Abstract
The impact produced when cavitation bubbles collapse can be utilized to modify surfaces in the same way as shot peening and it is called cavitation peening (CP). CP is one of a number of surface modification techniques used to improve the fatigue strength of metallic materials by introducing compressive residual stress. Although it has been shown by an X-ray diffraction method that CP decreases the micro-strain related to dislocations in the sub-surface of a polycrystalline material, the mechanism for this decrease is unclear. In this paper, the movement of dislocations by CP was observed using transmission electron microscopy (TEM).
Highlights
Cavitation normally causes severe damage in hydraulic machinery such as pumps and turbines by the impact produced by cavitation bubbles collapsing
It was found that mechanical finishing and/or heat treatment give(s) rise to micro-strain in the sub-surface of a polycrystalline metal due to the compressive residual stress introduced and that this micro-strain can be reduced by cavitation peening (CP) [6]
The mechanism by which micro-strain is reduced by CP is unclear; in this work, the sub-surface of a polycrystalline metal peened by CP was directly observed using transmission electron microscopy (TEM)
Summary
Cavitation normally causes severe damage in hydraulic machinery such as pumps and turbines by the impact produced by cavitation bubbles collapsing. (2015) Movement of Dislocations in the Sub-Surface of a Polycrystalline Metal by Cavitation Peening Observed by Transmission Electron Microscopy. The mechanism by which micro-strain is reduced by CP is unclear; in this work, the sub-surface of a polycrystalline metal peened by CP was directly observed using transmission electron microscopy (TEM). CP enhances the fatigue strength of metallic materials by introducing compressive residual stress in the sub-surface in the same way as shot peening [1]-[5]. In order to clarify the mechanism by which micro-strain is decreased by CP, the sub-surface microstructure of peened samples was observed using TEM and scanning electron microscopy (SEM). It is noted that this is the first time that movement of dislocations in the sub-surface of polycrystalline metal by CP has been reported
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