| The effects of cold working and annealing temperature on the shape memory effect(SME) and tensile properties of Fe-30Mn-5Si-1Co alloy have been studied. Neel temperature(T_N) was decreased by the addition of 1wt% Co. After the specimens were cold rolled and annealed at various temperatures, the recovery of each specimens was measured. A maximum recovery was obtained at 600℃. Above 600℃, the SME decreased with the increase of annealing temperature due to the decrease of matrix strength by the recrystallization. Below 600℃, retained α` martensite and ε martensite diminished the SME. The M_d temperature decreased as the reduction ratio increased, which means that the γ→ε martensite transformation was suppressed. As a consequence, the SME decreased. The deformation mode changed from the usual slip to the stress-induced γ→εmartensite transformation as the deformation temperature lowered. And as the deformation temperature lowered, the SME became enhanced because of the increasing driving force of γ→εmartensite transformation. |
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