Abstract: A body of partially solidified metal emerging as ingot from the exit end 10 of an open ended mold 2, is direct cooled by charging liquid coolant into an annular retention chamber 32 circumposed about the exit end opening of the mold in the body thereof, and discharging the coolant from the chamber onto the surface of the ingot through a first passage 14 opening into the exit end of the mold and communicating with the chamber at an opening 50 therein. At times, such as in the butt-forming stage, a second passage 46 is formed in the chamber which is serially interconnected with the first passage 14 at the chamber opening 50 and operable to deliver the chamber coolant to the first passage at an increased rate of flow, relative to the rate at which the coolant was charged into the chamber.

Abstract: A body of partially solidified metal emerging as ingot from the exit end of an open-ended mold, is direct cooled by discharging liquid coolant onto the surface of the ingot through a passage of the mold opening into the exit end of the mold at an aperture therein; and at times, such as in the butt-forming stage, by the added step of forcing pressurized gas into the coolant through a body of solid but porous, gas-permeable material incorporated into the wall of the passage at a surface thereof which extends generally parallel to the flow of coolant in the passage and coterminates with the exit end of the mold at the aperture to form an edge thereof. When the gas is added, the coolant discharges through the aperture in a discontinuous liquid phase in which it is laden with bubbles of undissolved gas that will alter the heat transfer characteristics of the coolant on the surface of the ingot to vary the rate at which heat is lost therefrom.

Abstract: The mold comprises a generally rectangularly shaped, machine duplicatable band which is monolithically circumferentially continuous and inherently convexly bowed on the relatively longer and shorter sides thereof, so that it forms crowns on the opposing side walls of the ingot operatively formed therein. The bow in the relatively longer sides of the band has an inherent deflection adapted to form a crown intermediate between that adapted to compensate for shrinkage during the butt forming stage of the casting operation, and that adapted to compensate for shrinkage when the casting operation is conducted at operating speed.