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.