AN ULTRASONIC SYSTEM AND A CAUSE-DETECTION OF SURFACE CRACK GENERATION DURING HSS ROLLING PROCESS IN AN ULTRASONIC SYSTEM TO AVOID ROLL FAILURE THROUGH CORRECTIVE ACTION IN ROLL COOLING PHASE

摘要

The invention relates to an ultrasonic system and a cause-detection of surface crack generaztion during HSS rolling process in an ultrasonic system to avoid roll failure through corrective action in roll cooling phase, the method comprises the steps of providing a system having at least two ultrasonic transducers, a probe holder, and an ultrasonic flaw detector unit; transmitting by a first transducer a surface wave of frequency 0.5MHz into a test object; exciting the transducer by the flaw detector; receiving in the first transducer the transmitted signal, the probe holder holding both the transducers at a fixed distance; monitoring in a display device of the flow detector the axial travel of the signal by placing the probe diametrically along the length of the test object and measuring the travel velocity of the signal in the central region of the object; monitoring in the display the travel velocity of the signal by placing the probe perpendicularly along the length of the test object and measuring the velocity of the signal in the central region of the object, wherein a calibration curve for the ultrasonic wave velocity difference in the axial and radial directions is generated with respect to the stress values measured by a x-ray diffraction technique.