17 results about "Fracture Toughness Testing" patented technology

This invention discloses a test method for evaluating the hydrogen embrittlement susceptibility index of welded joints using principal component analysis, belonging to the field of material performance evaluation technology. The method includes the following steps: S1, processing the pipe welded joint into a notched round bar slow strain rate tensile specimen and conducting a slow strain rate tensile test; S2, processing the pipe welded joint into a stepped-notch CT specimen for fracture toughness and conducting a fracture toughness test; S3, calculating the specific performance loss rate under hydrogen-doped conditions and performing standardization; S4, calculating the hydrogen embrittlement susceptibility evaluation index I. PC S5. Perform scanning electron microscopy analysis on the slow strain rate tensile fracture surface to determine the risk level of hydrogen-induced cracking in the sample; S6. Determine the I-value that distinguishes different risk levels of hydrogen-induced cracking. PC Scope. This invention employs the aforementioned test method for evaluating the hydrogen embrittlement sensitivity index of welded joints using principal component analysis, which improves the statistical significance of small sample data and yields a more objective and comprehensive evaluation system for hydrogen embrittlement sensitivity.

This invention discloses a testing device and method for fracture toughness testing of welded joints in pipeline steel under corrosive environments, belonging to the technical field of fracture toughness testing equipment. It includes a test vessel unit and a testing unit. The test vessel unit comprises a test vessel body and a test vessel lid, the lid of which can close onto the opening of the test vessel body. The test vessel lid has an air inlet and an air outlet; the air inlet is used to connect to an air inlet pipe, and the air outlet is used to connect to an air outlet pipe. The testing unit includes a bending clamp assembly and a loading linear displacement measuring assembly. The bending clamp assembly is connected to the shaft of the testing machine and can be used to clamp the test specimen. Driven by the shaft of the testing machine, the bending clamp assembly can press down on the test specimen. The loading linear displacement measuring assembly is connected to a measuring point on the test specimen and is used to measure the linear displacement of the measuring point. This invention enables fracture toughness testing of welded joints under corrosive environments, ensuring the accuracy and safety of the test.

The application discloses a kind of based on ENDB sample dynamic fracture toughness testing device, including test auxiliary device and Hopkinson bar experimental device, Hopkinson bar experimental device includes incident bar and transmission rod, test auxiliary device includes load transmission structure, dial, support seat component, sample fixing assembly and auxiliary fixing assembly, dial, sample fixing assembly and support seat are fixed by distance adjusting component of three through three connections.This application can accurately adjust the included angle α between loading rod and prefabricated crack, so that the dynamic fracture toughness test of a variety of different angles III and I, III mixed type can be realized, the dynamic fracture toughness test experiment of a variety of diameter sizes ENDB sample can be satisfied, and a certain fracture failure play space is reserved between dial and sample, to improve sample damage effect and the accuracy of experimental results.The whole device has no direct or indirect contact with the outside world, reduces the loss of energy, improves the accuracy of experimental results.

This application belongs to the field of fracture toughness testing under corrosive environments, and specifically discloses a method for calibrating the stress intensity factor loading rate in fracture toughness testing under corrosive environments. The method includes: preparing a specimen and creating a pre-crack; using a corrosive solution to create a pre-corrosive environment at the crack tip; establishing a corrosive environment on a testing machine and performing a three-point bending test on the specimen in the corrosive environment at a preset testing machine loading rate to obtain the specimen's yield strength; loading the specimen in the corrosive environment using multiple different testing machine loading rates to 60%-90% of the yield strength, and recording the force-time curves for each loading; calculating the corresponding stress intensity factor loading rate based on the force-time curves and performing linear fitting to obtain the corresponding functional relationship. This application solves the problem that when conducting fracture toughness testing under corrosive environments, it is impossible to directly set the stress intensity factor loading rate, and existing calibration methods cannot accurately reflect the coupling effect of the corrosive environment.

