120
steels at 200°C per hour, and alloy steels at a rate of 30-100°C per hour. is cooled.
In this case, a solid structure is obtained without any gaps .
purpose of softening is to remove internal stresses, achieve
uniformity of structure ,
improve workability, and prepare for the next heat treatment operation.
Normalization
is 30-50 ° C from the critical points Ac
3
and As
m
heating to
a higher temperature, holding at this temperature, and cooling in still air are referred
to. During normalization,
internal stresses are reduced, steel is crystallized, and
the large-particle structure of welds, castings, and forgings is crushed.
increase the hardness, strength and elasticity of steel .
Forging
is the process of heating steel to a
temperature above the phase
transition , holding it at that temperature, and then rapidly cooling it.
Annealing
is the final operation of heat treatment, which consists of heating
the steel from the critical point (Ac
1
) to a low temperature ,
holding it at this
temperature, and cooling it slowly or rapidly. The purpose of exercise is to remove
or lose weight in the body , increase the strength of the muscles , and
reduce the
stiffness .
Chemical-thermal treatment
refers to the treatment associated with the
process of combined thermal and chemical effects on metals and alloys in order to
change
the chemical composition, structure and properties of the surface layer of
metals and alloys.
Thermomechanical treatment
is a new strengthening method that combines
strengthening heat treatment (forging, tempering)
with plastic deformation, while
maintaining the plasticity of steel . During thermomechanical processing , the steel
is deformed to the state of austenite , then it is quickly cooled and a hardened steel
structure (martensite) is formed , in which the state of austenite refinement occurs ,
in this regard, the mechanical properties of the steel increase .
