A technology has been proposed for obtaining rolled plates with the use of calcium carbide instead of
vacuum degassing. The technology makes it possible to obtain steel that is equivalent to vacuum-degassed
steel with respect to the composition and quantity of nonmetallic inclusions and the quality of the finished
plates. It is shown that the use of calcium carbide reduces the content of nonmetallic inclusions by a factor
of roughly 1.5 compared to use of the standard technology without vacuum degassing. The percentage of
hot-rolled plates rejected for defects detected in ultrasonic tests is also decreased.
One of the biggest challenges in steel production is minimizing the steel’s content of nonmetallic inclusions (NI)
before casting in order satisfy customers’ requirements. To do this, the electric steelmaking shop at the Severstal’ plant has
begun working on lowering the NI content of steel in the cast state.
The plant previously subjected all grades of plate steel (for plates thicker than 15 mm) to vacuum degassing and pre-
ceded this treatment by the addition of up to 2.5 kg of pig aluminum per ton of steel.
To eliminate the degassing operation and improve the purity of the steel, calcium carbide was tried out as the deox-
idizer for some of the grades. This material has traditionally been used to make acetylene in the chemicals industry. The use
of calcium carbide makes it possible to decrease the degree of oxidation of the steel without contaminating it with inclusions
. The calcium carbide is delivered in 25-kg casks (GOST 1460-81).
The technology developed for the out-of-furnace treatment of steel with calcium carbide (without treatment on a
vacuum-degassing unit as well) includes heating and deoxidation of the slag with portions of silicon carbide and calcium car-
bide, the addition of ferroalloys, the addition of more calcium carbide before the introduction of aluminum, and the intro-
duction of silico-calcium cored wire.
Deoxidation takes place at the slag–metal interface in accordance with the reaction
+ 3[O] = (CaO) + 2CO.
The introduction of a large amount of CaC
results in carbonization of the steel by means of the reaction
→ [Ca] + [C]. Thus, the amount of CaC
used must be limited when low-carbon steel is being made.
Metallurgist, Vol. 51, Nos. 9–10, 2007
TECHNOLOGY FOR OUT-OF-FURNACE TREATMENT
OF STEEL WITH THE USE OF A NEW DEOXIDIZER
A. N. Lutsenko,
A. A. Nemtinov,
S. B. Eroshkin,
K. É. Prudov,
O. V. Popov,
A. V. Kuklev,
and V. V. Sosnin
Translated from Metallurg, No. 10, pp. 48–51, October, 2007.
2007 Springer Science+Business Media, Inc.
Cherepovets Metallurgical Plant Severstal’.