Abstract: A turbine wheel including blades and rim made in one piece, a notch in the peripheral surface of the rim between each two successive blades, and a through-hole in the rim radially inwardly of and parallel to each notch. The through-holes permit cooling air to flow from one side of the turbine wheel to the other. Each through hole is spaced closely to its respective notch to define a narrow rated breaking point between the two. The through-holes may be of circular, oval, or elliptical cross-sectional shape. A tubular baffle is arranged in each through-hole, the baffle being open at one end to receive cooling air, but the other end of the baffle being blocked. The wall of the baffle is perforated. Longitudinally-extending webs may support each baffle in spaced relation to the wall of the through hole. Annular plates may be arranged over opposite sides of the wheel to define air flow openings to and exhaust openings from the through-holes.