Effect of alloyes on mechanical properties of steel

1. SUBMITTED BY:
ASAD RIAZ
HASSAM HASHMI
ROLL NO:
15053323-015
15053323-007
SUBMITTED TO:
ENGER. MUHAMMAD SAJID

2. EFFECTS OF ALLOYING ELEMENTS
ON MECHANICAL PROPERTIES

3. WHY ALLOY ADDED TO STEEL
• ALLOYING ELEMENTS ARE ADDED TO EFFECT CHANGES IN THE PROPERTIES OF
STEELS.
THE BASIS IS TO CHANGE THE PROPERTIES OR EFFECTIVENESS OF STEEL.

4. Benefits of Steel Alloying Agents:
 Stabilizing austenite
 Stabilizing ferrite
 Carbide forming
 Graphitizing
 Increase corrosion resistance

5. CONTI…
Stabilizing austenite: Elements such as nickel,
manganese, cobalt, and copper increase the temperatures
range in which austenite exists.

6. Contni…
Stabilizing ferrite: Chromium, tungsten, molybdenum,
vanadium, aluminum, and silicon can have the effect of
lowering carbon's solubility in austenite. This results in an
increase in the amount of carbides in the steel

7. Contni…
■ Carbide forming: Many minor metals, including chromium,
tungsten, molybdenum, titanium, niobium, tantalum and
zirconium, form strong carbides that - in steel - increase
hardness and strength. Such steels are often used to make
high-speed steel and hot work tool steel.

8. CONTNI…
•Graphitizing: Silicon, nickel, cobalt and aluminum
can decrease the stability of carbides in steel,
promoting their breakdown and the formation of
free graphite.

9. CONTNI….
• INCREASE CORROSION RESISTANCE: ALUMINUM,
SILICON AND CHROMIUM FORM PROTECTIVE
OXIDE LAYERS ON THE SURFACE OF STEEL,
THEREBY PROTECTING THE METAL FROM
FURTHER DETERIORATION IN CERTAIN
ENVIRONMENTS.

10. Alloying elements added
following are the elements which are added to increase the properties
Carbon
Manganese
Chromium
Silicon
Nickel
Molybdenum
Vanadium
Tungsten
Copper
Niobium
Boron
Titanium

11. Alloying elements
 Carbon
Carbon is the single most important alloying element in steel.
Carbon is essential to the formation of cementite (as well as other carbides), and to
the formation of pearlite, spheroidite, bainite, and iron-carbon martensite,
The hardness of steel (or more accurately, the hardenability) is increased by the
addition of more carbon, up to about 0.65 percent.
Beyond this amount, increases of carbon reduce toughness and
increase brittleness.

12. CEMENTITE
CEMENTITE, ALSO KNOWN AS
IRON CARBIDE, IS AN
INTERMETALLIC COMPOUND
OF IRON AND CARBON, MORE
PRECISELY AN INTERMEDIATE
TRANSITION METAL CARBIDE
WITH THE FORMULA FE₃C

13. PEARLITE
A FINELY LAMINATED
MIXTURE OF FERRITE AND
CEMENTITE PRESENT IN
CAST IRON AND STEEL,
FORMED BY THE COOLING
OF AUSTENITE.

14. BAINITE
BAINITE IS A PLATE-LIKE
MICROSTRUCTURE THAT
FORMS IN STEELS AT
TEMPERATURES OF 250–550 °C
(DEPENDING ON ALLOY
CONTENT).

15. Percentage present
• The steels of interest to knifemakers generally contain
between 0.5 and 1.5 percent carbon. They are described
as follows:
• Low Carbon: Under 0.4 percent
• Medium Carbon: 0.4 - 0.6 percent
• High Carbon: 0.7 - 1.5 percent

16. Manganese
•Manganese slightly increases the strength of ferrite,
and also increases the hardness penetration of steel
in the quench by decreasing the critical quenching
speed.
•Steels with manganese can be quenched in oil rather
than water.
•Manganese is present in most commercially made
steels.

17. CHROMIUM
• As with manganese, chromium has a tendency to increase hardness penetration.
This element has many interesting effects on steel. When 5 percent chromium
or more is used in conjunction with manganese, the critical quenching speed is
reduced to the point that the steel becomes air hardening.
• Chromium can also increase the toughness of steel . Probably one of the most
well known effects of chromium on steel is the tendency to resist staining and
corrosion.
• Steels with 14 percent or more chromium are referred to as stainless steels.
• Steels with chromium also have higher critical temperatures in heat
treatment.

18. SILICON
• Silicon is used as a deoxidizer in the manufacture of steel.
• It slightly increases the
strength of ferrite, and when used in conjunction with other alloys
can help increase the
toughness and hardness penetration of steel.

19. Nickel
• Nickel increases the strength of ferrite, therefore increasing the strength of the
steel.
• It is used in low alloy steels to increase toughness and hardenability.
• Nickel also tends to help reduce distortion and cracking during the quenching
phase of heat treatment.

20. MOLYBDENUM
• Molybdenum increases the hardness penetration of steel,
slows the critical quenching speed, and increases high
temperature tensile strength.

22. Copper
•The addition of copper in amounts of 0.2 to 0.5
percent primarily improves steels resistance to
atmospheric corrosion.

23. Boron
Boron can significantly increase the hardenability of
steel without loss of ductility. Its effectiveness is most
noticeable at lower carbon levels. The addition of boron
is usually in very small amounts ranging from 0.0005 to
0.003 percent.

24. •