The non-proportional behaviour of a nickel-based superalloy at room temperature, and characterisation of the additional hardening response by a modified cyclic hardening curve

Multi-axial deformation strain-controlled testing was completed at Swansea University to characterise the non-proportional hardening response of a nickel-based superalloy. The data was used to assess the validity of a non-proportional cyclic hardening curve correction to represent the hardening response of this alloy. A square strain path, equivalent to a fully out-of-phase loading, was found to exhibit additional hardening at moderate peak applied strains compared to the proportional in-phase case. This additional hardening was not observed at low strain levels or at a test condition applying a lower level of non-proportionality in the applied strain path, and was dependent on strain range.