CN116793776A - Analysis system and method for dynamic evolution of microstructure strain in ultra-high temperature deformation of materials - Google Patents

Abstract

The present invention provides an analysis system and method for the dynamic evolution of microstructure strain of ultra-high temperature deformation of materials. The system uses a sample preparation mechanism to cut sheet-shaped materials to be tested, and preprocesses according to test requirements to obtain effective material samples; The test speckle formation mechanism produces high-contrast random speckles for the material sample; then the in-situ tensile observation mechanism performs an in-situ tensile test on the speckle material sample in an ultra-high temperature environment based on a set displacement rate, using laser scanning The confocal microscope conducts real-time observation of the video and dynamic images of the sample; finally, the deformation strain evolution analysis module analyzes the dynamic images of the test process based on the DIC algorithm, constructs the displacement field on the surface of the speckle material sample, and calculates the corresponding strain field. ; Overcoming the comprehensive limitations of traditional technology, the microscopic failure mechanism of ultra-high temperature materials can also be observed in a refined manner, which is more practical and can further reliably analyze the evolution of the strain field of various material deformations.

Description

Analysis system and method for dynamic evolution of microstructure strain in ultra-high temperature deformation of materials

Technical field

The invention relates to the technical field of material failure observation and analysis, and in particular to an analysis system and method for the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials, which is used for in-situ observation of materials when they are subjected to tensile/compression (fatigue) loads under ultra-high temperature conditions. Material surface structure, strain evolution, crack initiation, propagation, failure and other phenomena, and analyze the evolution rules.

Background technique

The microstructure state of the material interacts with the service environment (such as coupling with the temperature field, stress field, etc.), which directly affects the performance and service life of the material. In recent years, the field has been continuously committed to the research of in-situ testing technology that can accurately simulate the service conditions of materials, realize microscopic testing and research on the surface structure of materials, observe the changes in the microstructure of the material surface under the action of external fields at different scales, and obtain materials Fracture damage behavior under loading.

There is a close relationship between the stress and strain characteristics of materials and their failure behavior. In particular, the stress and strain state of materials in the micron-scale micro-region range is often used to explain macroscopic failure phenomena. It is difficult to achieve stress and strain testing and analysis at the micron level with the existing conventional testing techniques. In recent years, the newly developed electron backscattered diffraction (EBSD) technology has become a powerful means to analyze the stress and strain state of micro-areas. Using an in-situ stretching table The scanning electron microscope (SEM) can study the stress and strain concentration problem during the deformation process, but the maximum test temperature allowed by the SEM in a high-temperature environment is 1200°C, which cannot meet the test requirements for in-situ observation of ultra-high temperature tensile stress. In addition, EBSD technology measures lattice strain and cannot analyze the plastic strain of the material.

The information disclosed in the Background of the Invention section is merely intended to enhance understanding of the general background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art that is already known to those skilled in the art.

Contents of the invention

In order to solve the above problems, the present invention provides an analysis system for the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials. By combining ultra-high temperature laser scanning confocal microscopy with DIC analysis technology, the system can analyze the structure of the material deformation process under ultra-high temperature. Through in-situ observation and analysis of processes such as evolution and strain dynamic evolution, we can reveal the initiation and development mechanism of cracks at ultra-high temperatures from a mesoscopic scale, and provide an effective research method for studying the microscopic failure mechanisms of ultra-high temperature materials. In one embodiment, the system includes:

The sample preparation mechanism is configured to cut sheet-shaped materials to be tested, and preprocess them according to test requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation testing of materials;

A test speckle formation mechanism configured to produce high-contrast random speckles for the obtained material sample to obtain a speckle material sample; the speckles are speckle particles with a size in the submicron/nanometer range and stable performance;

An in-situ tensile observation mechanism configured to perform an in-situ tensile test on the speckle material sample based on a set displacement rate using a high-temperature tension and compression system in a high-temperature heating furnace environment cavity. Laser scanning is used during the test process. The confocal microscope can observe and save the video and dynamic images of the sample in real time;

The deformation strain evolution analysis module is connected to the in-situ tensile observation mechanism and is configured to analyze the dynamic image of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckle material sample, and calculate the corresponding strain field.

Preferably, the sample preparation mechanism includes a material cutting module and a material processing module;

The material cutting module is used to cut sheet materials of a set size from the plate by wire cutting according to the experimental requirements of ultra-high temperature in-situ observation;

The material processing module is configured to use a sandpaper smoothing device to smooth both sides of the cut sheet material, select one side as the observation surface, and use a metallographic sandpaper device to polish step by step until the observation requirements are met; and then use a marking device to The observation surface marks the observation area, and the marking device is a microhardness tester.

Further, the test speckle forming mechanism includes:

The primer spraying module is configured to evenly spray a set thickness of matte high-temperature primer on the observation surface of the material test while ensuring that the surface of the material sample is clean and free of dirt;

A speckle spray module configured to further spray dispersed and randomly distributed high-contrast high-temperature paint on the high-temperature primer.

As a further improvement of the present invention, the test speckle forming mechanism also includes

The speckle sample baking module uses a muffle furnace to bake the material sample after speckle spraying at a constant temperature according to the set temperature and duration, so that the speckles have high temperature stability.

