Simple Stress and Strain MCQ with answer and solution

Concept

Carbon content of structural mild steel

Formula

NONE

Step-by-step solution

1. Carbon steel is categorized according to its carbon percentage by weight. 2. Low carbon steel (mild steel) contains between 0.05% and 0.25% carbon, which provides balanced ductility and tensile strength. 3. Medium carbon steel contains 0.3% to 0.6% carbon, while high carbon steel contains 0.6% to 1.4% carbon. 4. Thus, mild steel typically contains 0.05-0.25% carbon. Answer: A

Explanation

Mild steel is classified as low-carbon steel containing approximately 0.05% to 0.25% carbon by weight. This specific carbon concentration ensures high ductility, good formability, and reliable weldability for structural framing. Higher carbon fractions significantly increase hardness but reduce ductility and toughness.

Why the other options are wrong

B) 0.3-0.6% carbon defines medium carbon steel used for forged shafts and axles. C) 0.6-1.0% carbon defines high carbon steel used for springs and cutting tools. D) >1.5% carbon characterizes cast iron alloys.

Shortcut

Mild steel ≤ 0.25% carbon; Medium = 0.3-0.6%; High = 0.6-1.0%.

Common mistake

Confusing structural mild steel with medium carbon steel used in railway rails and machinery.