Peening

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

On the Influence of Cold Work on Eddy Current Characterization of Near-Surface Residual Stress in Shot-Peened Nickel-Base Superalloys

Abstract: Shot-peened nickel-base superalloys exhibit 1–2% increase in apparent eddy current conductivity (AECC), which can be exploited for nondestructive residual stress assessment. Experimental evidence indicates that the excess AECC is due in part to elastic strains, i.e., residual stress, and in part to plastic strains, i.e., cold work. The very fact that the conductivity increases rather than decreases was originally thought to indicate that there was no significant cold work contribution to the observed AECC increase. This assumption was also supported by X-ray diffraction (XRD) results on fully relaxed specimens showing that the cold work induced widening of the diffraction beam only partially vanishes when both the residual stress and the AECC completely disappear due to thermal relaxation. However, we show in this paper that assuming that the conductivity change is entirely due to residual stress via the piezoresistivity of the material could result in an unacceptable overestimation of the magnitude of the compressive residual stress. Therefore, we investigated the different mechanisms through which cold work could influence the AECC in surface-treated nickel-base superalloys. It was found that neither the magnetic susceptibility nor the piezoresistivity of the material is affected significantly by cold work up to 50% plastic strain level, but the electrical conductivity does substantially increase due to microstructural changes. Based on these observations, we suggest that in future research the complex variations caused by cold work should be modeled by at least two main types of cold work parameters rather than by a single one in order to properly account for the otherwise contradictory effects of plastic deformation on eddy current conductivity and XRD measurements.

The use of ultrasonic cavitation peening to improve micro-burr-free surfaces.

Abstract: Advances in machining technology, particularly in the field of micro-machining, have led to the design and creation of miniature components suitable for use in the precision engineering industry. However, the need to contain ubiquitous burrs still exists and has to be addressed. Previous studies on deburring have mostly focused on the parametric investigations of orientation, temperature, type of liquid media and abrasives, frequency, deburring time and power. It is hypothesized that by inducing compressive residual stresses on a pre-machined workpiece surface, the resulting burrs caused by machining can be minimized or even eliminated. The paper presents the findings of an investigative study into the possibility of inducing compressive residual stresses on machined surfaces by the use of ultrasonic cavitation, with the aim of reducing or eliminating burr formation. The paper also briefly reviews the development of ultrasonic cavitation and covers published work on deburring by ultrasonic cavitation. Experimental results are presented on the performance of ultrasonic cavitation peening on the residual stress in Stavax stainless steels and on micro-burr formation.

Effect of high repetition laser shock peening on biocompatibility and corrosion resistance of magnesium

Abstract: Magnesium, as a biomaterial has the potential to replace conventional implant materials owing to its numerous advantages. However, high corrosion rate is a major obstacle that has to be addressed for its implementation as implants. This study aims to evaluate the feasibility and effects of High Repetition Laser Shock Peening (HRLSP) on biocompatibility and corrosion resistance of Mg samples and as well as to analyze the effect of operational parameters such as peening with overlap on corrosion rate. From the results obtained using hydrogen evolution and mass loss methods, it was found that corrosion rates of both 0% overlap and 66% overlap peened samples reduced by more than 50% compared to that of unpeened sample and sample peened with 66% overlap exhibited least corrosion. The biocompatibility of peened Mg samples was also enhanced as there was neither rapid pH variation nor large hydrogen bubble formation around samples.

Simulation of Residual Stress Distribution on Shot Peening.

Abstract: It is generally recognized that one of the reasons for improvement on fatigue durability by shot peening is surface compressive residual stress. And a shot peening condition decides a residual stress profile on surface layer. But, at this moment the method to confirm this profile is only measurement by X-ray difractometer. In this study, a simulation technique was applied to predict the residual stress distribution caused by shot peening. Firstly, the residual stress on shot peened plate specimens was measured by X-ray difractometer and the effect of shot peening condition on profile was confirmed. The equation to simulate the profile was obtained by the superposition method of simple three stresses, based on the equation that Y.F. Al-Obaid suggested. It was confirmed that the predicted stress profile shows good correspondence with the experimental value every shot peening condition of this experiment.