types of heat treatment processes with common metal properties

1. PRESENTED BY -
1. ANIL
2. BALJINDER
3. AMAR
4. DEEPAK

2. HEAT
TREATMENTS

3. INTRODUCTION
• THE VARIOUS MICROSTUCTURES
DEVELOPED DURING METAL
PROCESSING CAN BE MODIFIED BY
HEAT TREATMENT
TECHNIQUES,INVOLVING
CONTROLLED HEATING AND COOLING
OF THE ALLOYS AT VARIOUS RATES
(ALSO KNOWN AS THERMAL
TREATMENT) .

4. PROPERTIESOFMATERIAL
• The internal reactions of a metal to external
forces are known as mechanical properties. The
mechanical properties are directly related to each
other. A change in one property usually causes a
change in one or more additional properties.
For example, if the hardness of a metal is
increased, the brittleness usually increases and the
toughness usually decreases. Following is a brief
explanation of the mechanical properties and how
they relate to each other.

5. TYPESOF PROPERTIES
TENSILE STRENGTH
SHEAR STRENGTH
COMPRESSIVE STRENGTH
ELASTICITY
DUCTILITY

6. MALLEABILITY
TOUGHNESS
HARDNESS
MACHINABILITY AND WELDABILITY
HEAT AND ELECTRICAL
CONDUCTIVITY
BRITTLENESS

7. TENSILE STRENGTH
• Tensile strength is the ability of a metal to
resist being pulled apart by opposing forces
acting in a straight line (Figure 2-1).It is
expressed as the number of pounds of force
required to pull apart a bar of the material 1
inch wide and 1 inch thick.

8. SHEAR STRENGTH
• Shear strength is the ability of a metal to resist
being fractured by opposing forces not acting
in straight line (Figure 2-2). Shear strength can
be controlled by varying the hardness of the
metal.

9. COMPRESSIVE STRENGTH
• Compressive strength is the ability of a metal
to withstand pressures acting on a given plane
(Figure 2-3).

10. ELASTICITY
• Elasticity is the ability of metal to return to its
original size and shape after being stretched
or pulled out of shape (Figure2-4).

11. DUCTILITY
• Ductility is the ability of a metal to be drawn or
stretched permanently without rupture or
fracture (Figure 2-5). Metals that lack ductility will
crack or break before bending.

12. MALLEABILITY
• Malleability is the ability of a metal to be
hammered,rolled, or pressed into various shapes
without rupture or fracture (Figure 2-6).

13. TOUGHNESS
• Toughness is the ability of a metal
to resist fracture plus the ability
to resist failure after the damage
has begun. A tough metal can
withstand considerable stress,
slowly or suddenly applied, and
will deform before failure.

14. HARDNESS
• Hardness is the ability of a metal to resist
penetration and wear by another metal or
material. It takes a combination of hardness
and toughness to withstand heavy pounding.
The hardness of a metal limits the ease with
which it can be machined, since toughness
decreases as hardness increases.The hardness
of a metal can usually be controlled by heat
treatment.

15. CORROSION RESISTANCE
•Corrosion resistance is the
resistance to eating or
wearing away by air,
moisture, or other agents.

16. MACHINABILITY AND
WELDABILITY
•Machinability and
weldability are the ease or
difficulty with which a
material can be machined
or welded.

17. HEAT AND ELECTRICAL
CONDUCTIVITY
•Heat and electrical
conductivity is the ease
with which a metal
conducts or transfers heat
or electricity.

18. BRITTLENESS
• Brittleness is the tendency of a
material to fracture or break with
little or no deformation, bending,
or twisting.Brittleness is usually
not a desirable mechanical
property. Normally, the harder
the metal, the more brittle it is.

19. TREATMENT PROCESSES
ANEALING
NORMALIZING
TEMPERING
QUENCHING
CASE HARDENING.
CARBURIZING

20. ANEALING

23. NORMALIZING

26. TEMPERING
• Tempering is a process of heat treating, which is used
to increase the toughness of iron-based alloys.
Tempering is usually performed after hardening, to
reduce some of the excess hardness, and is done by
heating the metal to some temperature below the
critical point for a certain period of time, then allowing
it to cool in still air. The exact temperature determines
the amount of hardness removed, and depends on
both the specific composition of the alloy and on the
desired properties in the finished product. For
instance, very hard tools are often tempered at low
temperatures, while springs are tempered to much
higher temperatures.

28. QUIENCHING
• Quench hardening is a mechanical process in
which steel and cast iron alloys are strengthened
and hardened. These metals consist of ferrous
metals and alloys. This is done by heating the
material to a certain temperature, depending on
the material. This produces a harder material by
either surface hardening or through-hardening
varying on the rate at which the material is
cooled. The material is then often tempered to
reduce the brittleness that may increase from the
quench hardening process. Items that may be
quenched include gears, shafts, and wear blocks.

30. HARDENING

33. NITRIDING

34. CAUSES AND REMEDIES

38. THE END