What is Fe-Mn-Si based alloys?

What is Fe-Mn-Si based alloys?

Fe-Mn-Si based alloys have two distinctive functions, depending on their composition.

One is shape memory effect and the other is remarkably excellent fatigue durability.

Both of these two properties are obtained by utilizing the stress-induced martensitic transformation of Fe-Mn-Si alloys and their inverse transformation.

Shape memory effect　：The stress-induced martensite phase generated during deformation returns to the original austenite phase by heating.　
Fatigue drability :　The stress-induced martensite generated during deformation returns to the original austenite phase due to the reverse stress. 

Conceptual diagram showing stress-induced martensitic transformation of Fe-Mn-Si alloy
and reverse transformation due to heating or reverse deformation

Typical composition of the alloys

Fe-28Mn-6Si-5Cr alloy can be applied to applications (fastening members) that recover shape only once by utilizing the shape memory effect.Fe-15Mn-4Si-10Cr-8Ni alloy can be used as a material for seismic control dampers due to its excellent fatigue durability.