A gas turbine blade is used for closed steam cooling. A partition, preferably designed as a metal sheet, divides a first part cavity in the axial direction. This is done in such a way that steam is capable of being guided out of the first subspace into an inlet edge cavity and from this into a second subspace with an impact-cooling effect, This has the advantage that closed steam cooling is designed to be particularly simple and cost-effective in manufacturing terms, while at the same time the inlet edge has an aerodynamically favorable shape.