In situ X-ray microdiffraction study of deformation-induced phase transformation in 304 austenitic stainless steel

Suppression of twinning and phase transformation in an ultrafine grained 2 GPa strong metastable austenitic steel: Experiment and simulation

“…However, synchrotron X-ray diffraction study on the phase transformation kinetics and texture evolution of a 304L SS steel subjected to conventional compression testing [20] revealed phase transformation only at cryogenic temperatures (À70°C). An in-situ X-ray micro-diffraction study in conjunction with uniaxial tensile loading conducted at À63°C substantiated the occurrence of a phase-transformation-enhanced strain/stress accommodation mechanism in this material [21].…”

“…In that context earlier papers reported nanoscale embryos of martensite within the microstructure of a tensile deformed austenitic steel [21,36]. These various observations and phenomena encouraged us to explore the feasibility of obtaining bulk UFG steels through severe plastic deformation, particularly via accumulative rolling.…”

“…Several works have shown that twinning and martensitic transformation play key roles for the deformation of 304SS and that the volume fraction of martensite formed during severe deformation is strongly dependent on the pre-strain, stress and strain magnitude, strain rate, and deformation temperature [21,[32][33][34][35][36][37][38]. In that context earlier papers reported nanoscale embryos of martensite within the microstructure of a tensile deformed austenitic steel [21,36].…”

Coupling between plasticity and phase transition of polycrystalline iron under shock compressions

“…Analyses of a large amount of published data relating the fraction of martensites to plastic strain suggest that the SAT is more appropriate for interpreting experimental data than the SIT (Das et al, 2011). Moreover, most recent experiments conducted by Li and coworkers (Li et al, 2014) have shown that selections of martensitic variants obey minimum strain work criterion (Humbert et al, 2007) rather than Schmid factor criterion. Interestingly, the minimum strain work criterion satisfies minimum free energy condition under near equilibrium state according to the Formula (2), which indicates that the SAT is the underlying mechanism of the deformation induced transformation in the SS under the tensile deformation.…”

“…The second step is a shuffle among alternate (110) BCC planes to establish a HCP lattice with its c axis lying along [110] BCC . Although this transition mechanism could well explain the transition deformation and the orientation relationships (ORs) between parent phase (BCC) and transition products (HCP), it cannot predict detailed transformation scenario for preferred selections of the transition products (martensitic variants) which is of key importance for micromechanical behaviors of materials exhibiting martensitic transition (Cherkaoui et al, 2000;Li et al, 2014). It is well known that the phase transition is preceded by plasticity in experiments at nanosecond time scale.…”