Cast Iron vs Cast Steel
May 26, 2025
What’s the difference between cast iron and cast steel?
Composition
Cast Iron: Contains a high amount of carbon, usually between 2% and 4%. It also includes silicon (1–3%) and small amounts of manganese. The carbon in cast iron can appear in different forms—either as graphite flakes (gray iron), spheres (ductile or nodular iron), or in a malleable form after heat treatment.
Cast Steel: Has a lower carbon content, typically below 2%. It may include alloying elements like chromium, nickel, molybdenum, or vanadium to improve specific properties. This allows for more control over strength, toughness, and resistance to wear or corrosion.
Mechanical Properties
Cast Iron
1. Brittle and less ductile due to its high carbon content.
2. Excellent compressive strength but poor tensile strength.
3. Good wear resistance and damping capacity, making it ideal for reducing vibration.
4. Lower melting point and better fluidity during casting, which makes it easier to produce complex shapes.
Cast Steel
1. Stronger and tougher than cast iron.
2. Higher tensile and impact strength, making it suitable for heavy-duty applications.
3. Better weldability and machinability compared to cast iron.
4. Can be heat-treated to achieve desired hardness or toughness.
Manufacturing Process
Cast Iron: Easier to melt and pour due to better fluidity. Requires simpler molds and lower pouring temperatures. Suitable for mass production of detailed parts.
Cast Steel: More difficult to cast because of higher melting temperature and lower fluidity. Requires more precise mold design and better foundry techniques.
Common Applications
Cast Iron
1. Engine blocks and cylinder heads.
2. Pipe fittings and valves.
3. Machine tool bases and frames.
4. Cookware (e.g., cast iron pans).
5. Brake rotors and other wear-resistant components.
Cast Steel
1. Structural parts for bridges and buildings.
2. Railway components, such as wheels and frames.
3. Mining and construction equipment.
4. Marine and offshore structures.
5. Parts that need high strength and impact resistance.
Summary
Choose cast iron when you need good wear resistance, vibration damping, and cost-effective casting of complex parts. Use cast steel when your application demands high strength, toughness, and the ability to handle dynamic loads or extreme temperatures.
Both materials have their strengths and are selected based on performance needs, cost, and manufacturing capabilities.