Heat treatment that alters the microstructure of a material causing changes in properties such as strength, hardness, and ductility

3. Heat treatment that alters the microstructure of a
material causing changes in properties such as
strength, hardness, and ductility
 It the process of heating solid metal to high
temperatures and cooling it slowly so that its
particles arrange into a defined lattice

4. Full annealing
Processannealing
Stress reliefannealing
 Recrystallizationannealing
Spheroidiseannealing.

5.  Heating the steal to a temperature at or near the criticalpoint ,
holding there for a time period and then allowing it to cool slowly in
the furnace itself . Example In full annealingof hypoeutectoid steels
less than0.77% is heated to 723 to 910 C above A3 line convert to
single phase austenitecooled slowlyin room temperature . Resulting
structure is coarse pearlite with excess of ferrite it isquite soft and
more ductile
 Cooling rate of fullannealingis 30-40 C

6.  Process annealing is a heat treatment that is often used
to soften and increase the ductility of a previously strain
hardened metal . Ductility is important in shaping and
creating a more refined piece of work through
processes such as rolling, drawing, forging, spinning,
extruding and he ading.
 Example it is extensively employed for steel wires and
sheet products (especially low carbon steels) A1
temperature and cooled at any desired rate
 The temperature range for process annealing ranges
from 260 °C (500 °F) to 760 °C (1400 °F), depending on
the alloy in question.

7.  It is an annealing process below the
transformation temperature Ac1, with
subsequent slow cooling, the aim of which is
to reduce the internal residual stresses in a
work piece without intentionally changing its
structure and mechanical properties

8.  The process is limited to steels in excess of 0.5% carbon and consists of
heating the steel to temperature about A1 (727°C). At this temperature any
cold worked ferrite will recrystallise and the iron carbide present in pearlite
willform as spheroids or “ball up”. As a result of change of carbides shape the
strength and hardness are reduced.
 To remove coarse pearlite and making machining process easy .
 It forms spherodite structure of maximum soft and ductility easyto
machining and deforming. Objectives
 To soften steels
 To increase ductility and toughnees

9.  A heat treatment process consisting of austenitizingat
temperatures of 30–80˚C above the AC3 transformation
temperature followed by slow cooling(usually in air) The
aim of whichis to obtain a fine- grained, uniformly
distributed, ferrite–pearlite structure Normalizing is
applied mainly to unalloyed and low-alloy hypoeutectoid
steels For hypereutectoid steels the austenitizing
temperature is 30– 80˚C

10.  It is a heat treatment process in which steel or iron is heated to a
temperature, below the melting point, in the presence of a
liquid, solid, or gaseous material which decomposes so as to release
carbon when heated to the temperature used. The outer case or
surface will have higher carbon content thanthe primary material.
When the steel or iron is rapidly cooled by quenching, the higher
carbon content on the outer surface becomes hard, while the core
remains tough and soft.

11.  In many engineering applications, it is necessary to have the surface of
the component hard enough to resist wear and erosion, while
maintaining ductility and toughness, to withstand impact and shock
loading. This can be achieved by local austentitizing and quenching, and
diffusion of hardening elements like carbon or nitrogen into the surface.
Processes involved for this purpose are known as flame hardening,
induction hardening, nitriding and carbonitriding.

12.  Flame hardening is used to harden only a portionof a
metal. Unlike differential hardening,where the entire
piece is heated andthencooledat differentrates, in
flame hardening, only a portionof the metal is heated
before quenching. This isusuallyeasierthan
differential hardening,butoften produces an
extremely brittlezone between the heated metal and
the unheated metal, as coolingat the edge of this heat
affectedzone is extremely rapid.

13.  Inductionhardeningis asurfacehardening techniquein which
thesurfaceofthemetalis heatedvery quickly, using a no-contact
methodofinduction heating.The alloyis thenquenched,
producing a martensitetransformationatthe surfacewhile
leavingtheunderlying metalunchanged.This createsa very hard,
wear resistantsurfacewhilemaintainingtheproper toughnessin
themajorityofthe object.Crankshaftjournals are a good
exampleofan induction hardenedsurface.

14.  Case hardening is a thermochemical diffusion process in which an
alloying element, most commonly carbon or nitrogen, diffuses into the
surface of a monolithic metal. The resulting interstitial solid solution is
harder than the base material, which improves wear resistance without
sacrificing toughness.
 Laser surface engineering is a surface treatment with high versatility,
selectivity and novel properties. Since the cooling rate is very high in
laser treatment, metastable even metallic glass can be obtained by this
method.

15. THANK YOU