Further, the in-situ stretching observation mechanism includes a stretching and compression workbench arranged in the environmental cavity of the high-temperature heating furnace and two loading mechanisms;

The loading mechanism is used to install speckle material samples. The first loading mechanism is fixed on the tension and compression workbench, and the other is connected to the linear driver of the high temperature tension and compression system.

Optionally, the laser scanning confocal microscope of the in-situ stretching observation mechanism uses a purple laser VL2000DX with a wavelength of 408 nm and a scanning speed of 15 to 120 frames per second.

Further, the in-situ tensile observation mechanism also includes a test preprocessing module, which is configured to evacuate the vacuum chamber and use ultra-high-purity argon gas after installing the speckle material sample on the loading mechanism and before heating. Purge to reduce oxygen content and protect the specimen surface from oxidation.

As a further improvement of the present invention, the laser scanning confocal microscope tracks the marked area of the material sample in real time during shooting, so that the marked area is always located in the center of the field of view during the entire stretching process, and the observation video is saved in real time and at set time intervals. Save the picture at the corresponding moment and record the tensile curve of the test in real time.

Preferably, the deformation strain evolution analysis module includes an image screening unit and a strain analysis unit;

The image screening unit is configured to screen the material surface photos of the in-situ stretching process obtained through ultra-high temperature laser scanning confocal microscopy, and select effective speckle images whose grayscale distribution meets the set requirements;

The strain analysis unit is configured to use the DIC algorithm to calculate the filtered effective speckle images to achieve matching of deformation points on the object surface, and reconstruct the coordinates of the calculation points on the object surface based on the parallax data of each corresponding point; and by comparing each deformation The coordinate changes of each point in the state measurement area are used to obtain the displacement field on the object surface, and then the strain field on the object surface is calculated using GOM software and VIC-2D software.

Based on the application of the system described in any one or more of the above embodiments, the present invention also provides a method for analyzing the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials, which method includes:

The sample preparation step is to cut the sheet material to be tested and preprocess it according to the test requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation testing of materials;

The test speckle formation step is to produce high-contrast random speckles for the obtained material sample to obtain a speckle material sample; the speckles are speckle particles with a size in the submicron/nanometer range and stable performance;

In the tensile in-situ observation step, in the environmental cavity of a high-temperature heating furnace, a high-temperature tensile and compression system is used to perform an in-situ tensile test on the speckle material sample based on a set displacement rate. A laser scanning confocal microscope is used during the test process. Observe and save the video and dynamic images of the specimen in real time;

The deformation strain evolution analysis step is configured to analyze the dynamic image of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckle material sample, and calculate the corresponding strain field.

Compared with the closest existing technology, the present invention also has the following beneficial effects:

The invention provides an analysis system and method for the dynamic evolution of ultra-high temperature deformation microstructure strain of materials. The sheet-shaped material to be tested is cut and pre-processed to obtain an effective material sample, and then a test speckle forming mechanism is used to create high-performance material samples. Contrast random speckles provide a basis for analysis of material tensile stress field evolution based on the DIC algorithm, and can also improve the quality and stability of observation images;

Then based on the set displacement rate, the speckle material sample in the ultra-high temperature environment was subjected to in-situ tensile testing, and a laser scanning confocal microscope was used to observe the video and dynamic images of the sample in real time; finally, the deformation strain evolution analysis module was based on The DIC algorithm analyzes the dynamic images of the test process, constructs the displacement field on the surface of the speckle material sample, and calculates the corresponding strain field; it solves the problem that conventional DIC tests cannot observe the microstructure using high-speed cameras, and breaks through traditional technology. Due to the test temperature limitations that exist in ultra-high temperature materials, the microscopic failure mechanism of ultra-high temperature materials can also be observed in detail, which is more practical. It can also realize the dynamic evolution of strains and the crack initiation mechanism of the tensile deformation failure process of various materials under ultra-high temperature conditions. further reliable analysis.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and obtained by the structure particularly pointed out in the written description, claims and appended drawings.

Description of the drawings

The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation of the present invention. In the attached picture:

Figure 1 is a schematic structural diagram of an analysis system for the dynamic evolution of microstructure strain under ultra-high temperature deformation of materials provided by an embodiment of the present invention;

Figure 2 is an example diagram of the size of a material sample of the analysis system for the dynamic evolution of ultra-high temperature deformation microstructure strain of materials provided by the embodiment of the present invention;

Figure 3 is an example diagram of speckle preparation of the analysis system for the dynamic evolution of ultra-high temperature deformation microstructure strain of materials provided by another embodiment of the present invention;

Figure 4 is a composition diagram of the in-situ tensile observation mechanism of the analysis system for the dynamic evolution of microstructure strain under ultra-high temperature deformation of materials according to the embodiment of the present invention;

Figure 5 is an example diagram of the DIC algorithm principle of the analysis system for the dynamic evolution of ultra-high temperature deformation microstructure strain of materials provided by an embodiment of the present invention;

Figure 6 is a schematic flowchart of a method for analyzing the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials provided by yet another embodiment of the present invention.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, whereby practitioners of the present invention can fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects and based on the above implementation process Implement the present invention concretely. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features of the embodiments can be combined with each other, and the resulting technical solutions are within the protection scope of the present invention.

Although the flowcharts depict various operations as sequential processes, many of the operations may be performed in parallel, concurrently, or simultaneously. The order of operations can be rearranged. The process may be terminated when its operations are completed, but may also have additional steps not included in the figures. A process may correspond to a method, function, procedure, subroutine, subroutine, etc.

