Community Research and Development Information Service - CORDIS


The object of this research project was to solve the problem of coupling the slabs coming from the continuous casting machine to a new ultrasonic transducer to detect internal defects by the electromagnetic-acoustic method (EMA). It proved desirable to avoid cooling down the surface of the cast products below the Curie temperature because of the technological difficulties of the cooling itself and of the opposition expressed by the steelmakers, who wanted to avoid cracking the surface of various steel grades and vaporising large quantities of water. For this purpose, the EMA transducer was rebuilt and protected against thermal radiation. Where the steel is no longer cooled, no ferromagnetic surface layer is formed and this makes the generation of ultrasound more difficult. The whole electronic equipment had to be improved: in particular the emitted power and the sensitivity of the detection were increased and the noise level was lowered. With this prototype equipment, artificial defects of 3 x 50 mm2 were detected with a signal to noise ratio of 14 dB. Tests on billets at 850 C revealed internal cracks without cooling or descaling the surface. However, the resolution of the Baumann print can not yet be reached.

Additional information

Authors: NEUMANN N, Centre de Recherches Métallurgiques, 11, rue Ernest Solvay, B-4000 Liège (BE);PIRLET R, Centre de Recherches Métallurgiques, 11, rue Ernest Solvay, B-4000 Liège (BE)
Bibliographic Reference: EUR 12133 FR (1989) MF, 78 pp., ECU 4, blow-up copy ECU 10
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