Question

it is about plastic deformation and elastic deformation

can you explain annealed case and non-annealed case relation to workhardening and elongation with stress- strain curve
and
the reason although area decrease, force increase , can you explain this with slide, twinning, dislocations, heat change ?

Answer 1

Annealing is the process to relieve of strain hardending and residual stresses along with manipulation of mechanical properties. Work hardening leads to hinderence to movement of dislocations and strengthening of material , since the material shows more resistance to dislocation, hence we need to apply more force to overcome that resistance and what we witness is despite of decrease in area (necking) , we need to apply more force to fracture the material in plastic deformation zone. Alloys not amenable to heat treatment are strain hardened. In the stress strain curve , the region beyond the yield point experiences strain hardening due to plastic deformation and we see increase in stress due to work hardening.