The terms "first", "second", etc. may be used herein to describe various units, but these units should not be limited by these terms, which are used solely to distinguish one unit from another unit. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. When an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the exemplary embodiments. As used herein, the singular forms "a," "an" and "an" are intended to include the plural referents as well, unless the context clearly dictates otherwise. It will also be understood that the terms "comprising" and/or "comprising" as used herein specify the presence of stated features, integers, steps, operations, units and/or components without excluding the presence or addition of one or more Other characteristics, integers, steps, operations, units, components and/or combinations thereof.

The interaction between the material's microstructure and the service environment (such as coupling with the temperature field and stress field, etc.) directly affects the material's performance and service life. In recent years, in-situ testing technology that can simulate the service conditions of materials has been developed at home and abroad. It combines the loading effect with the microscopic testing research of the material surface structure, and tracks and observes the microstructure evolution of the material surface under the action of external fields in real time at different scales. Characteristics, analyzing the deformation mechanism and fracture damage behavior of materials. There is a close relationship between the stress and strain characteristics of materials and their failure behavior. In particular, the stress and strain state of materials in the micron-scale micro-region range is often used to explain macroscopic failure phenomena. It is difficult to achieve stress and strain testing and analysis at the micron level with existing conventional testing techniques. In recent years, the newly developed electron backscattered diffraction (EBSD) technology has become a powerful means to analyze the stress and strain state of micro-regions. Scanning electron microscopy (SEM) with an in-situ stretching stage combined with EBSD technology can study the stress and strain concentration problem during deformation. However, the maximum test temperature allowed by the SEM in a high-temperature environment is 1200°C, which cannot meet the requirements of ultra-high temperature in-situ stretching. Observed test requirements. In addition, EBSD technology measures lattice strain rather than plastic strain. At present, there is a lack of methods to analyze the structural strain distribution and dynamic evolution process of materials based on observing the ultra-high temperature structural changes and crack initiation and expansion processes.

For example, CN112881195A provides a hot and cold in-situ tensile microstress testing system, which can realize tensile experiments and observations under a set temperature environment. The imaging lens of the DIC microstrain measurement system is set to face the tensile cavity. The transparent window is set up, and the digital image correlation method and binocular stereomicroscope technology are combined to microscopically observe and measure the three-dimensional coordinates, displacement and strain of the sample surface during the deformation process of the sample in the tensile cavity. Although this testing system can achieve stable temperature and humidity in the tensile chamber and can be flexibly adjusted according to test needs. The DIC microstrain measurement system provides real-time imaging and damage observation of the test process, but its available test temperature conditions have limitations and cannot be measured. The tensile strain of materials in ultra-high temperature environments, and it is impossible to analyze the tissue strain distribution and dynamic evolution process on the basis of observing the ultra-high temperature structural changes and crack initiation and expansion processes of materials.

The technicians of the present invention considered that the laser scanning confocal microscope (LSCM) can observe in real time and continuously the changes in the surface structure and metallographic phase of the material as well as the initiation, expansion and failure of cracks when it is subjected to tensile/compressive (fatigue) external forces at high temperatures. Phenomenon, etc., and at the same time, real-time, in-situ and high-definition observation and analysis of changes in material structure can be achieved at high temperatures or even ultra-high temperatures.

Based on this, the present invention provides a solution that uses ultra-high-temperature laser scanning confocal microscopy combined with DIC technology to realize the dynamic evolution analysis of microstructure strain of ultra-high temperature deformation of materials, and analyzes the structural evolution and strain dynamic evolution process of the material deformation process at ultra-high temperature. , can reveal the initiation and development mechanism of cracks at ultra-high temperatures from a mesoscopic scale, overcoming the problem that existing in-situ observation technology cannot study the deformation structure of ultra-high temperature (above 1200°C) materials and effectively analyze the dynamic evolution process of strains.

Next, the detailed process of the analysis system according to the embodiment of the present invention will be described in detail based on the accompanying drawings. Although a logical sequence of operations is shown in the Principles of System Operation content, under certain circumstances, the operations shown or described may be performed in a sequence different from that described herein.

Embodiment 1

Figure 1 shows a schematic structural diagram of a system for analyzing the dynamic evolution of microstructure strain under ultra-high temperature deformation of materials provided in Embodiment 1 of the present invention. Referring to the information in Figure 1, it can be seen that the system includes:

The sample preparation mechanism is configured to cut sheet-shaped materials to be tested, and preprocess them according to test requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation testing of materials;

A test speckle formation mechanism configured to produce high-contrast random speckles for the obtained material sample to obtain a speckle material sample; the speckles are speckle particles with a size in the submicron or nanometer range and stable performance;

An in-situ tensile observation mechanism configured to perform an in-situ tensile test on the speckle material sample based on a set displacement rate using a high-temperature tension and compression system in a high-temperature heating furnace environment cavity. Laser scanning is used during the test process. The confocal microscope can observe and save the video and dynamic images of the sample in real time;

The deformation strain evolution analysis module is connected to the in-situ tensile observation mechanism and is configured to analyze the dynamic image of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckle material sample, and calculate the corresponding strain field.

