Measurements on High-Temperature Steels
The noncontact EMAT technique has met many demands in the steel industry from the early time of development, because the steel products (billets, plates, pipes, ...) are heated over 1000°C for thermomechanical processing while being moved at high speeds. Tight control of dimensions and qualities requires the on-line and noncontact/nondestructive assessment of interior conditions of intermediate products. Sensing should not perturb the process. Previous researches have demonstrated the usefulness of EMAT techniques for reconstructing the liquid-solid interface in partially solidified steel strands during continuous casting as well as the internal temperature (Kawashima et al., 1979; Boyd, 1990), and for measuring the wall thickness of hot seamless steel tubes (Yamaguchi et al., 1986), to name a few. These two approaches have proven promising through field testing in commercial production lines and will be reviewed in the following sections. They used EMATs to launch and detect pulsed longitudinal wave in the low-MHz range. The time-of-flight becomes an interior temperature gauge, enabling noncontact and real-time monitoring.
KeywordsLongitudinal Wave Cast Speed Steel Slab Transmitter Coil Sensor Coil
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