Properties and uses of different kinds of steel
3 marks · NormalExplain, in terms of properties, why a railway company would choose to use high-carbon steel for making the rails but mild steel for the carriage bodies.
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Also accept: High-carbon steel is harder and more resistant to wear than mild steel, so rails will last longer under heavy loads. Mild steel is more malleable and easier to shape, making it suitable for the bodies, and can absorb impacts without breaking.
Common mistakes: Not distinguishing between hardness and malleability.; Mixing up which steel is used for which part.
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Marking points
M1 · 1 mark · Links the use of high-carbon steel for rails to its hardness/wear resistance.
M2 · 1 mark · Links the use of mild steel for carriage bodies to its malleability/ductility.
A1 · 1 mark · Provides a clear comparative explanation, e.g., high-carbon steel resists wear, mild steel is easier to shape or absorbs impacts.
Worked solution
High-carbon steel is chosen for rails because it is hard and wear-resistant, so it can withstand the constant friction and heavy loads. Mild steel is used for carriage bodies because it is more malleable and ductile, making it easier to shape and less likely to crack from impacts or vibrations.