EBSDによる塑性加工および形状回復時のFe-Mn-Si合金の結晶構造解析

抄録

The shape memory effect (SME) in Fe-Mn-Si based alloy is associated with γ ⇄ ε martensitic transformation. It is necessary to suppress the sliding deformation and preferentially generate the martensitic transformation in order to improve the SME. In this study, each specimen was rolled and/or annealed and then the elastic and shape recovery ratios of them were quantified by means of the bending mechanical test. Crystal structures also were inspected by electron backscatter diffraction (EBSD) for obtaining the phase distribution maps and then pole figures were determined. On the specimens rolled as 20% and 40% reduction rate the axis of some crystals oriented to one of [001], [2√2 0 1], [√2 √6 1], [√2 √6 1] and the other of [001], [2√2 0 1], [√2 √6 1], [√2 √6 1]. The elastic recovery ratio improved from 27% to 36% at the reduction ratio (RR) as 20% and to 40% at the RR 40% and the shape recovery did no change. After the 600°C annealing the shape recovery improved from 20% to 50% in the RR 20% and 40% specimens. Due to the cold rolling the yield stress raising and martensite phase expanding, which enhance the pseudoelastic effect, induced the increase of elastic recovery ratio. On the other hand there are two reasons for improving the SME, the texture formation gains the martensitic transformation and the austenite phase, which easily transforms martensite phase, generates.