Peening

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

Influence of anodization on the fatigue strength of 7050-T7451 aluminium alloy

Abstract: In recent years, with higher demand for improved quality and corrosion resistance, recovered substrates have been extensively used. Consequently residual stresses originated from these coatings reduce the fatigue strength of a component. Due to this negative influence occasioned by corrosion resistance protective coatings, an effective process like shot peening must be considered to improve the fatigue strength. The shot peening treatment pushes the crack sources beneath the surface in most of medium and high cycle cases due to the compressive residual stress field (CRSF) induced. The aim of this study was to evaluate the influence on the fatigue life of anodic films grown on 7050-T7451 aluminium alloy by sulphuric acid anodizing, chromic acid anodizing and hard anodizing. The influence on the rotating and reverse bending fatigue strength of anodic films grown on the aluminium alloy is to degrade the stress life fatigue performance of the base material. A consistent gain in fatigue life in relation to the base material was obtained through the shot peening process in coated specimens, associated to a residual stress field compressive near the surface, useful to avoid fatigue crack nucleation and delay or even stop crack propagation.

Effect of coverage and double peening treatments on the fatigue life of a quenched and tempered structural steel

Abstract: The effects of shot peening treatments comprising different degrees of coverage and also the influence of double treatments applied to a quenched and tempered medium-carbon alloyed steel were analyzed. The latter consisted, in one case, of high intensity peening followed by a lower intensity peening treatment and, in the other, of the removal of the damaged surface layer. Surface roughness, subsurface hardening and the residual stress profiles were determined and compared. Furthermore, the fatigue life corresponding to the different shot peening treatments was assessed on a rotating beam machine under alternative stresses of 50% of the tensile strength of the steel. The full coverage peening treatment gave rise to the best fatigue behavior, as under-coverage produces a heterogeneous surface stress field, while overlong shot peening treatments probably lead to surface damage. On the other hand, double surface treatments are at least partially able to mitigate the surface damage produced by a first high intensity peening treatment. Nevertheless, none of the applied double treatments was able to exceed the fatigue life of the optimal single shot peening.

Shot, devices, and installations for ultrasonic peening, and parts treated thereby

Abstract: A system for ultrasonically peeing surfaces includes a sonotrode comprising a body material and a vibrating surface, the vibrating surface coated with a coating material having a hardness greater than the body material, a treatment chamber defined at least in part by the vibrating surface, and at least one piece of shot within the treatment chamber to be excited by the vibrating surface of the sonotrode, the at least one piece of shot having a hardness greater than or equal to 800 HV.