Static Recovery and the Orthogonal Strain Path Change Effect in IF Steel

Tensile tests have been carried out in the rolling and transverse directions of 'interstitialfree' (IF) steel cold rolled to a strain of εh= -0.18. Tests in the transverse direction showed the characteristic features of the orthogonal strain path change effect, with an initially increased flow stress- compared to tests in the rolling direction- followed by a transient regime of very low strain hardening. Tests were also carried out following recovery annealing of the prestrained sheet at 500°C and 600°C. Static recovery had a marked effect on the strain-induced anisotropy, but this was not eliminated even when the cell structure generated by prestraining haD condensed to one consisting of low-angle boundaries. This supports the view that the length scale, with respect to active slip systems, between boundary obstacles is a significant factor in the orthogonal path change effect.