SOME ASPECTS OF CONTINUOUS CASTING OF LOW CARBON MICROALLOYED STEELS WITH NIOBIUM AND TITANIUM

An analysis of the causes of transverse corner and surface crack formation during continuous casting of low carbon niobium and titanium-containing steel into square billets is presented in this paper. Using X - ray analysis method, the chemical composition of non- metallic phases inside corner cracks was determined. The temperature ranges of the occurrence of nitrides and carbonitrides of Nb, Ti and Al were established using FactSage 6.2., a commercial computer program. The need for the precise selection of cooling conditions during casting of billets both in the mould and in spray cooling regions was pointed out with the aim of obtaining the optimum surface, and particularly corner temperature of the billet before its entrance to the straightening stand.