Heat Resistant Steel Castings

Castings are classified as heat resistant cast alloys if they are capable of continuous operation when subjected continuously or intermittently to operating temperatures that result in metal temperatures in excess of 650°C (1200°F). Cast steels for such service include iron-chromium (straight chromium), iron-chromium-nickel and iron-nickel-chromium alloys.

Considerations in the application of heat resistant cast alloys include:

• Strong resistance to corrosion at high temperatures
• Stability (resistance to deformation, cracking or thermal fatigue)
• Creep strength (resistance to plastic flow)

The structures of chromium-nickel and nickel-chromium cast steels must be fully austenitic or highly austenitic with some ferrite if these alloys are to be used for heat-resistant service.?

Depending on the chromium and nickel content, the structures of these iron-base alloys can be austenitic (stable), ferritic (stable, but also soft, weak and ductile) or martensitic (unstable). Therefore, the chromium and nickel levels should be selected to achieve good strength at elevated temperatures combined with resistance to carburization and hot gas.

A fine dispersion of carbides or intermetallic compounds in an austenitic matrix significantly increases the high temperature strength.

Heat Resistant Steels Casting Applications:

Heat resistant castings alloys are used in metalworking furnaces, gas turbines, aircraft engines, military equipment, oil refinery furnaces, cement mill equipment, petrochemical furnaces, power plant equipment, steel mill equipment.