Residual magnetic scanning measurement for visualization evaluation on different damage stages of remanufactured blanks

Different degrees of damage to ferromagnetic materials can be induced under external loading, which affects the service properties of components. The service life of these materials can be extended via remanufacturing. Nondestructive testing (NDT) of scrapped blanks is a critical step in remanufacturing, because it directly affects the quality of subsequent restoration processes. The traditional residual magnetic field (RMF) detection method, which relies primarily on magnetic signals obtained from one-dimensional (1-D) scanning lines for damage analysis, is prone to missed detection or false detection issues. Therefore, two-dimensional (2-D) residual magnetic scanning measurement (RMSM) technology is proposed in this paper to visualize the RMF distributions of the H_p(x), H_p(y), and H_p(z) components at different damage stages of ferromagnetic materials. The results show that the 2-D RMF distribution pattern of the H_p(x) component is highly consistent with the strain field measured by the digital image correlation (DIC) method. The H_p(x) magnetic field intensity has a linear fitting relationship with the strain. The 2-D RMF of the H_p(y) component can accurately invert the change process of the defect size under loading, and the 2-D RMF of the H_p(z) component visually shows the outline and the degree of necked of the samples. In addition, an automotive connecting rod remanufactured blank is selected to validate the feasibility of 2-D RMSM technology. These findings reveal that the stress concentration and crack damage can be effectively identified by 2-D RMSM, and its evaluation accuracy is greater than that of the traditional 1-D RMF.