Abstract: Flutter of the tip sections of the blades of an axial-flow steam turbine wheel is inhibited by interconnection of the blades by ball-ended elongate members which are pre-stressed in compression. Each member exerts thrusts on two adjacent blades to pre-stress the blades torsionally each in a sense corresponding to untwisting of the blades. The thrusts are each exerted on the respective blade through socket elements received in respective openings in the blades. Either one or each socket element of each member is in screw-threaded engagement in its opening. Where only one is so engaged, the other is a close sliding fit in its opening.