Restoration of obliterated stamped marks is a common investigative technique used in criminal investigation. Considering the evolution of the obliteration techniques used by criminals, a study of the feasibility of sensitive, effective, and nondestructive techniques is needed. This study aims to evaluate the performance and sensibility of two nondestructive techniques: magnetic particle restoration and magneto-optical imaging. To this end, steel samples from automobile chassis were analyzed. The samples were characterized in order to obtain information regarding material microstructure, magnetic characteristic, and hardness, followed by the restoration of stamp marks. Both magnetic particle restoration and magneto-optical imaging were capable of partially restoring the identification code obliterated by overstamping. In addition, nondestructive techniques showed a restoration depth limit of 260?μm below the cavity.
展开▼
