METHOD OF CONTROLLING ACOUSTIC CONTACT DURING ULTRASONIC FLAW DETECTION.

摘要

A method of controlling acoustic contact during ultrasonic flaw detection provides that the angle ( beta ) of the prisms of the generating (1) and receiving (2) ultrasonic converters is designed to be smaller than the first critical angle, the converters (1, 2) are placed on the surface (3) of the weld joint (4) at a distance (A) from the longitudinal axis (6) of the weld joint (5), said distance being chosen on the basis of the thickness ( delta ) of the welded elements (7), of the width ( DELTA 1, DELTA 2) of the reinforcing beads (8, 9) and of the angles ( alpha l, alpha t) between the directions of the longitudinal (l2) and transverse (t1) ultrasonic waves generated in the weld joint (4), on the one hand, and the perpendicular (13) to the surface (3) in the point of generating the waves, on the other hand. The quality of the acoustic contact is then evaluated on the basis of the amplitude of the reflected echo-pulse registered at a moment (t) chosen on the basis of the time (to) of propagation of the ultrasonic wave in the material of the converters (1, 2) and on the basis of the velocities (Cl, Ct) of propagation of the longitudinal (l2, l1) and transverse (t1, t2) waves in the material of the weld joint (4).