Abstract: In a straight barrel type vacuum refining apparatus, use is made of a combination of: a decarburization method wherein the flow rate of oxygen fed into a vacuum tank and the flow rate of an inert gas fed into the vacuum tank are regulated and, at the same time, the flow rate of oxygen gas blown is reduced at a rate of 0.5 to 12.5 Nm3/h/t/min in a low carbon concentration region having a carbon concentration of not more than the critical carbon concentration; and a vacuum refining apparatus provided with dust accumulation preventing means.

Abstract: A method for vacuum decarburization refining of a molten steel includes providing a vacuum tank having a one-legged, straight barrel snorkel as a lower portion of the vacuum tank. The a degree of vacuum in the vacuum tank is regulated at a high carbon concentration region to a value in a range of −35 to −20 in terms of G defined by the following equation (1): G=5.96×10−3×T×ln(P/Pco)  (1), wherein Pco=760{10(−13800/T+8.75)}×(% C)/(% Cr)  (2), and wherein P<760, T represents molten steel temperature, K, and P represents the degree of vacuum in the vacuum tank, Torr.

Abstract: A twin belt continuous casting machine for producing thin slabs includes a pair of belts and a pair of edge dams for forming a metal pool, which are movable in the transverse direction of the belt. A plurality of cooling/heating chambers partitioned in the transverse direction of the belt are provided on the rear surface of the belt in the vicinity of respective side end portions of the belts. A plurality of supporting members which are capable of pressing the rear surface of the belt are respectively provided in the plurality of cooling/heating chambers. The movement of the edge dams is synchronized with the operation of the plurality of supporting members. A fluid introduced into each of the cooling/heating chambers is changed into a heating fluid or a cooling fluid in synchronism with the movement of the edge dams.

Abstract: A continuous casting machine has a mold of a rectangular cross-section having short sides formed by parallel runs of a pair of metallic belts and short sides constituted by parallel runs of a pair of endless loops each comprising a plurality of dam blocks. The parallel runs of each endless loop are guided by inner and outer guide rails sandwiched between the edges of the parallel runs of the metallic belts and moved in the same direction as the movements of the metallic belts and substantially in synchronism therewith. So as to vary the widthwise dimension of a slab to be cast by the mold, the inner and outer guide rails are independently movable. The endless loop comprises first and second groups of dam blocks which groups are respectively shifted widthwise of the slab by one of the guide rails and by the other guide rail, whereby the width of the slab can be varied perpendicularly to the length of the slab being cast.