Effect of carbon on the paramagnetic-antiferromagnetic transition and gamma ->epsilon martensitic transformation of Fe-24Mn alloys

The effect of C content (0.014 similar to 0.39 wt pet) on the paramagnetic- antiferromagnetic transition and gamma --> epsilon martensitic transformati on of Fe-24Mn alloys has been investigated by the resistivity, dilation, te nsile properties measurement and microstructure examination. The results ha ve shown that C decreases T-N; increases the thermal expansion coefficients both above and below the Tu; increases the resistivity above the TN and an tiferromagnetic scattering resistivity below TN. It strongly depresses the gamma --> epsilon martensitic transformation and reduces the Ms of Fe-24Mn alloys. Moreover, it increases the lattice parameter of austenite, enhances the tensile ductility, but almost does not affect the tensile strength. Wi th increasing C content from 0.014 to 0.19 wt pet, the yield strength of Fe -24Mn alloy decreases obviously arising from the decreasing of preexisting epsilon martensite, but it increases from 0.19 to 0.39 wt pet C due to the solution hardening of C.