Peening

About: Peening is a research topic. Over the lifetime, 5538 publications have been published within this topic receiving 73073 citations.

Influence of process parameters of ultrasonic shot peening on surface roughness and hydrophilicity of pure titanium

Abstract: Ultrasonic shot peening (USP) can be employed to realize surface nanocrystallization and cause the changes of surface roughness and hydrophilicity at the same time, which may help improving the surface biological properties of pure titanium. In this paper, three-dimensional surface topography image, surface roughness and static contact angle of pure titanium treated by USP with different process parameters were obtained by non-contact optical surface profilometer and contact angle meter. Based on the experimental results, the influence rules and mechanism of process parameters, including peening duration, shot diameter, sonotrode amplitude and peening distance, on surface roughness and hydrophilicity of peened pure titanium were studied and the relation between surface roughness and hardness was also analyzed. After that, two relationship expressions were identified: one was between the surface roughness and surface hardness of pure titanium treated by USP while the other one was between the surface roughness and the process parameters with a correlation coefficient equal to 0.9804. According to the Wenzel model, the changes of the roughness factor r and the Young angle θ of pure titanium with different process parameters were calculated, then the influence of the surface roughness and the Young angle θ on the hydrophilicity of pure titanium were also discussed.

Enhanced fatigue durability of Al-6Mg alloy by applying ultrasonic impact peening: Effects of surface hardening and reinforcement with AlCuFe quasicrystalline particles

Abstract: Composite layer reinforced with quasicrystalline (QC) Al63Cu25Fe12 particles was fabricated on the surface of Al–6 Mg alloy specimens by ultrasonic impact peening (UIP). Stress-controlled fatigue response of the specimens was studied and compared with those for the annealed and UIP-treated specimens. The notch effect of the UIP induced surface roughness calculated in terms of the stress concentration factor does not exceed∼10%. XRD, OM and SEM analyses were used to characterize formed surface layers and fatigue fracture surfaces. Surface composite layer of 40–50 μm thick contains the homogeneously dispersed QC particles (the volume fraction Vf∼0.15) trapped by high compressive residual stresses. The layer demonstrates almost triple increase in microhardness comparing to that for the annealed alloy and twice exceeding of that for the UIP-treated specimen. Superior fatigue endurance of Al–6 Mg alloy after the UIP process and the UIP-induced formation of the composite layer is explained by sub-surface fatigue cracks’ initiation promoted with high compressive residual stresses and tight interfacial bonding of QC reinforcement and the matrix alloy. The improved fatigue behavior of the UIP-treated specimens in both the low cycle and high cycle regimes can be ensured by combination of the following favorable characteristics: (i) sufficiently high ductility and resistance to fatigue damage and crack growth in the core parent material along with (ii) superior fatigue strength supported by high microhardness and compressive stresses in the surface layer, which contains fine grained matrix and/or uniformly distributed and tightly bonded QC reinforcements.