Modelling the evolution of residual stresses during tensile testing of elastoplastic wires subjected to a previous bending operation

During coiling operations high residual stresses are frequently developed in steel wire. In this paper the stress distribution in wires during coiling, unwinding and subsequent tensile testing is modelled for numerous bending degrees, assuming perfect Voce plastic deformation and linear elastic behaviour. The influence of such residual stresses on the observed tensile test data can be deduced. It is shown that coiling with spool radii as used today industrially can lead to measurement of wire properties deviating significantly from the `true' properties of a properly coiled wire. Also, a method is proposed to deduce the original flow behaviour of coiled samples from tensile test curves, hence filtering the effect of the residual stresses.