Nonсontact Spectral Express Method for Detecting Corrosion Damage to Metal Products

We propose to use the shape of the envelope of the spectrum of the collection of pulses received from metal products by a straight-beam electromagnetic-acoustic transducer as a new criterion for the presence of a defect at the bottom surface of the product. A new flaw detection method to test pipes, sheets, and shells has been developed, which includes excitation and reception of packet ultrasonic pulses with a given duration and carrier frequency, determining the shape of the envelope of the spectrum of the total received signal, comparing the resulting spectrum envelope with the envelope of the spectrum of bottom signals in a defect-free reference section, and making a decision about the presence of a defective metal section based on the results of comparison. It has been experimentally proved that the developed method is effective both in the presence and in the absence of echoes reflected from defects in a realization. The effectiveness of the developed method has been confirmed experimentally by identifying defective areas at the bottom surface of a product.