Material Knowledge Cast Iron
A family of ferrous alloys consisting of iron, carbon and silicon
The term cast iron refers to a family of ferrous alloys consisting of iron, carbon (containing 2.1 to approx. 4.5%) and silicon (up to 3.5%).
The addition of carbon lowers the melting point of the metal and makes it more fluid, giving it excellent casting properties and enabling the production of parts with complex shapes at low cost.
When carbon is present in the form of graphite in cast iron, it is referred to as grey cast iron, which is the type predominantly used in machining.
More Information About Cast Materials
It is typical to distinguish between grey cast iron with a grey appearance after fracturing and white cast iron with a white appearance after fracturing.
Because of its excellent casting properties, white cast iron is often used for the production of substantial objects (radiators, stoves, anvils, etc.) or large decorative items.
Grey cast iron is used mainly in machining because of its easy machining characteristics and lower production costs compared to other cast iron alloys.
Contrary to popular belief, cast iron is not heavier than steel — in fact, it has a slightly lower density.
Overview
Definition Cast Iron
Gusseisen sind Eisen-Kohlenstoff-Legierungen mit einem Kohlenstoffgehalt von mehr als 2% und weiteren Legierungsbestandteilen, wie Silizium. Gusseisen werden als Roheisen, Kreislaufmaterialien oder Recyclingmaterialien in Kupolöfen oder Elektroöfen geschmolzen und vergossen. Zur Gruppe des grauen Gusseisens gehört das Gusseisen mit Lamellengraphit und das Gusseisen mit Kugelgraphit.
Am häufigsten wird in der Industrie Gusseisen mit Lamellengraphit, auch GJL genannt, eingesetzt. Bei diesem liegt der freie Kohlenstoff im Wesentlichen in lamellarer Form vor. Gusseisen mit Lamellengraphit wird auch als Grauguss bezeichnet.
Beim Gusseisen mit Kugelgraphit (auch GJS) ist der Graphit in der metallischen Grundmasse in Form von Kugeln eingebettet. Die kugelige Form verhindert die an den Graphitlamellen auftretenden Spannungsspitzen.
Corrosion resistant
Wear resistant
Good casting properties
Good thermal conductivity
Good machinability
Vibration absorbing
Temperature resistant
Good shape rigidity
The special properties of cast iron are responsible for its continued use in a wide range of applications.
Corrosion Resistance – Why is Cast Iron Corrosion Resistant?
Cast iron parts with an undamaged cast skin have good corrosion resistance, which can be further increased by adding silicon, chromium and nickel or by painting or coating in some other way.
Wear Resistance – Why is Cast Iron Wear Resistant?
The lamellae form a three-dimensional structure in the cast iron and, although this leads to very low ductility, it provides an extremely high resistance to wear.
Classification of Cast Iron
| Classification | Overview | Product example |
|---|---|---|
| CAST IRON WITH LAMELLAR GRAPHITE | EN-GJL-200 | |
| EN-GJL-250 | ||
| EN-GJL-300 | ||
| GCAST IRON WITH SPHEROIDAL GRAPHITE | EN-GJS-400 |
Application fields for Cast Iron
Grey cast iron has excellent casting properties and is highly economical. These positive properties contribute to the use of cast iron in many industries. In addition to classic fixture construction, cast iron is used in the automotive sector and in the manufacture of complex geometries. The properties that enable use in respective application areas are explained behind the individual headings.
Cast Iron in fixture construction
The principal properties required for machining using cast iron are:
High vibration damping capacity
High corrosion resistance
Noise absorption
High rigidity
These properties make grey cast iron the ideal material to use for basic elements in fixture construction.
The norelem basic elements:
Cast Iron in the automobile industry
Cast iron finds many uses in industry due to its simple and inexpensive production. About half of the cast iron produced is processed in the automotive industry, such as in crankshafts, camshafts, suspension struts, brake callipers or wheel hubs.
Cast iron components are well established in the automotive industry due to their outstanding capabilities. The exceptional vibration damping properties and very good dimensional stability have an additional positive effect for use in the automotive industry.
Cast Iron for components with complex Geometries
Due to its casting properties, cast iron is ideally suited for the production of components with very complex geometries; from filigree thin-walled components to complex components weighing several tonnes. Highly complex geometries with particularly resistant materials can be produced with very high processing stability.
In addition to its versatile forming and excellent mechanical properties, the material is completely recyclable.