length extension direction of the test block, the transverse holes are totally provided with 5 groups, the depth of each group of transverse holes is respectively 1mm, 2mm, 3mm, 4mm and 5mm, 2 and 3 are two cracks with length of 4mm and width of 0.5mm, and 4 is an artificial unfused defect with inclination angle of 45 degrees and height of 4 mm. The test block is prefabricated with cracks, pores and 3 different types of defects which are not fused. The aluminum alloy weld defects with the base metal thickness smaller than 8mm can be accurately positioned and qualified through the reference block.

In the actual welding manufacturing process, sometimes, in order to pursue the complexity of the structure, the deformation amount after welding needs to be controlled, and all process parameters in the welding process cannot be simultaneously satisfied, which may cause the welding defects such as non-welding, weak connection, holes and the like on the interface as shown in fig. 2. The weld formed by diffusion welding is a quasi-two-dimensional interface region with a small thickness, so that the defect of diffusion welding can be equivalent to the defect of a two-dimensional plane without the thickness.

The lack of welding refers to the existence of obvious continuous defects at the welding interface, and the main reasons for the occurrence of the defects are generally low welding temperature, insufficient welding pressure, insufficient heat preservation time or low vacuum degree and other process deviations. Or the surface to be welded is polluted or has high roughness, the defect of non-welding of the interface is easily generated. Usually, the edge portion of the welded sample is liable to be unwelded due to uneven distribution of interfacial stress.

The weak connection means that the two welding interfaces are only in close physical contact without atomic bonding, and the gap size is in the micron order. The void defects are discrete small voids, typically on the order of microns in size, which is one of the most common defects in diffusion welding. When the welding temperature is low, the welding pressure is low, or the roughness of the surface to be welded is large, the interface hole is not completely closed, and then the defect of the micro-hole is formed.

Because the diffusion welding defects exist in the joint, namely the diffusion welding interface position, and the dimension is micron-sized, the position precision cannot be ensured and the dimension precision cannot be ensured by the traditional machining mode, namely the machining of the internal micron-sized artificial reflector is difficult to realize. Although the method of surface turning and processing threads on the surface to be welded can realize defect prefabrication at a diffusion welding interface, the dimensional precision is difficult to ensure, the shape is uneven, and a test block is difficult to form.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide an ultrasonic detection test block and a preparation method thereof.

The invention is realized by the following steps:

in a first aspect, the invention provides an ultrasonic detection test block, which comprises a cover plate and a defect plate which are connected through diffusion welding, wherein a plurality of line groove-shaped defects with different widths are milled at the position of a diffusion welding interface of the defect plate before the diffusion welding, the width range of the line groove-shaped defects is 80-1200 μm, and the depth range of the line groove-shaped defects is 2-6 mm.

In an alternative embodiment, the line-shaped defects are arranged in at least one row in parallel, and in any row, the distance between any two adjacent line-shaped defects is 8-12 mm.

In an optional embodiment, the widths of the trench-shaped defects are at least two of 90-110 μm, 140-;

in an alternative embodiment, the widths of a plurality of the line-shaped defects increase sequentially from left to right.

In an alternative embodiment, the groove depth of the linear groove defect is the same as the width of the linear groove defect.

In an optional embodiment, one side of the cover plate, which is far away from the defect plate, is stepped, and the defect plate corresponding to each step is provided with the linear groove-shaped defect.

In a second aspect, the invention provides a method for preparing an ultrasonic detection test block, wherein a plurality of line groove-shaped defects with different widths are milled on the surface to be welded of a defect plate, a cover plate, the defect plate and the surface to be welded are assembled and then diffusion welding is carried out, and the width range of the line groove-shaped defects is 80-1200 μm.

In an alternative embodiment, before welding, the method further comprises the step of cleaning the surface of the cover plate and the surface to be welded of the non-defect position of the defect plate;

preferably, the cover plate and the defect plate are ground and polished;

preferably, the surfaces of the cover plate and the defect plate are polished by a polishing liquid;

preferably, the polishing solution is silica sol and hydrogen peroxide in a volume ratio of 8-12: 1;

preferably, after cleaning, the method also comprises the steps of carrying out acid cleaning on the sample to be welded for 1-2min, carrying out ultrasonic cleaning for 8-12min, carrying out water cleaning for 20-40min, and then drying;

preferably, the sample to be welded is acid-washed with a Keller reagent until surface atomization occurs.