Based on the above analysis system, the present invention uses an ultra-high temperature laser scanning confocal microscope to obtain high-resolution images during the material deformation process in real time, solving the problem that traditional DIC tests cannot observe the microstructure using high-speed cameras. On the other hand, By combining ultra-high-temperature laser scanning confocal microscopy with DIC analysis technology, the problem that SEM+EBSD methods cannot study the dynamic evolution process of material deformation and strain at ultra-high temperature is solved, and it provides a practical way to study the microscopic failure mechanism of ultra-high temperature materials. This effective research solution can be effectively applied to various demand scenarios in the field of material failure analysis, and provides an effective observation method for the study of strain dynamic evolution and crack initiation mechanism in the material deformation and failure process under ultra-high temperature conditions.

In a preferred embodiment, the sample preparation mechanism includes a material cutting module and a material processing module;

The material cutting module is used to cut sheet materials of a set size from the plate by wire cutting according to the experimental requirements of ultra-high temperature in-situ observation;

The material processing module is configured to use a sandpaper smoothing device to smooth both sides of the cut sheet material, select one side as the observation surface, and use a metallographic sandpaper device to polish step by step until the observation requirements are met; and then use a marking device to The observation surface marks the observation area, and the marking device is a microhardness tester.

Specifically, in actual application, according to the experimental requirements of ultra-high temperature in-situ observation, in-situ tensile specimens are cut from the plate by wire cutting (the size of the sheet specimen is selected as shown in Figure 2), and the gauge length is It is 17mm, width is 5mm, and thickness is 1.5mm. In order to facilitate the installation of the sample onto the loading device of the in-situ tensile observation mechanism, a hole with a diameter of 5.1 mm is reserved at the set position of the sample clamping end for loading and unloading the sample and the loading device.

The size of the sheet sample required for setting up the high-temperature tensile experiment in the present invention is shown in Figure 2. This size is a standard size. In actual application, except that the size of the two ends and the size of the hole are fixed corresponding to the needs, the size of the middle Part length, width and thickness can be changed appropriately.

Then use metallographic sandpaper to smooth both sides of the sample. Select one side to be used as the observation surface. Use metallographic sandpaper to grind it step by step to 2000 mesh, and then mechanically polish it to a mirror surface to facilitate fine observation.

Further, in the embodiment of the present invention, a microhardness tester is used to prepare indentations at four corners of the observation area for marking. When preparing the indentations, the preparation load can be set to 0.5N. The present invention uses a microhardness tester to prepare indentations as marks of the observation area. On the basis of ensuring the accuracy of the mark position, even if the material sample deforms during the tensile test, it will not affect the effectiveness of the mark in the observation area, and Maintains stability even in ultra-high temperature environments.

After the sample is prepared, surface impurities are removed through alcohol cleaning or ultrasonic cleaning, and surface moisture is removed by drying.

After obtaining a material sample whose observation surface meets the test requirements and is clean, in order to obtain a high-contrast random grayscale distribution image, the surface of the sample must have random characteristics. Before measurement, the measured object needs to be sprayed and stained. The present invention A test speckle forming mechanism is used to produce high-contrast random speckles for the obtained material sample to obtain a speckle material sample; in one embodiment, the test speckle forming mechanism includes:

The primer spraying module is configured to evenly spray a set thickness of matte high-temperature primer on the observation surface of the material test while ensuring that the surface of the material sample is clean and free of dirt;

A speckle spray module configured to further spray dispersed and randomly distributed high-contrast high-temperature paint on the high-temperature primer.

Further, in a preferred embodiment, the test speckle forming mechanism further includes

The speckle sample baking module uses a muffle furnace to bake the material sample after speckle spraying at a constant temperature according to the set temperature and duration, so that the speckles have high temperature stability.

In practical application, the present invention can first spray a layer of white high-temperature paint as a primer on the sample, and then spray a dispersed and randomly distributed black high-temperature paint on the primer. In order to improve the deformation measurement sensitivity and spatial resolution of speckle photography technology, the present invention produces speckle particles with a size in the submicron/nanometer range and stable performance. At the same time, in order to ensure the stability of the prepared high-temperature speckles, the sample is placed Baked in a muffle furnace, the baking temperature is 230°C and the baking time is 30 minutes, which provides basic support for the effective development of ultra-high temperature tests.

The quality of speckles directly affects the accuracy of analysis results. In order to obtain reliable experimental observation results, it is very important to prepare high-quality speckle legends. In the present invention, it is set to produce high-quality speckles that meet the following rules:

(1) Random speckle spots: Speckle spots need to be randomly distributed rather than regularly arranged;

(2) High contrast: The more obvious the contrast between black and white, the better;

(3) Uniform size: The size of speckle spots needs to be consistent, and try to avoid the appearance of different speckle spot sizes;

(4) 50% ratio: black and white each account for 50%. If the surface color of the sample is white, black speckles need to be made.

Specifically, nanopowders and dispersants can be used to prepare high-quality speckles that meet the above conditions through the following operations:

Speckle materials used in the preparation process include: nanopowder (such as nano-SiO ₂ ), dispersant and base material, and equipment includes ultrasonic cleaning machines and droppers.

