3. One step to the next
Dislocations are
happened because
of stress applied.
1
There can be millions
of dislocations in each
cubic millimeter of a
metal
2
The presence
of dislocations strongly
influences many of the
properties of materials
3
5. CAUSES OF DISLOCATION
They cause “PLASTIC DEFORMATION”.
i,e..nothing but the material returns to its
original shape and size after the applied
stress (load) is released.
1
The ability of a metal to undergo plastic
deformation is one of the important property
which is utilized for shaping of metals by
various fabrication process such as rolling,
forging, drawing, extrusion etc.,
2
6. SLIP FORMATION
Slip involves sliding of one
plane of atoms over the
other.
1
Slip is a permanent
displacement of one part
of crystal relative to the
other part.
2
7. TWINNING FORMATION
Twinning is a process in
which the atoms in a part
of the crystal subjected to
stress rearrange
themselves
1
The plane across which
the two part are mirror
images is called twinning
plane or composition
plane.
2
8. DISLOCATIONS ARE CLASSIFIED INTO FOUR
Where mixed and partial
dislocations are not so
important as screw and
edge dislocation.
9. CHARACTRESTICS
1
When a metal is plastically deformed,most of energy is
dissipated as heat but app 0.5% is stored internally.
2
Distortions of lattice around dislocation line causes
lattice strains.
3
In screw dislocations-shear strains.This strain field can
affect other dislocations.
4
Same sign on same plane repulse each other whereas
opposite signs attract and annihilate on meeting.
10. Thank you
Monika.M
+001 521 123456
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