Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading

Abstract

In the past studies, it has been discovered that the shape memory effect (SME) in the Fe-Mn-Si shape memory alloy (Fe-SMA) can gradually be enhanced by a pre-process called as shape memory training process under cyclic thermo-mechanical loading. On the other hand, it has been shown that the SME of Fe-SMA can also be affected by changing the strain rate. Therefore, it is possible to improve the SME by combining the strain rate sensitivity and shape memory training process. However, the improvement of SME caused by the training process under impact condition is still unclear. For the training process under impact condition, it is difficult to interrupt the test at the desired strain level due to many reflections of stress waves, which reload the specimen from the free ends. In this paper, to obtain reliable experimental results of SME after the training process under impact condition, the stress waves after first loading are eliminated by the double momentum-trap structure introduced into the impact tensile testing apparatus based on the split Hopkinson pressure bar method. In order to achieve an optimum design of the structure used in experiments, the finite element simulation of the structure is performed. Then, tensile tests in the training process of Fe-28Mn-6Si-5Cr alloy at different strain rates including the impact level are conducted and temperature change of the specimen is measured during training and heating process. As a result, the improvement of SME in the alloy after the training process under quasi-static and impact loading is compared with that under quasi-static loading through verification processes. Fe-Mn-Si shape memory alloy, training, cyclic thermo-mechanical process, split Hopkinson pressure bar, momentumtrap, impact deformation Citation: Sun Q, Cao B, Iwamoto T, et al. Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading.

Thermodynamic modeling and computational predictions of NbC precipitation in Fe–Mn–Si-based shape memory alloys by the classical nucleation and growth theories

“…However, the recovery strain of the polycrystalline Fe-Mn-Si-based alloy obtained by conventional manufacturing process consisting of forging, rolling, and subsequent solution treatment is only 2%-3%, which cannot meet the engineering application requirements. Modification of alloying elements [7,8], heat treatment [9][10][11], plastic deformation [12][13][14], thermomechanical processing [15], training treatment [16], and second-phase precipitation [17][18][19][20] have been employed to improve the shape recovery strain. The precipitation of nanosized second-phase was first proposed by Kajiwara as an effective method to improve the shape memory effect in Fe-Mn-Si-based alloys [17,21].…”

Isothermal Mechanical Cycling of Saponite–Titanium Composites in Conditions of Complex Stressed State

“…The above-mentioned phenomena are usually initiated by martensitic reactions associated with thermal cycling of the material. Work on mechanocycling of ESM material in a complex stress state in most cases is devoted to the determination of long-term strength, less often the structure of the material under similar exposure is studied [5]. The authors [6] recorded that during isothermal mechanocycling in the two-phase state, the material was more plastic and less susceptible to equalization of the voltage intensity ampli-tude.…”