Which metal contains a low carbon content?

• A. High-carbon steel
• B. Cast iron
• C. Stainless steel
• D. Mild steel

Answer: (D)

In steel, carbon content largely dictates how the metal behaves: low carbon makes it soft, ductile, and easy to form or weld, while higher carbon increases hardness and strength but reduces ductility. The metal with the lowest carbon content is mild steel, which typically contains about 0.05% to 0.25% carbon. That combination gives good formability for sheet metal work and general fabrication.

High-carbon steel has substantially more carbon, making it hard but more brittle and harder to work with. Cast iron contains a lot more carbon (often around 2% or more) and tends to be brittle due to its graphite structure. Stainless steel is an alloy with chromium and other elements to resist corrosion; its carbon content varies by grade and isn’t defined by being low-carbon in the same way as mild steel.