Proposal of an alternative method for residual stress measurements in clad nickel alloy after shot peening

Abstract

Cladding of Ni-based superalloy 625 is often used to enhance mechanical resistance and corrosion performance of the high strength low alloy pipeline, for use in CO2 injection units in oil wells. It is well known that the use of the shot peening can improve its properties by creating a thin surface layer with compressive residual stresses. In this regard, the aim of this work is to propose an alternative method to evaluate the residual stresses of clad Ni-based superalloy 625 based on the deflection measurements of a thin strip separated from the shot peened samples by EDM cutting. The stress distribution in shot peened layer was measured by XRD sin2ψ method with electrolytic removal of surface layers. Measurements by the alternative and XRD method showed that the difference between the average stress values determined by these methods is 4%.