Increasing the fatigue strength of parts by ultrasonic surface treatment

1. Surface ultrasonic treatment of turbine blades makes it possible to increase their fatigue strength by 15–25%. Ultrasonic equipment maybe used for treating shafts, disks, gears, and other machine parts experiencing cyclic loads, for which the resonant dimensions of the chamber are chosen in accordance with the part dimensions. 2. The increase in part fatigue strength is caused by the formation of compressive stresses of 50–80 kgf/mm2 at a depth of 100–400 μm under the action of impacts of balls, to which kinetic energy is transmitted by the wall of the working chamber oscillating at ultrasonic frequency. 3. The distribution of dislocations and internal stresses in an ultrasonically strengthened layer is more uniform than in normal static deformation, which decreases the probability of appearance of potential points of origin of fatigue cracks.