Analysis of crystallographic twinning and slip in fcc crystals under plane strain compression

Influence of Aging Treatment on Microstructure and Tensile Properties of a Hot Deformed UNS S32750 Super Duplex Stainless Steel (SDSS) Alloy

“…Observations made in the case of microstructural analysis, for all TM processed states, concerning typical deformation morphologies for both the δ-phase (belonging to a BCC crystallographic system) and γ-phase (belonging to an FCC crystallographic system) are related to the higher potential of deformation/strain accommodation by slip/twinning and/or grain rotations of FCC systems, compared with BCC systems [29][30][31][32] for the same deformation stress level. For the same deformation stress level, if one considers the slip/twinning deformation mechanisms in correlation with the potential of deformation/strain accommodation, they will observe that the main influence factor is represented by the atomic density on the easiest to activate slip/twinning system [33,34].…”

“…In the case of FCC systems, the easiest to activate slip system is {111} <110>, while the easiest to activate twinning system is {111} <112>. In the case of BCC systems, the easiest to activate slip system is {110} <111>, while the easiest to activate twinning system is {112} <111> [29][30][31][32]35]. The highest atomic density, almost double, is exhibited by FCC {111} atomic planes, compared with the BCC {110} and {112} atomic planes, which shows that FCC systems better accommodate deformation/strain, by slip/twinning and/or grain rotations, compared with BCC systems, for the same deformation stress level.…”

Microstructure Evolution during Hot Deformation of UNS S32750 Super-Duplex Stainless Steel Alloy

“…When considering the austenite-γ phase, it must be highlighted that it is more ductile than ferrite δ, due to the fcc crystalline structure of γ, as opposed to the bcc crystalline structure of δ. The reason is that the atomic density is nearly double for the fcc crystal structure when compared to the bcc crystal structure [ 34 , 35 ]; this leads to a lower critical energy necessary for activating the slip/twinning processes that assure easier deformation behavior. Consequently, it results that the δ phase (ferrite) manifests a higher strength and resistance to plastic deformation compared to austenite, due to a lower potential to accommodate plastic deformation and a higher critical energy for activating the slip/twinning systems [ 24 , 25 , 26 , 27 ].…”

“…Taking into account the criteria of minimum activation energy, the easiest slip system to activate for the fcc crystals is the {111} <110> primary system, while for bcc crystals it is the {110} <111> system; as for the easiest to activate twinning system, for the fcc crystals it is the {111} <112> primary system, while for the bcc crystals it is the {112} <111> system [ 24 , 25 , 26 , 27 , 35 ]. Therefore, the double atomic density mentioned above for austenite-γ is manifested in the fcc {111} atomic twinning/slip planes compared to {110} and {112} twinning/slip planes corresponding to the bcc system.…”