Fatigue Damage Evaluation on Ferromagnetic Materials Using Magnetic Memory Method

Measuring magnetic parameters nondestructively is important for understanding fatigue phenomena of ferromagnetic materials. In this study, metal magnetic memory method is used as a new diagnostic tool to evaluate fatigue process. Both normal and tangential components of residual magnetic field have been studied on medium carbon steel specimens subjected to rotary bending fatigue. The results indicate that the normal component is related to different stress states while the variation trend of the tangential component with number of cycles shows a good agreement with the fatigue stages. This approach seems to be able to predicate fatigue lifetime.