Peening

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

An analysis of stress concentrations caused by shot peening and its application in predicting fatigue strength

Abstract: — In order to calculate the stress concentration caused by shot-peening dents, three simplified models, namely a one-pit model, a seven-pit model and a pit-loop model, are proposed in this paper. By using a finite element program for automatic dynamic incremental non-linear analysis, the stress concentration coefficients based on these models are calculated for different pit parameters and different stress fields. When considering the stress concentration and residual stress field produced by shot peening, a modified Goodman formula is proposed and used for forecasting the fatigue strength of peened specimens having the fatigue sources at the surface. The forecasted results were verified by peening followed by fatigue tests on 40Cr steel.

Ultrahigh dense and gradient nano-precipitates generated by warm laser shock peening for combination of high strength and ductility

Abstract: Nanocrystalline materials generated by severe plastic deformation often come with high strength but low ductility due to the inability to accumulate dislocations and thus the low work hardening rate. In this study, a unique high strain rate deformation process – warm laser shock peening (WLSP) – is studied to generate extremely high-density nano-precipitates in precipitation hardenable alloy. Aluminum alloy (AA) 7075 was selected to evaluate the generation of ultra-high-density precipitates by WLSP and the effects on the strength and ductility. WLSP integrates the advantages of laser shock peening (LSP), dynamic strain aging (DSA) and dynamic precipitation (DP). The nanoscale precipitate particles generated by WLSP effectively block dislocations and thus increase the material strength. The precipitate–dislocation interaction has been observed by high resolution TEM (HR-TEM) and modeled by the multiscale discrete dislocation dynamic (MDDD) model. It has been demonstrated that compared with room temperature LSP, WLSP can improve material strength by 32.3% without compromising the ductility, in that elongation remains 20%. These ultra-high-density nano-precipitates greatly improve dislocation accumulation capacity and thus effectively increase ductility.

The modelling of residual stresses due to surface peening using eigenstrain distributions

Abstract: The beneficial effect of surface peening (including shot peening, laser shock peening, low plasticity burnishing, etc.) on fatigue resistance of structural alloys is well documented and widely used in industry to improve component life. It is perhaps the most widely used technique that relies on the introduction of residual stresses into the component by direct mechanical means. The resulting stress states are usually evaluated experimentally by X-ray diffraction or other stress measurement techniques. In order for shot peening operations to be effective and reliable, the process of introducing residual stresses and strains into peened components must not only be controlled but also be predictable and quantifiable.The present paper establishes a framework for predictive modelling of the residual stress states due to surface peening. Firstly, uniform (within planes parallel to the surface) plastic deformation of the surface layer taking place during shot peening of a thin plate is simulated using the conce...

Laser peening without coating on aluminum alloy Al-6061-T6 using low energy Nd:YAG laser

Abstract: The present study investigates the effect of laser peening without coating on aluminum alloy Al-6061-T6 with a 300 mJ infrared laser The surface topography, microstructure, surface topography, surface residual stress and micro-hardness of peened and unpeened surfaces were studied The study shows that laser peening without coating can significantly improve surface compressive stress and micro-hardness with trivial increase in surface roughness Microstructure evaluation confirmed there was no near surface solidification after LPwC

Multi-Axial Contour Method for Mapping Residual Stresses in Continuously Processed Bodies

Abstract: This paper describes a method for extending the capability of the contour method to allow for the measurement of spatially varying multi-axial residual stresses in prismatic, continuously processed bodies Currently, the contour method is used to determine a 2D map of the residual stress normal to a plane This work uses an approach similar to the contour method to quantify multiple components of eigenstrain in continuously processed bodies, which are used to calculate residual stress The result of the measurement is an estimate of the full residual stress tensor at every point in the body The approach is first outlined for a 2D body and the accuracy of the methodology is demonstrated for a representative case using a numerical experiment Next, an extension to the 3D case is given and the accuracy is demonstrated for representative cases using numerical experiments Finally, measurements are performed on a thin sheet of Ti-6Al-4V with a band of laser peening down the center (assumed to be 2D) and a thick laser peened plate of 316L stainless steel to show that the approach is valid under real experimental conditions