Achieving strength ductility synergy of multiple hetero-structured Fe–24Mn–10Al–1C duplex lightweight steel

Abstract

Herein, a hetero-structured Fe-24Mn-10Al-1C (wt.%) lightweight steel is fabricated by a novel two-stage heat treatment strategy. The hetero-structured sample showed excellent mechanical characteristics, with a yield strength of 938 MPa, tensile strength of 1120 MPa and a total elongation of 41 %. In order to clarify the reason why the investigated hetero-structured lightweight steel can achieve excellent mechanical properties, we studied the microscopic deformation behavior of its various phases. By characterizing the microstructure evolution, the pile-up of massive dislocations at grain boundaries and domain boundaries results in significant hetero deformation induced (HDI) stress. This multiple HDI strengthening has an excellent contribution to high strength and good ductility.