The preparation operations include: polishing the surface of the sample to be tested to a bright, scratch-free mirror surface; fully mixing the nanopowder and dispersant according to the required different ratios, and using ultrasonic to disperse evenly; keeping the treated surface to be tested horizontally, and taking a portion The dispersed mixture is dropped vertically on the surface to be measured as a speckle mixture, allowing the mixture to spread freely on the surface to be measured. Then use filter paper to absorb the droplets on the surface from the edge of the droplet, and then slowly move the surface to be measured. Tilt it at 40° to 80°, rinse with absolute ethanol, and then quickly dry the surface to be tested to obtain speckles on the surface to be tested;

In addition, in order to ensure that the finished speckle products put into the tensile test are qualified, after the speckles are prepared, multiple samples can be prepared in the same group, microscopic photos of the surface to be tested are also taken, and the sample image is analyzed to identify whether the nanoparticle distribution is uniform. , and if the number of samples with an area of 30%-50% of the nanoparticles in the photo reaches the set value, the requirements are met. If not all requirements are met, adjust the parameters of the preparation operation and prepare again according to the above steps until the prepared speckles are If the conditions are met, the corresponding preparation operation parameters are applied to the sample processing before the tensile test of the present invention.

If the size of a speckle spot is 5 pixels, then its distance from the next speckle spot should also be 5 pixels (5 pixels black, 5 pixels white), as shown in Figure 3.

Furthermore, in order to improve the deformation measurement sensitivity and spatial resolution, the present invention produces speckle particles with a size in the submicron/nanometer range and stable performance. The specific operation method of speckle preparation is:

(1) Ensure that the surface of the test sample is clean and free of dirt;

(2) Spray a layer of white high-temperature paint as the primer on the sample. Shake well before spraying to avoid blocking during the spraying process;

(3) Spray white matte paint evenly, and the thickness should not be too thick or too thin;

(4) Then spray dispersed and randomly distributed black high-temperature paint on the white primer; in order to ensure the stability of the prepared high-temperature speckles, the prepared speckle samples are placed in a muffle furnace and baked. The temperature is 230℃ and the baking time is 30min.

During the high-temperature tensile in-situ observation test, the structural changes and failure process on the sample surface can be directly observed through a laser scanning confocal microscope, but strain evolution analysis cannot be performed. As a non-contact measurement method, DIC technology can achieve full-field strain measurement; speckles are prepared on the sample surface to facilitate pixel tracking by the DIC method.

After obtaining a material sample with random speckles, the material sample is placed in an in-situ tensile observation mechanism to conduct an in-situ tensile test. The present invention uses a high-temperature tensile and compression system through the in-situ tensile observation mechanism based on the set displacement. The team conducted in-situ tensile testing on speckle material samples in a high-temperature heating furnace environment. During the testing process, a laser scanning confocal microscope was used to observe and save the video and dynamic images of the samples in real time.

In one embodiment, as shown in Figure 4, the in-situ stretching observation mechanism includes a stretching and compression workbench arranged in the environmental cavity of a high-temperature heating furnace and two loading mechanisms;

The loading mechanism is used to install speckle material samples. The first loading mechanism is fixed on the tension and compression workbench, and the other is connected to the linear driver of the high-temperature tension and compression system; among them, the high-temperature heating furnace is mainly used to provide high-temperature tension and compression. The test environment cavity for the stretching and compression process, and the high-temperature heating furnace is equipped with a stretching and compression workbench.

In one embodiment, the laser scanning confocal microscope of the in-situ stretching observation mechanism uses a purple laser VL2000DX with a wavelength of 408 nm. The scanning speed can reach 15 to 120 frames per second, which can observe and save dynamic images in real time at high speed. .

The high-temperature tensile and compression system uses dual halogen lamps to conduct reflective heating of the specimen. The effective heating area is A loading mechanism in the furnace environmental chamber is used to mount small tensile specimens. Of the two loading mechanisms, one is fixed and the other is connected to the linear drive. A constant load or constant displacement rate will be applied to the specimen, with a driving speed of 0.01 to 20mm/min and an effective test stroke of 80mm.

Further, in one embodiment, the in-situ tensile observation mechanism also includes a test preprocessing module, which is configured to evacuate the vacuum chamber and use Ultra-high purity argon purge to reduce oxygen content and protect the sample surface from oxidation.

Considering that the marked area will continue to move with the stretching process, in an optional embodiment, the laser scanning confocal microscope is set to track the marked area of the material sample in real time when taking pictures, so that the marked area is always located during the entire stretching process. In the center of the field of view, the observation video is saved in real time, and pictures at corresponding moments are saved at set time intervals. At the same time, the tensile curve of the test is recorded in real time. Among them, the tensile curve refers to the computer control system that will output file records recording load, displacement and other related data during the tensile test. According to the data in the file, the tensile curve that changes with time can be obtained.

Taking a certain material sample to be tested as an example, a targeted ultra-high temperature in-situ tensile test can be achieved through the following steps:

(1) Using an ultra-high temperature laser scanning confocal microscope (LSCM) with tension and compression function, the sample is installed on the loading fixture through bolts. Before heating, the vacuum chamber is evacuated and purged with ultra-high purity argon gas. To reduce the oxygen content (nitrogen flow rate 100ml/min) to protect the sample surface from oxidation.

(2) Focus by adjusting the distance between the lens and the sample surface until the lens obtains a clear image; adjust the position of the lens so that the marked area is in the center of the field of view; set the magnification reasonably and ensure that the magnification remains unchanged during the shooting process.

