Nature of soundability for large forgings with varying microstructure through the cross section

1.Results of USM are governed both by the location of actual defects and by microstructure through the forging cross section.2.Pulses observed from the remains of boundaries in overheated structure [1] and a simultaneous reduction in the number BES are apparently caused by a change in the angle of reflection of untrasonic (US) waves at the pearlite-ferrite boundary with partial energy dissipation [3].3."Grey whiskers" observed in each forging without obvious defects are differentiated with sufficient reliability from actual defects by controlling the power of the ultrasonic signal and receiver sensitivity for the US defectoscope under conditions when the remains of overheated structure boundaries are absent from the microstructure.