In an alternative embodiment, assembling the cover plate and the defect plate includes: attaching and centering to-be-welded surfaces of the cover plate and the defect plate, and adding a solder mask for preventing diffusion bonding at a position where the cover plate and the defect plate are in contact with a welding pressure head;

preferably, the solder resist layer comprises a mica sheet.

In an alternative embodiment, welding the assembled cap plate and the defect plate includes: keeping the temperature for 50-70min under the conditions that the welding temperature is 800-; and cooling after the heat preservation is finished.

The invention has the following beneficial effects:

the ultrasonic testing test block provided by the application has a plurality of line groove-shaped defects with different widths through milling at the position of a to-be-welded interface of a defect plate in advance before diffusion welding, then diffusion welding is carried out to connect a cover plate and the defect plate, so that the line groove-shaped defects are kept at the position of the diffusion welding interface, the defect range is wide through the method, especially, the defect of accurate and micron-sized size can be obtained compared with the mode of traditional mechanical processing, and the defect can be accurately controlled at any depth position. Adopt the line groove form defect can obtain the even test block of shape in this application, be favorable to promoting the detection precision of test block, promote the detection effect that the diffusion welding defect detected.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic structural diagram of a sheet aluminum alloy weld joint ultrasonic detection defect comparison test block in the prior art;

FIG. 2 is a view of a diffusion bond joint interface defect wherein (a) indicates no bonding, (b) indicates a weak bond, and (c) indicates a void;

fig. 3 is a schematic structural diagram of an ultrasonic testing block provided in embodiment 1 of the present application;

fig. 4 is a schematic structural diagram of an ultrasonic testing block provided in embodiment 2 of the present application;

FIG. 5 is a schematic diagram of a pre-fabricated defect profile provided in the first experimental example of the present application;

FIG. 6 is an ultrasonic C-scan image of a pre-fabricated defect provided in Experimental example II of the present application;

FIG. 7 is a waveform diagram of a defect echo at a 100 μm defect in a test block of example 1 according to the third experimental example of the present application;

FIG. 8 shows a sample of comparative example 1 provided in Experimental example III of the present applicationScanning a picture for the flat bottom hole defect C;

fig. 9 shows the diffusion welding interface morphology at 775 ℃ provided by comparative example 2 in the third experimental example of the present application.

Icon: 100-ultrasonic testing of a test block; 110-a cover plate; 120-defect plate; 121-line trough defects.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The application provides an ultrasonic detection test block 100, which comprises a cover plate 110 and a defect plate 120 which are connected through diffusion welding, wherein a plurality of line groove-shaped defects 121 with different widths are milled and processed at the position of a diffusion welding interface of the defect plate 120 before the diffusion welding, the width range of the line groove-shaped defects 121 is 80-1200 mu m, and the depth range is 2-6 mm.

In the application, a plurality of line groove-shaped defects 121 with different widths are milled on the surface to be welded of the defect plate 120 in advance before diffusion welding, the width range of the line groove-shaped defects 121 is 80-1200 μm and is wide, especially, the line groove-shaped defects 121 with small widths can be machined, and after the line groove-shaped defects 121 are machined, welding is carried out, so that the position and the size of the obtained ultrasonic detection test block 100 are machined accurately. In addition, the depth range of the linear groove-shaped defect 121 in the application is wide, and in the actual processing process, the width of the linear groove-shaped defect 121 can be adaptively modified according to the selection of the depth, so that a test block which is more matched with the defect can be obtained.

In the application, the distance between any two adjacent linear groove defects 121 is 8-12mm, and the design of the distance can effectively avoid the mutual influence of ultrasonic signals between the adjacent linear groove defects 121.

It should be understood that the shape of the defects in the present application can have a variety of configurations including, but not limited to, flat bottom holes or wire groove shapes. The dimensions of the line trench defect 121 in the present application can also be selected from a variety of options, including but limited to at least two of 90-110 μm, 140-. The size of other linear trough defects 121 can also be selected according to the size of the actual workpiece. Preferably, the widths of the plurality of line-groove-like defects 121 increase sequentially from left to right. Through the design of gradually increasing the width, the test block corresponding to the size of the workpiece can be found more conveniently during detection.