The utility model provides a sample preparation tool for an I-type fracture toughness test. The sample preparation tool comprises a platform, the upper surface of the platform is horizontal and is used for placing a lower-layer base material; a base material limiting mechanism; the limiting device is arranged on the upper surface of the platform and is used for limiting the end parts of the laminated lower-layer base material and the upper-layer base material and limiting the displacement of the lower-layer base material and the upper-layer base material in the horizontal direction; the film fixing mechanism comprises a first gasket, a second gasket and a gasket pressing part; the first gasket is arranged on the upper surface of the platform, and the thickness of the first gasket is the same as that of the lower-layer base material located at the bottom; the second gasket is arranged on the first gasket, and the thickness of the second gasket is the same as that of an adhesive layer between the lower-layer base material and the thin film; the gasket pressing part is used for pressing the second gasket and the first gasket to the upper surface of the platform. When the sample preparation tool for the I-type fracture toughness test is used for sample preparation, the accurate position of a film in a sample and the accurate and uniform thickness of an adhesive layer can be ensured, and the tool is simple to operate and high in sample preparation efficiency.

The application discloses a pipeline girth weld fracture toughness testing method, which comprises the following steps: processing a notch and a fatigue pre-crack on a test piece with a predetermined size, wherein the length direction of the test piece is consistent with the axial direction of the pipeline; expanding the fatigue pre-crack at the front end of the notch of the test piece and performing fatigue pre-cracking; after the fatigue pre-cracking reaches a target value, processing a side groove on the test piece; continuously loading the test piece at a constant rate, while monitoring the load and displacement during the loading process; stopping after the test piece reaches a preset degree of crack expansion; during the continuous loading, measuring the crack expansion by using a regularization method; measuring the initial crack length and the final crack length; and inversing the crack length in the crack expansion process according to the measured initial crack length and the final crack length. The application can accurately obtain the fracture toughness of the pipeline girth weld, make the safety evaluation of the pipeline girth weld more accurate, and thus guarantee the safe operation of the pipeline.

The invention relates to the technical field of post-irradiation mechanical sample processing, and provides a post-irradiation mechanical fracture sample processing and recycling method which comprises the following steps: selecting a metal sample which is subjected to neutron irradiation and is fractured after finishing a Charpy impact test or a fracture toughness test; a linear cutting machining mode is adopted, a plastic deformation area at the fracture of the broken metal sample is removed, and a machining unit body in a regular geometrical shape is obtained; detecting the processing unit body by adopting a Vickers hardness detection method; according to the actual size of the machining unit body, machining positions and machining directions of the small-size samples are planned; machining the machining unit bodies into a plurality of small-size samples in a machining manner; after machining is completed, the size of the small-size sample is detected in a non-contact mode through an optical measuring device; and carrying out mechanical property test on the small-size sample by using load test equipment. According to the method, dozens of small-size samples are processed from one standard fracture sample, and the utilization rate of the samples is increased.

The application relates to a fatigue life prediction method based on a physical failure mechanism under a liquid lead-bismuth environment, which comprises the following steps: establishing a representative volume element model and defining elements belonging to a slip band; defining a crystal plasticity constitutive equation; determining parameters in the crystal plasticity constitutive equation; calculating an average shear strain range of the slip band; carrying out a fracture toughness test to obtain a specific fracture energy; establishing a fatigue life prediction model based on the physical failure mechanism; carrying out a low-cycle fatigue test of a metal material under a high-temperature and high-oxygen liquid lead-bismuth environment to determine an oxide film thickness; and establishing a fatigue life prediction model under a high-oxygen-concentration liquid lead-bismuth environment to predict the fatigue life of the metal material under the high-oxygen-concentration liquid lead-bismuth environment. The low-cycle fatigue test for calibrating parameters of the crystal plasticity constitutive equation in the prediction temperature air and the fracture toughness test in the air and the liquid lead-bismuth environment can be carried out, so that the fatigue life under the liquid lead-bismuth environment can be predicted.

