A direct comparison in the fatigue resistance enhanced by surface severe plastic deformation and shot peening in a C-2000 superalloy

In this study, we present the first evidence and modeling efforts showing that surface severe plastic deformation (S2PD) can be more effective in producing metallic components with superior fatigue properties than shot peening (SP). With the aid of a wide battery of characterization techniques (i.e., X-ray diffractometry, optical microscopy, scanning electron microscopy, transmission electron microscopy, and 3-dimensional non-contact optical profilometry), micro- and nano-hardness testing, and finite element modeling, we have identified the underlying mechanism for the fatigue improvement. It is shown that the enhancement in the fatigue limit is derived from a nanocrystalline surface layer, a work-hardened surface region, and residual compressive stresses at the surface, all of which are introduced by S2PD and more substantial than that introduced by SP.