Effects of several factors on damping capacity of Fe-17%Mn martensitic alloy

Damping capacity of an Fe-17%Mn alloy has been studied with respect to several variables, volume fraction of ε martensite, carbon content and deformation. In case of subzero cooling, the damping capacity of an Fe-17%Mn alloy increases with increasing ε martensite content, while in case of thermal cycling, the damping capacity decreases with increasing ε martensite content. The decrease in damping capacity is ascribed to the dislocations introduced during thermal cycling, which act as barriers to operation of the damping sources, such as stacking faults in ε martensite, boundaries between ε plates with different variants and γ/ε interfaces. The carbon content above 0.06 wt.% deteriorates the damping capacity of the Fe-17%Mn alloy, being due to interaction between damping sources and carbon atoms in addition to decrease in volume fraction of ε martensite with increasing carbon content. The damping capacity shows a maximum value around 10% reduction in thickness, and decreases with further deformation. The increase in damping capacity up to 10% is probably due to an increase in number of the damping sources per unit volume due to an increase in ε martensite volume fraction, and a decrease in damping capacity over 10% is attributed to formation of α′ martensite and dislocations.