The document discusses the thermodynamic properties of iron-based alloys. It describes the various phases in the Fe-C phase diagram, including α-ferrite, γ-austenite, and Fe3C cementite. It notes that eutectic and eutectoid reactions are important for heat treating steel. The microstructure of steel depends on its carbon content and heat treatment. Hypoeutectoid steel contains ferrite and pearlite, while hypereutectoid steel contains cementite and pearlite. The effect of adding silicon and manganese to iron-carbon alloys is to decrease stability of cementite, increase stability of ferrite, and decrease eutectic/eut

1. THERMODYNAMIC PROPERTIES OF IRON
BASED ALLOYS
GROUP 8

2. Study of Fe-C alloy using
Phase Diagram
By
M. Sri Harsha
G. Ravi Teja
Aniket Mawlankar

3. PHASES IN FE–FE3C PHASE DIAGRAM:
-FERRITE, -AUSTENITE, -FERRITE,
FE3C (CEMENTITE), FE-C LIQUID SOLUTION
In their simplest form,
steels are alloys of Iron
(Fe) and
Carbon (C). The Fe-C
phase diagram is a fairly
complex
one, but we will only
consider the steel part
of the diagram,
up to around 7%
Carbon
PHASE DIAGRAM of
Fe-C alloy
eutectic
eutectoid

4. Eutectic and eutectoid reactions in Fe–Fe3C
Eutectic: 4.30 wt% C, 1147 °C
L ↔ γ + Fe3C
Eutectoid: 0.76 wt% C, 727 °C
γ(0.76 wt% C) ↔ α (0.022 wt% C) + Fe3C
Peritectic: 0.18wt%C, 1493°C
L + δ ↔ γ
Eutectic and eutectoid reactions are very
important in heat treatment of steel.

5. Development of Microstructure in Iron -
Carbon alloys
Microstructure depends on composition (carbon content) and
heat treatment. Microstructure of eutectoid steel
Alloy of eutectoid composition (0.76 wt %
C) is
cooled slowly it forms pearlite, a lamellar or
layered
structure of two phases: α-ferrite and
cementite (Fe3C)
(This is because most steel is
relatively slowly cooled through the
eutectoid phase transformation.)
Mechanically, pearlite has properties
intermediate to soft,
ductile ferrite and hard, brittle cementite.

6. Compositions to the left of eutectoid (0.022 - 0.76 wt % C) hypoeutectoid
(less than eutectoid -Greek) alloys.
γ → α + γ → α + Fe3C
Compositions to the right of eutectoid (0.76 - 2.14 wt % C)hypereutectoid
(more than eutectoid -Greek) alloys.
γ → γ + Fe3C → α + Fe3C
Microstructure of hypo/hyper eutectoid steel

7. Hypoeutectoid alloys contain proeutectoid ferrite (formed
above the eutectoid temperature) plus the eutectoid perlite
that contain eutectoid ferrite and cementite.
Hypereutectoid alloys contain proeutectoid cementite
(formed above the eutectoid temperature) plus perlite that
contain eutectoid ferrite and cementite.

8. Thermodynamic
Properties Of
IRON-BASE ALLOYS
BY:- AMIT KOHAD, MITESH KUMAWAT, TARUN KUMAR

9. Fe-C Phase Diagram

10. For The Stable System, With Graphite As The
Equilibrium High‐carbon Phase
1)For Liquid phase ,1152 to 2000 °C (2106 to 3632 °F),
 log Xcmax = ‐ (12.728)/T + 0.727 logT ‐ 3.049
 Xcmax is the maximum solubility of graphite in liquid iron in mole
fraction.
 T is the temperature in kelvin.
2) For austenite:
 wt%Cmax = 1.3 + (2.57 × 10^‐3 x t) + 1.61 × 10^‐6 (t^2)
3)For ferrite:
wt%Cmax = 2.46 × 10^3 exp(‐11460/T)

11. For The Metastable System, With Fe3c As
The Equilibrium High carbon Phase
1)For Liquid phase:
 wt%Cmax = 4.34 + 1874(t‐1150) ‐200 x ln (t/1150)
2) For austenite:
 wt%Cmax = ‐0.628 + 1.222 × 10^‐3 t + 1.045 × 10‐3 t^2
3)For ferrite:
 wt%Cmax = 1.8 × 10^3 exp (‐10908/T)

12. Phases in Fe–Fe3C Phase Diagram
1) α-ferrite - solid solution of C in BCC Fe
• Stable form of iron at room temperature.
• The maximum solubility of C is 0.022 wt%
• Transforms to FCC γ-austenite at 912 °C
2) γ-austenite - solid solution of C in FCC Fe
• The maximum solubility of C is 2.14 wt %.
• Transforms to BCC δ-ferrite at 1395 °C
• Is not stable below the eutectic temperature (727 ° C) unless cooled rapidly
3) δ-ferrite solid solution of C in BCC Fe
• This intermetallic compound is metastable, it remains as a compound indefinitely at
room T, but decomposes (very slowly, within several years) into α-Fe and C (graphite) at
650 - 700 °C

13. Effect of addition of
silicon to Iron Carbon
alloy on temperature
and solubility
BY SUMEDH GHOGARE AND AJITESH SINGH

14. Effect of addition of silicon to Iron Carbon alloy on
temperature and solubility
• Silicon is used as a deoxidising (killing) agent in the
melting of steel, as a result, most steels contain a
small percentage of silicon.
• Silicon contributes to hardening of the ferrite
phase in steels and for this reason silicon killed
steels are somewhat harder and stiffer than
aluminium killed steels.

15. Fe-C-Si system Charecteristics
The addition of silicon to Iron-Carbon alloy effects in the following way
• Decreases the stability of Fe3C,which is already a
metastable component
• Increases the stability of Ferrite(The α region is enlarged
& the Y region is constricted),
• As the Si-content in the Fe-C-Si system increases, the
carbon contents of the eutectic & eutectoid decreases
while the eutectic & eutectoid temperatures increases

16. Effect of addition of silicon to Iron Carbon
alloy on temperature and solubility

17. Effect of addition of manganese
to Iron Carbon alloy on
temperature and solubility
By
Dewashish Kumar Dey
Abhinav Rathor
Jatin Yadav

18. WHY WE ARE STUDYING IT?

19. IRON-CARBON PHASE DIAGRAM
GOOGLE
IMAGES

20. Fe-C-Mn System
The influence of increasing Mn in Fe-C-Mn
System:
 Eutectoid interval is increased, i.e., the
range of temperature and Carbon contents
over which α, γ and carbide coexist
 Decreases the Carbon content in the
eutectoid and in the eutectic.
 Eutectoid temperature is decreased.
 Increases the eutectic temperature(by
about 3°F or 5°F for each 1% Mn).

21. Effect of addition of manganese
S
C
O
P
U
S

22. Advantages
of adding Manganese to Fe-C System
 Increases hardenability by decreasing the critical
quenching speed and lowering the transformation
points
 Improves hot working properties
 Increases strength by eliminating the formation of iron
sulphides
 Acts as an austenite forming element
 Also improves ductility and wear resistance

23. THANKS