Shot-Peening of Pre-Oxidized Plates of Zirconium: Influence of Residual Stress on Oxidation

Abstract

Abstract. The present study deals with the oxidation behavior under residual stress of shot-peened plates of "commercially pure" Zirconium exposed for 30 min at 650°C. The influence of the shot-peening on a preoxidizedmaterial is presented. The results have been used to determine the influences of these chemical (preoxidation) and mechanical (shot-peening) treatments on the high temperature oxidation of Zirconium. The oxygen profile was revealed using micro-hardness techniques and confirmed by SEM-EDS techniques. After pre-oxidation the samples were first resurfaced then shot-peened in order to introduce residual stress. A significant increase of the hardness of about +400 HV was observed on pre-oxidized shot-peened samples. The thermogravimetric analysis for 30 min at 650°C under 200mbar O 2 shows a significantly slower oxidation rate for shot-peened samples.A comparison with our computations points out the role of the residual stresses on the diffusion and, consequently, on the oxidation.

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

“…From about 7 up to 40 h, the value of n becomes 1.7 for US and 1. 9 for LSP. The masse gain variation is close to a parabolic kinetic law which corresponds to a rate-limiting process given by the oxygen diffusion through a dense and protective barrier.…”

“…Indeed, large compressive stresses and surface hardening induced by mechanical treatments, such as shot-peening (SP) with WC balls, has been reported to play a positive role in the oxidation resistance of zirconium for instance [9][10]. A beneficial effect of SP treatments on the high fatigue performance of several titanium alloys has also been reported [11].…”

Influence of machining processes on rim zone properties and high temperature oxidation behavior of 42CrMo4

“…Anionic diffusion of oxygen into the metal lattice can be influenced by present stress gradients and thereby impact the oxidation process. In this case, the oxide growth rate was decreased due to present compressive residual stresses …”

“…Very recent publications on the oxidation behavior of commercially pure zirconium with consideration of targeted compressive residual stresses have demonstrated decreased oxidation rates . Anionic diffusion of oxygen into the metal lattice can be influenced by present stress gradients and thereby impact the oxidation process.…”

Influence of the Residual Stresses Induced by Shot-Peening on the Oxidation of Zr Plates

“…The high residual stress values as well the very high stress gradients are susceptible to modify the diffusion of the oxygen and then influence the corrosion behavior of the material. In our previous works [1] we investigated the influence of the shot-peening on the corrosion for the Zirconium for short oxidation times (30 min) at high temperature (650°C) and we noticed that the shot-peened samples have oxidation rates sensibly lower than the original material. The Zr have been used in this study because of the interest of the nuclear industry on the corrosion of this metal and because of the anionic nature of the oxidation at high temperature, with bulk diffusion of the O 2-ions.…”