Uniaxial Ratcheting Behaviours of Materials with Different Crystal Structures

Abstract

This report overviews the influence of asymmetric fatigue cycling on the nature of accumulation of ratcheting strain of different materials with varying crystal structures which include aluminium alloy, interstitial free steel and AISI 304LN stainless steel. Stress-controlled fatigue tests have been carried out at room temperature (300 K) under various combinations of mean stress (σm) and stress amplitude (σa). The results highlight that accumulation of ratcheting strain is dependent on the magnitude of employed levels of σm and/or σa for all the investigated materials. The nature of strain accumulation has been corroborated with plastic damage occurring during cyclic deformation, dislocation cell formation during asymmetric cyclic loading, martensitic transformation in 304LN stainless steel as well as variations of the crystal structure and corresponding stacking fault energies of the materials.