Influence Of Shot Peening On Notched Fatigue Strength Of Ti-6a1-4v

Author:  Gerdes, C. and Leutjering, G.
Source:  Conf Proc: ICSP-2, (p.175-180)
Doc ID:  1984033
Year of Publication:  1984
Abstract:  
The fatigue strength of smooth and notched specimens was investigated for four different microstructures of the Ti-6A1-4V alloy. Comparing the S-N curves of smooth and notched specimens in the electrolytically polished condition and plotting the maximum stress at the root of the notch (oa.Kt) for the notched specimens the same 10(7) cycles fatigue strength was obtained if resistance against crack nucleation determined the fatigue strength. A higher fatigue strength for the notched specimens was obtained if resistance against microcrack propagation determined the fatigue strength. This latter behavior was also found for all shot peened conditions indicating that the influence of residual compressive stresses on microcrack propagation determined the fatigue strength. This point could be proven by measuring the fatigue strength of shot peened specimens after the internal stresses had been relieved to a large extent by annealing. furthermore, by separating the remaining two parameters (surface roughness and dislocation density) the tremendous beneficial effect of dislocation density on fatigue strength can be seen. Descriptors: Fatigue strength; Smooth and notched specimens; Electrolytically polished surface; Shot peening; Residual stresses; Surface roughness; Dislocation density