High-strength Fe-20Mn-Al-C-based Alloys with Low Density

摘要

Mechanical properties of Fe-20Mn-(10-14)Al-(0-1.8)C (mass%) quaternary and Fe-20Mn-(10-14)Al-(0.75-1.8)C-5Cr (mass%) quinary alloys were investigated by hardness, cold-workability and tensile tests at room temperature. The γ(fcc) alloys in both quaternary and quinary systems with a low density of less than 7.0g/cm~3 showed an excellent ductility and their hardness and tensile strength increased with increasing Al and C contents. The γ+ α(bcc) duplex alloys also exhibited a high tensile strength by controlling the α volume fraction. TEM observation confirmed that high hardness and tensile strength of the alloys with high Al and C contents are caused by the precipitation of nano-size x-carbide with perovskite structure during cooling from the annealing temperature. Fe-20Mn-11Al-1.8C-5Cr alloy with a density of 6.51 g/cm~3 showed a high specific strength of more than 180MPa-cm~3/g with a good tensile elongation of 40%. The present Fe-20Mn-Al-C(-5Cr) alloys showed a higher specific strength than conventional steels.