Shape Recovery in Stainless FeMnSiCrNi(-Co) SMA processed by ECAE

摘要

Stainless shape memory steels presents reasonable shape recovery but, lower than the traditional NiTi shape memory alloys (SMA). However, recent results have shown that the shape recovery could be improved by decreasing the austenitic grain size. The present work describes the influence of the austenite grain size on the shape recovery in stainless shape memory steel deformed by equal channel angular extrusion (ECAE) using a die intersection angle of 120°. Two alloys, FeMnSiCrNi and FeMnSiCrNiCo, were deformed by 1 ECAE pass and then they were compared in the deformed state; deformed and annealed at different temperatures for 1 h, resulting different grain sizes. Both alloys were evaluated by compression tests and the results shows an increase in the total shape recovery related to the grain refinement. The best total shape recovery was 73% after a pre-strain of 4% for FeMnSiCrNi alloy.