9th ECCC European Continuous Casting Conference – ECCC 2017

The dual strand casting machine CC No.4 at Linz steel plant is the eldest machine in operation and casts 215 mm thick slabs of ultra-low carbon, low carbon and HSLA steel. Recently bothering sliver defects appeared on the hot bands in a certain width range of approx. 1000 to 1200 mm when casting micro-alloyed construction steel. Such defects were not seen on hot band when rolling slabs from the other casting machines in the plant. Primetals Technologies did a comprehensive study work on the entire air-mist spray cooling in cooperation with voestalpine experts. The cooling setup and operational adjustment was reviewed. Spray performance of each used nozzle was checked in PT test facility and water distribution across slab width was created by simulation tools. By this, realistic spray pattern for each cooling loop as well accumulated patterns at certain decisive positions were established and constructively reviewed. Exceptional situation with collision of sprays with neighboring equipment were considered in the nozzle tests and simulations. Critical situations and items leading in local overcooling were recognized and was brought in relation to the above mentioned quality issues. A stepwise plan for improvements was developed. Most of dominant product quality drawbacks were resolved after implementation of first short-term modifications. Currently the medium-term modifications are in preparation.