(3) During the test, the temperature in the chamber was measured by a thermocouple. According to the experimental requirements, set a certain heating rate on the control end to raise the temperature to the specified temperature. Also set a constant displacement rate at the control end, and stretch the sample at a certain displacement rate at the set experimental temperature until it breaks.

(4) During the test, the speckle images of each deformation stage of the sample are collected in real time. Since the marked area will continue to move with the stretching process, it is necessary to track the marked area in real time when shooting; during the entire stretching process, the microstructure evolution and cracks on the surface of the sample during the high-temperature stretching process can be observed and recorded in real time through the microscopic imaging system genesis and expansion process. During the experiment, the observation video is saved in real time and one picture is saved every second. The picture format is JPG or PNG. At the same time, the stretching curve is recorded in real time.

Carry out the tensile test according to the above logic until the material test breaks into an invalid state and the test is completed.

During the high-temperature tensile in-situ observation test, the structural changes and failure process on the sample surface can be directly observed through a laser scanning confocal microscope, but strain evolution analysis cannot be performed.

As a non-contact measurement method, DIC technology can realize the measurement of full-field strain; further, according to the test requirements, researchers can use the deformation strain evolution analysis module to analyze the test based on the DIC algorithm during the test or after the test is completed. Part or all of the dynamic images of the process are analyzed to construct the displacement field on the surface of the speckle material sample and calculate the corresponding strain field. The digital image correlation (DIC) method is based on a speckle pattern with a certain distribution of feature points. These feature points are based on pixel points as coordinates, and use the grayscale of the pixel as the information carrier. Before the relevant algorithm is run, a square image is selected. Sub-area, the center of this sub-area is the pixel of interest. During the process of image movement or deformation, the displacement vector at the center point of the sub-region can be obtained by tracking the position of the image sub-region in the deformed image (ie, the target image). After analyzing the displacement vectors of the center points of multiple sub-areas, the displacement field of the entire analysis area is formed.

As shown in Figure 5, one of them is used as a reference image and the other is used as the image to be matched. In the reference image, take (2M+1)×(2M+1) centered on the point to be matched (x, y). In the image to be matched, through a certain search method and performing correlation calculations according to a certain correlation function, find the rectangular sub-image with the largest correlation coefficient with the selected sub-image centered on (x′, y′) sub-image, then point (x′, y′) is the corresponding point of point (x, y) in the image to be matched.

In one embodiment, the deformation strain evolution analysis module includes an image screening unit and a strain analysis unit;

The image screening unit is configured to screen the material surface photos of the in-situ stretching process obtained through ultra-high temperature laser scanning confocal microscopy, and select effective speckle images whose grayscale distribution meets the set requirements;

The strain analysis unit is configured to use the DIC algorithm to calculate the filtered effective speckle images to achieve matching of deformation points on the object surface, and reconstruct the coordinates of the calculation points on the object surface based on the parallax data of each corresponding point; and by comparing each deformation The coordinate changes of each point in the state measurement area are used to obtain the displacement field on the object surface, and then the strain field on the object surface is calculated using GOM software and VIC-2D software.

Specifically, in one embodiment, the strain analysis unit uses GOM software and VIC-2D software to calculate the strain value of each pixel; the strain increase at each pixel under the loading step can be calculated through two adjacent deformation images. quantity, combined with the image processing function to form the corresponding strain distribution image and strain increment distribution image.

For practical application, the material surface failure photos of the in-situ stretching process obtained through ultra-high temperature laser scanning confocal microscopy (LSCM) are first screened to select high-quality speckle images with a certain grayscale distribution.

The present invention uses a digital image (DIC) correlation algorithm to analyze photos obtained by in-situ stretching of an ultra-high temperature laser scanning confocal microscope (LSCM) (selecting speckle images with a certain grayscale distribution) to achieve matching of deformation points on the object surface. , based on the parallax data of each point, the coordinates of the calculated points on the object surface are reconstructed; and the displacement field of the object surface is obtained by comparing the coordinate changes of each point in the measurement area of each deformation state, and the strain field of the object surface is further calculated. By comparing the speckle pattern of the material surface before and after deformation and using the full-field displacement and strain obtained by relevant algorithms, the research and analysis of the strain distribution and dynamic evolution process of the microstructure of the sample surface are realized; for example, GOM software and VIC-2D software are used to calculate each The strain value of a pixel. The strain increment at each pixel under the loading step can be calculated through two adjacent deformation images. Through the image processing function of the software, the strain distribution image and strain increment distribution image can be obtained. By comparing the speckle pattern before and after deformation of the material surface under the action of external load or other factors and using the full-field displacement and strain obtained by using relevant algorithms, the research and analysis of the microstructure strain distribution and dynamic evolution process of the sample surface can be achieved.

This invention solves the problem that the existing SEM combined with EBSD in-situ observation technology cannot study the dynamic failure process of ultra-high temperature (above 1200°C) materials. It uses ultra-high temperature laser scanning confocal microscope (LSCM) combined with DIC technology to detect the deformation of materials under ultra-high temperature. Analyzing the dynamic evolution of strain during the process provides an effective method for revealing the initiation and development mechanism of cracks at ultra-high temperatures. It can be used in the field of material failure analysis to provide reliable observation data for the study of the strain dynamic evolution and crack initiation mechanism of the material deformation and failure process under ultra-high temperature conditions.

In the analysis system for the dynamic evolution of ultra-high temperature deformation microstructure strain of materials provided by embodiments of the present invention, each module or unit structure can be operated independently or in combination according to experimental requirements and calculation requirements to achieve corresponding technical effects.

