Speaker
Description
Primetals Technologies develops a new monitoring tool to evaluate the defect rate of a strand after casting based on its chemical analysis and its casting history. The defect monitor calculates different types of defect indices, for internal defects and for surface defects. All these indices are mathematical models mainly based on thermodynamical properties, like phase fraction, liquidus and solidus temperature, etc., that can be calculated by a modified version of the Primetals Technologies software DynaPhase and process parameters like temperature history, casting speed and external strain rates due to bending and unbending. The initial mathematical formulation of the indices has been developed in a joint research project of Primetals Technologies, voestalpine Stahl Linz, Montanuniversitaet Leoben and Aalto University in Helsinki. In an ongoing research cooperation with voestalpine Stahl Linz and Montanuniversitaet Leoben a trial version of the defect monitor is now installed on a continuous casting machine (CCM) of voestalpine Stahl Linz.
The defect indices are calculated for predefined segment lengths of the casted products for different points over the cross section of the segment, like corner, center, narrow side and wide side of a slab. The indices will then be used for quality rating of the casted products and help to decide which post-processing steps are necessary for different casting products (e.g. scarfing, down-grading….).
Unlike other quality rating tools, the defect monitor combines thermodynamical properties with process parameters and distils all this information with the help of physical considerations into simple defect indices with values between 0 and 1.
In this paper the defect monitor will be described in some detail. Moreover, some preliminary results of the validation process of the trial installation on a CCM of voestalpine Stahl Linz will be presented.