Peening

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

A one-dimensional hydrodynamic model for pressures induced near the coating-water interface during laser shock peening

Abstract: In laser shock peening (LSP) under a water-confinement regime, laser-matter interaction near the coating-water interface can induce very high pressures in the order of gigapascal, which can impart compressive residual stresses into metal workpieces to improve fatigue and corrosion properties. However, self-closed models with spatial distribution considerations for the induced pressures near the coating-water interface in LSP are rarely reported in literature. In this paper, a self-closed model is developed by numerically solving the one-dimensional hydrodynamic equations, supplemented with appropriate equations of state of water and the coating material. The model can produce the one-dimensional spatial distributions of the material responses near the water-coating interface in LSP. The model-predicted pressures have been compared with experimental measurements under a variety of conditions typical for LSP, and good agreements have been found for both the transient pressure history and the peak pressure magnitude.

Effect of laser shock peening on the high temperature oxidation resistance of titanium

Abstract: The effect of laser shock peening on the high temperature oxidation resistance of commercial pure titanium at high temperature (700 °C) was studied in long-time (3000 h) exposure under dry air. A reduction of the gain mass by a factor 4 was found for laser-shock peened (LSP) samples compared to untreated titanium, which supports the interest of laser-shock treatment for the improvement of high temperature resistance. Short-durations (10 h and 100 h) oxidation experiments, devoted to investigate the influence of the LSP treatment on the first stages of the oxidation process, were also carried out by TGA. Several techniques as scanning electron microsco-py, hardness and roughness measurements, X-ray diffraction and X-ray photoelectron spectrometry, micro-Raman spectroscopy, nuclear reaction analysis and electron backscattered diffraction were used to characterize the sample after laser treatment and oxidations. The formation of a continuous nitrogen-rich layer between the oxide layer and the α-case area in LSP samples appears to be the key factor to explain the reduction of oxygen diffusion, and thus the improvement of the oxidation resistance of laser shocked titanium. Moreover, the grain-texture of LSP samples after oxidation can also explain the improvement of the high temperature oxidation resistance after long times exposures.

Modeling Residual Stress Development in Thermal Spray Coatings: Current Status and Way Forward

Abstract: An overview of analytical and numerical methods for prediction of residual stresses in thermal spray coatings is presented. The various sources and mechanisms underlying residual stress development in thermal spray coatings are discussed, then the various difficulties associated with experimental residual stress measurement in thermal spray coatings are highlighted. The various analytical and numerical models used for prediction of residual stresses in thermal spray coatings are thoroughly discussed. While analytical models for prediction of postdeposition thermal mismatch stresses are fully developed, analytical quenching and peening stress models still require extensive development. Various schemes for prediction of residual stresses using the finite element method are identified. The results of the various numerical and analytical models are critically analyzed, and their accuracy and validity, when compared with experiments, are discussed. Issues regarding the accuracy and applicability of the models for predicting residual stresses in thermal spray coatings are highlighted, and several suggestions for future development of the models are given.

Monitored laser shock peening

Abstract: A pulse laser is configured for projecting a pulsed laser beam at a target site on a fluid film atop a workpiece for laser shock peening the workpiece. The fluid film is monitored by a probe laser which projects a probe laser beam at the target site, and an optical detector which detects reflection of the probe beam from the target site. The pulse laser is coordinated by the detector in order to emit the pulsed beam in response to the condition of the monitored film.