Effect of the Steelmaking and Continuously-Casting Conditions on Non-Metallic Inclusion of the Steel For Cold Rolled Sheet

Abstract

In order to produce continuously-cast slabs provided for mother material of cold rolled sheet, liquid steels were deoxidized with deoxidizers of Al-Si-Mn system. Non-metallic inclusions of manganesesilicate and alumina were studied with reference to its steelmaking and casting conditions.
The results are as follows.
(1) To reduce the amount of manganese-silicate inclusion,
(a) keep the (blow-off [C]×(T-Fe)) higher,
(b) keep the yield of silicon added as deoxidizers at tapping more than 95%,
(c) furnish tundish-dam, and
(d) keep the casting speed higher.
(2) To reduce the amount of alumina,
(a) keep the blow-off carbon content higher,
(b) reduce Al/Si ratio of the deoxidizers added at tapping,
(c) keep the blow-off temperature higher, and
(d) keep the casting speed higher.
As stated above, steelmaking conditions have a strong connection with the non-metallic inclusions. Therefore, the main source of inclusion is considered to deoxidation products.