Characterisation of work hardening and springback in Ti

Plastic effectsduring sheet metal forming can lead to undesirable distortions in formed components. Here, the three-stage work hardening and plastic strain recovery ("springback") in a cold-rolled, commercially pure titanium is examined. Interrupted standard tensile tests within situ x-ray diffraction and quasi-in situ electron backscatter diffraction show that twinning plays a minor role in both of these phenomena. The experiments give evidence that theobserved work hardening plateau is the result of an abrupt activation and multiplication of  <c+a> slip and a subsequent redistribution of load between grain families. The springback can be attributed to inelastic backwards motion and annihilation of dislocations, driven by backstresses from dislocation-based hardening during loading. The peak broadening behavior, observed by x-ray diffraction, suggests that the internal stress state is highest in the rolling direction, resulting in consistently higher springback magnitude along this direction.