Flowvis : measurement, prediction and control of steel flows in the casting nozzle and mould

Control of steel flow through the casting nozzle and within the mould is an important determinant of steel cleanness and surface quality. Techniques including visualisation of steel flow in the nozzle using electromagnetic, ultrasonic and thermal sensors in combination with the measurement of steel flow velocities and distribution in the mould allow project partners Corus RD & T, Sidenor I + D, BFI, Saarstahl and MEFOS to develop a physical picture of the steel flow behaviour during the casting process, including effects such as nozzle clogging and flow asymmetry/biased flow. In addition, a full-scale physical model of a slab caster has been designed and manufactured using a low-temperature liquid metal to simulate the casting process. Work has been carried out using these techniques to correlate with existing data, product grading schemes and both product cleanness and surface quality. An assessment has been made of the influence of flow pattern in the SEN and mould on solidification. A study was made of reasons for changes observed in flow patterns, including determination of why flow patterns change during stable casting. An investigation into the influence of casting parameters on clogging and wear has been carried out, including criteria for monitoring the condition of the nozzle during casting. From these assessments recommendations have been made for process optimisation. These include the control of flow pattern in the SEN, optimisation of SEN immersion depth and online monitoring of clogging. A comparison was made between the various techniques, indicating their capability and limitations.