Internal stresses and the mechanism of work hardening in twinning-induced plasticity steels

An analysis of the loading–unloading behaviour of tensile tests of a 22Mn–0.6C (wt.%) twinning-induced plasticity steel shows the development of a very high level of internal stresses concomitant with its peculiar, nearly constant strain-hardening rate. A composite-type strengthening contribution from the increasing volume fraction of twin lamellae offers an explanation for an enhanced internal stress development in this type of materials. Proof of the quantitative significance of the composite-type strengthening requires, however, further study.