Abstract
The strength and deformation behavior of an Fe-Mn-Al-Ni shape memory alloy at different strain rates was studied. Furthermore, the effect of grain size was investigated. To this end, a batch with bamboo-like grain arrangement and a batch with smaller, nevertheless coarse, grains were analyzed. Tensile tests at quasi-static, intermediate, and dynamic loading rates were performed. Digital image correlation and microstructural analysis revealed the localized deformation and phase transformation in favorable oriented grains. At higher strain rates, a increased number of orientations was activated for the phase transformation. A higher strain rate resulted in an increased strength for the coarse-grained material while the bamboo-like material did not show this effect. The analysis of fracture surfaces revealed ductile fracture and cleavage fracture for all strain rates.
Highlights
Shape memory alloys (SMA) that exhibit pseudoelastic behavior are suitable for structural applications, e.g. as energy absorbers in an earthquake environment [1]
The present study presents the strain rate dependent mechanical and microstructural behavior of an iron-based shape memory alloy with two different microstructures
It was shown that the stress plateau due to the pseudoelastic deformation was only detectable at the lowest strain rates
Summary
Shape memory alloys (SMA) that exhibit pseudoelastic behavior are suitable for structural applications, e.g. as energy absorbers in an earthquake environment [1]. Fe-based shape memory alloys (Fe-SMA) offer promising advantages compared to conventional SMA, e.g. NiTi-based SMA. One obvious advantage is the lower cost of the alloying elements. Vollmer et al [2] investigated the pseudoelastic behavior and showed its degradation with cyclic loading. The degradation was caused by activating different martensite variants. The effect of the loading rate was not studied
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