Annealing

                                       Annealing

definition

annealing primarily is the process of heating metal is in a metable or distracted structure state to a temperature which will remove the instability and then cooling in so that the room temperature structure is stable and strain-free

purpose

1.defining the homogenize structure
2.reducing hardness
3.improve machinability
4.improve cold working
5.producing the desired microstructure
6.removing residual stresses
7.removing gases

concept

when applied to ferrous alloys the term annealing generally implies full when applied to non-ferrous alloys the taken term annealing implies a heat treatment designed to an age-hardened alloy by accusing nearly complete precipitation of the second phase in relatively coarse fp\orm

process annealing

1.process annealing is usually subtracted annealing and is applied to remove the effect of cold work to soften and permits further cold work as in sheet and arrive industries

2.ferrous alloys are heated to a temperature close to but below the lower  limit of the transformation

range 550c-650c  held at the temperature and then cold usually in the air in order to soften the alloys for further cold working as in wire 

3.process annealing associated with it any partical recrystallization of the distracted term cementite and since mild steel contains any a small volume of strained a high degree of softening is include process annealing does not involve any phase change and the constituents  feranite and cementite remain present in structure throughout the process