Plain-carbon steel classification by carbon percentage Steel containing up to 0.15% carbon is commonly designated as which category in engineering practice?

Introduction / Context:
Plain-carbon steels are categorized by carbon content because carbon controls achievable hardness, strength, weldability, and ductility. Very low-carbon steels are used when high formability and weldability are paramount.

Given Data / Assumptions:

• Carbon content up to 0.15%.
• Terminology reflects traditional engineering usage.
• Mechanical property expectations: high ductility, excellent cold formability, easy welding, low hardenability.

Concept / Approach:
“Dead mild steel” refers to very low-carbon steels (roughly C ≤ 0.15%). Such steels are soft and highly formable; they are widely used for deep drawing, sheet-metal work, and applications where toughness and weldability matter more than strength. “Mild steel” more broadly often covers 0.15–0.30% C; “medium carbon” typically 0.3–0.6% C; “high carbon” above ~0.6% C; tool steels are a separate category with alloying for hardness and wear resistance.

Step-by-Step Solution:
Match the given carbon level (≤ 0.15%) to standard nomenclature.Recognize that this range is labeled “dead mild steel”.Eliminate other categories that imply higher carbon contents.Therefore, choose “dead mild steel”.

Verification / Alternative check:
Materials handbooks and standards for low-carbon sheet and plate align this range with deep-drawing quality steels, often designated by grades emphasizing very low carbon and controlled impurities.

Why Other Options Are Wrong:
Generic “mild steel” is broader and may extend above 0.15% C; medium and high carbon steels exceed the stated limit; tool steels are alloyed for hardness and wear resistance, not appropriate at such low carbon.

Common Pitfalls:
Using “mild steel” and “dead mild steel” interchangeably; the former is a wider envelope, whereas the latter specifically indicates very low carbon content suited for severe forming.

Final Answer:
dead mild steel