AN ULTRASONIC MEASURING METHOD IN AN-APPARATUS ADAPTING A SINGLE CRYSTAL 90˚ ANGLE SURFACE WAVE PROBE TO DETECT A SURFACE CRACK INCLUDING DIRECT MEASUREMENT OF THE DEPTH OF THE CRACKS ON ROLLED STRUCTURES

摘要

The invention relates to an ultrasonic measuring method using a single crystal 90° angle surface wave probe to detect a surface crack including direct measurement of the depth of the cracks on rolled structures made of steel, cast iron or forging, the method comprising the steps of providing an apparatus for ultrasonic detection of cracks, the apparatus deploying a single crystal 90° angle surface wave probe, producing a plurality of calibration blocks of steel or cast iron with several pre measured notches with depth between 0.04 mm to 1.94 mm for calibrating the apparatus, detecting presence or absence of a surface crack by using the apparatus; establishing a relationship between the data representing amplitude of the reflected signals captured in the calibration blocks and that captured in the rolled rolls; and measuring the depth of the crack if detected based on the relationship formed on the amplitude of the reflected flaw-back signals on the calibration block and the apparatus.