Annealing is one of the last steps of thin section steel production. This step is performed for a large part on continuous annealing high speed lines. SOLLAC and IRSID developed an industrial testing system for packaging steel. This system uses ultrasonic Lamb waves generated by EMAT transducers which allow non contact testing. The lift-off between transducers and product is about 3 mm. Inspection is performed with product speed up to 12 m/s on 0.2 to 0.3 mm thick products. The measurement permits to detect very low recrystallization level resulting of hot rolling and annealing processes. Thresholds have been fixed by on site learning. The industrial use of this testing system generates an increasing productivity.
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