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A Mechanism Test Method for Fatigue Crack Growth Based on Small Time Scale

A fatigue crack propagation, small time scale technology, applied in the direction of applying repetitive force/pulsation force to test the strength of materials, etc., can solve the problems of large analysis time scale, neglect of metallographic corrosion, low accuracy, etc., to achieve the effect of improving analysis accuracy

Inactive Publication Date: 2017-05-10
BEIHANG UNIV
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Problems solved by technology

[0004] In view of the above-mentioned technical problems, the present invention provides a testing method to solve the existing in-situ fatigue crack growth mechanism analysis problems of large analysis time scale, low precision, and ignoring the influence of metallographic corrosion on the microstructure of materials

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  • A Mechanism Test Method for Fatigue Crack Growth Based on Small Time Scale
  • A Mechanism Test Method for Fatigue Crack Growth Based on Small Time Scale
  • A Mechanism Test Method for Fatigue Crack Growth Based on Small Time Scale

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Embodiment Construction

[0027] The method of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0028] (1) Prepare plane stress specimens.

[0029] According to the requirements of the in-situ stretching table equipped with the scanning electron microscope, the in-situ crack growth specimens in the plane stress state were prepared, such as figure 1 As shown; 0.2mm diameter molybdenum wire was used for wire cutting to prefabricate the sample gap; all samples were numbered.

[0030] (2) Metallographic structure analysis and calibration.

[0031] The surface of the sample is roughly ground, using metallographic sandpaper with a particle size of 400, 600 and 800, and the sample is roughly ground from coarse to fine. Every time the No. 1 sandpaper is replaced, the grinding surface of the sample must be turned 90 degrees until the surface is clear Scratches appear; the surface of the sample is finely ground, and the sample is finely ground with 1500, ...

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Abstract

The invention relates to metal material crack propagation mechanism testing method and specifically relates to a fatigue crack propagation mechanism testing method based on a small time scale. The fatigue crack propagation mechanism testing method based on the small time scale comprises the following steps: firstly, performing metallographic-phase treatment on a test sample, observing microstructures such as grains, grain boundary and second phase particles on the surface of the test sample, and calibrating the grade boundary and the position of the second phase particles; next, performing a fatigue crack prefabrication test and an in-situ fatigue loading and small time scale position calibrating test, setting a load cycle to be the small time scale, loading by use of the small time scale, and performing metallographic-phase processing; and finally, finding out each small time scale stress marking point according to a marking position in a scanning electron microscope and analyzing the influence of the microstructures on the crack propagation in one load cycle. According to the method, no metallographic-phase treatment is performed before in-situ fatigue loading and the influence of corrosion to the microstructures such as the grain boundary is eliminated; the small time scale method is adopted for loading and stress point marking in the in-situ test, and the study accuracy of a fatigue crack propagation mechanism is improved.

Description

technical field [0001] The invention relates to a metal material testing method, in particular to a small time scale-based fatigue crack propagation mechanism testing method. Background technique [0002] Fatigue research of materials has always been a hot topic, and the mechanism of fatigue crack growth is one of the difficulties. The mechanism of fatigue crack growth is related to many factors. Changes in the microstructure of materials and subtle changes in the environment may significantly change its fatigue crack growth behavior and remaining life. Therefore, to study the fatigue crack growth mechanism of materials and grasp the essential causes of damage, Then take corresponding measures to achieve the purpose of optimizing the structural characteristics of the material to improve the resistance to fatigue crack growth. With the development of material science and technology, people can use various technical methods to analyze material damage, and have a deeper unders...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/32
Inventor 王畏寒张卫方张慰何晶靖王红勋金博刘天娇陈惠鹏董邦林
Owner BEIHANG UNIV
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