Hot Deformation Behavior of Fe-Mn-Al-C Low Density Steel

The compression experiments of three Fe-Mn-Al-C low density steels with aluminum content of 8wt%, 10wt% and 12wt% were conducted by Gleeble-3500 hot simulator at different deformation temperatures from 950 ℃ to 1 150 ℃ and different strain rates from 0.01 s-1 to 1.0 s-1. The hot deformation behaviors of this low density steels were studied at high temperatures and the microstructures before and after compression were observed. The results show that during deformation at the temperatures from 950 ℃ to 1 150 ℃ and strain rates from 0.01 s-1 to 1.0 s-1, the flow stresses of three tested steels were all sensitive to the temperatures and strain rates and increased with the increase of strain rate and with the decrease of the deformation temperature. After deformation, the ferrite in the microstructure of the tested steel with 12wt% aluminum was belt-like and distributed discontinuously in austenite matrix. The grains of ferrite and austenite grown larger and larger with the temperature rising at the same strain rate and were relatively fine at a relative high strain rate at the same temperature. The apparent activation energy of the tested steel with 12wt% aluminum was 592.437 kJ·mol-1 and the Zener-Hollomon parameter equation was listed as Z=ε·exp(592.437/RT).