This invention relates to a method for simulating the uniaxial tensile behavior of a liquid lead-bismuth environment. The method involves conducting uniaxial tensile tests on metallic material specimens in an air environment to obtain stress-strain curves; establishing a two-scale finite element model of the metallic material specimen using ABAQUS finite element software and simulating the uniaxial tension of the two-scale finite element model in the air environment; conducting fracture toughness tests and uniaxial tensile tests on the metallic material in a liquid lead-bismuth environment to obtain stress-strain curves; and simulating the uniaxial tension of the two-scale finite element model in the liquid lead-bismuth environment using ABAQUS finite element software. This invention establishes a finite element model and uses ABAQUS finite element software for calculation, allowing for intuitive observation of the damage behavior of metallic materials during tensile processes in both air and liquid lead-bismuth environments. The established model and parameters can predict different structures and boundary conditions, offering advantages such as accurate results, high efficiency, and low cost. The established two-scale finite element model effectively reduces computational costs.

The utility model provides a preparation and monitoring device suitable for precracks of multi-size fracture toughness samples. The preparation and monitoring device suitable for the precracks of the multi-size fracture toughness samples comprises two clamps which are symmetrically arranged, two supporting rollers are symmetrically installed on the clamps, a same loading pin is arranged between the same supporting roller, the two ends of the loading pin extend into the supporting rollers correspondingly, and the two ends of the loading pin extend into the supporting rollers correspondingly. The same to-be-tested sample is mounted on the two loading pins, and a stress sheet is mounted on one side of the to-be-tested sample. The preparation and monitoring device suitable for the multi-size fracture toughness sample precracks has the advantages that the preparation and monitoring device is suitable for fracture toughness test tools of various sizes, the crack length is monitored by a strain monitoring method, and the high-frequency use of a COD (Chemical Oxygen Demand) gauge is reduced.

The embodiment of the application provides a material fracture toughness testing device and method, and relates to the technical field of material fracture toughness testing.The device comprises a support assembly, which comprises a workpiece platform and two support rollers;two mark points P1 and P2 are arranged on the parallel lines along the axes of the two support rollers on the A plane of the workpiece platform;the loading assembly comprises a liftable loading roller;two first light emitters are arranged on the two sides of the bottom of the loading roller, and the projection points of the two first light emitters on the A plane are O1 and O2;an image recognition system is arranged and is used for acquiring the images of P1, P2, O1 and O2;the control system is used for controlling the translation and rotation of the workpiece platform, so that the line segment P1P2 is collinear with the line segment O1O2;the auxiliary positioning structure comprises a limiting element and a second light emitter, and can ensure that the prefabricated notch of the test workpiece is accurately located directly below the axis of the loading roller.The application can ensure that the test workpiece meets the spatial geometric constraint conditions of the fracture toughness test, and improves the accuracy and reliability of the test.

The present application belongs to the technical field of metal material fracture performance test, and provides a large-diameter metal thin-walled pipe fracture toughness test method and system. In the present application, the load-displacement curve of the crack curved surface sample of the large-diameter metal thin-walled pipe, and the initial crack length and the terminal crack length of the crack curved surface sample section are obtained. First, the real-time crack length and the crack propagation amount Δa are directly obtained by the regularization method. Then, the J integral value of the crack curved surface sample is calculated according to the obtained real-time crack length and the load, and the J integral expression. Finally, the J-Δa resistance curve is obtained according to the crack propagation amount Δa and the J integral value. The data processing process is simple, and the fracture toughness of the material can be obtained only by simply processing the sample load-displacement curve obtained by the experiment.

