Assessment of cyclic properties of 18G2A low-alloy steel at biaxial stress state

Abstract

An evolution of plastic properties of the 18G2A low-alloy steel due to cyclic predeformation in different directions of the two-dimensional stress space (σ xx ,τ xy ) is assessed on the basis of cyclic curves. The initial material properties have been experimentally evaluated by the analysis of preliminary yield surface. It was made by studying the position in stress space and typical dimensions of the yield surface. The initial yield locus has been determined using a number of specimens which were loaded up to the plastic range along different stress directions. This surface was used as the starting point for comparative studies of plastic properties evolution due to the cyclic prestraining. Cyclic predeformations were induced by monotonic loading at ambient temperature under constant and gradually decreasing amplitude. It is shown that prior cyclic loading induced a softening effect observed during subsequent monotonic loading of the steel. A new concept of the assessment of plastic properties of the cyclically prestrained material is proposed. It deals with the “cyclic yield surface” determination.