1. GOVERNMENT COLLEGE OF ENGINEERING, SALEM.
CAST IRON
PRESENTED BY
JEEVA.T
YASODHA.M

2. INTRODUCTION
Cast iron usually refers to grey iron, but also identifies a large group of ferrous alloys, which solidify with a eutectic.
Cast iron tends to be brittle, except for malleable cast irons.
The color of a fractured surface can be used to identify an alloy.

3. CONTENTS CAST IRON. CLASSIFICATION. APPLICATIONS OF CAST IRONS.
WHITE.
MALLEABLE.
GRAY.
DUCTILE.
APPLICATIONS OF CAST IRONS.
HEAT TREATING TO CONTROL STRUCTURE.

4. ABOUT CAST IRON Family of ferrous alloys.
Cast into desired shape – not worked.
2-4% C and 1-3% Si.
Instability of Fe3C:
Cementite / graphite flakes / graphite nodules.

5. TYPES OF CAST IRON Alloying elements. Grey cast iron. White cast iron.
Malleable cast iron.
Ductile cast iron.

6. CAST IRON

7. SCHEMATIC OF TYPES OF CAST IRONS

8. PART 2 OF SCHEMATIC

9. CLASSIFICATION OF CAST IRON
S.NO
TYPES OF CAST IRON
GRAPHITE
DUCTILITY
PROPERTY 1
WHITE NO
FAST COOLING RATES 2
GRAY
Flake
SLOW COOLING RATES 3
MALLEABLE
Anneal:
flake to
nodule
YES
WHITE IRON + ANNEALING
HEAT TREATMENT 4
NODULAR
Nodular
ADDITIONS MADE SO THAT
NODULES OF GRAPHITE
FORM INSTEAD OF FLAKES

10. FACTORS INFLUENCING WHICH WILL FORM
TEMPERATURE (COOLING RATE)

11. COMPOSITION AND TYPE OF CAST IRON

12. COOLING RATE AND TYPE OF CAST IRON

13. GREY VS NODULAR CAST IRON (X250)
Ferritic
pearlitic
Gray – graphite as Nodular – graphite as Flakes nodules
Brittle Ductile

14. WHITE CAST IRON Fe3 C+ pearlite. Hard, brittle.
Shows a “white” crystalline fractured surface. 
Excellent wear resistance. 
High compressive stress.

15. MALLEABLE CAST IRON White cast iron + annealing treatment.
During annealing treatment graphite nucleates and grows from the Fe3C to form nodules.

16. GRAY CAST IRON
During slow solidification carbon in Fe separates or graphitizes to form separate graphite flakes.

17. DUCTILE/NODULAR CAST IRON
Mg added to molten iron.
Helps to spheroids graphite.
Low levels of minor elements such as S and P.

18. GENERAL CHARACTERISTICS/ ADVANTAGES OF GRAY CAST IRON
Cheap.
Low melting point.
Fluid – easy to cast, especially advantageous into large complex shapes.
Excellent machine ability.
Excellent bearing properties.
Excellent damping properties.
Excellent wear resistance (hi C).
Can be heat treated (surface hardened etc.).
Can be alloyed etc.
Essentially steel + graphite.

19. GREAT AT DAMPENING
Relative ability of ferrous metals to dampen vibrations. The energy absorbed per cycle, or specific damping capacity of these can differ by more than 10 times.

20. GRAY CAST IRON (EXAMPLE)
graphite forms as flakes during solidification.
Have γ dendrites + eutectic γ + graphite flakes at T < 1153°C.
99% γ + 1 % graphite flakes.

21. COMMENTS ON TENSILE PROPERTIES
Ferritic – softest; pearlitic – strongest.
Variation in elastic modulus.
0 ductility – tensile strengths only quoted.
C – %, Si %
Graphite flake types and size.
Fine uniform size wanted, get by:
increased superheat to casting.
Inoculation with ferrosilicon or calcium silicon.

22. TENSILE PROPERTIES

23. APPLICATIONS OF DUCTILE CAST IRONS

24. DUCTILE/NODULAR CAST IRON
Gray iron composition for C and Si.
Impurity level control important as it will affect nodule formation.
Have nodule instead of flake if we add in 0.05% Mg and/or Ce.
As cast structure: graphite forms as nodules instead of flakes.

25. NODULAR CAST IRON γ + graphite on cooling below A1 must decide:
γ α +Fe3C
Favored by slow cooling rates, short diffusion paths etc.
γ first follows a) in regions surrounding nodules.
Carbon diffuses to existing nodules.
As T decreases and diffusion path increases remaining.
γ α +Fe3C(pearlite).

26. HEAT TREATMENT CONTROL
If we want more ductility (less strength) heat.
Treat to convert pearlitic areas to α + graphite.
Heat to 900°C
Cool at 20°C/hr from 790° to 650°CF
Normal furnace cooling.
Could be done as one step with slower.
Original cooling.

27. CONCLUSION
Finally we concluded that we are all known about the “BASICS OF CAST IRON” which is above in the paper.

28. THANK YOU…..