Characterize the individual grain behavior during springback of titanium alloys

Springback is defined as the behavior of the material when unloading the stress applied to it; if this behavior is linear, it is well understood and easily predictable because it is governed by classical elasticity. On the other hand, and this is the subject of our study, a non-linear unloading behavior is observed during the stamping of sheets for example and the mechanisms responsible for this behavior are poorly understood and controversial. Although many authors have observed nonlinear springback, paradoxically, few have observed it at fine scales and the hypotheses are numerous. Some authors attribute it to second-order elasticity, others to residual stress heterogeneities, fracture mechanisms, textural softening induced by deformation, detwinning, but there is currently no direct evidence of this phenomenon.