Study On Preheating Free Ladle Shroud With Long Service Life

The ladle shroud is one of the important refractories in the continuous casting to besure the quality of the steel. Sec-oxidation and steering and splashing of melt steel canbe avoided by using it. The service life of ladle shroud is asked for prolonging with theimprovement of steel casting technology. Researches about how to improve the ladleshroud material properties have been done in this study including granularitycomposition, adding graphite, resin, fused SiO2, zircon mullite and SiC. A longservice life ladle shroud has been producted based on the above conclusion. Then thedamage mechanism of the long service life ladle shroud has been studied by SEM. Themain conclusions have been drawn as follows.The apparent porosity, bulk density, room and high temperature strength,coefficient of thermal expansion decrease with the mount of graphite increasing. Thecoefficient of thermal expansion decreases rapidly when the graphite is over15wt%.The room temperature strength, high temperature strength, abrasion loss of the sampledecrease hugely when the graphite is over25wt%.The formulas of Dinger is used to study the granularity composition. The bulkdensity of the sample is the highest, the coefficient of thermal expansion is low, themicro structure of the sample is even when n equals0.5.When the amounts of graphite is20wt%the grain size is increasing gradually,room and high temperature strength is heightening gradually with the amounts of theresins increasing. The bulk density is the highest, the micro structure of the sample iseven when the amounts of resin is11%.The bulk density, room and high temperature strength, coefficient of thermal expansion go down obviously when the amounts of fused silica increases. Theappropriate amount of fused silica is10wt%.The bulk density, room and high temperature strength of the sample keep levelingoff, the coefficient of thermal expansion decreases gradually, thermal shock resistancegot improved with the amounts of zircon mullite increasing.The coefficient of thermal expansion decreases, the thermal shock resistancebecomes better and better with the amounts of SiC increasing. While the strength of thesample goes down rapidly when the amount of SiC is over6wt%.The main damage mechanism is decarbonization by studying on the inside walland powder line of used ladle shroud by SEM. The service life is likely prolonged withdecreasing the amount of carbon of ladle shroud.