Abstract: The invention comprises a continuous hot rolling method in which a rear end portion of a preceding metal block and a fore end portion of a succeeding metal block are cut and the metal blocks are joined to each other by heating and pressing followed by a finish rolling. A region of each metal block is restrained from a clamping position to the end portion thereof in order to prevent a change in level of the metal blocks in heating and pressing the piece. The end portions of the metal blocks can be thus prevented from deformation.

Abstract: The present invention belongs to a technical field in the oxygen steel making, more particularly in the steel making by blowing oxygen into a converter from its top and bottom. The total amount of oxygen to be blown into a top and bottom blowing converter is substantially the same as that of oxygen to be blown into a bottom blowing converter, but a part of the total amount of the oxygen is blown into the converter from its top. Therefore, the injection capacity for lime powder is necessarily decreased corresponding to the decrease of the blow rate of the bottom blown oxygen, and the decrease of the injection capacity causes the initial stage blowing up, being generated often in the case where blowing of lime powder is not carried out in the bottom blowing.

Abstract: Methods for controlling blowing, controlling the slag formation and predicting sloping in the blowing of molten pig iron in LD converter are carried out by measuring acceleration of the horizontal movement of a detector, such as a lance provided in the converter, which is caused only by the slag impinging against the lance, by an accelerator, integrating the measured values to obtain integrated average values at every several seconds, and programming the integrated average values in a computer.

Abstract: Method and apparatus for separating slag and pouring molten steel out of a container such as a converter or the like, which makes use of a gas jet member for jetting an inert gas into the flow of the molten steel in a descending portion of a U-shaped passage communicated with a molten steel outlet opening of the converter, whereby the gas jet causes the flow speed of the molten steel to retard so as to eliminate the influence of inertia force of the flow of the molten steel exerted to a balance between the static pressure of the residual molten steel and the static pressure of the residual slag in the U-shaped passage.