27.
Material Treatment
Hardening is a metallurgical metalworking
process used to increase the desire result
from steel.
Heat Treatment of Steel
• Heat treating works by altering the shape and
alignment of a metal's crystalline structure.
• The changing of the metal's properties occurs
when a metal is heated to a high temperature.
• Heat treatment is an important process in the
refining and petrochemical industry. It gives us
the ability to alter the metallurgical
characteristics of steel and equipment to better
suit their intended applications. Oftentimes, this
means altering a material's hardness, strength,
toughness, ductility, and elasticity.
Types of Heat Treatment Steel
The 4 Types of Heat Treatment Steel Undergoes
• Heat Treatment Steel: Annealing.
• Heat Treatment Steel: Normalizing.
• Heat Treatment Steel: Hardening.
• Heat Treatment Steel: Tempering.
• Annealing is a heat treatment process which
alters the microstructure of a material to change
its mechanical or electrical properties. Typically,
in steels, annealing is used to reduce hardness,
increase ductility and help eliminate internal
stresses.
• Annealing steel or any other metal
involves heating it to a specific temperature and
allowing it to cool at a specified rate..
Types of Heat Treatment Steel
• Normalization removes impurities in steel • Hardening is a metallurgical metalworking
and improves its strength and hardness and process used to increase the hardness of a
will increases its ductility. This happens by metal.
changing the size of the grain, making it
more uniform throughout the piece of steel. • A harder metal will have a higher resistance to
plastic deformation than a less hard metal.
• The steel is first heated up to a specific
temperature, then cooled by air. In addition, • The main objective of hardening the machine
normalizing helps reduce internal stresses components made of structural steels of the
induced by such operations as forging, pearlitic class is, to develop high, yield strength
casting, machining, forming or welding. with good toughness and ductility, so that higher
working stresses are allowed.
• Quenching improves a metal's performance by
rapidly cooling the heated metal, thereby altering
its molecular structure and increasing its
hardness.
Types of Heat Treatment Steel
• Tempering is a heat treatment technique
applied to ferrous alloys, such as steel or
cast iron, to achieve greater toughness by
decreasing the hardness of the alloy. The
reduction in hardness is usually accompanied
by an increase in ductility, thereby decreasing
the brittleness of the metal.
• Tempering is commonly performed after
hardening to reduce excess hardness, since
untampered steel is very hard yet too brittle
for most industrial applications. Tempering
can change ductility, hardness, strength,
structural stability and toughness.
