Ultrasonic Non-destructive Testing Method For Continuous Casting Slab Defect Detection And Experiment Research

In recent years, even though the continuous casting technology has had a greatdevelopment, due to the various of influence factors during the continuous castingprocess, some kind of surface and interior defects can never be avoided in thecontinuous casting slabs. If the continuous casting slab with defects do not be found outwith an available way, but keep processing. That is not only a waste of energy andresource, but also leave a big hidden danger, which may give rise to massive lose. Whenit comes to continuous casting slab defect detection, we usually make it by means ofnon-destructive detection technology(NDT).In this thesis, simulations and experiments have been done on the ultrasonic testingin the continuous casting slab defect detection. The research achievements andconclusions are as follows:①Based on the Rayleigh integral method, mathematical models of the ultrasonicsound field about the round and rectangular transducers were established. Andresearches on the ultrasonic sound field of the transducers have been done by theoreticalcalculation and experiment ways. The experiment results of measuring the ultrasonicsound field of the transducers show that: the ultrasonic sound field attenuatescontinuously with the angle between transmitting direction and measuring directionincreasing, and ultrasonic propagating. The energy of ultrasonic sound field concentratein±20°of transmitting direction. And we can also find that strength of transmittingdirection is most powerful. Which can provide theoretical foundation and guide function,when do the transducer research and design, type selection and signal analysis.②Mathematical model of ultrasonic propagating in solid was established, andthen, the ultrasonic propagation in solid was visualized by matlab. At the same time,simulation of the ultrasonic propagation was also been done by the sound wavesimulation software Wave2000Pulse, which proved the mathematical model establishedof the ultrasonic propagation was correct. And on this basis simulation researches onultrasonic testing in the continuous casting slab defect detection have been done withWave2000Pulse. Defects involved were interior transverse crack, interior longitudinalcrack, interior hole defect, surface transverse crack, surface slant crack. The simulationresults showed that, Signal of defects were strong in A-scan images and B-scan imagesexcept the interior longitudinal crack. interaction between ultrasonic and defect was obvious, ultrasonic testing was fit for continuous casting slab defect detection. At thesame time, an available method of signal analysis was been proposed.③On the basis of theoretical analysis and simulation analysis, experimentresearches on continuous casting slab defect detection with ultrasonic were conducted.Defects involved were surface transverse crack, surface slant crack, interior hole defectand angle groove. Works of defect detection with ultrasonic and signal analysis havebeen done. Theory system on continuous casting slab defect detection with ultrasonicwas further completed after the comparison and verification between simulation resultsand experiment results. The simulation results and experiment results were basically thesame.④An available research method on continuous casting slab defect detection withultrasonic was proposed, and an equipment of ultrasonic testing for continuous castingdefect detection was developed.