Further, in the present application, the groove depth of the line-shaped defect 121 is the same as the width of the line-shaped defect 121, so that the cross section of the line-shaped defect 121 is square. In the present application, one side of the cover plate 110, which is far away from the defect plate 120, is stepped, and the corresponding defect plate 120 under each stepped cover plate 110 is provided with a plurality of linear groove defects 121 with different widths. The stepped design can provide a greater range of applications for the thickness of the test block.

The application also provides a preparation method of the ultrasonic detection test block 100, which comprises the following steps:

s1, milling a plurality of line groove-shaped defects 121 with different widths on the surface to be welded of the defect plate 120, wherein the line groove-shaped defects 121 are arranged in parallel in at least one row, and the width range of any line groove-shaped defect 121 in any row is 80-1200 mu m.

In the application, the line-groove-shaped defects 121 are milled on the surfaces to be welded of the defect plates 120, so that micron-scale defects with more accurate machining sizes can be obtained. And can fix defects at the interface of diffusion welding.

And S2, cleaning and washing the defective plate 120 and the cover plate 110.

Preferably, the cover plate 110 and the defect plate 120 are ground and polished; the grinding and polishing can clean the surface to be welded so as to ensure the subsequent welding quality. Specifically, in the application, the surfaces to be welded are ground by using sand paper, and the surfaces of the cover plate 110 and the defect plate 120 are polished to be mirror surfaces by using polishing liquid and keep parallelism; the polishing solution is silica sol and hydrogen peroxide in a volume ratio of 8-12: 1.

Preferably, after cleaning, the method also comprises the steps of carrying out acid cleaning on the sample to be welded for 1-2min, carrying out ultrasonic cleaning for 8-12min, carrying out water cleaning for 20-40min, and then drying;

specifically, in this example, a Keller reagent was used to perform acid washing on the sample to be welded until the surface was atomized. In the present application, the Keller reagent comprises 1ml HF +1.5ml HCl +2.5ml HNO₃+95ml H₂And O. The Keller reagent is used for acid washing, so that an oxide layer on the surface of a sample to be welded can be effectively removed, and the subsequent welding effect is improved.

And S3, assembling the cover plate 110 and the defect plate 120 with the surface to be welded.

Attaching and centering to-be-welded surfaces of a cover plate 110 and a defect plate 120, and adding a solder resist layer for preventing diffusion bonding at a position where the cover plate 110 and the defect plate 120 are in contact with a welding head;

preferably, the solder mask comprises a mica sheet.

And S4, performing diffusion welding on the cover plate 110 and the defect plate 120.

Keeping the temperature for 50-70min under the conditions that the welding temperature is 800-; and cooling after the heat preservation is finished.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment provides an ultrasonic testing block 100, and the preparation method thereof comprises the following steps:

s1 processing line groove-shaped defects 121

And milling a plurality of line groove-shaped defects 121 with different widths on the to-be-welded surface of the defect plate 120 by using milling cutters with different processing sizes to obtain line groove-shaped defects 121 with the widths of 100, 150, 200, 250, 300, 600, 800 and 1000 micrometers from left to right, wherein the center distance is set to be 10mm in order to ensure that ultrasonic echo signals of the grooves do not influence each other.

The cover plate 110 of the present application is a flat plate structure, and only one group of line groove-shaped defects 121 need to be processed.

And S2, cleaning and washing the defective plate 120 and the cover plate 110.

Grinding the surfaces to be welded by using sand paper, and polishing the surfaces of the cover plate 110 and the defect plate 120 by using polishing liquid to a mirror surface and keeping parallelism; the polishing solution is silica sol and hydrogen peroxide in a volume ratio of 10: 1. Keller reagent (1ml HF +1.5ml HCl +2.5ml HNO) was used₃+95ml H₂O) carrying out acid cleaning on a sample to be welded for 2min until the surface is atomized, carrying out ultrasonic cleaning for 10min, washing for 30min, and then drying;

and S3, assembling the cover plate 110 and the defect plate 120 with the surface to be welded.

When a sample to be welded is loaded in a furnace, firstly, the sample is reasonably assembled, the surfaces to be welded of the cover plate 110 and the defect plate 120 are attached and centered, the misalignment of the sample is prevented to ensure that the pressure can be uniformly applied to the surface to be welded, and mica sheets are added between the upper surface and the lower surface of the sample and the contact position of a pressure head to serve as solder masks, so that the diffusion bonding between the sample and the pressure head is prevented. After the sample was assembled, it was placed in an FJK-2 type diffusion welder at a height centered in the oven cavity and initial pressure was applied to bring the joints into intimate contact.

