Unlock instant, AI-driven research and patent intelligence for your innovation.

Metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization

A metal magnetic memory and crystallographic technology, applied in the direction of material magnetic variables, can solve problems such as stay, achieve the effect of removing interference, novel and reasonable design, and easy operation

Inactive Publication Date: 2012-06-27
BEIJING UNIV OF TECH
View PDF4 Cites 8 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The metal magnetic memory detection technology is based on the magnetic flux leakage signal that appears in the area where the component stress is concentrated, and its tangential component Hp(x) has a maximum value, while the normal component Hp(y) changes direction and has a zero-crossing value, that is, when the detected It is a theory that the stress concentration area on the surface of the object generates a leakage magnetic field gradient, but it is found in the actual application test that the value of Hp(y) in the stress concentration area does not necessarily cross zero, so this theory still needs to be continuously improved and needs to be further developed. Research
At present, most of the research on this method stays in the macroscopic field, and seldom studies it from the microscopic field (micro-nano level).

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization
  • Metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization
  • Metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] The same steel material, with tensile stress applied

[0043] Select the typical steel material Q235, prepare the sample by the above method, and make electron microscopic indentation as the research area B. The initial state (no tensile test) is measured in the SEM-EBSD system. figure 1 (a) Image with orientation, see figure 2 (a), under the light microscope, the magnetic domain topography of area B is taken on the cover of the magnetic suspension under the light microscope, see image 3 (a); Then when the sample is stretched to a strain of 0.3% on a uniaxial stretching machine, the scan diagram of the measurement area B is shown in figure 1 (b) and Orientation Imaging Diagram, see figure 2 (b), Magnetic domain topography, see image 3 (b); in the same way, when the sample is stretched to 0.6% and 0.9% of the strain respectively, the scanned image of area B is measured, see figure 1(c), (d) and orientation imaging, see figure 2 (c), (d), magnetic domain topogra...

Embodiment 2

[0046] Same steel material, apply fatigue stress

[0047] Compared with Example 1, Example 2 changes the way of applying stress and adopts fatigue loading (ie, periodic loading). Because the fatigue failure of iron and steel materials is one of the main failure modes of metal components, it is very meaningful to study the change law of crystallographic and magnetic information under fatigue loading to characterize the magnetic memory of metals. In order to make the applied fatigue stress meaningful, the present invention sets the maximum fatigue load to simulate the service process of the steel piece as 0.7σs (σs is the yield strength of the material), and the stress ratio is 0.1 to carry out the tensile fatigue loading mode. The SEM images, orientation maps, and magnetic domain images of the material were measured at different fatigue times, and the rest of the steps and analysis methods were the same as in Example 1.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention discloses a metal magnetic memory detection method based on metal in-situ crystallography and magnetic domain characterization, belonging to the research field of metal magnetic memory nondestructive detection. The method is characterized by using a metal material itself as a research object, acquiring the corresponding magnetic domain images by bitter powder pattern method under different stress states (different stretching stages or different fatigue cycle numbers), and acquiring SEM morphology, orientation and other crystallographic information by using an SEM-EBSD system, so as to acquiring the relationship among the crystallographic information, magnetic domain and stress of the metal material. According to the method, by combining the metal material itself, the material microscopic dimension magnetic signal magnitude, magnetic moment direction and crystallographic information are acquired, and the influence of other factors aside from the material itself is removed, thus the method has good reliability and overcomes the errors in the particle application.

Description

technical field [0001] The invention relates to a metal magnetic memory detection method based on metal "in situ" crystallography and magnetic domain characterization, and belongs to the research field of metal magnetic memory non-destructive detection. Background technique [0002] At present, metal materials are widely used in aviation, aerospace, electric power, petrochemical, railway, boiler pressure vessel and other industries. Metal components and equipment are very easy to be damaged under stress corrosion during use, and it is very easy to cause major accidents. So effective non-destructive testing technology is the focus of current research. Conventional nondestructive testing methods (such as ray, ultrasonic, magnetic particle and penetrant testing, etc.) can only detect macroscopic defects of a certain size, and it is difficult to find microscopic defects. The metal magnetic memory detection technology can detect the stress concentration parts that may induce da...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): G01N27/83
Inventor 张鸥徐学东张海张登宇安栋
Owner BEIJING UNIV OF TECH