In a first cooling zone (21) on an upper side of a vertical section (20), an air-water ratio A.sub.1/R.sub.1 defined by an amount of water R.sub.1 (L/min) and an amount of air A.sub.1 (L/min) per one cooling spray nozzle is set to 10 or more, an impinging pressure of cooling water colliding with the surface of a slab (1) from the cooling spray nozzle is set to 12 gf/cm.sup.2 or more, a cooling intensity W.sub.1×t.sub.1 defined by a cooling water density (W.sub.1) (L/min/m.sup.2) and a passing time t.sub.1 (min) of the first cooling zone (21) is 350 or more, and a recuperating time from having passed through the first cooling zone (21) until reaching a bent section (30) is set to 0.5 min or more.

A horizontal continuous casting apparatus includes a fluid supply pipe for supplying a lubricating fluid to the hollow portion of the mold, which is arranged on one end side of the mold; and, a cooling water cavity for accommodating cooling water cooling an inner peripheral surface of the hollow portion of the mold, which is formed outside the inner peripheral surface, wherein the inner peripheral surface and the inner bottom surface of the cooling water cavity facing the inner peripheral surface form parallel surfaces with each other, and a cooling wall of the mold between the inner peripheral surface and the inner bottom surface is formed so that the heat flux value per unit area from the molten aluminum alloy to the cooling water is 10×10.sup.5 W/m.sup.2 or more.

A horizontal continuous casting apparatus includes a fluid supply pipe for supplying a lubricating fluid to the hollow portion of the mold, which is arranged on one end side of the mold; and, a cooling water cavity for accommodating cooling water cooling an inner peripheral surface of the hollow portion of the mold, which is formed outside the inner peripheral surface, wherein the inner peripheral surface and the inner bottom surface of the cooling water cavity facing the inner peripheral surface form parallel surfaces with each other, and a cooling wall of the mold between the inner peripheral surface and the inner bottom surface is formed so that the heat flux value per unit area from the molten aluminum alloy to the cooling water is 10×10.sup.5 W/m.sup.2 or more.

In production of a reactive metal using a melting furnace for producing metal having a hearth, ingots can be efficiently produced by efficiently cooling the ingots extracted from the mold provided in the melting furnace. In addition, an apparatus structure in which multiple ingots can be produced with high efficiency and high quality from one hearth, is provided. A melting furnace for producing metal is provided, the furnace has a hearth for having molten metal formed by melting raw material, a mold in which the molten metal is poured, an extracting jig which is provided below the mold for extracting ingot cooled and solidified downwardly, a cooling member for cooling the ingot extracted downwardly of the mold, and an outer case for keeping the hearth, the mold, the extracting jig, and the cooling member separated from the air, wherein at least one mold and extracting jig are provided in the outer case, and the cooling member is provided between the outer case and the ingot, or between the multiple ingots.

In a first cooling zone (21) on an upper side of a vertical section (20), an air-water ratio A.sub.1/R.sub.1 defined by an amount of water R.sub.1 (L/min) and an amount of air A.sub.1 (L/min) per one cooling spray nozzle is set to 10 or more, an impinging pressure of cooling water colliding with the surface of a slab (1) from the cooling spray nozzle is set to 12 gf/cm.sup.2 or more, a cooling intensity W.sub.1×t.sub.1 defined by a cooling water density (W.sub.1) (L/min/m.sup.2) and a passing time t.sub.1 (min) of the first cooling zone (21) is 350 or more, and a recuperating time from having passed through the first cooling zone (21) until reaching a bent section (30) is set to 0.5 min or more.

A method for improving center segregation and surface crack of continuous casting medium-thick slab of peritectic steel reduces the cooling intensity at the earlier stage of solidification and enhancing the cooling intensity at the final stage of solidification. For example, the cooling water amount of the wide face of the mould is 3400-3600 L/min, and the cooling water amount of the narrow face of the mould is 480-530 L/min. The cooling water amount of the wide face of the foot roller section is 239-298 L/min, and the cooling water amount of the narrow face of the foot roller section is 61-65 L/min. The total cooling water amount of the sector segment is 1517-2166 L/min.

A twin roll casting system includes a pair of counter-rotating casting rolls, a casting roll controller is configured to adjust at least one process control setpoint for the casting rolls in response to control signals. A cast strip sensor measures at least one parameter of the cast strip. A controller receives measurement signals from the cast strip sensor provides control signals to the casting roll controller. The controller is a data-driven model comprising a database of state-input pairs; and executes the following steps at each time step: measure a state-input similarity between a new state observation and samples, assign a weight to each consequent output of samples based on the similarity measured, and sum the weighted outputs and predict an output of a new state observation. The controller is configured to provide the control signals to the casting roll controller based on the predicted output of the new state observation.

A method for improving center segregation and surface crack of continuous casting medium-thick slab of peritectic steel reduces the cooling intensity at the earlier stage of solidification and enhancing the cooling intensity at the final stage of solidification. For example, the cooling water amount of the wide face of the mould is 3400-3600 L/min, and the cooling water amount of the narrow face of the mould is 480-530 L/min. The cooling water amount of the wide face of the foot roller section is 239-298 L/min, and the cooling water amount of the narrow face of the foot roller section is 61-65 L/min. The total cooling water amount of the sector segment is 1517-2166 L/min.

A method of heat treatment of a non-metallic or metallic item is provided. The method includes at least one step A) of heat transfer between the item and a heat transfer fluid A′ including a fluid medium and nanoparticles. The heat transfer fluid has a heat transfer coefficient above the heat transfer coefficient of water. The method also includes at least one step B) of heat transfer between the item and a heat transfer fluid B′ including a fluid medium and nanoparticles. The heat transfer fluid B′ has a heat transfer coefficient different from the heat transfer coefficient of A′ and above the heat transfer coefficient of water. The heat transfer fluids A′ and B′ are different.

A method of heat treatment of a non-metallic or metallic item is provided. The method includes at least one step of heat transfer between the item and a heat transfer fluid A′. The heat transfer fluid A′ includes a fluid medium and nanoparticles having a lateral size between 26 and 50 μm. The heat transfer fluid has a heat transfer coefficient below the heat transfer coefficient of water.