Experimental study on strengthening the magneto-mechanical coupling effect of X80 steel by weak magnetic excitation

Current magnetic stress detection techniques are significantly affected by external noise. Magnetic stress detection technology under magnetic field excitation is proposed to weaken the external noise signals on the detection results. In this study, the uniaxial tensile magnetic signal testing system with the excitation magnetic field was developed. The enhancement of the weak magnetic excitation in magnetic signals has been analyzed and the concept of optimal weak excitation magnetic field has been proposed. The response law between triaxial magnetic induction intensity and stress under the excitation magnetic field is determined. The results indicate that the weak excitation magnetic field significantly enhances the magnetic induction signal intensity, more importantly, the linearity of the magnetic signal and stress response is also enhanced. Furthermore, the optimal excitation magnetic field under uniaxial stress states is 600 A m-1, and the corresponding stress-magnetic change rate is 0.002 Oe MPa-1. This study provides a theoretical basis for the long-distance detection of pipelines under weak magnetic excitation. The long-distance magnetic stress detection results of pipelines will become more accurate with the weak magnetic excitation which has a good engineering significance.