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Ductile iron is not a single material but is part of a group of materials which can be produced to have a wide range of properties through control of the microstructure.
Structure
The common defining characteristic of this group of materials is the shape of the graphite. In ductile irons, the graphite is in the form of nodules rather than flakes as it is in grey iron. The sharp shape of the flakes of graphite create stress concentration points within the metal matrix and the rounded shape of the nodules less so, thus inhibiting the creation of cracks and providing the enhanced ductility that gives the alloy its name.
The formation of nodules is achieved by the addition of nodulizing elements, most commonly magnesium (note magnesium boils at 1100°C and iron melts at 1500°C) and, less often now, cerium (usually in the form of Mischmetal). Tellurium has also been used. Yttrium, often a component of Misch metal, has also been studied as a possible nodulizer.
Mictrostructure of Ductile Cast Iron
Physical and Mechanical Properties
Item according to DIN EN 1563 |
Measure Unit |
EN-GJS-350-22-LT |
EN-GJS-400-18-LT |
EN-GJS-400-18 |
EN-GJS-500-7 |
EN-GJS-600-3 |
EN-GJS-700-2 |
EN-GJS-800-2 |
EN-JS 1015 |
EN-JS 1025 |
EN-JS 1020 |
EN-JS 1050 |
EN-JS 1060 |
EN-JS 1070 |
EN-JS 1080 |
Tensile Strength |
Rm min.MPA |
350 |
400 |
400 |
500 |
600 |
700 |
800 |
0.2% Yield Strength |
Rp0,2 min.MPA |
220 |
240 |
250 |
320 |
370 |
420 2) |
480 2) |
Elongation Strength |
A % |
22,0 |
18,0 |
18,0 |
7,0 |
3,0 |
2,0 |
2,0 |
Brinell hardness |
HB |
110-150 |
120-160 |
140-190 |
170-220 |
200-250 |
230-280 |
250-330 |
Structures |
|
mainly ferritic |
mainly ferritic |
mainly ferritic |
ferritic + pearlite |
ferritic + pearlite |
mainly pearlite |
all pearlite |
ISO-V impact test by -40 ± 2 ºC |
|
12,0 |
|
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|
|
|
|
ISO-V impact test by -20 ± 2 ºC |
|
|
12,0 |
|
|
|
|
|
ISO-V impact test by +23 ± 5 ºC |
Kv min.J |
17,0 3) |
14,0 3) |
|
|
|
|
|
Shear Stress |
σaB MPa |
315 |
360 |
360 |
450 |
540 |
630 |
720 |
Torsion |
TtB MPa |
315 |
360 |
360 |
450 |
540 |
630 |
720 |
Modules of elasticity |
E GPa |
170 |
170 |
170 |
175 |
175 |
175 |
175 |
Poisson number |
v – |
0,280 |
0,280 |
0,280 |
0,280 |
0,280 |
0,280 |
0,280 |
Compressive Strength |
σdB MPa |
– |
700 |
700 |
800 |
870 |
1000 |
1150 |
Frature Toughness |
Klc MPa ·√m |
31 |
30 |
30 |
25 |
20 |
15 |
14 |
Density |
g/cm3 |
7,1 |
7,1 |
7,1 |
7,1 |
7,2 |
7,2 |
7,2 |
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