The influence of shot peening on the fatigue behaviour of duplex stainless steels

Abstract

Stainless steel bars are currently used to reinforce large concrete structures when they need to guarantee a reliable service in saline environments. As these structures are also usually submitted to cyclic loads, their fatigue performance is an important issue to take into account. It is also well known that shot peening is a process largely employed to improve the fatigue behaviour of metal products. In this process the metallic surface of a component is peened with small spherical shots in order to induce plastic deformations which generate compressive residual stresses and, consequently, the component fatigue resistance is significantly enhanced.AISI 2205 duplex stainless steel bars, already largely used for concrete reinforcement, was the material choice in this work. The bars were hot rolled and afterwards different shot peening treatments were applied, which were fully characterised by means of Almen intensity and coverage ratio. Residual stresses were also measured by means of Xray diffraction. The S-N fatigue curves of the bars submitted to the different shot peening treatments were determined and the improvement due to shot peening explained taking into account the shot peening effects on the surface of the bars.