Study on electromagnetic ultrasonic testing method for determining solidified shell thickness during continuous casting

Abstract

One of the areas in the high-temperature continuous casting process that has not been definitively addressed is a method for accurately determining of solidified shell thickness. Therefore, this paper investigates a novel method for non-destructive detection of the solidified shell thickness based on the electromagnetic ultrasonic (EMA) technology. In this method, an electromagnetic ultrasonic transducer (EMAT) was utilized for exciting ultrasonic waves in the continu­ous casting slab. According to the fact that the propagation velocity of ultrasonic waves is a considerable difference in the solid and liquid metal, the TOF delay caused by the reflection and refraction at a solid-liquid interface of ultrasonic waves has been analyzed. Furthermore, studies on the effect of solidification shell thickness on ultrasonic echoes have been carried out by finite element simulation. Through the construction of the experimental platform, the measured data show close agreement with the simulation results and thus verify the reasonable and feasible of the proposed method which can provide reference for on-line detection of solidified shell thickness during continuous casting.