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

Abstract

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 deformationdeformation 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 factorsthe 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.

Hierarchical Multiple Precursors Induced Heterogeneous Structures in Super Austenitic Stainless Steels by Cryogenic Rolling and Annealing

“…Compared with the Cold-R samples, the annealed Cryo-R samples show a larger heterogeneity and wider grain-size distributions; this phenomenon can be attributed to the hierarchical multiple precursors which experience competition among reverse transformation, recrystallization and recovery. For instance, the reversed austenite is prone to inherit the nano-lath morphology of martensite [ 33 ], while the growth of recrystallized grains in the deformation twin is strongly suppressed by the twin plane [ 34 ], and they exhibit a significantly smaller grain size than those nucleating in the dislocation cell boundaries. Moreover, the Cryo-R process leads to higher deformation stored energy than the Cold-R at an equivalent strain [ 35 ], which facilitates the improvement in the nucleation rate and contributes to a smaller average grain size [ 29 ].…”