Visualization evaluation of damage degree on remanufacturing cores based on residual magnetic scanning measurement

•Propose a RMSM method for visualization damage evaluation on remanufacturing cores.•2-D RMF grayscale map can invert plastic residual stress zone and defect size.•Inversion error of defect size is less than 10 % with the resolution reaching 0.2 mm.•RMSM method is appropriate to damage inversion on a real remanufacturing gear core. A novel residual magnetic scanning measurement (RMSM) method with easy operation, low cost and good universality based on metal magnetic memory (MMM) is proposed to evaluate the damage degree of remanufacturing cores. The two-dimensional (2-D) grayscale maps of residual magnetic field (RMF) and residual stress can be visualized, respectively, by constructing the relationship among magnetic field, stress and pixel gray value. The contour of high residual stress zone which enters the plastic stage can be extracted from the 2-D grayscale map based on the gray thresholds representing the yield strength. The defect size can also be inverted with the evaluation error below 10 % and the resolution reaching 0.2 mm. To prove the feasibility of RMSM applying into the damage evaluation on remanufacturing cores, the RMF distribution and the high residual stress zone of a damaged gear are also visualized. The 2-D grayscale maps of RMF and residual stress can clearly show the profile of gear and the plastic deformation damage zone. The RMSM method can facilitate the accurate damage evaluation on remanufacturing cores and provide the support for the subsequent repairing process design.