Ball-Burnishing and Roller-Burnishing to Improve Fatigue Performance of Structural Alloys

On the effect of deep-rolling and laser-peening on the stress-controlled low- and high-cycle fatigue behavior of Ti–6Al–4V at elevated temperatures up to 550°C

“…an increase of the plastic strain amplitude with increasing number of cycles) to cyclic softening followed by cyclic hardening. This observation is consistent to previous studies on Ti-6Al-4V [40][41][42], which showed that at 350°C cyclic softening was followed by cyclic hardening for low strain amplitudes whereas monotonic cyclic softening occurred at high strain amplitudes, with no saturation in cyclic hardening apparent [9].…”

“…However, there are other surface treatments in addition to shot peening [7] that have been used to increase resistance to early fatigue crack initiation and growth in metallic structures, notably deep-rolling [8], roller-burnishing [9] or low-plasticity burnishing 2 [10], and laser-shock (or laser) peening [11][12][13][14]. Shot peening, with or without subsequent polishing, has been utilized now for decades to induce favorable near-surface microstructures and compressive residual stress states [15,16], although several recent studies have revealed the superiority of the so-called alternative surface treatments [8].…”

Surface layer properties and fatigue behavior in Al 7075‐T73 and Ti‐6Al‐4V

“…Mechanical surface treatments are cheap and efficient methods for enhancing fatigue life and strength of metallic light‐weight materials (Wagner et al , 2009; Altenberger et al , 2008). The basic strengthening mechanisms of mechanical surface treatments have been identified: localized elastic‐plastic deformations in near‐surface regions give rise to the formation of compressive residual stresses and severe microstructural changes (usually associated with significant work hardening), enabling the strengthened near‐surface regions to resist or delay fatigue crack initiation and propagation (Wagner, 1999).…”

Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

“…Particularly, in the HCF regime, fatigue strength is known to diminish drastically with increasing grain size due to premature and sudden crack formation [17]. Thermochemical processes such as nitriding and mechanical surface treatments such as shot peening, ball-burnishing and rollerburnishing are known to induce subsurface crack nucleation [43,53,54]. These form as a result of tensile stresses in the treatment/substrate interfacial regions, which balance out the compressive residual stresses induced in the surface by the diffusion process.…”