There are many types of carbon and alloy steels used for castings. The choice of which will depend greatly on the application.

Cast steels can be broken into five ge-neric groups, (Table 1), which depend on the carbon and alloy content.

Table 1 - General Alloying Content

Steels will also contain many different alloying elements within their chemical composition. Table 2 shows the various alloying elements and the effects that they have on the steel alloy. The more common elements are carbon, silicon (0.2%-2.5%), manganese (0.25% - 2.0%), and sulfur (max 0.05%).

Cast steels are often used when the im-pact properties or elongation of irons are insufficient for the application. Cast steels must also be specified if the part is to be welded. Cast steel alloys are formulated to exhibit certain material properties. This could range from enhancing mechanical properties like tensile strength and elongation, to improved machinability or hardenability.

A cast steel part is almost always heat treated after shakeout in order to get the required material properties for the part. Exceptions would include consumable wear castings. The mechanical properties that are achievable are greatly dependent on the alloy being heat treated.

The more common heat treat processes are:

Anneal – provides a soft low strength structure with maximum ductility
Normalize – provides a medium strength and hardness with improved ductility
Quench and Temper – Provides the maximum strength levels with good ductility and wear resistance.

Table 2 - Steel Alloying Elements

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