METHOD FOR DETECTING CORROSION OF A SURFACE NOT EXPOSED TO VIEW OF A METAL PIECE, BY MEANS OF THERMOGRAPHIC ANALYSIS

摘要

In a method for detecting corrosion of a surface (30b) not exposed to view of a metal piece (3,30) radiant thermal energy is directed against the metal piece (3,30) by illumination with a pulsed laser beam (F) so as to cause heating of said metal piece. The infrared radiation emitted by the metal piece (3,30) is detected by a thermoghraphic camera (6) so that corroded portions (X) of said surface (30b) are detected due to a different thermal response as a function of time with respect to the non-corroded portions. The laser light beam (F) is directed against a face (30a) exposed to view of a wall (30) of said metal piece (3) whose opposite face (30b) is the surface on which corrosion must be detected. The thermographic camera (6) is provided on the same side where a laser head (5) for emitting said pulsed laser beam (F) is provided and has a processing electronic control system (E1) configured for performing a "Lock-in" thermography. Detection of the corroded portions (C) of said surface (30b) is carried out by comparing the response of different surface portions during cooling of the piece, after that illumination with the laser beam (F) has been interrupted.