In-situ tensile deformation of multiphase stainless steel

In this work, the microstructural evolution of a multiphase stainless steel with martensite ( ), delta-ferrite (δ) and reversed austenite (RA) during tensile deformation was systematically investigated by combining in-situ EBSD and TEM techniques, with particular emphasis on the role of δ in plastic deformation. The results demonstrate that δ yields with 0.5% strain and accumulates a large number of geometrically necessary dislocations (GNDs), which progressively entangle to form dislocation walls and subsequently evolve into stable sub-grains. The formation of sub-grains not only refines the microstructure but is also accompanied by lattice rotation, effectively reduces the local Schmid factor (SF) from 0.36 to 0.30, enhances dislocation storage, and promotes strain hardening. This structural evolution contributes to mitigating stress concentration near soft–hard phase boundaries and consequently delays the onset of macroscopic damage.