Magnetic non-destructive testing method for thin-plate aluminum alloys

The current study proposes a non-destructive testing method for thin-plate aluminum alloys based on the geomagnetic field. A high-precision magnetic sensor was used to measure slight changes in the magnetic field strength. The relative permeability of aluminum alloys was proven to be greater than that of aluminum through the magnetization of aluminum alloy materials. Therefore, aluminum and its alloys are paramagnetic materials. The aims of the current study are to analyze the effect of magnetic field on defects and to determine the test mechanism based on the differences in relative permeability. A thin-plate aluminum alloy 2024, with a thickness of less than 2 mm, was used as a specimen. An artificial groove defect was set in the specimen. The result shows that the signal from the magnetic field was obvious and unusual at the location of the artificial defect. A metallographic test verified that the other abnormities observed from the signal were consistent with the natural defects of the specimen. The magnetic method was found to be accurate, and a clear test mechanism was observed. The magnetic method provides the foundation for non-destructive testing of thin-plate aluminum alloys.