Crack Conductivity Measurement Method Based on Four-terminal DC Potential Detection Signal
A technology of DC potential and detection signal, applied in the direction of material resistance, etc., can solve the problems of unclear conductivity distribution characteristics, inability to measure conductivity accurately, affecting the quantitative accuracy of eddy current detection, etc., achieving easy operation and small amount of data. , the effect of accurate scanning
Active Publication Date: 2017-12-26
XI AN JIAOTONG UNIV
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However, since stress corrosion cracks are different from ordinary artificial cracks, the shape and outline of stress corrosion cracks are dry dendrites, and there is a partial conductivity in the crack area that is weaker than that of the matrix material. However, the distribution characteristics of the electrical conductivity are not clear so far. , seriously affecting the improvement of the quantitative accuracy of eddy current testing
The current four-terminal conductivity measurement method is limited to the measurement of infinitely large specimens, that is, the ratio of the thickness of the specimen to the distance between the probes L / s = ∞ or a strip-shaped specimen with regular shape, which cannot accurately measure the thickness and probe distance. Conductivity of equally spaced or irregularly shaped samples
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[0030] Such as figure 1 Shown is the measurement flow chart of the electrical conductivity distribution of stress corrosion cracks along the depth direction of the present invention. First, a four-terminal DC potential measurement system is built independently, and then the stress corrosion crack test piece is made, and the crack length direction is cut, and processed to include part of the stress corrosion crack. The sliced specimens with cracks were measured experimentally with a self-built four-terminal DC potential measurement system to obtain the potential distribution in the area near the crack and calculate the potential difference distribution. Secondly, the control equation based on the constant current field Calculate the potential difference distribution under different conductivity conditions, and finally compare the experimentally measured and calculated potential difference signals to measure the conductivity value of the stress corrosion crack.
[0031] The f...
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Abstract
Based on the crack conductivity measurement method of the four-terminal DC potential detection signal, a four-terminal DC potential measurement system is firstly built, and the stress corrosion cracked flat plate specimen is processed and cut along the crack length direction to obtain a sliced specimen containing part of the stress corrosion crack. , and then use the built DC potential measurement system to measure the potential distribution in the area near the crack of the sliced specimen, and calculate the potential difference between two adjacent points; further use the control equation of the constant current field to calculate the potential difference distribution under different conductivity conditions, By comparing and analyzing the potential difference signal measured in the experiment and the calculation result of the potential difference under different conductivity conditions, the conductivity value of the stress corrosion crack at the scanning position is obtained. The method of the invention can simply and accurately measure the electrical conductivity of complex structural parts, has the advantages of simple operation, easy implementation, small data volume, and small target measurement area, and can be widely used in the electrical conductivity measurement of solid conductive materials.
Description
technical field [0001] The invention relates to a method for measuring the electrical conductivity of a crack based on a four-terminal DC potential detection signal, in particular to a method for measuring the electrical conductivity of a stress corrosion crack based on a four-terminal DC potential detection signal. Background technique [0002] Stainless steel and high-nickel alloy materials that are sensitive to stress corrosion are widely used in nuclear power plants, and the presence of tensile stress caused by welding and assembly in nuclear power structures, as well as the corrosiveness of the operating environment, make stress corrosion cracks widely exist in the key to nuclear power plants. Among the components, such as the expansion of the heat exchange tube sheet of the steam generator, the fuel cladding and structural components in the stack, the welding part of the main cooling tube platform, etc. The existence of stress corrosion cracks poses a huge threat to th...
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IPC IPC(8): G01N27/20
Inventor 陈振茂蔡文路解社娟裴翠祥
Owner XI AN JIAOTONG UNIV