Evaluation of hardening degree on plates containing vehicle identification number (VIN)

The metallographic examination is one of the most widely used methods for the revealing of Vehicular Identification Number (VIN) on tampered vehicles, allowing a fast and reliable mean of identification. The application of the method is possible only in plates that contain hardening and residual stresses levels arising from the original recording process, persistent after the suppression of original coding. The higher the degree of hardening generated in the original recording process, the greater the probability of success in revealing the suppressed NIV. Optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray fluorescence techniques were used to characterize two groups of plates containing stamped NIV. Residual stresses were measured by X-ray diffraction and results showed that the stamping recording method makes the revealing of the suppressed coding easier. (author)