In case of Al-killed grades, the steel bath contains high melting point Al2O3 inclusions which can lead to nozzle clogging at the continuous caster, poor transverse mechanical properties after rolling, bad resistance to HIC and bad machinability. The addition of Ca during ladle refining transforms Al2O3 into(CaO)x(Al2O3)y which has a low melting point and also remains globular during rolling, thus eliminating the above problems.

12[Ca]+11[Al2O3] →12CaO.7Al2O3+8[Al]


 Phase-diagram CaO-Al2O3 (click)



Due to the high and stable recovery of additions practised by way of cored-wire, a very accurate and reproducible steel chemistry can be achieved which in turn permits to optimize the mechanical properties and / or heat treatment as well as eliminate rejection or downgrading of heats out of the chemistry specification. Most popular for this purpose are cored-wires containing carbon, sulfur, manganese, FeTi

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