Embodiment 2

The structure of the system is described in detail in the above disclosed embodiments of the present invention. Based on the operating principles of the system described in any one or more of the above embodiments, the present invention also provides an analysis of the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials. Method, which method is applied to the analysis system for the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials described in any one or more of the above embodiments. Specific examples are given below for detailed description.

Specifically, Figure 6 shows a schematic flow chart of the analysis method for the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials provided in the embodiment of the present invention. As shown in Figure 6, the method includes:

The sample preparation step is to cut the sheet material to be tested and preprocess it according to the test requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation testing of materials;

The test speckle formation step is to produce high-contrast random speckles for the obtained material sample to obtain a speckle material sample; the speckles are speckle particles with a size in the submicron/nanometer range and stable performance;

In the tensile in-situ observation step, in the environmental cavity of a high-temperature heating furnace, a high-temperature tensile and compression system is used to perform an in-situ tensile test on the speckle material sample based on a set displacement rate. A laser scanning confocal microscope is used during the test process. Observe and save the video and dynamic images of the specimen in real time;

The deformation strain evolution analysis step is configured to analyze the dynamic image of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckle material sample, and calculate the corresponding strain field.

Further, in one embodiment, the sample preparation step includes:

In the material cutting step, according to the experimental requirements of ultra-high temperature in-situ observation, wire cutting is used to cut sheet materials of set sizes from the plate;

In the material processing step, use a sandpaper smoothing device to smooth both sides of the cut sheet material, select one side as the observation surface, and use a metallographic sandpaper device to polish step by step until the observation requirements are met; then use a marking device to mark the observation surface. Observation area, the marking device is a microhardness tester.

In a preferred embodiment, the test speckle formation step includes:

In the primer spraying step, when ensuring that the surface of the material sample is clean and free of dirt, spray a set thickness of matte high-temperature primer evenly on the observation surface of the material test;

In the speckle spraying step, the high-temperature primer is further sprayed with dispersed and randomly distributed high-contrast high-temperature paint.

Further, the test speckle formation step also includes

The speckle sample baking step uses a muffle furnace, which is used to bake the material sample after speckle spraying at a constant temperature according to the set temperature and duration, so that the speckle has high temperature stability.

Specifically, in one embodiment, the step of tensile in-situ observation includes installing the obtained speckle material test on the loading mechanism of the tensile and compression workbench in the environmental cavity of the high-temperature heating furnace. The driver controls the in-situ tensile test. Among them, there are two loading mechanisms in the environmental cavity of the high-temperature heating furnace; the first loading mechanism is fixed on the stretching and compression workbench, and the other is connected to the linear drive of the high-temperature stretching and compression system.

The laser scanning confocal microscope of the in-situ stretching observation mechanism uses a purple laser VL2000DX with a wavelength of 408 nm and a scanning speed of 15 to 120 frames per second.

On the other hand, in order to ensure that the state of the sample to be tested for the test is reliable and that there is no interference from other external factors, therefore, in one embodiment, the tensile in-situ observation step also includes a test preprocessing step: After the plaque material sample is installed on the loading mechanism, before heating, the vacuum chamber is evacuated and purged with ultra-high purity argon gas to reduce the oxygen content and protect the sample surface from oxidation.

Further, in one embodiment, the step of in-situ observation during the stretching further includes: tracking the marked area of the material sample in real time when photographed by the laser scanning confocal microscope, so that the marked area is always visible during the entire stretching process. Located in the center of the field of view, it saves observation videos in real time, saves pictures at corresponding moments according to set time intervals, and records the stretching curve in real time.

Further, in a preferred embodiment, the deformation strain evolution analysis step includes:

The image screening step is to screen the material surface photos of the in-situ stretching process obtained through ultra-high temperature laser scanning confocal microscopy, and select effective speckle images whose grayscale distribution meets the set requirements;

In the strain analysis step, the DIC algorithm is used to calculate the screened effective speckle images to achieve matching of deformation points on the object surface. Based on the parallax data of each corresponding point, the coordinates of the calculation points on the object surface are reconstructed; and by comparing each deformation state measurement area The coordinate changes of each point in the object are used to obtain the displacement field on the object surface, and then the strain field on the object surface is calculated using GOM software and VIC-2D software.

For the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, Some steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily necessary for the present invention.

It should be pointed out that in other embodiments of the present invention, this method can also be used to obtain a new dynamic evolution analysis method of ultra-high temperature deformation microstructure strain of materials by combining one or more of the above embodiments. Enable comprehensive analysis of material failure studies.

It should be noted that, based on the method in any one or more of the above embodiments of the present invention, the present invention also provides a storage medium, which stores information that can implement the method as described in any one or more of the above embodiments. The program code, when executed by the operating system, can implement the above-mentioned analysis method of the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials.

It should be understood that the disclosed embodiments of the present invention are not limited to the specific structures, process steps, or materials disclosed herein, but extend to equivalents of these features as understood by those of ordinary skill in the relevant art. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

Reference in the specification to "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, appearances of the phrase "one embodiment" in various places throughout this specification do not necessarily refer to the same embodiment.

