Shot Peening on Pelton Wheels: Methods of Control and Results

Author:  Marconi, Lauro, Bozzolo
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002019
Year of Publication:  2002
Abstract:  
Authors Paolo Marconi, 2 Effe Engineering s.u.r.l., Manerba del Garda, Italy Marco Lauro, Enel Produzione S.p.A., Turin, Italy Walter Bozzolo, Enel Produzione S.p.A., Turin, Italy Abstract Shot peening is normally used to increase fatigue resistance in rather small-sized mechanical parts (gears, transmission shafts, connecting rods). Residual stresss induced by this treatment has been studied extensively in the past decade. Some automobile manufacturers have recently introduced specifications concerning the depth of residual stress in gears. Most of the research done on this topic has made use of the X-ray diffraction method to determine residual stress. Because of the configuration of Pelton wheels, shot peened areas cannot be easily accessed with portable diffraction meters. For this reason, the authors have used the Barkhausen noise method to measure residual stress and have then compared results before and after peening. The Barkhausen noise method was calibrated against Almen strips by X-ray diffraction and by hole drilling methods.