The invention discloses a method for evaluating hydrogen embrittlement of a metal material by replacing a high-pressure hydrogen environment with an alkaline environment, which comprises the following steps of: obtaining the percentage reduction of area, the elongation percentage, the tensile strength and the fracture toughness of a sample through a slow tensile test and a fracture toughness test in the high-pressure hydrogen environment and an inert gas environment; an alkaline environment system is used for replacing a high-pressure hydrogen environment, a high-pressure slow tensile test and a high-pressure fracture toughness test are simulated, and the high-pressure hydrogen embrittlement risk of the metal material is evaluated according to test results.

The application provides a method for predicting crack arrest toughness of marine crack arrest steel based on fracture toughness test, and relates to the field of fracture and crack arrest technology evaluation of high-strength crack arrest steel. ca The method adopts swallow tail crack arrest toughness test, double tension crack arrest toughness test, obtains data through fracture toughness test, and converts to establish a crack arrest toughness K ca Correlation model of fracture toughness δ, so as to predict the crack arrest toughness of the material by using the model. The method of the application has simple process, low operation difficulty, low cost for establishing the prediction model, high efficiency, high precision, and is beneficial to large-scale industrial application and promotion.

The application discloses a true triaxial condition rock fracture toughness testing device and testing method, and relates to the technical field of rock mechanics and engineering; the testing device comprises a lateral confining pressure loading system located in a loading chamber; the loading chamber is located between a pressurizing base and a cover plate, and the three form a sealed space; hydraulic oil is continuously filled into the sealed space to apply confining pressure on a rock test piece in the vertical direction; an upper loading column is installed at the bottom of the cover plate, and the upper loading column is in contact with the rock test piece as a fracture fulcrum; a vertical load loading plate is arranged on the pressurizing base, and a lower loading column is fixed on the vertical load loading plate; the lower loading column is lifted under the drive of a hydraulic drive to apply fracture load on the rock test piece; the application can restore the three-direction stress state of the rock under the ground, test the rock fracture toughness under different three-direction confining pressure conditions, and provide important parameter support for the compressibility evaluation of unconventional oil and gas resources and the fracturing engineering design.

The invention discloses a hydrogen-doped pipeline material fracture toughness testing system and a testing method thereof. The hydrogen-doped pipeline material fracture toughness testing system comprises an environment box, a gas supply assembly, a loading and fixing device, an acoustic emission monitoring system and a signal processing and control system. A test cavity is defined in the environment box, the environment box comprises a box body and a cover plate, the cover plate covers the top of the box body, and a first air inlet, a second air inlet and an exhaust port are formed in the cover plate. The gas supply assembly comprises a hydrogen tank, a hydrogen pipeline, an inert gas tank and an inert gas pipeline, the loading and fixing device is used for clamping a CT sample and loading a tensile load on the CT sample, and the DIC strain measurement device is used for performing continuous imaging on the surface of the CT sample; the acoustic emission monitoring system is used for collecting acoustic signals generated in the tensile process of the CT sample in real time. According to the system for testing the fracture toughness of the hydrogen-doped pipeline material, the accuracy and the reliability of a test result are remarkably improved.

The present application belongs to the technical field of material fracture mechanics test, and discloses a metal material ductile-brittle transition temperature confirmation method. Based on selected samples and determined test temperature range, impact tests, fracture toughness tests are carried out on the selected samples at different temperatures, and experimental data are recorded. Based on the experimental data of each sample obtained at different temperatures, experimental data points are plotted, and the ductile-brittle transition temperature is obtained based on the experimental data points. The Charpy impact CVN, fracture toughness CTOD / J test data at five different temperatures can be used to calculate the ductile-brittle transition temperature. The present application can obtain accurate ductile-brittle transition temperature value through five effective tests, effectively reducing the test cost and time. Especially for the characteristics of high-strength structural steel ring weld joint toughness dispersion, the present method can quickly and accurately obtain the ductile-brittle transition temperature of high-strength structural steel and ring weld joint DBTT CTOD50 、 DBTT CVN50 and DBTT J50 .