This research aims at clarifying the mechanical-property distribution in cold roll-formed steel square tubes. It is found that both corners and flat portion are significantly hardened and consequently that increases in strength, and decrease both in elongation and impact energy. However, these deficiencies are recovered by temperature annealing and normalizing. In test scope, mechanical-properties make recovery with temperature annealing. However, steel's softening was ahead of recovery on the heat treatment of normalizing.
