Low temperature shape memory behavior of Fe-15Mn-4Si-10Cr-8Ni seismic damping alloy at various strain rate

Abstract

Fe-15Mn-4Si-10Cr-8Ni seismic damping alloy (FMS) has recently emerged as a promising seismic damping material owing to its enhanced low-cycle fatigue resistance. However, its low-temperature shape recovery behavior and strain-rate sensitivity remain poorly understood. In this work, the superelastic response, recovery strain, and shape memory training process of FMS at 213 K under both quasi-static and impact loading were investigated systematically. A U-shaped striker-modified double momentum trap-split Hopkinson pressure bar (DMT-SHPB) was employed to minimize residual stress waves in impact tests. We demonstrate that (i) no superelastic behavior was observed in the quasi-static range at 213 and 273 K, however, large recovered strain during unloading can be found. (ii) True stress and recovery strain exhibited clear positive strain-rate sensitivity at 213 K. (iii) Under impact training, recovery strain is markedly higher than under the corresponding quasi-static conditions (maximum ${\epsilon }_{ri}$=0.0198, and $\eta$=46.85%), reaching a maximum of 0.0267 in the fourth cycle, while shape recovery ratio attains its peak of 49.85% in the third cycle. (iv) Electron backscatter diffraction revealed that impact training produces finer, more homogeneous grains and possibly promotes single-variant martensite selection, underpinning the observed enhancement in shape memory effect.