Quantitative non-destructive testing to determine the complete parameters of corrosion pits based on the multi-dimensional characteristics of transient magnetic fields

In modern industry, metal materials are widely applied but are highly susceptible to corrosion and existing detection methods have limitations. This paper proposes evaluating the diameter, depth and hidden depth of corrosion pits based on the interaction mechanism between the electromagnetic field and the corrosion pits, utilising the multi-dimensional characteristics of the transient magnetic field. The transient magnetic field is analysed from different perspectives and dimensions: the surface area is represented by two-dimensional planar image features, enabling intuitive identification of the size of surface corrosion pits but showing insensitivity to vertical characteristics. The analysis of the linear area reveals that although it is less intuitive than two-dimensional planar images, it can detect the radius, depth and hidden depth of corrosion pits with rich feature information by effectively extracting the one-dimensional magnetic field distribution. After improving the structure of the excitation coil, the coil area can comprehensively detect corrosion pit parameters; however, the curve changes are not intuitive and there is mutual coupling among various dimensional parameters. This study provides accurate and reliable technical support for non-destructive testing of corrosion pits, ensuring equipment safety. The conclusions indicate that this method, which combines the analysis of different areas, has its own advantages and disadvantages, providing an effective approach for the quantitative non-destructive testing of complete parameters of corrosion pits, enriching the theoretical system of electromagnetic testing and offering new ideas for practical engineering applications.