DETECTING SUBHORIZONTAL DEFECTS ON METAL PRODUCTS BY NON-DESTRUCTIVE ULTRASONIC CONTROL

摘要

The invention concerns automatic detection of subhorizontal defects in metal tubes which consists in: applying to the tube a recurrent pulsed ultrasonic beam (Em) to the tube, and in picking up the reflected echo signals (Dv, Ds). The echo signals are then selected in part (Fe1, Fe2) of the interval of recurrence (Tr) to identify possible defects in the metal product. The invention is characterised in that it consists in constructing a time curve, called echodynamic curve (ECHODYN), of the intensity levels of echoes in said parts of intervals and in analysing the variations of said curve, so as to locate a convolution of at least two elementary peaks, indicating the presence of subhorizontal defects.