A high-strength-ductility 304L stainless steel with heterogeneous lamella structure (HLS) was fabricated by cold rolling and subsequent partial recrystallization. The HLS was composed of lamellar recrystallized grains (mean grain size of ∼4.1 μm) embedded in a hard matrix of ultra-fine grains (mean grain size of ∼0.65 μm) and dislocation-cell structure. It exhibited a superior cryogenic impact property compared with coarse-grained, fine-grained and cold-rolled 304L stainless steels. This was mainly attributed to the suppression of crack propagation by lamellar recrystallized grains, dislocation-cell structure and TRIP effect. In addition, the extra fracture energy was also caused by the delamination in ultra-fine grains. This work will give an important theoretical guidance for the cryogenic applications of the HLS 304L stainless steel.
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