Abstract: An apparatus for controlling a flow of a molten steel in a mold, the apparatus including: a casting-condition acquiring unit for acquiring at least five casting conditions; a calculating unit for calculating a molten steel flow velocity on a molten steel bath surface in accordance with the acquired casting conditions; a determining unit for determining whether the acquired molten steel flow velocity is higher or lower than a mold-powder entrainment critical flow velocity; a control unit for applying a shifting magnetic field to impart a braking force to a discharge flow from an immersion nozzle and applying a shifting magnetic field to rotate the molten steel in a horizontal direction; and a shifting magnetic field generating apparatus.

Abstract: An apparatus for controlling a flow of a molten steel in a mold, the apparatus comprising: a casting-condition acquiring means for acquiring at least five casting conditions; a calculating means for calculating a molten steel flow velocity on a molten steel bath surface in accordance with the acquired casting conditions; a determining means for determining whether the acquired molten steel flow velocity is higher or lower than a mold-powder entrainment critical flow velocity; a control means for applying a shifting magnetic field to impart a braking force to a discharge flow from an immersion nozzle and applying a shifting magnetic field to rotate the molten steel in a horizontal direction; and a shifting magnetic field generating apparatus.

Abstract: A method for controlling a flow of molten steel in a slab continuous casting machine including controlling a molten steel flow velocity on a molten steel bath surface to a predetermined flow velocity by applying a shifting magnetic field; controlling the molten steel flow velocity on the molten steel bath surface from an inclusion-adherence critical flow velocity or more to a mold-powder entrainment critical flow velocity or less by applying a shifting magnetic field; and controlling the molten steel flow velocity on the molten steel bath surface from the inclusion-adherence critical flow velocity or more to the mold-powder entrainment critical flow velocity or less by applying a shifting magnetic field.

Abstract: A method for controlling a flow of molten steel in a slab continuous casting machine including controlling a molten steel flow velocity on a molten steel bath surface to a predetermined flow velocity by applying a shifting magnetic field; controlling the molten steel flow velocity on the molten steel bath surface from an inclusion-adherence critical flow velocity or more to a mold-powder entrainment critical flow velocity or less by applying a shifting magnetic field; and controlling the molten steel flow velocity on the molten steel bath surface from the inclusion-adherence critical flow velocity or more to the mold-powder entrainment critical flow velocity or less by applying a shifting magnetic field.

Abstract: A poured molten metal quantity control device includes a fixed plate brick having at least one pouring port, a collector nozzle brick, a slide plate brick sandwiched therebetween, an outer race mounted so as to be turned on the outer peripheral side of the fixed plate brick by an extendable unit, and a frame having the slide plate brick mounted thereon that is mounted on the outer race through a pivotal hinge so as to be capable of opening and closing movements. The frame can be opened and closed through the pivotal hinge independently of the turning of the outer race with the extendable unit.

Abstract: When a molten steel flow velocity (u) on a bath surface is higher than a mold-powder entrainment critical flow velocity of 0.32 m/sec, the molten steel flow velocity (u) is controlled to a predetermined molten steel flow velocity by applying a shifting magnetic field to impart a braking force to a discharge flow from an immersion nozzle. When the molten steel flow velocity (u) is lower than an inclusion-adherence critical flow velocity of 0.20 m/sec and is higher than or equal to a bath-surface skinning critical flow velocity of 0.10 m/sec, the molten steel flow velocity (u) is controlled to the range of 0.20-0.32 m/sec by applying a shifting magnetic field to rotate the intra-mold molten steel in a horizontal direction. When the molten steel flow velocity (u) is lower than the inclusion-adherence critical flow velocity, the molten steel flow velocity (u) is controlled to the range of 0.20-0.

Abstract: A fixed plate (15) is provided in a fixed metal frame (14). An opening and closing metal frame (17) having a movable plate (21) is attached to the fixed metal frame (14) so as to be openable and closable. The fixed metal frame (14) is provided with a pressurizing mechanism (23) applying a pressure in a closing direction generated by a spring (25) to the opening and closing metal frame (17) in a closed state. An actuating member (29) is movably provided at a position facing the pressurizing mechanism (23). Cam surfaces (30d, 32a) are provided between the actuating member (29) and the pressurizing mechanism (23). The spring (25) is deformed against an urging force thereof on the basis of operations of the cam surfaces (30d, 32a) in accordance with a movement of the actuating member (29), and the pressure applied to the opening and closing metal frame (17) is strengthened.

