Steam exhaust ports are located around a perimeter of a direct chill casting pit, at various locations from below the top of the pit to the pit bottom to rapidly remove steam from the casting pit with addition of dry excess air. Gas introduction ports are also located around a perimeter of the casting pit and configured to introduce an inert gas into the casting pit interior.

The present disclosure shows a superplastic-forming aluminum alloy plate that has excellent properties for superplastic-forming, such as blow forming, and that has excellent surface properties after forming. Shown is a superplastic-forming aluminum alloy plate and a production method therefor, the superplastic-forming aluminum alloy plate being characterized by comprising an aluminum alloy which contains 2.0 to 6.0 mass % Mg, 0.5 to 1.8 mass % Mn and 0.40 mass % or less Cr and in which the balance consists of Al and unavoidable impurities, wherein the unavoidable impurities are restricted to have 0.20 mass % or less Fe and 0.20 mass % or less Si, the 0.2% proof stress is 340 MPa or more, and the density of intermetallic compounds having an equivalent circular diameter of 5 to 15 μm at the RD-TD plane which extends along the center of the plate cross-section is 50 to 400 pieces/mm.sup.2.

The present disclosure shows a superplastic-forming aluminum alloy plate that has excellent properties for superplastic-forming, such as blow forming, and that has excellent surface properties after forming. Shown is a superplastic-forming aluminum alloy plate and a production method therefor, the superplastic-forming aluminum alloy plate being characterized by comprising an aluminum alloy which contains 2.0 to 6.0 mass % Mg, 0.5 to 1.8 mass % Mn and 0.40 mass % or less Cr and in which the balance consists of Al and unavoidable impurities, wherein the unavoidable impurities are restricted to have 0.20 mass % or less Fe and 0.20 mass % or less Si, the 0.2% proof stress is 340 MPa or more, and the density of intermetallic compounds having an equivalent circular diameter of 5 to 15 μm at the RD-TD plane which extends along the center of the plate cross-section is 50 to 400 pieces/mm.sup.2.

A method of casting a metal ingot with a microstructure that facilitates further working, such as hot and cold rolling. The metal is cast in a direct chill casting mold, or the equivalent, that directs a spray of coolant liquid onto the outer surface of the ingot to achieve rapid cooling. The coolant is removed from the surface at a location where the emerging embryonic ingot is still not completely solid, such that the latent heat of solidification and the sensible heat of the molten core raises the temperature of the adjacent solid shell to a convergence temperature that is above a transition temperature for in-situ homogenization of the metal. A further conventional homogenization step is then not required. The invention also relates to the heat-treatment of such ingots prior to hot working.

A method of casting a metal ingot with a microstructure that facilitates further working, such as hot and cold rolling. The metal is cast in a direct chill casting mold, or the equivalent, that directs a spray of coolant liquid onto the outer surface of the ingot to achieve rapid cooling. The coolant is removed from the surface at a location where the emerging embryonic ingot is still not completely solid, such that the latent heat of solidification and the sensible heat of the molten core raises the temperature of the adjacent solid shell to a convergence temperature that is above a transition temperature for in-situ homogenization of the metal. A further conventional homogenization step is then not required. The invention also relates to the heat-treatment of such ingots prior to hot working.

The present disclosure shows a superplastic-forming aluminum alloy plate that has excellent properties for superplastic-forming, such as blow forming, and that has excellent surface properties after forming. Shown is a superplastic-forming aluminum alloy plate and a production method therefor, the superplastic-forming aluminum alloy plate being characterized by comprising an aluminum alloy which contains 2.0 to 6.0 mass % Mg, 0.5 to 1.8 mass % Mn and 0.40 mass % or less Cr and in which the balance consists of Al and unavoidable impurities, wherein the unavoidable impurities are restricted to have 0.20 mass % or less Fe and 0.20 mass % or less Si, the 0.2% proof stress is 340 MPa or more, and the density of intermetallic compounds having an equivalent circular diameter of 5 to 15 μm at the RD-TD plane which extends along the center of the plate cross-section is 50 to 400 pieces/mm.sup.2.

The present invention provides a cold crucible for continuously casting high-purity light metal thin slab, which can control the electromagnetic force applied from the inner wall surface of a cold crucible to the surface of molten metal in order to change the shape of the cold crucible to various shapes during electromagnetic casting, while stabilizing the molten metal inside the cold crucible and casting an ingot having uniform particles.

The present invention provides a cold crucible for continuously casting high-purity light metal thin slab, which can control the electromagnetic force applied from the inner wall surface of a cold crucible to the surface of molten metal in order to change the shape of the cold crucible to various shapes during electromagnetic casting, while stabilizing the molten metal inside the cold crucible and casting an ingot having uniform particles.

A liquid metal jet supplying molten metal during a direct chill casting operation can be optimized to erode the slurry region of the molten sump, but not the solidified metal, at a rate equal to the casting speed. A model of the erosion of solidifying grains in the slurry region of the molten sump can be non-dimensionalized to be used to generate casting parameters (e.g., optimally sized nozzle openings and optimal molten metal flow rates) that would provide the optimized liquid metal jet during the casting process. An ingot cast using such an optimized liquid metal jet would have improved macrosegregation properties (e.g., reduced macrosegregation or more evenly distributed macrosegregation), such as having ingot solute concentrations varying from the molten metal supply concentration approximately 10% or less or 5% or less across the width or height of the ingot.

A method to determine a presence or absence of water in a cavity of a starter block having a non-horizontal surface of DC casting equipment including emitting a wave using a device containing a sensor, the wave propagating along a virtual beam path, directing the wave towards the cavity of the starter block such that the wave is reflected on a horizontal surface of the water, if water is present in the cavity, or is reflected on a non-horizontal surface of the cavity of the starter block, if no water is present in the cavity, detecting the reflected wave using the sensor, or not detecting the wave using the sensor, determining that there is water present in the cavity if the sensor detects the reflected wave, and determining that water is absent in the cavity if the sensor does not detect the wave while the sensor emits the wave.