EFFECT OF ROUGHNESS OF THE CONTACT SURFACE ON THE READINGS OF ULTRASONIC THICKNESS GAUGES

The dependence of the error in the readings of ultrasonic thickness gauges on the parameters of the rough layer on the contact surface of a product is analyzed. The dependence is shown to be oscillatory because the parameters of the ultrasonic waves vary under the effect of interference processes. The nature of these processes for irregularities with rectangular and triangular groove profiles is specified more exactly. Direct measurements confirm that the amplitude and wavelength of the ultrasonic wave are oscillatory functions of the depth Rz of the layer. Ways of extending the zone of reliable ultrasonic inspection to high values of Rz are analyzed. The ''floating'' nature of the liquid - metal interface for the ultrasonic wave in this case is also confirmed.