What is plastic deformation?
- Plastic deformation is a process in which the size and shape of the object changed due to external load or forces. Plastic deformation is a permanent deformation which does not change after removal of external load or forces.
- Plastic deformation is an irreversible process of deformation.
- In a plastic deformation, we can observe a strain hardening effect.
- It depends on a loading path.
- It takes place due to the slip and twinning mechanism.
Use of plastic deformation:
Plastic deformation is used for shaping different types of metals by the process such as rolling, forging, drawing and extrusion.
Mechanism of plastic deformation:
As we know, plastic deformation takes place due to slip, twinning, and the combination of slip and twinning.
|Slip Mechanism Diagram|
1. In this mechanism, one place slides over another plane. This sliding of one plane over another plane does not affect the crystal structure of the metal. Also, no change observed in the arrangement of atoms at this time.
Slip planes and slip directions for basic crystal structures are given below in table form.
|Crystal Structure||Slip Planes||Slip Directions||Metal Example|
|B.C.C.||(1 1 0)||< 1 1 1 >||Mo, Fe|
|F.C.C.||(1 1 1)||< 1 0 >||Al, Cu|
|H.C.P.||(0 0 0 1)||<1 1 2 0 >||Mg, Co|
|Twinning Mechanism Diagram|
|Crystal Structure||Twin Plane||Twin Direction|
|B.C.C.||(1 1 2)||[ 1 1 1 ]|
|F.C.C.||(1 1 1)||[1 1 2 ]|
|H.C.P.||(1 0 1 2)||[ 1 0 1 2 ]|