Effects of an even secondary cooling mode on the temperature and stress fields of round billet continuous casting steel

An unequal interval arrangement of nozzles (UIAN) in the casting direction of the secondary cooling process for round billet continuous casting has been presented. The cooling coefficient, spray width in the casting direction and water flow density distribution around the round billet circumference of the nozzles have been accurately determined. The effects of transverse nozzle arrangement, inter-zone distance, number of segments, and length of cooling zone on the temperature and stress fields of round billets were analyzed with a thermal-mechanical finite-element model. Alternating the maximum and minimum water flux by rotating 22.5° between the odd and even rows nozzles can prevent the cooling intensity from being too strong at the same position along the casting direction of a round billet, and enhance the quality of the strand. Decreasing the inter-zone distance can help to even out the surface temperature and stress distribution of a round billet. Careful design of the number of segments number and length of the cooling zone can avoid sharp fluctuations in temperature at the spray cooling end position. An optimized secondary cooling system for achieving even secondary cooling has been designed and applied to an actual round billet casting machine, and the surface temperature of the round billets was very even, with mid-way cracks being completely eliminated.