Method for predicting initiation location or expansion direction of cracks on metal surface

Abstract

The invention relates to a method for predicting an initiation location or an expansion direction of cracks on a metal surface, and belongs to the technical field of mechanical behaviors of materials,and the method comprises the following steps of observing the microstructure after electrochemical polishing and corrosion on the surface of the metal material to be measured, and depositing a layerof metal in the physical vapor phase on the metal surface after exposure and development of the mask plate and photoresist on the metal surface by a photoengraving machine, so as to form a regular grid shape; using SEM-EBSD to characterize the crystal orientation of the material surface in the grid area to be measured; measuring the change of the relative coordinate values of grid node before andafter plastic deformation of the material surface, and accordingly calculating and analyzing the information such as the strain concentration distribution of the micro area, the strain concentration area and plastic deformation direction, and determining the dislocation slip direction of the material surface, so as to predict the initiation location and expansion direction of cracks on the metal surface. The invention realizes the method for predicting an initiation location or an expansion direction of cracks on a metal surface by the combination of a physical vapor deposition mesh method anda SEM-EBSD method.

Description

technical field [0001] The invention relates to a method for predicting the initiation position or extension direction of a metal surface crack, belonging to the technical field of material mechanical behavior. Background technique [0002] As the aviation industry has higher and higher requirements for long life and high reliability of the engine, the research on the failure behavior of the engine structural materials under the action of unidirectional or multidirectional static and alternating loads has also attracted more and more attention from researchers. General structural materials (polycrystalline materials, composite materials, thin film materials) are aggregated from characteristic structures with different shapes and randomly distributed orientations, and often exhibit isotropic uniformity in macroscopic mechanical properties. However, due to the different crystal structures, physical and mechanical properties of the characteristic structures of each composition,...

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Problems solved by technology

[0003] The amount of deformation in the micro-area of ​​metal materials is directly related to the crack initiation and propagation behavior. By establishing the relationship between crystal orientation and deformation distribution, it is helpful to reveal the failure mechanism and life prediction of metal materials. At present, DIC experiments are mostly used for the collection of full-field strain distribution on the surface of materials. However, limited by the test accuracy and experimental conditions of the DIC equipment, it is impossible to accurately characterize the small deformation behavior of the micro-area

[0004] With the urgent need for research on the failure mechanism and life prediction of aircraft engine structural materials, the characterization and measurement of the plastic strain at the microscopic scale of the material and the characterization of the crystal orientation and dislocation slip direction in the corresponding area are the key technical conditions for completing the above research , and the existing methods of measuring plastic strain on the surface of materials are difficult to meet the above research needs, and the method of combining strain and crystal orientation has not yet been established to predict crack initiation and propagation behavior

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