Abstract: In a rotary nozzle brick body formed into a substantially egg-like shape in it's plan view, the present invention secures a contact area of a nozzle portion and improves a configuration factor which considerably affecting the durability of the body. A rotary nozzle brick body is characterized in that the external shape in plan view is comprised of first circular portions (G), second circular portions (H), third circular portions (K), and tangent lines connecting the first circular portions and third circular portions so that a substantially elliptical shape is formed by increasing the circular portion and shortening the tangent lines, instead of a substantially egg-like shape having long tangent lines.

Abstract: A pierced shell of an austenitic stainless steel having a good inner surface condition is provided, and a means is established which can perform mass production on an industrial scale of a good quality seamless steel pipe of stainless steel. An austenitic stainless steel billet with a P content of at most 0.040% and an S content of at most 0.020% is pierced under conditions such that the pipe expansion ratio H (outer diameter of shell/diameter of billet to be worked) satisfies the following equation to obtain a tube shell of an austenitic stainless steel. {P(%)/(0.025×H?0.01)}2+{S(%)/(0.015×H?0.01)}2?1. When manufacturing a seamless steel pipe of an austenitic stainless steel, the above-described shell is rolled to form a pipe.

Abstract: A poured molten metal quantity control device includes a fixed plate brick having at least one pouring port, a collector nozzle brick, a slide plate brick sandwiched therebetween, an outer race mounted so as to be turned on the outer peripheral side of the fixed plate brick by an extendable unit, and a frame having the slide plate brick mounted thereon that is mounted on the outer race through a pivotal hinge so as to be capable or open and close operation, wherein the frame can be opened and closed by the pivotal hinge irrespectively of a turning means composed of the extendable unit as well as the outer race is turned by a crank mechanism using triangle points consisting of a support pivot P1, a center of turn P3, and a pivot P2, and the positions of the triangle points are defined such that the completely open/close positions of the pouring port are matched to the end point and the start point of the stroke of the extendable unit.

Abstract: A pierced shell of an austenitic stainless steel having a good inner surface condition is provided, and a means is established which can perform mass production on an industrial scale of a good quality seamless steel pipe of stainless steel. An austenitic stainless steel billet with a P content of at most 0.040% and an S content of at most 0.020% is pierced under conditions such that the pipe expansion ratio H (outer diameter of shell/diameter of billet to be worked) satisfies the following equation to obtain a tube shell of an austenitic stainless steel. {P(%)/(0.025×H?0.01)}2+{S(%)/(0.015×H?0.01)}2?1 When manufacturing a seamless steel pipe of an austenitic stainless steel, the above-described shell is rolled to form a pipe.

Abstract: In a rotary nozzle brick body formed into a substantially egg-like shape in its plan view, the present invention secures a contact area of a nozzle portion and improves a configuration factor which considerably affecting the durability of the body. A rotary nozzle brick body is characterized in that the external shape in plan view is comprised of first circular portions (G), second circular portions (H), third circular portions (K) and tangent lines connecting the first circular portions and the third circular portions so that a substantially elliptical shape is formed by increasing the circular portions and shortening the tangent lines, instead of a substantially egg-like shape having long tangent lines.

Abstract: When a molten steel flow velocity (u) on a bath surface is higher than a mold-powder entrainment critical flow velocity of 0.32 m/sec, the molten steel flow velocity (u) is controlled to a predetermined molten steel flow velocity by applying a shifting magnetic field to impart a braking force to a discharge flow from an immersion nozzle. When the molten steel flow velocity (u) is lower than an inclusion-adherence critical flow velocity of 0.20 m/sec and is higher than or equal to a bath-surface skinning critical flow velocity of 0.10 m/sec, the molten steel flow velocity (u) is control to the range of 0.20-0.32 m/sec by applying a shifting magnetic field to rotate the intra-mold molten steel in a horizontal direction. When the molten steel flow velocity (u) is lower than the inclusion-adherence critical flow velocity, the molten steel flow velocity (u) is controlled to the range of 0.20-0.

