Pulsed eddy current detection method and detection device for conductivity of ferromagnetic metal material

Abstract

The invention discloses a pulsed eddy current detection method and a detection device for conductivity of a ferromagnetic metal material, and belongs to the technical field of electromagnetic nondestructive testing. The method comprises the following steps of: using an inductive voltage measurement curve to establish the least squares problem between a measured value of an induced voltage time domain signal and a theoretical calculated value to invert the conductivity and magnetic permeability of a ferromagnetic member to be tested, based on a time-domain analytical solution of an induced voltage of a pulsed eddy current detection model of a ferromagnetic plate; obtaining a change curve of conductivity inversion results under different amplitude pulse current excitations by gradually increasing the amplitude of a pulse excitation current; and finding an intersection point of the change curve of the conductivity inversion results and an ordinate axis by a curve fitting method, that is,the conductivity of the ferromagnetic member to be tested. The method and device provided by the invention can provide non-contact and nondestructive detection for the conductivity of the ferromagnetic metal material in the industry, weaken the influence of the nonlinear change of the magnetic permeability on the conductivity detection result, and improve the accuracy and reliability.

Description

technical field [0001] The invention belongs to the technical field of electromagnetic nondestructive testing, and in particular relates to a pulsed eddy current testing method and a testing device for the conductivity of ferromagnetic metal materials. Background technique [0002] Electrical conductivity is an important parameter to characterize the electrical conductivity of metal materials, and it is closely related to the material, microstructure, and heat treatment state of the material. By detecting the conductivity of ferromagnetic metal materials, it is possible to sort and identify raw materials, judge the heat treatment status such as annealing and quenching, evaluate the hardness and mechanical properties of ferromagnetic components, and detect the residual stress and metallographic changes in ferromagnetic components, etc. . Therefore, the nondestructive testing of the conductivity of ferromagnetic metal materials has important application value. [0003] For n...

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Problems solved by technology

In addition, ferromagnetic metal materials are good conductors, which require a large current excitation to generate a large enough voltage signal. Due to the thermal effect of the excitation current and the measurement error of the weak voltage signal, the four-probe method will cause errors in the detection of the conductivity of ferromagnetic metal materials. Larger, poor repeatability of test results

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