And S4, performing diffusion welding on the cover plate 110 and the defect plate 120.

Inputting set process parameters (the welding temperature is 850 ℃, the welding pressure is 2MPa and the heat preservation time is 60min) at a control panel of the diffusion welding machine, and operating a program to weld. And slowly cooling after heat preservation is finished to form a diffusion welding joint, and reserving the prefabricated defects at the diffusion welding interface position to form the ultrasonic detection test block 100 shown in the figure 3.

Example 2

This example is substantially the same as example 1, except that: the cover plate 110 in this embodiment is a three-step structure, and three groups of the same linear groove-shaped defects 121 are processed.

An ultrasonic test block 100 is formed as shown in fig. 4.

Example 3

The embodiment provides an ultrasonic testing block 100, and the preparation method thereof comprises the following steps:

s1 processing line groove-shaped defects 121

And milling a plurality of line groove-shaped defects 121 with different widths on the to-be-welded surface of the defect plate 120 by using milling cutters with different processing sizes to obtain line groove-shaped defects 121 with the widths of 90 micrometers, 140 micrometers, 190 micrometers, 240 micrometers, 290 micrometers, 590 micrometers, 790 micrometers and 990 micrometers from left to right in sequence, wherein the center distance is set to be 8mm in order to ensure that ultrasonic echo signals of the grooves do not influence one another.

The cover plate 110 in this embodiment is a three-step structure, and three groups of the same linear groove-shaped defects 121 are processed.

And S2, cleaning and washing the defective plate 120 and the cover plate 110.

Grinding the surface to be welded by sand paper, and polishingPolishing the surfaces of the cover plate 110 and the defect plate 120 to a mirror surface by the liquid and keeping the parallelism; the polishing solution is silica sol and hydrogen peroxide in a volume ratio of 10: 1. Keller reagent (1ml HF +1.5ml HCl +2.5ml HNO) was used₃+95ml H₂O) carrying out acid cleaning on a sample to be welded for 2min until the surface is atomized, carrying out ultrasonic cleaning for 12min, washing for 40min, and then drying;

and S3, assembling the cover plate 110 and the defect plate 120 with the surface to be welded.

When a sample to be welded is loaded in a furnace, firstly, the sample is reasonably assembled, the surfaces to be welded of the cover plate 110 and the defect plate 120 are attached and centered, the misalignment of the sample is prevented to ensure that the pressure can be uniformly applied to the surface to be welded, and mica sheets are added between the upper surface and the lower surface of the sample and the contact position of a pressure head to serve as solder masks, so that the diffusion bonding between the sample and the pressure head is prevented. After the sample was assembled, it was placed in an FJK-2 type diffusion welder at a height centered in the oven cavity and initial pressure was applied to bring the joints into intimate contact.

And S4, performing diffusion welding on the cover plate 110 and the defect plate 120.

Inputting set process parameters (welding temperature 900 ℃, welding pressure 2MPa and heat preservation time 70min) at a control panel of the diffusion welding machine, and operating a program to weld. And slowly cooling after heat preservation is finished to form a diffusion welding joint, and reserving the prefabricated defects at the diffusion welding interface position to form a test block.

Comparative example 1

The line trough defect 121 in example 1 was changed to a flat bottom hole defect.

Comparative example 2

The soldering temperature in example 1 was changed to 775 ℃.

Examples of the experiments

First, defect size determination

Sectioning the diffusion welding interface position of the prefabricated defect test block, observing the defect appearance under a scanning electron microscope after polishing and corrosion, wherein the defect is square in shape, the titanium alloy and defect interface is straight, no unwelded and hole defects are found in the diffusion welding interface at the non-defect position, and the influence of non-uniform interface is eliminated, as shown in figure 5. And measuring the size of the defect to obtain the real size of the defect, wherein the deviation of the actual size and the designed size is 1.2 mu m at most from the measurement result, and the design requirement is basically and completely met.

