What are castings made of?
Castings have iron as their base material. At around 5% of the total, iron is one of the most abundant elements in the Earth’s crust. It is extracted via opencast and underground mining. Cast iron belongs to the group of iron-carbon alloys, but it can also contain silicon (for better castability) and alloying constituents of manganese, chromium or nickel. A distinction is made between grey cast iron (carbon in the form of graphite) and white cast iron (carbon in the form of carbide) and they can be identified by the corresponding colour when split open. In contrast to steel, cast iron is easy to cast but difficult to forge due to its high carbon content. The carbon makes the iron very hard and brittle with low plasticity. It is not as strong as cast steel, but the damping is higher and it has better resistance to corrosion than steel, particularly when the cast skin is intact.
Where are castings used?
Cast iron is processed in various different ways, from frying pans to machine tools. Around half of this particularly hard iron alloy is used in the automotive industry. It is cheap and easy to produce. Gas and water pipelines also take advantage of the beneficial properties of this iron alloy.
- Machine components (gearboxes and crankcases)
- Marine diesel engines
- Steam turbine housings
- Road construction (manhole covers)
- Pumps
- Valves
- Household (pans, cans, appliance parts)
Recycling castings
Cast iron is one of the original recycled products. Scrap iron parts have been melted down and re-processed for decades, thereby closing industrial material cycles.
