An Experimental Investigation of Volume Resistivity in Fe-28Mn-6Si-5Cr Shape Memory Alloy under Compression Test at Various Strain Rates

摘要

In the past, the rate insensitive shape memory effect (SME) in Fe-based shape memory alloy (Fe-SMA) during compressive tests is revealed. On the other hand, the significant difference of stress can be observed at quasi-static and impact during compressive deformation. From the viewpoint of SME, it is considered that the amount of the stress-induced martensite shows the similar value at various strain rate. However, the difference in stress may be caused by the different amount of the stress-induced martensite at various strain rate. From the above descriptions, two conflicting views can be found. Therefore, it is necessary to measure the amount of the stress-induced martensite in Fe-SMA by using a more accurate method during compressive deformation at various strain rate. In this study, compressive tests of Fe-28Mn-6Si-5Cr alloy, which is one of Fe-SMA, are conducted by two different testing apparatuses such as conventional material testing machine and impact testing machine based on the split Hopkinson pressure bar (SHPB) technique. During deformation, it is attempted that the relationship between the volume resistivity and true stress is measured by using the past-established circuit as well as temperature-strain curve. From the results of volume resistivity at each strain rate, the strain rate sensitivity of stress-induced martensite under compressive tests is investigated.