Detection of the position of the phase transition using Acoustic Emission

Purpose and goal

The purpose of the project was to detect and position the phase transformation in the cooling section of a hot strip mill. Positioning is done by monitoring three positions in the cooling section using sensors located on below the strip. The sound was measured through a water column in contact with the strip and with ultrasonic sensors. The method was sucessful. One major advantage is that measurements can be performed on a moving body from a distance- without mechanical contact. The performance of the method was sucessfully demonstrated in pilot scale .

Expected results and effects

The first tests were done with a piezoelectric sensor but the used sensor gave a weak a signal instead the project switched to ultrasonic sensors. One ultrasonic sensor was encapsulated for industrial tests at SSAB, however, the sensor did not properly fit in the production line. Instead, a pilot demo system was built and tested in Swerim´s continuous heating /cooling line. The method was demonstrated with great success. SIEMENS is interested in the technology for possible further development and SSAB find the technique useful if implemented in therir cooling line.

Planned approach and implementation

The project started with small scale functional tests, which contributed to a successful result. The large scale tests was delayed as the equipment did not fit into SSAB´s cooling line. Instead pilot tests were performed at Swerim, Luleå with great success. The method performed well in Swerim´s continuous pilot line. SSAB is interested in the method as knowledge of the position of the phase transformation is of great importance for the microstructure. However an industrial solution needs to cover a long distance and sensors are preferrably included in existing cooling pipes.