Manufacturing Ductile Iron Pipe
Ductile iron pipe is made from 100% recycled iron. Ductile iron is created by adding small, but precise amounts of magnesium to the molten iron. Samples of the molten iron are taken every 15 minutes for spectrographic analysis. Results are returned to the molten metal treatment station where adjustments are made by increasing or reducing alloys to required levels.
Pacific States Cast Iron Pipe Company uses the deLavaud casting process. Following spectrographic analysis, a controlled amount of molten iron is introduced into a rotating metal casting mold fitted with a bell core. The metal is then distributed over the interior of the mold's surface by centrifugal force ensuring proper thickness without voids. This force holds the metal in place until solidification occurs.
Typical Analysis
07-Jan-97 10:09:06 Sample: 16 TECH
Quality: MACHINE TASK: MACHINE
| Run |
C |
Si |
S |
Mg |
Cr |
Cu |
Pb |
Mn |
P |
All |
| 1> |
3.377 |
2.372 |
0.007 |
0.023 |
0.102 |
0.176 |
0.002 |
0.340 |
0.034 |
0.027 |
| 2> |
3.355 |
2.319 |
0.007 |
0.021 |
0.102 |
0.176 |
0.002 |
0.337 |
0.032 |
0.025 |
| AVG |
3.366 |
2.346 |
0.007 |
0.022 |
0.102 |
0.176 |
0.002 |
0.338 |
0.033 |
0.026 |
| Sd % |
0.476 |
1.577 |
1.200 |
6.625 |
0.451 |
0.123 |
5.775 |
0.511 |
4.747 |
5.045 |
| |
Ni |
B |
Sn |
As |
MO |
Fe % |
Feint |
|
|
|
| 1> |
0.061 |
0.000 |
0.011 |
0.008 |
0.011 |
93.449 |
87.402 |
|
|
|
| 2> |
0.062 |
0.000 |
0.010 |
0.007 |
0.011 |
93.534 |
88.403 |
|
|
|
| AVG |
0.062 |
0.000 |
0.011 |
0.007 |
0.011 |
93.491 |
87.902 |
|
|
|
| Sd % |
0.308 |
9.873 |
2.281 |
11.644 |
0.593 |
0.064 |
|
|
|
|
Ductile Iron Metallurgy
The increased strength and unique properties of ductile iron are attributable to the fact that the graphite or carbon within the ductile iron matrix exists in spheres or nodules. As a result of a carefully controlled annealing heat treatment of the pipe, the iron is transformed progressively from carbidic to pearlitic to ferritic iron. Ferrite provides the high ductility and strength of ductile iron pipe, while the graphite and silicon compositions ensure excellent machining characteristics and wear resistance.
Strength and ductility (the ability of the material to be deformed by elongation without fracture) are the greatest advantages of ductile iron pipe.