Abstract: The gap between an insertion hole formed in a covering of a ladle and an electrode inserted through the insertion hole is sealed by sealing means. The sealing means has a cap seal longitudinally and slidably fitted over the electrode. A base seal is hermetically disposed between the cap seal and the covering in such a manner that a gap is provided between the electrode and the base seal. The base seal has a gas injection nozzle intended to discharge a gas toward the electrode and another gas injection nozzle intended to discharge the gas downwardly. The use of the base and cap seals enables securing the sealing functions thereof despite any movement of the electrode, thus preventing the pickup of [N] as well as the reoxidation of molten steel. When a gas seal is effected by the formation of a flow of gas rotating around the electrode about the axis thereof, the sealing performance can be more enhanced.

Abstract: The invention provides a process for obtaining low-nitrogen steel by tapping molten steel from a converter without deoxidizing and by then deoxidizing the molten steel in a ladle refining furnace from which slag has been removed, and a process for obtaining low phosphorus steel by tapping molten steel from a converter without deoxidation at a tapping temperature lower than conventional processes, and by performing deoxidation and composition adjustment of the molten steel in a ladle refining furnace from which slag has been removed.

Abstract: Molten steel is tapped from a converter into a refining ladle, and an ore such as Nb.sub.2 O.sub.3 ore is charged into the molten steel. Then, the interior of the refining ladle is held in an inert gas atmosphere. A reducing agent such as an Al reducing agent is charged into the molten steel. Electrodes are dipped in slag on the molten steel to form an arc therebetween so as to heat the molten steel with an arc. The ore is reduced by the reducing agent, so that a metallic component of the ore is added to the molten steel. On the other hand, carbon electrodes each having a gas supply port at its lower end can be used to inject an ore powder or particles from the injection ports to the arc between the electrodes and molten steel. The ore is reduced by electrode carbon with arc heat, so that a desired component is added to the molten steel.

Abstract: A process for desulfurizing molten steel comprising the steps of: removing converter slag from molten steel; adding a desulfurizing flux onto the molten steel from which the converter slag has been removed; supplying power to electrodes at a predetermined distance from the molten steel so as to generate an electric arc, the desulfurizing flux being melted by arc-heating so as to form the slag; and introducing a gas into the molten steel through a lance submerged into the molten steel to stir the molten steel and the slag which are arc-heated. In the process the desulfurizing flux is melted to a slag consisting essentially of 53 to 62% of CaO, 0 to 15% of SiO.sub.2, and 30 to 45% of Al.sub.2 O.sub.3.

Abstract: The invention relates to a method of operating a ladle refining furnace for blowing Ar gas through bubbling lances submerged in molten steel in a ladle to stir the molten steel. The flow rate and the rate of change in the flow rate of the Ar gas blown through the bubbling lances are adjusted to prevent the iron lumps from attaching to the bubbling lances.

Abstract: Nondeoxidized molten steel is removed from a steel converter and poured into a ladle. Carbon electrodes are submerged in a slag layer on the molten steel and are separated by a predetermined distance from the molten steel. The electrodes are energized to generate arcs with the molten steel. Argon gas is blown into the molten steel through a lance submerged in the molten steel to stir the molten steel with the gas. The molten steel is arc-heated and at the same time stirred. Carbon in the molten steel reacts with residual unstable oxygen in the steel to deoxidize the molten steel. The molten steel is also decarburized, thereby preventing an increase in carbon content of the molten steel in the arc process.

Abstract: Molten steel is refined in a converter and is poured from the converter to a ladle. A ferro-alloy containing a component to be adjusted is added to the molten steel as needed. An amount of the alloy to be added to the molten steel in the ladle is calculated from a composition analysis value of the molten steel in the converter, and the amount of the alloy which is added when the molten steel is poured from the converter. The thus calculated amount of the alloy is added to the molten steel in the ladle. Electrodes are submerged in a slag layer on the molten steel so as to be arranged a predetermined distance from the molten steel. Power is supplied to the electrodes so as to generate electric arcs between the electrodes and the molten steel, thereby, arc-heating the molten steel. Simultaneously, a lance is submerged in the molten steel, and an Ar gas is injected in the molten steel therethrough, thus strirring the molten steel.