Stored-energy-dependent dual precipitation and partial recrystallization during heterostructure formation in a lightweight steel

The role of rolling-induced stored energy in regulating dual precipitation and recrystallization behavior was investigated in a Fe–26Mn–8Al–1.2C–5Ni–3Mo austenitic lightweight steel. Two processing routes—hot rolling and cold rolling followed by annealing at 825 °C were employed to introduce distinct stored-energy states and thereby regulate precipitation behavior and microstructural evolution. Compared with the hot-rolled and annealed sample (H825), the cold-rolled and annealed sample (C825) exhibited a higher recrystallized fraction, a finer average grain size, and a higher number density of finer precipitates. These observations suggest that the higher stored-energy state introduced by cold rolling is associated with more extensive recrystallization and finer dual precipitation after annealing. Consequently, C825 achieves a superior strength-ductility synergy, with yield strength of 1570 MPa and ultimate tensile strength of 1840 MPa, while maintaining a ductility of 15.9%. These findings highlight the important role of deformation stored energy in tailoring the precipitate characteristics and RX/URX heterostructure and provide guidance for designing optimized heterostructure of lightweight steels to improve strength–ductility synergy.