METHOD AND APPARATUS FOR MEASUREMENT OF DEPTH OF QUENCHED AND HARDENED LAYER

摘要

PURPOSE: To obtain a method wherein the depth of the quenched and hardened layer of forged steel or the like is measured non-destructively. ;CONSTITUTION: In the measuring method of the depth of a quenched and hardened layer, concentric and arbitrary multiple layers are set around the axial center in the circular cross section of a cylindrical object 1, under test, on which a quenched and hardened layer 2 has been formed in an outer-shell part. The attenuation rate of ultrasonic waves in a first layer is found from the following: the reception energy of ultrasonic beams which are transmitted in the chord direction of a depth corresponding to the depth (d₁) of the first layer in the outermost layer of said object 1 under test; and the route length (between T and R) of a propagated chord. The attenuation rate of individual layers is found sequentially from the following in the same manner: the reception energy of ultrasonic beams corresponding to depths (d₂), (d₃) of the individual layers; and the route length of chords. The depth of the quenched and hardened layer 2 is estimated from the depth of a layer in which the attenuation rate of the ultrasonic beams is increased sharply.;COPYRIGHT: (C)1993,JPO&Japio