Mild steel falls into which carbon content range?

• A. 0.15-0.30%
• B. 0.05-0.30%
• C. 0.30-0.45%
• D. 0.75-1.50%

Answer: (A)

Low carbon content defines mild steel, giving it excellent ductility and good weldability. In practice, mild steel is typically considered to contain about 0.05% to 0.30% carbon.

The range 0.15–0.30% falls right inside that mild-steel band, representing common grades used in welding practice. This level of carbon keeps the steel easy to form and weld while still providing enough strength for general structural uses, which is why this range is a standard teaching example.

Raising carbon into the 0.30–0.45% range moves into medium-carbon steel—stronger but less ductile and harder to weld. Very high carbon levels, like 0.75–1.50%, are high-carbon steels that are much harder and more brittle, not the typical choice when we talk about mild steel.