Abstract: A process for cooling a metal substrate running in a longitudinal direction, said process including ejecting at least one first cooling fluid jet on a first surface of said substrate and at least one second cooling fluid jet on a second surface of said substrate, said first and second cooling fluid jets being ejected at a cooling fluid velocity higher than or equal to 5 m/s, so as to form on said first surface and on said second surface a first laminar cooling fluid flow and a second laminar flow respectively, said first and second laminar cooling fluid flows being tangential to the substrate, said first and second laminar cooling fluid flows extending over a first predetermined length and a second predetermined length of the substrate respectively, said first and second lengths being determined so that the substrate is cooled from a first temperature to a second temperature by nucleate boiling.

Abstract: A process for secondary descaling of running metal strips, especially made of steel, during hot-rolling by-spraying water onto the surface of the running metal strips with spray rails having nozzles supplied with pressurized water, wherein the nozzles are supplied at a hydraulic pressure of from 3 to 30 bar, and wherein the nozzles are regulated so that heat flux density extracted from the strip (HF) resulting from the cooling of its surface by the sprayed water is between 6.5 and 20 MW/m2 for a strip temperature between 900 and 1100° C.

Abstract: A process for cooling a metal substrate running in a longitudinal direction, said process including ejecting at least one first cooling fluid jet on a first surface of said substrate and at least one second cooling fluid jet on a second surface of said substrate, said first and second cooling fluid jets being ejected at a cooling fluid velocity higher than or equal to 5 m/s, so as to form on said first surface and on said second surface a first laminar cooling fluid flow and a second laminar flow respectively, said first and second laminar cooling fluid flows being tangential to the substrate, said first and second laminar cooling fluid flows extending over a first predetermined length and a second predetermined length of the substrate respectively, said first and second lengths being determined so that the substrate is cooled from a first temperature to a second temperature by nucleate boiling.

Abstract: This process for the secondary descaling of running metal strips, especially made of steel, during the hot-rolling thereof, by spraying water onto the surface thereof using spray rails having nozzles supplied with pressurized water, is characterized in that the nozzles are supplied at low hydraulic pressure, not exceeding 30 bar (preferably below 10 bar, but without going below 4 bar), and in that for the purpose of providing a thermal effect of the water sprayed onto the surface to be descaled quantitatively similar to the thermal effect obtained with the usual known method of secondary descaling at high pressure, namely a cooling of the strip which reduces its surface temperature to approximately 600° C., so that the heat flux density extracted from the strip (HF) resulting from the cooling of its surface by the sprayed water is similar to that achieved with said known high-pressure practice.