Deformation Structures and Strengthening Mechanisms Associated with κ-Carbides Precipitation in an Austenitic-Based Low-Density Steel

To control the precipitation sites of carbides, the cold rolling, annealing, and aging processes were employed to process Fe-26Mn-10.2Al-0.98C-0.15 V (wt.%) steels with duplex structure. After aging, the alloy achieved a good combination of strength and plasticity, which had a yield strength of 1120 MPa, tensile strength of 1285 MPa, and elongation of 17%. The precipitation strengthening of the κ-carbides shows a significant contribution to the high yield strength of this alloy. The strengthening models were employed to calculate the precipitation strengthening from coherent κ-carbides, and show good prediction performance. The increase in strength slows down with increasing aging time, which is influenced by the critical grain size of the precipitated particles and the antiphase boundary energy (({gamma }_{mathrm{APB}})). Furthermore, the deformation mechanism of this alloy is influenced by the high SFE and the softening effect of the intragranular κ-carbide sliding surface. The analyses of the deformed structure revealed that the plastic deformation was dominated by the planar slip, resulting in the formation of the Taylor lattice, a special dislocation substructure.