Effect of deformation twins on damping capacity in extruded pure magnesium

The damping capacity, which was characterized by bending vibration decay, was examined in extruded pure magnesium to understand the role played by pre-existing twins introduced by pre-strain. For materials without pre-strain, the damping capacity consisted of the strain-independent and the strain-dependent parts, which emerged above a critical strain. The critical strain observed for the damping capacity corresponded to the proportional limit observed for the tensile or compressive curves. For materials pre-strained to −1% and −8% in the extrusion direction, the damping capacity began to increase at low strains below the proportional limit and was higher than that without pre-strain. The higher damping capacity is thought to occur because of the alternate shrinkage and growth of pre-existing twins.