The effect of the amount of ε-martensite and dislocations on the damping capacity of Fe–12.5Cr–20.5wt%Mn alloy was investigated by using a free-decay method of flexural resonant vibration with both free ends. The amount of ε-martensite was varied by the number of the thermo-mechanical treatment cycles which consist of annealing, sub-zero treatment and cold rolling. The behavior of dislocations was observed by transmission electron microscopy. The volume fraction of ε-martensite was increased with the number of treatment cycles and more than 80% of the volume fraction was attained with 4- and 5-cycle specimens. The damping capacity increased as the volume fraction of ε-martensite increased because of the increasing damping sources such as stacking fault boundaries in the ε and γ phases, the interface and ε-martensite variant boundaries. However, even though the 5-cycle specimen had the same content of ε-martensite as the 4-cycle specimen, the damping capacity of the 5-cycle specimen was significantly decreased. It was concluded that relatively many dislocations formed in the ε-martensite phase in the 5-cycle specimen which interfered with operation of the damping sources.

Effects of ε-Martensite and Dislocations Behavior by Thermo-Mechanical Treatment on Fe–Cr–Mn Damping Alloy. G.H.Kim, Y.Nishimura, Y.Watanabe, H.Sato, Y.Nishino, H.R.Jung, C.Y.Kang, I.S.Kim: Materials Science and Engineering A, 2009, 521-522, 368-71