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The two primary methods of deformation in metals are slip and twinning. Slip occurs by dislocation glide of either screw or edge dislocations within a slip plane. Slip is by far the most common mechanism. Twinning is less common but readily occurs under some circumstances. Twinning occurs when there are not enough slip systems to accommodate ...
The deformation field at the slip-band is due to three-dimensional elastic and plastic strains where the concentrated shear of the slip band tip deforms the grain in its vicinity. The elastic strains describe the stress concentration ahead of the slip band , which is important as it can affect the transfer of plastic deformation across grain ...
Typically, slip bands induce surface steps (i.e. roughness due persistent slip bands during fatigue) and a stress concentration which can be a crack nucleation site. Slip bands extend until impinged by a boundary, and the generated stress from dislocation pile-up against that boundary will either stop or transmit the operating slip. [9] [10]
Therefore, a quantitative study of deformation twinning in TWIP steels is critical to understand their strain-hardening mechanisms and mechanical properties. Deformation twinning can be considered as a nucleation and growth process. Twin growth is assumed to proceed by co-operative movement of Shockley partials on subsequent {111} planes.
Plasticity in a crystal of pure metal is primarily caused by two modes of deformation in the crystal lattice: slip and twinning. Slip is a shear deformation which moves the atoms through many interatomic distances relative to their initial positions.
While undergoing deformation, slip motion will take place. Grain boundaries act as an impediment to dislocation motion for the following two reasons: 1. Dislocation must change its direction of motion due to the differing orientation of grains. [4] 2. Discontinuity of slip planes from grain one to grain two. [4]
Deformation twinning is a response to shear stress. The crystal structure is displaced along successive planes of the crystal, a process also called glide. The twinning is always reflection twinning and the glide plane is also the mirror plane. Deformation twinning can be observed in a calcite cleavage fragment by applying gentle pressure with ...
The resulting slip bands appear at the lower yield point and propagate along the gauge length, at constant stress, until the Lüders strain is reached, and deformation becomes uniform. Beyond the Lüders strain, the stress increases due to strain hardening until it reaches the ultimate tensile stress.