Ductile iron

Ductile iron microstructure at 100× magnification, showing carbon islanding effect around nodules.
Another micrograph showing the carbon islanding effect, with nodules surrounded by areas depleted of carbon

Type of graphite-rich cast iron discovered in 1943 by Keith Millis.

- Ductile iron

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Cast iron

Class of iron–carbon alloys with a carbon content more than 2%.

Iron-cementite meta-stable diagram
Pair of English firedogs, 1576. These, with firebacks, were common early uses of cast iron, as little strength in the metal was needed.
Cast-iron artifact dated from 5th century BC found in Jiangsu, China
Diorama model of a Han dynasty blast furnace blower
The Iron Lion of Cangzhou, the largest surviving cast-iron artwork from China, 953 AD, Later Zhou period
Cast-iron drain, waste and vent piping
Cast-iron plate on grand piano
Cast-iron waffle iron, an example of cast-iron cookware
The Iron Bridge over the River Severn at Coalbrookdale, England (finished 1779)
The Eglinton Tournament Bridge (completed c1845), North Ayrshire, Scotland, built from cast iron
Original Tay Bridge from the north (finished 1878)
Fallen Tay Bridge from the north

The alloy constituents affect its color when fractured: white cast iron has carbide impurities which allow cracks to pass straight through, grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, and ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing.


Chemical element with the symbol Mg and atomic number 12.

Magnesium is brittle, and fractures along shear bands when its thickness is reduced by only 10% by cold rolling (top). However, after alloying Mg with 1% Al and 0.1% Ca, its thickness could be reduced by 54% using the same process (bottom).
Magnesium sheets and ingots
An unusual application of magnesium as an illumination source while wakeskating in 1931
Mg alloy motorcycle engine blocks
Products made of magnesium: firestarter and shavings, sharpener, magnesium ribbon
Examples of food sources of magnesium (clockwise from top left): bran muffins, pumpkin seeds, barley, buckwheat flour, low-fat vanilla yogurt, trail mix, halibut steaks, garbanzo beans, lima beans, soybeans, and spinach

As an additive agent in conventional propellants and the production of nodular graphite in cast iron.

Keith Millis

Gold ore from Boundary Red Mountain Mine, Washington, US

Keith Dwight Millis (May 20, 1915 – July 6, 1992) was an American metallurgical engineer and inventor of ductile iron.


Chemical element with the symbol Y and atomic number 39.

Left: Soluble yttrium salts reacts with carbonate, forming white precipitate yttrium carbonate. Right: Yttrium carbonate is soluble in excess alkali metal carbonate solution
Mira is an example of the type of red giant star in which most of the yttrium in the solar system was created
Johan Gadolin discovered yttrium oxide
Xenotime crystals contain yttrium
A piece of yttrium. Yttrium is difficult to separate from other rare-earth elements.
Yttrium is one of the elements that was used to make the red color in CRT televisions
Nd:YAG laser rod 0.5 cm in diameter
YBCO superconductor

Yttrium has been studied as a nodulizer in ductile cast iron, forming the graphite into compact nodules instead of flakes to increase ductility and fatigue resistance.

Ductile iron pipe

Section of DICL pipe (ductile iron concrete lined), commonly used for utility water mains, showing iron casing, concrete lining, and textured polymer protective coatings on the inner and outer surfaces.

Ductile iron pipe is pipe made of ductile cast iron commonly used for potable water transmission and distribution.


Chemical element with symbol Fe and atomic number 26.

