Micromagnetic Non-Destructive Testing for Carbon Content and Microstructure Component Proportion of Carbon Steels

Magnetic Buckhausen noise (MBN) is a typical non-destructive testing technique for ferromagnetic materials. Since this technique is very sensitive to the microstructural properties of the material, it can be used to characterize multiple physical parameters.At the same time, hysteresis loop is a macroscopic magnetic signal that also has the ability to characterize the physical properties of materials. In recent years, the application of hysteresis loops and magnetic Barkhausen noise methods to testing the physical properties of carbon steel materials has become a research hotspot. In this study, a sensor for testing the micromagnetic signals of carbon steel materials is designed, which can achieve synchronous testing of MBN signals and hysteresis loop signals. The experiment tested and characterized the micromagnetic signals of carbon steels with different carbon contents and dual-phase steels with different component proportions. The experimental results show that the MBN envelope peak increases linearly with the increase of carbon content. At the same time, the coercivity of the hysteresis loop increases, and the saturation magnetization decreases. The experiment involved quenched and tempered ferrite-martensite dual phase materials with different component proportions. The experiment results of dual phase materials show that the MBN peak corresponding to the martensite component increases with the increase of ferrite proportion. The experiment results of the hysteresis loop show that with the increase of ferrite proportion, the coercivity shows a linear decreasing trend.