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Sample table for scanning electron microscope in-situ observation of stress corrosion cracking of metal material

A technology of stress corrosion and metal materials, applied in the field of scanning electron microscope sample stage, which can solve the problems of limitations

Inactive Publication Date: 2014-03-05
YANSHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This directly limits the application of the SEM in situ stretching method

Method used

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  • Sample table for scanning electron microscope in-situ observation of stress corrosion cracking of metal material
  • Sample table for scanning electron microscope in-situ observation of stress corrosion cracking of metal material
  • Sample table for scanning electron microscope in-situ observation of stress corrosion cracking of metal material

Examples

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Effect test

Embodiment 1

[0030] Using the present invention, the SEM in-situ observation process of stress corrosion cracking of U75V steel in a 1.0% HCl aqueous solution was recorded. The process is given by 4 SEM images: the topography of the prefabricated crack maintained in a constant displacement state; the topography of the prefabricated crack maintained in a 1.0% HCl aqueous solution for 20 hours, it can be seen that the surface corrodes and the crack propagates; maintained for 40 hours The morphological image, crack propagation, and passivation of the crack tip; maintaining the morphological image for 60 hours, the corrosion is aggravated, the crack is extended, and the micro-crack connection before the crack tip. The crack propagation was increased from 20 hours to 40 hours, and the measured crack tip opening displacement was increased by 3.13 μm from 5.0 μm to 8.13 μm. That is: 6=3.13 μm.

Embodiment 2

[0032] H62 brass at 0.5MNH recorded using the present invention 4 SEM in situ observation process of stress corrosion cracking in OH aqueous solution. The process is given by two SEM images, which are: the prefabricated crack morphology image that maintains a constant displacement state, and the crack tip forms a slip line; at 0.5MNH 4 The morphology image of the OH aqueous solution kept under load for 5 minutes shows that a small amount of corrosion products appeared on the surfaces of both sides of the crack. It was measured that the crack length expanded from 116.0 μm in the initial state to 130.0 μm, an increase of 14.0 μm. The crack growth rate was calculated: da / dt=14.0 / 5=2.8 μm / min.

Embodiment 3

[0034]The present invention records the SEM in-situ observation process of stress corrosion cracking of 7075-T6 aged aluminum alloy in 0.5M NaCl aqueous solution. The process is given by two SEM images, which are the stress corrosion fracture image of the crack in 0.5M NaCl aqueous solution for 1.0h, the magnification is 30 times; the surface of the sample is corroded, and a step crack appears at the crack tip; the crack growth morphology after 2.0h , the magnification is 200 times, and the step crack expands, showing the effect of precipitation relative to crack expansion. The length of the front end of the step crack extends from 179.0 μm to 320.0 μm, an increase of 141.0 μm. Calculate the crack growth rate: da / dt=141.0 / 60=2.33 μm / min.

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Abstract

The invention belongs to the field of research of environmental cracking of materials, and provides a sample table for scanning electron microscope (SEM) in-situ observation of stress corrosion cracking, which can realize the SEM in-situ observation of the stress corrosion cracking of a metal material in a liquid medium. The sample table is designed according to a spatial size of an SEM sample room; a micro tension sample can be loaded and kept in a constant displacement state in the aspect of loading the sample; and the sample table is placed in the liquid medium together with a constant displacement sample to produce the stress corrosion cracking, is taken out of the medium and is arranged in the SEM sample room, so that a continuous process of stress corrosion crack propagation can be observed and recorded. Meanwhile, the crack propagation speed and crack tip opening displacement can be accurately calculated according to a stress corrosion cracking SEM image. Through the sample table, the problem that the stress corrosion cracking of the material in the liquid medium cannot be observed by an SEM is solved, and the sample table is an effective tool for researching a stress corrosion cracking micromechanism of the material.

Description

technical field [0001] The invention belongs to the field of material environmental fracture research, and is a scanning electron microscope sample stage, which is used for in-situ observation and recording of stress corrosion fracture of metal materials in a liquid medium. technical background [0002] The fracture research of materials is an important topic in the development of materials. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in situ observation of material fractures can directly observe the microscopic continuous process of material fractures under the electron microscope. It provides the most direct evidence at the microscopic level for the analysis of the fracture mechanism, so it is the most effective method for mechanism analysis. [0003] In the early 1980s, Kobayashir and Ohr first used transmission electron microscopy (TEM in situ tension) method to study the fracture behavior of Mo, W, Cu, Al, and directly observed and reco...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01Q30/02
Inventor 张静武要天开李慧王亚纯
Owner YANSHAN UNIV
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