1. Defects & Cause. Defects Root Cause Shrinkage
Rusty charge: very high chilling tendency in this iron
low content of CE
EFFECT OF SUPERHEATING
Metal Holding
Excess magnesium
Under inoculation or over inoculation
High Pouring temp
Chunky graphite
High Purity charge materials
High CE
High %RE(rare earth)
High Pouring Temp
Mech Failure
Poor Charge Mix
Fadding
ELEMENT SEGREGATION TENDENCY
Blow Hole
Low Pouring Temp
Slag inclusion
Rusty charge materials
Poor Pouring Practice

2. Types of shrinkage Decrease in volume of the metal as it solidifies
Outer sunks:
Outer sunks (pull downs, sinks) can be seen from the outside of the casting, usually as a smooth depression in the casting surface.
Macro shrinkage:
Macro shrinkages are usually found inside the casting and close to heat centers. They appear as larger holes,
Defect size >5mm
Micro shrinkages:
Micro shrinkages are smaller cavities with irregular surfaces. Defect size <3mm also called porosity

3. Shrinkage Rusty charge: High Magnesium:
very high chilling tendency in this metal
High Magnesium:
Very high chilling tendency in this metal
High magnesium content acts to promote carbidic microstructures and increase shrinkage

4. Shrinkage Effect of Superheating: Holding:
the temperature of any melt is increased above the normal melt temperature (high superheat), nucleation has been reduced.
Holding:
The longer the hold times, at any temperature, the greater the loss of nucleation.

5. Shrinkage Under inoculation:
Not enough to precipitate Carbon as a graphite
Over inoculation:
Too many nucleation points are active early in the solidification
feeders become inactive and contraction takes place, there is no graphite

6. Chunky Graphite Entrapment of gases in the cavity while pouring
Chunky Graphite Entrapment of gases in the cavity while pouring. Occurrence: were the casting thickness is more
High RE:
Excessive cerium in the metal will cause the chunky graphite.
Wall thickness < 25 mm Ce 0,020 – 0,015 %
25 – 50 mm Ce 0,015 – 0,010 %
50 – 100 mm Ce 0,010 – 0,005 %
100 – 250 mm Ce 0,005 – 0,002 %
250 mm Ce 0,002 – 0,000 %
High Purity Charge material:
Charge more than 50% sorrel PI cause there is no trace element eg: Pb,Bi,Sb etc
High Pouring Temp & Holding:
Both will affect the nucleation of SG to form CHG.
High CE:
Increased volume of the graphite

7. Mechanical Failure Exploded Graphite
Excess, rare earths can
cause exploded graphite.
At very high carbon equivalent (CE).
Exploded graphite is normally found in thicker section castings with slow cooling rates.
High purity charges are used which are low in detrimental tramp elements such as lead, bismuth, antimony, titanium etc

8. Mechanical Failure Graphite Flotation
At very high carbon equivalent (CE).
The nodules, being of a lower density than the matrix, tend to float towards the surface of the casting.

9. CE
shrinkage
V1/V
V2/V

10. Slag Inclusion A product resulting from the action of a flux on the oxidized non-metallic con­stituents of molten metals. Occurrence: Any place of the casting
Rusty Charge:
Charge containing oxide products (e.g:Rust CRS & Borings), that one oxidize the metal. it will cause Heavy slag formation in the metal.
Pouring Practice:
Slag should be removed thoroughly.
Metal level should be maintained 75% of basin capacity during the pouring.
Min 300Kg metal maintained in the Basin
Material Charge Mix
Slag
steel
1-2%
DI Returns
5-10%
Pig iron
0.12%
rusty scrap
12%
Borings
25%

11. Dross Non metallic inclusion is called Dross Occurrence: Surface of the casting
Excess residual Mg (>0.050%)in the metal react with oxygen & sulphur to form Mgo,Mgs respectively. It will appear on the surface of the casting.
Low pouring Temp:
mg easily react with Si to form Mgsi2
(During Inoculations)
Turbulence:
Rapid flow of metal into the mould
Will cause Dross

12. Blow Hole Entrapment of gases in the cavity while pouring
Blow Hole Entrapment of gases in the cavity while pouring. Occurrence: Any place of the casting
Low Pouring Temp:
Gas molecules not easily escape from the mould at low temp.
Ti & Al content in metal:
it will promote the evolution of the gas in the metal.

13. Requirements for cast-on sample as per standard DIN 1563-2003-02[5]
Requirements for cast-on sample as per standard DIN [5]
Material designation
Walll
Impact Mean(J)
Impact Individual(J)
Min. tensile
Min. Yeild
% Elong
thickness, t(mm)
strength(N/mm2)
EN-GJS U-LT
Impact at - 40 ± 2℃
< 30 12 9
350
220 22
30 < t ≤ 60
330
210 18
60 < t ≤ 200 10 7
320
200 15
EN-GJS U-LT
Impact at - 20 ± 2℃
400
240
390
230
370

14. Mechanical Failure
The following Metallurgical defect Can cause the Mechanical failure.
1.Fading
2.Exploded Graphite
3.Chunky Graphite
4.Compacted Graphite
5.Graphite Flotation
6.Spiky Graphite

15. Mechanical Failure Fading
Holding the metal after treatment will cause Fading
High Sulphur content in the bath
Inadequate inoculation

16. Mechanical Failure Compacted Graphite
Incorrect weighing of the nodulariser.
Although a long holding time in the ladle or excessive temperatures.

17. Mechanical Failure Spiky Graphite
Excess, Trace elements such as lead, bismuth, titanium and antimony present in the metal to form Spiky Graphite.

18. Grey & SG iron
ASTM A48 (Class 30, 35, 40? Gray Iron Castings ASTM 159 or SAE J431 ( G4000, G3500, G3000, G2500, G1800) Automotive Gray Iron Castings ASTM A319 Class I, II, III Gray Iron Castings for Elevated Temperatures ASTM A436 (DIN 1694, BS 3468) Ni-Resist Castings, Austenitic Gray Iron Castings DIN 1691 (GG10, GG15, GG20, GG25, GG30, GG35) EN 1561 （EN-GJL-200, EN-GJL-250, EN-GJS-300, EN-GJS-350,EN-GJS-400,
EN-GJS-500, EN-GJS-600, EN-GJS-700) ,
ISO 185
SG IRON
ASTM A536 ( , , ? , , 500-7, 600-3) Ductile Iron Casting ASTM A439 (DIN 1694, BS 3468) Austenitic Ductile Iron ASTM A897 Austempered Ductile Iron ADI ASTM A571 Low Temp, Pressure-Containing DIN 1693 (GGG-30, GGG-40, GGG-50, GGG-60, GGG-70, GGG-80) EN 1563 (EN-GJS , EN-GJS , EN-GJS-500-7,
EN-GJS-600-3, EN 1563 EN-GJS LT) SAE J434（D4018, D4512, D5506?D5504?D7003, D700, D800, D400) ISO 1083, BS 2789

19. THANK U