Deformation behaviour of additively manufactured graphene-reinforced 316L stainless steel composites

This study explores the deformation behaviour of a novel graphene-reinforced stainless steel 316L (Gr-SS316L) composite, demonstrating significant enhancement in strength while maintaining good ductility. The composite was fabricated using the laser-powder bed fusion method to achieve homogeneous dispersion of graphene within the stainless steel matrix. Strain-induced lattice rotation altered the crystallographic texture from <001> || BD to <110> || BD in the Gr-SS316L composite. The incorporation of graphene nanoplatelets has enhanced the yield strength by approximately 62% as compared to that of the additively manufactured stainless steel. The primary reason for this improved strength is attributed to the increased overall dislocation density (∼10 15 m -2 ). Several strengthening models have been proposed to explain this phenomenon in the Gr-SS316L composite. The deformed microstructures of Gr-SS316L composites consisted of dislocation pile-ups, deformation nano-twins, stacking faults, shear bands and dislocation locks. The addition of GNP in SS316L promotes the formation of deformation twins, a mechanism that has not been addressed in previous research. Hence, a comprehensive investigation using microscopy was conducted to understand the physics of deformation in Gr-SS316L composites. • Graphene reinforcement enables a synergistic ∼62% gain in yield strength without ductility loss in additively manufactured 316L stainless steel. • Graphene addition refined the grain size and transforms the crystallographic texture from <001> to <110> along the build direction. • A tenfold rise in dislocation density (10 14 to 10 15 m -2 ) emerges as the dominant strengthening mechanism, supported by models incorporating grain refinement, Orowan looping, and CTE mismatch. • Enhanced strain hardening in Gr-SS316L is governed by the interplay of deformation nano-twins, Lomer–Cottrell locks, including slip, twinning, stacking faults, and shear banding. • Graphene acts as a microstructural architect, refining grains, altering texture and activating twinning to overcome the strength-ductility trade-off.