Composition:
Cast Iron: Contains a higher carbon content, typically between 2% to 4%. It also has more silicon and other impurities.
Steel: Has a lower carbon content, usually less than 2%, and fewer impurities, which allows for greater flexibility in alloying elements.
Structure:
Cast Iron: The higher carbon content causes carbon to exist mainly as graphite flakes or nodules, making it more brittle.
Steel: Carbon is mostly dissolved in iron, forming a more uniform and ductile structure, giving steel better toughness and flexibility.
Mechanical Properties:
Cast Iron: Hard, brittle, and strong in compression but weak in tension. It’s excellent for wear resistance and damping vibrations.
Steel: More ductile, malleable, and tougher, which makes it stronger under tension and impact.
Manufacturing Process:
Cast Iron: Typically produced by melting iron and casting it into molds, making it suitable for complex shapes but harder to weld or work.
Steel: Can be forged, rolled, and welded more easily due to its ductility, and is often heat-treated to enhance properties.
Applications:
Cast Iron: Used in engine blocks, pipes, cookware, and heavy machinery parts where compressive strength and wear resistance are needed.
Steel: Preferred for construction, automotive frames, tools, and structural components where toughness and flexibility are critical.
Cost:
Cast Iron: Generally cheaper to produce because of the simpler alloying and casting process.
Steel: More expensive due to the additional refining and alloying steps but offers better performance in many applications.