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

TL;DR

This study investigates how shot-peening affects residual stress and oxidation behavior in pre-oxidized zirconium plates at high temperature, revealing that shot-peening slows oxidation by altering diffusion processes.

Contribution

It demonstrates the combined effects of pre-oxidation and shot-peening on zirconium's oxidation resistance and residual stress influence, providing new insights into surface treatment impacts.

Findings

Shot-peening increases hardness by about 400 HV.

Shot-peened samples exhibit slower oxidation rates.

Residual stresses influence diffusion and oxidation processes.

Abstract

The present study deals with 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 pre-oxidized material 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. Thermogravimetric analysis for 30 min at 650 C under 200 mbar O2 showed 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.