Second, ultrasonic C-scan detection

And (3) selecting a probe with the frequency of 50MHz, the focal length of 10mm and the wafer diameter of 3mm to respectively detect the defects of the test block, and obtaining a result shown in fig. 6, wherein a C-scan image is displayed by a gray scale, each pixel point has a determined gray scale value between 0 and 255, wherein 0 represents black, 255 represents white, the gray scale value in the C-scan image is in direct proportion to the position of the pixel point, namely the interface reflected wave intensity of the scanning point, and the reflected wave intensity is represented by the waveform amplitude of the interface wave. When the diffusion welding interface is well welded and has no defects, the interface echo intensity acquired by the probe is 0, namely the gray value is 0, the picture is represented as black, when the interface has defects, the probe acquires the interface echo with certain intensity, the gray value is increased along with the increase of the intensity of the interface echo, the maximum gray value is 255, and the picture is represented as white. It can be seen from fig. 6 that the width of the gray-white color in the C-scan increases as the defect size increases, and the black areas indicate that the non-defect locations are in a fully welded condition.

Thirdly, evaluating the ultrasonic detection result

The ultrasonic testing test blocks obtained in the above examples 1-3 and comparative examples 1-2 are used for calibrating the testing system, and the method comprises the following steps:

before ultrasonic detection, a test block is needed to be calibrated so as to adjust equipment detection parameters corresponding to the probe and detect the size of the expected defect. That is, the smaller the size of the defect prefabricated in the test block is, the more regular and uniform the shape is, and the smaller the defect can be detected, the higher the detection precision is. Aiming at the water immersion focusing probe, the steps of adjusting detection parameters by using a test block are as follows:

for a defect of 100 μm in example 1, a probe with a frequency of 50MHz, a focal length of 10mm, and a wafer diameter of 3mm is used, the height of the probe is adjusted, the focal point of the focused acoustic beam of the probe is focused on the depth of a diffusion welding interface, the probe is moved to be positioned in the center of the defect, the gain is adjusted to make the defect echo reach 90% of a full screen, the gain value is recorded to be-5 dB, the waveform of the defect echo is shown in fig. 7, and the ultrasonic C-scan is shown in fig. 6. And recording the gain values of all defects and an ultrasonic C-scan picture for quantitative detection of the defects of 100-1000 mu m.

Compared with the example 1, the embodiment 2 has the advantages that the thickness (step height, 2mm, 4mm and 6mm) variables are increased, the gain values of all sizes and all thicknesses are recorded, and the detection parameters are adjusted, so that the method can be used for quantitative detection of defects of 100-1000 mu m at different depth positions.

Example 3 the same as example 1 can ensure the dimensional accuracy of the preliminary defects at the diffusion-welded interface position.

Comparative example 1, prefabricating at diffusion welding interfaceThe flat bottom hole, the parameters adjusted, the ultrasound C-scan image obtained is shown in FIG. 8. It can be seen that the shape is not uniform and cannot be used as a standard test block for adjusting detection parameters, and the defect is a non-through hole defect and is located inside a diffusion welding test block material, and the defect size cannot be obtained by sectioning as shown in fig. 5, because the integrity of the test block can be damaged.

In comparative example 2, the non-defective position of the cover plate and the defective plate cannot be reliably connected by lowering the TC4 titanium alloy diffusion welding temperature, as shown in FIG. 9, the diffusion welding interface at 775 ℃ can retain the defect of an unwelded hole, the uniformity of the test block is affected, and the diffusion welding interface cannot be used as a standard test block for adjusting and detecting parameters.

The test pieces obtained in examples 1 to 3 and comparative examples 1 to 2 were calibrated, and the calibration results were as follows:

examples of the invention	Quantitative determination accuracy (minimum quantitative determination size)
		Example 1	100μm
Example 2	100μm
		Example 3	100μm
Comparative example 1	Greater than 1000 μm
		Comparative example 2	Greater than 100 μm

As can be seen from the above table, the method for preparing the ultrasonic testing test block by using the diffusion welding method used in the present application has the highest quantitative detection precision.

To sum up, the ultrasonic testing block 100 provided by the present application is milled and processed with a plurality of line groove-shaped defects 121 with different widths at the diffusion welding interface position of the defect plate 120 in advance before diffusion welding, and then diffusion welding is performed to connect the cover plate 110 and the defect plate 120, so that the line groove-shaped defects 121 can be maintained at the diffusion welding interface position, and by this method, a wide defect range can be obtained, and especially, compared with the conventional machining mode, the defects with precise and micron-sized dimensions can be obtained, and the defects can be precisely controlled at any depth position. Adopt wire casing form defect 121 can obtain the even test block of shape in this application, be favorable to promoting the detection precision of test block, promote the detection effect that the diffusion welding defect detected.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.