Possible Slip Systems in Body Centered Cubic Iron

Abstract

The slip systems along the h111i direction in bcc iron are investigated by the energy of the generalized stacking fault, or of the stacking fault between two adjacent crystallographic planes of perfect crystals, in order to obtain the knowledge of the slip phenomena in bcc single crystals. For systematic study, the 15 kinds of slip systems along the h111i direction from f110gh111i up to f954gh111i, f972gh111i and f981gh111i slip systems are taken into account. The energy of the stacking fault is evaluated by the molecular mechanics method with the embedded atom potential of Finnis-Sinclair type as a function of relative displacement of one side of the two half-crystals across the fault plane in the h111i direction. The maximum values of the fault energies for the slip systems whose slip planes have angles of less than approximately 15 degrees to the {110} plane are nearly same as that for the most preferable f110gh111i slip system. The maximum value for the f321gh111i slip system is the greatest among the currently analyzed 15 slip systems. The maximum value for the f211gh111i slip system is in the middle of those for the f110gh111i and f321gh111i slip systems, and those for the slip systems whose slip planes have angles between approximately 20 degrees and 30 degrees to the {110} plane are close to that for the f211gh111i slip system. In general, there is not inverse correlation between the maximum value of the fault energies for the slip system and the interplanar spacing of the considered slip system, although there is inverse correlation between them within the three slip systems which have three lowest index planes, namely, the f110gh111i, f211gh111i and f321gh111i slip systems.

Development of local plasticity around voids during tensile deformation

“…Another material given as a comparison is a bainite steel (SA508) where the void imposes a higher image stress compared to DD6 yet demonstrate significant void growth [15,49]. Note that on the one hand, the SA508 steel has BCC crystal structure where slip on the {110}, {112}, and {123} planes [50] offer 36 slip systems compared to 12 in FCC Ni. On the other hand, the significant void growth in SA508 is typically either found in front of a crack [15] or after the UTS and thus during necking [49].…”