Monitoring of Steel Microstructures using Electromagnetic Sensors

The characterization of steel microstructures is an important tool for metallurgists as mechanical properties are controlled by microstructural parameters such as grain size, phase balance and precipitates. This paper descr-ibes multi frequency electromagnetic(EM)sensors that have been designed to detect changes in the relative permea-bility and resistivity of steel on-line during steel processing, which can be directly related to changes in microstructure. Examples presented in this paper include both laboratory hot tests and industrial field trials for monitoring ofphase transformation in steels, detection of decarburization on a steel rod surface, and imaging of molten steel in the submerged entry nozzle (SEN) during continuous casting