Molar volume vs. pressure for α iron at room temperature
Low-pressure phase diagram of pure iron
Magnetization curves of 9 ferromagnetic materials, showing saturation. 1.Sheet steel, 2.Silicon steel, 3.Cast steel, 4.Tungsten steel, 5.Magnet steel, 6.Cast iron, 7.Nickel, 8.Cobalt, 9.Magnetite
A polished and chemically etched piece of an iron meteorite, believed to be similar in composition to the Earth's metallic core, showing individual crystals of the iron-nickel alloy (Widmanstatten pattern)
Ochre path in Roussillon.
Banded iron formation in McKinley Park, Minnesota.
Pourbaix diagram of iron
Hydrated iron(III) chloride (ferric chloride)
Comparison of colors of solutions of ferrate (left) and permanganate (right)
Blue-green iron(II) sulfate heptahydrate
The two enantiomorphs of the ferrioxalate ion
Crystal structure of iron(II) oxalate dihydrate, showing iron (gray), oxygen (red), carbon (black), and hydrogen (white) atoms.
Blood-red positive thiocyanate test for iron(III)
Iron penta- carbonyl
Prussian blue
Iron harpoon head from Greenland. The iron edge covers a narwhal tusk harpoon using meteorite iron from the Cape York meteorite, one of the largest iron meteorites known.
The symbol for Mars has been used since antiquity to represent iron.
The iron pillar of Delhi is an example of the iron extraction and processing methodologies of early India.
Iron sickle from Ancient Greece.
Coalbrookdale by Night, 1801. Blast furnaces light the iron making town of Coalbrookdale.
"Gold gab ich für Eisen" – "I gave gold for iron". German-American brooch from WWI.
Iron powder
Iron furnace in Columbus, Ohio, 1922
17th century Chinese illustration of workers at a blast furnace, making wrought iron from pig iron
How iron was extracted in the 19th century
This heap of iron ore pellets will be used in steel production.
A pot of molten iron being used to make steel
Iron-carbon phase diagram
Photon mass attenuation coefficient for iron.
Structure of Heme b; in the protein additional ligand(s) would be attached to Fe.
A heme unit of human carboxyhemoglobin, showing the carbonyl ligand at the apical position, trans to the histidine residue

A newer variant of gray iron, referred to as ductile iron, is specially treated with trace amounts of magnesium to alter the shape of graphite to spheroids, or nodules, reducing the stress concentrations and vastly increasing the toughness and strength of the material.


Trademark for an engineering process to make a range of cast irons produced under specific and carefully controlled conditions to precise internationally recognized specifications.

Registered trademark symbol

High duty flake or gray irons; high duty “nodular” or ductile iron (SG); and a group consisting of special types for applications requiring resistance to heat, wear and corrosion.

Directional boring

Minimal impact trenchless method of installing underground utilities such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path using a surface-launched drilling rig.

Small HDD Drill Rig
Maxi-Sized Drill Rig
Typical Maxi-Sized HDD Rig Spread (approximately 50,000 sq ft.)
Starting pit with pilot hole and some drilling fluid in the pit
Empty conduits laid by directional boring

Directional Boring/HDD can be utilized with various pipe materials such as PVC, polyethylene, polypropylene, ductile iron, and steel provided that the pipe's properties (wall thickness and material strength) enable it to be both installed and operated (if applicable) under acceptable stress limits.

Water metering

Practice of measuring water use.

A typical residential water meter
Water meter in Belo Horizonte.
A velocity water meter.
Internal structure of a velocity water meter.
Electromagnetic flow meter
A typical water meter register showing a meter reading of 8.3 gallons. Notice the black "1" on the odometer has not yet fully turned over, so only the red hand is read.
Water meters connected to remote reading devices through three-wire cables
Water meter in building

Turbine meter bodies are commonly made of bronze, cast iron or ductile iron.

Deep foundation

Type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths.

A deep foundation installation for a bridge in Napa, California, United States.
Pile driving operations in the Port of Tampa, Florida.
Deep foundations of The Marina Torch, a skyscraper in Dubai
Pipe piles being driven into the ground
Illustration of a hand-operated pile driver in Germany after 1480
A pile machine in Amsterdam.
Sheet piles are used to restrain soft soil above the bedrock in this excavation
A soldier pile wall using reclaimed railway sleepers as lagging.
Adfreeze piles supporting a building in Utqiaġvik, Alaska
Sheet piling, by a bridge, was used to block a canal in New Orleans after Hurricane Katrina damaged it.
Cutaway illustration. Deep inclined (battered) pipe piles support a precast segmented skyway where upper soil layers are weak muds.
'Pile jackets' encasing old concrete piles in a saltwater environment to prevent corrosion and consequential weakening of the piles when cracks allow saltwater to contact the internal steel reinforcement rods

These may be ductile.