Before we discuss the practical uses for ductile iron – also referred to as spheroidal or nodular iron – let’s talk about what it is and what makes it different.
What is Ductile Iron?
Invented in 1943, ductile iron is a group of irons that due to their microstructure, exhibit greater flexibility, strength and elasticity and are far more durable than other irons. This type of iron is considered to be a modern iteration of cast iron. Cast iron and ductile iron have contrasting physical properties caused by differences in their microstructures.
Ductile Iron has more flexibility than cast iron because it typically contains over 3 percent carbon so it can be bent, twisted or deformed without fracturing. Ductile iron has properties that are similar to steel which makes ductile iron stronger than most standard cast Iron.
How do we make objects with Ductile Iron?
When casting ductile iron molten ductile iron is poured to the voids in a mold. The results we get are solid metal objects in the shape of the mold we choose. This occurs because the ductile iron will cool and solidify into the shape of the void in the mold.
The graphite and carbon contained in cast iron occur as a flake. These flakes can cause cracks to form when the tensile loading is above the natural tensile strength which propagates out from stress points. Cast iron has virtually no elongation and is much more material than ductile Iron so we are limited in the way we use cast iron.
When casting ductile iron, the graphite creates spheroids which is why ductile iron is often referred to as spheroidal graphite. Sometimes you may hear it referred to as nodular iron since the carbon contained in ductile iron forms nodules. This is why ductile iron is capable of withstanding bending and shock loading far better than traditional cast iron.
What is Ductile Iron made from?
The primary source of infeed for ductile iron is pig iron. Ductile iron can also be produced from steel or iron scrap, but pig iron is more commonly used by foundries in the making of most modern ductile iron. Pig iron refers to the primary iron production of the old-fashioned method of casting blast furnace iron into molds arranged in sand beds in a blast furnace that contains over ninety percent iron. The molds used to resemble a litter of suckling pigs, so we referred the pieces of iron as pigs.
Today, these little “pigs” get made in continuous pig casting machines.
Practical Uses for Ductile Iron
Ductile Iron offers several advantages and practical uses:
- It’s easy to cast and machine ductile iron.
- Ductile iron is a lot cheaper to make than steel.
- Ductile iron has superior castability and machinability.
- The strength to weight ratio of ductile iron is considered to be excellent.
- Ductile iron provides an unbeatable combination of reliability, toughness, and low-cost manufacturing.
- Ductile iron aka nodular cast iron is suitable for large and complex shapes.
What are the Best Uses for Ductile Iron?
Because ductile iron has greater strength and ductility then gray iron, it can be used effectively in a wide variety of industrial applications. Some of the best uses for the durable, flexible, and cost-effective ductile are included:
- Water and sewer lines. Ductile iron competes with PVC pipe and the like because the polymeric materials of that nature, though lighter than steel or ductile iron, are softer and weaker and require more protection from physical damage.
- Automotive components
- Pump housings
- Machine frames for the wind-power industry
- Off-highway diesel trucks
- Class 8 trucks
- Agricultural tractors
- Oil well pumps
When seeking to create something with ductile iron, reach out to a reliable foundry. Faircast Inc. is here for all your casting needs. We are experts in understanding the practical uses for casting ductile iron and will have one of our engineers meet with you to discuss your project at length.