Analysis of mechanical behaviour of single-phase austenitic stainless steels based on microstructure deformation mechanism

The single-phase austenitic stainless steel has attracted widespread attention from scientists because of its special composition. This steel with single-phase but duplex microstructure consists of coarse non-recrystallised grains with nanotwinned austenitic (nt-γ) structures and soft statically recrystallised matrix. Additionally, during uniaxial tension, microstructure deformation – deformation twins will occur. Owing to its bimodal grain size distribution and the effect of nt-γ structures, this steel can make a balance between strength and toughness. To analyse the mechanical behaviour of single-phase austenitic stainless steels, the authors proposed a theoretical model based on their physical deformation mechanism. It was found that the flow stress of single-phase austenitic stainless steels will be affected by five factors – the twin spacing, the volume fraction of twins, grain sizes of coarse-grained phase and matrix phase and the ratio of volume fractions of the two phases.