Which material is used for car bodies and girders due to its ductility but is prone to rusting?

• A. Mild Steel
• B. High carbon steel
• C. Stainless steel
• D. Iron

Answer: (A)

Material choice for car bodies and girders hinges on ductility to form complex shapes and absorb impacts, and on corrosion tendency since these parts are exposed to the environment. Mild steel, with its low carbon content, is easily formed, welded, and shaped into panels and large structural members, giving the necessary ductility and workability. Its main drawback is rusting, which is why protective coatings or galvanizing are used; when properly protected, its cost-efficiency and forming performance make it ideal for these roles. Other options either lack ductility (high carbon steel), resist rust but cost more and are harder to form (stainless steel), or are brittle and also rust easily (iron), so they are less suitable for the combination required.