Author(s)

H. Naoi, M. Wada, T. Koike, H. Yamamoto & T. Maruyama

Abstract

Ferrous shape memory alloy has recently been developed. The shape recovery characteristics of Fe-28%Mn-6%Si-5%Cr shape memory alloy are reported by uni-axially pre-strained test. The alloy has drawn strong attention for application for structural components such as steel pipe joints and crane rail joints. In order to apply the alloy to the joints, we estimate the joint strength for its structural design. So investigation of shape recovery stress has been significant. In this study, Fe-28%Mn-6%Si-5%Cr alloy are melted. Thin plates are manufactured by rolling and are heat-treated as solution treatment. We conduct the uniaxial test for evaluation of shape recovery stress. Specimens of the plates are pulled to the designated strain in the longitudinal direction by tensile test equipment. They are heated for shape recovery and simultaneously the pulling load is controlled at the value of zero until the displacement reaches to the designated value. After reaching at the designated value of displacement, the specimen is fully restricted without displacement. And the stress induced in the specimen is measured during heating up to over austenitic transformation temperature and cooling down to room temperature. Stress - strain - temperature diagrams are measured through the heating and cooling process. We conclude that the stress induced by restriction increases with the increase of restricted strain. Keywords: ferrous shape memory alloy, shape recovery stress, uni-axially prestrained, pipe joints, solution treatment, austenitic transformation, restricted strain, ε martensite transformation, shape recovery strain.

Keywords

ferrous shape memory alloy, shape recovery stress, uni-axially prestrained, pipe joints, solution treatment, austenitic transformation, restricted strain, ε martensite transformation, shape recovery strain.