1. Name : Patel Ishan P. Sub. : MSM Enr No. : 130940119083
Branch : Mechanical -B
Guided By ,
Umang Patel ..

2. CAST IRON

3. Cast Iron
Ferrous
Steels
Cast iron
Grey
White
Nodular
Malleable

4. What is cast iron?

5. Iron accounts for more than 95 wt% of the alloy material, while the main alloying elements are carbon (between  wt%) and silicon (normally 1-3 wt%).
From the iron-iron carbide phase diagram, cast iron has a eutectic point at 1153 °C and 4.2 wt% carbon.
Since cast iron has roughly this composition, its melting temperature of 1150 to 1200 °C is about 300 °C lower than the melting point of pure iron.
The most common cast iron types are: grey, white, nodular, malleable and compacted graphite.

6. Grey Cast Iron

7. graphite flakes surrounded by a- ferrite or pearlite matrix
Grey cast iron is named after its grey fractured surface that occurs when the graphitic flakes deflect a passing crack and initiate many new cracks as the material breaks.
graphite flakes surrounded by a- ferrite or pearlite matrix
weak & brittle in tension (the graphite flake tips are sharp; act as stress raisers)
stronger in compression
excellent vibrational dampening
wear resistant
grey
grey

8. Grey Cast Iron Carbon content: 3.0 – 4.0 wt%
Silicon content: 1.0 – 3.0 wt %
Modifying silicon content and cooling rate affects microstructure.
Casting shrinkage is low

9. Microstructure of Grey Cast Iron
(200X, Nital etch.)

10. White Cast Iron

11. White cast iron is named after its white surface when fractured due to its carbide impurities that allow cracks to pass straight through; the crystalline fractures are shiny compared to the dull gray fractures of graphite irons.
< 1 wt% Si, rapid cooling rates
pearlite + most of the carbon forms cementite, not graphite.
very hard and brittle;

12. White Cast Iron
thickness may result in non-uniform microstructure from variable cooling; white iron develops from faster cooling;
slower cooling rate yields grey iron.
limited applications; used as intermediate to produce malleable cast iron.

13. Nodular Cast Iron
(Ductile)

14. graphite forms nodules not flakes Normally a pearlite matrix.
Nodular Cast Iron in Adding Mg and/or Cerium to grey iron before casting produces a distinctly different microstructure and mechanical properties.
graphite forms nodules not flakes
Normally a pearlite matrix.
grey
nodular
nodular
(Nodular Cast Iron)

15. Nodular Cast Iron
Photo (nodular) shows ferrite matrix that was heat treated for several hours at 700˚C.
Castings are stronger and much more ductile than grey iron.

16. Malleable Cast Iron

17. reasonably strong and ductile (malleable)
white iron
nodular
Malleable cast iron formed by heat treating white iron at ºC for a prolonged period causes decomposition of cementite into graphite.
graphite forms clusters or rosettes that are surrounded by a ferrite or pearlite matrix.
reasonably strong and ductile (malleable)
Carbon content: 2.3 – 2.7 wt%
Silicon content: 1.0 – 1.75 wt %
malleable
malleable

18. Application & Properties of Cast Iron
Wide range of applications (including pipes, machine and car parts, such as cylinder heads, blocks and gearbox cases) due to:
low melting point,
good fluidity,
relatively easy to cast,
excellent machinability,
resistance to deformation
wear resistance
Cast iron tends to be brittle, except for malleable cast irons, so shaping these by deformation is very difficult.
Cast iron coated with durable porcelain enamel distributes heat slowly and evenly.

19. Variety of Cast Iron Microstructures
Gf , graphite flake
Gr , graphite rosettes
Gn, graphite nodules
P, pearlite = a + cementite
a, ferrite

20. Thank Youuu..