| 摘要 |
PURPOSE: To accurately measure the depth of a quenched hardness-layer by accurately focusing a transmitted ultrasonic wave to a boundary and then obtaining the difference between the propagation start time of a surface reflection wave and that of a boundary reflection wave. CONSTITUTION: First, a scanner 1b is set to a reference position and the ultrasonic wave of longitudinal wave is transmitted into a quenched hardness-layer W1 from the surface of a work W. Then, a surface reflection wave S and a boundary reflection wave R are received by a high-frequency probe 2. The relationship between the intensity and propagation time of the surface reflection wave S and the boundary reflection wave R is obtained, at the same time the rising angle between the intensity and propagation time of the boundary reflection wave R is obtained, and a scanner 1b is elevated so that the rising angle may be at least a specific angle threshold value for displacing a focus in depth directions. Then, the depth from the surface in the quenched layer W1 is obtained from the difference between the propagation time of the surface reflection wave S and that of the boundary reflection wave R. |
