Phase transitions and electrical resistance variations with temperature of the FM30 shape memory steel.

The Fe-31.6wt% Mn-6.45wt% Si (FM30) steel showed forward, reverse and isothermal martensitic transformations. These phenomena were detected by electrical resistance measurements as a function of temperature. The forward transformation failed at the appearance of the antiferromagnetism of the austenitic phase. However, a M(f), temperature can be considered as a end of evolution. By studying the reverse transformation epsilon --> gamma, it was shown that the fcc high temperature phase was unstable at 298 K when the quenching temperature was equal or higher than 1073 K.