Interfacial Reaction Between Ultra Low C Steel and Gas Generated from Refractory Material Used for Submerged Entry Nozzle for Continuous Casting

Growth of Initial Clog Deposits during Continuous Casting of Ti-ULC Steel – Formation and Reduction of the Initial Deposits at Nozzle/Steel Interface

“…28) On the other hand, actual nozzle clog deposit observed in a number of collected nozzles after the continuous casting of Ti-ULC steel does not contain appreciable content of the Fe t O, although a number of Fe drops could be found in the deposit, apart from a large frozen skull. 4,10,12) In the early reports of the present authors, [20][21][22][23] it was proposed that the liquid "FAT" may be a precursor to cause building up clogging materials during the continuous casting of Ti-ULC steel. It could be reduced either by Al in the liquid steel or C in the nozzle refractory, leaving Al 2 O 3 -TiO x and reduced Fe drops.…”

“…Its formation was confirmed by a series of laboratory scale experiments along with a thermodynamic analysis. 20,22,23) Growth of the initial clog deposit in the Ti-ULC steel could be suppressed by lowering oxygen potential at the interface between the nozzle and the liquid steel, according to the proposed scenario. This was validated in a subsequent study by controlling Al/Ti ratio in the steel and observing the growth of the deposit on the nozzle refractory.…”

“…The CO then oxidizes the liquid steel to form Al 2 O 3 in typical Al-killed steel: 2,9,24) 3CO(g) Al Al O s C 2 3 2 3 ( ) ................. (2) This is known to be a mechanism to initiate "network" alumina. In the previous research by the present authors, 22,23) a similar idea was applied to Ti-ULC steel that contains a few hundred ppm of Al and Ti, simultaneously. In this case, it was shown that not only Al but also Ti and Fe oxidize all together: This reoxidation of Ti-ULC steel at the interface causes the formation of a mixture of solid alumina and liquid Fe t O-Al 2 O 3 -TiO x (hereafter called FAT).…”

“…[13][14][15][16][17][18][19] In a recent series of reports, the present authors proposed a likely scenario regarding the growth mechanism of initial clog deposit during continuous casting of the Ti-ULC steel. 12,[20][21][22][23] A typical SEN is a refractory composed of several oxides with graphite, in order to endure thermal shock during its service. At a casting temperature, a carbothermic reaction takes place and it produces a gas…”

Calculation Accuracy and Efficiency of a Transient Model for Submerged Entry Nozzle Clogging

“…Most studies were made by postmortem analysis of inclusions or clog [13][14][15]30,[39][40][41][42][43] or through thermodynamic calculation of the involved phases (materials) related to clogging. [41,[44][45][46][47] These studies indicated that the clogging event was related to (or affected by) the thermodynamic or chemical properties of the involved materials, but no quantitative correlation between the clogging event and those thermodynamic or chemical properties was established. Therefore, further studies are required before an improved model can be developed by considering mechanisms 2 through 4.…”