Although the embodiments disclosed in the present invention are as above, the described contents are only used to facilitate the understanding of the present invention and are not intended to limit the present invention. Any person skilled in the technical field to which the present invention belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed by the present invention. However, the patent protection scope of the present invention shall not The scope defined by the appended claims shall prevail.

Claims (10)

1. An analysis system for dynamic evolution of strain in a material ultra-high temperature deformed microstructure, the system comprising:

the sample preparation mechanism is configured to cut a sheet-shaped material to be tested, and pretreat the sheet-shaped material to obtain an effective material sample according to the test requirement so as to put into test and realize the ultrahigh temperature deformation test of the material;

a test speckle forming mechanism configured to produce high-contrast random speckle for the obtained material sample, to obtain a speckle material sample; the speckles are speckles particles with the size of submicron or nanometer level and stable performance;

the in-situ stretching and observing mechanism is configured to perform in-situ stretching and testing on the speckle material sample based on a set displacement rate by utilizing a high-temperature stretching and compressing system in an environment cavity of the high-temperature heating furnace, and a laser scanning confocal microscope is adopted to observe and store videos and dynamic images of the sample in real time in the testing process;

the deformation strain evolution analysis module is connected with the in-situ stretching observation mechanism and is configured to analyze dynamic images of the testing process based on a DIC algorithm, construct a displacement field of the surface of the speckle material sample and calculate a corresponding strain field.

2. The system of claim 1, wherein the sample preparation mechanism comprises a material cutting module and a material processing module;

The material cutting module is used for cutting sheet materials with set sizes from the plates in a linear cutting mode according to the experimental requirements of ultrahigh-temperature in-situ observation;

the material processing module is configured to grind two sides of the cut sheet material by using a sand paper grinding device, one side is selected as an observation surface, and the sheet material is ground step by using a metallographic sand paper device until the observation requirement is met; and then marking the observation area on the observation surface by using a marking device, wherein the marking device is a microhardness meter.

3. The system of claim 1, wherein the trial speckle-forming mechanism comprises:

the primer spraying module is configured to uniformly spray a matte high-temperature primer with set thickness on an observation surface of a material test when the surface of a material sample is ensured to be clean and no dirt is attached;

a speckle spray module configured to further spray a dispersed and randomly distributed high contrast high temperature paint over the high temperature primer.

4. The system of claim 1, wherein the test speckle forming mechanism further comprises

And the speckle sample baking module adopts a muffle furnace and is used for baking the material sample sprayed with the speckle at a constant temperature according to a set temperature and a set time length so as to ensure that the speckle has high-temperature stability.

5. The system of claim 1, wherein the in-situ stretch viewing mechanism comprises a stretch compression table disposed within an environmental chamber of a high temperature furnace and two loading mechanisms;

the loading mechanism is used for installing a speckle material sample, the first loading mechanism is fixed on the stretching and compressing workbench, and the other loading mechanism is connected with a linear driver of the high-temperature stretching and compressing system.

6. The system of claim 1, wherein the in-situ tensile observation mechanism uses a violet laser VL2000DX with a wavelength of 408nm and a scanning speed of 15 to 120 frames per second.

7. The system of claim 1, wherein the in situ stretch viewing mechanism further comprises a test pre-treatment module configured to evacuate the vacuum chamber and purge with ultra-high purity argon to reduce oxygen content after mounting the sample of speckle material on the loading mechanism and prior to heating, to protect the sample surface from oxidation.

8. The system of claim 1, wherein the laser scanning confocal microscope captures a marked area of the material sample in real time, the marked area is always positioned in the center of the field of view during the whole stretching process, the observation video is stored in real time, pictures at corresponding moments are stored at set time intervals, and the stretching curve of the test is recorded in real time.

9. The system of claim 1, wherein the deformation strain evolution analysis module comprises an image screening unit and a strain analysis unit;

the image screening unit is configured to screen the surface photos of the material in the in-situ stretching process obtained by the ultra-high temperature laser scanning confocal microscope, and select effective speckle images with gray distribution meeting the set requirements;

the strain analysis unit is configured to calculate the screened effective speckle images by using a DIC algorithm, so as to realize the matching of deformation points on the surface of the object, and reconstruct coordinates of calculation points on the surface of the object according to parallax data of all corresponding points; and the displacement field of the object surface is obtained by comparing the coordinate changes of each point in each deformation state measuring area, and then the strain field of the object surface is obtained by calculating with GOM software and VIC-2D software.

10. An analysis method for dynamic evolution of strain of ultrahigh-temperature deformed microstructure of a material is characterized by comprising the following steps:

the preparation method comprises the steps of sample preparation, preprocessing a sheet-shaped material to be tested according to test requirements after cutting the material to be tested to obtain an effective material sample, and putting the material sample into a test to realize a material ultra-high temperature deformation test;

a test speckle forming step of preparing high-contrast random speckle for the obtained material sample to obtain a speckle material sample; the speckles are speckles particles with the size of submicron or nanometer level and stable performance;

In-situ stretching observation, namely in-situ stretching test is carried out on the speckle material sample by utilizing a high-temperature stretching compression system based on a set displacement rate in an environment cavity of a high-temperature heating furnace, and a laser scanning confocal microscope is adopted to observe and store videos and dynamic images of the sample in real time in the test process;

and a deformation strain evolution analysis step, which is configured to analyze dynamic images of the testing process based on a DIC algorithm, construct a displacement field of the surface of the speckle material sample and calculate a corresponding strain field.