A study of austenitic stability and mechanical properties of two series of Fe-30Mn-0.50C-xAl and Fe-30Mn-10Al-yC alloys containing 4.72-9.26 wt.% Al and 0.63-0.86 wt.% C has been undertaken.
Alloys containing less than 7.70 wt.% Al and having carbon content between 0.63 and 0.86 wt.% had austenitic microstructures after solution treatment at 1100℃ for 20 minutes. They exhibited high yield strength, ultimate tensile strength and elongation.
Microstructural and mechanical property investigations have been performed on specimens undergone various isothermal heat treatment.
In the alloys containing more than 0.84 wt.% C, grain boundary and intragranular precipitates were formed when the alloys were aged at temperatures higher than 600℃. The precipitates were identified as $(Fe,Mn)_3$ AlC of perovskite structure. Precipitate free zones were formed adjacent to the nodular growth, when the alloys were aged at 600℃ and 700℃.
The alloys manifested the precipitation hardening effect on aging. However, elongation decreased in the age hardened specimens.
The effects of Zr as an additive alloying element and the work-hardening rates of the alloys were also investigated.
