Lattice strain evolution during cyclic loading of stainless steel

A uniaxial tension/compression test specimen was cycled between fixed total strain limits of ±0.4% for eight successive cycles. The sample was loaded using a dedicated Instron hydraulic load frame on the ENGIN station of the PEARL beam line at the ISIS facility of the Rutherford Appleton Laboratory. The load frame was aligned to allow simultaneous monitoring of longitudinal and transverse lattice strain components. There was a strong experimental hkl-dependency of the lattice strain response in both the effective stiffness and in the lattice strain loop hysteresis. The experimental data were compared with numerical predictions obtained from a self-consistent elasto-plastic model for the simulation of polycrystal deformation. A cyclic hardening law was developed and implemented into the modelling scheme, providing theoretical predictions in good agreement with experimental observations.