Abstract
The final goal of this study is to develop an evaluation system of corrosion level in the inner surface of steel tubular sections as a maintenance engineering for steel structures. As the first step of this study, the ultrasonic testing with high frequency transducers was applied to the detection of artificial roughness in the steel plate's reverse side which was composed of parallel thin grooves. The correlation between the roughness and the ultrasonic echo was minutely examined on various conditions of both the roughness level and the ultrasonic excitation frequency, and the following results were obtained; (1) the change of thickness is related to a statistic amplitude of grooves such as Ry, and (2) the pitch of groove corresponds to the half wave length of the wave component in the echo excited by roughness.
