Finite-element and XRD methods for the determination of the residual surface stress field and the elastic–plastic behaviour of duplex steels

Duplex stainless steels have a complex microstructure with comparable volume fractions of austenite and ferrite. Due to differences in the mechanical properties, a heterogeneous distribution of stresses is generated in both phases. In this paper, a finite-element method and a thermo-mechanical model are described for determining the residual surface stress distribution on duplex steels. The stress distribution is calculated after various surface treatments and under straining conditions. The numerical calculations are then compared with the experimental results in order to verify the accuracy of the method. An original method based on successive XRD measurements is then proposed to study the elastic–plastic properties of both phases. The results are compared with those obtained from surface observations.