The microstructures and tensile properties of aged Fe-xMn-8Al-0.8C low-density steels

ABSTRACT

The microstructural evolution and deformation behaviour of Fe-(13, 16, 18)Mn-8Al-0.8C (wt-%) low-density steels were investigated in the present work. During aging treatment, the increase in the volume fraction of κ’-carbides significantly improved the yield strength. The formation of κ/α lamellae increased the strain hardening rate. However, large fractions of intergranular κ-carbides deteriorated the ductility of the materials. Mn element stabilised austenite, restricted the precipitation of intergranular κ-carbides and delayed the formation of intragranular κ’-carbides, leading to the uniform distribution of the strain. Increasing Mn content also postponed the peak aging. A good balance of strength and ductility can be achieved by short-time aging treatment in the low-Mn steels or long-time aging treatment in the high-Mn steels.

KEYWORDS:

• Fe–Mn–Al–C steels
• aging
• κ-carbide
• strain hardening rate

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant [U1760205, No. 51474062].