Properties and uses of different kinds of steel
5 marks · HardThree types of steel are shown below.
Describe the composition and one key property of mild steel.
Explain how the composition of high-carbon steel makes it different from mild steel in terms of its properties.
Identify the two main elements added to iron to make stainless steel and state why stainless steel does not rust easily.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Mild steel is iron with up to 0.25% carbon. It is malleable (or ductile, strong).
(b) High-carbon steel has more carbon, leading to it being harder but more brittle and less malleable than mild steel.
(c) Chromium and nickel; Chromium forms a protective oxide layer so stainless steel does not rust easily.
Common mistakes: Confusing which steel contains chromium and nickel; Stating ‘strong’ for all steels without comparison
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies composition of mild steel (iron with up to 0.25% carbon).
B2 (a) · 1 mark · States one property of mild steel (e.g., malleable/ductile/strong).
B3 (b) · 1 mark · Relates higher carbon content in high-carbon steel compared to mild steel.
B4 (b) · 1 mark · Explains resulting property (harder, more brittle, less malleable) of high-carbon steel.
B5 (c) · 1 mark · Identifies both chromium and nickel (or just chromium) and explains stainless steel’s resistance to rust, e.g., due to oxide layer.
Worked solution
(a) Mild steel is an alloy of iron with up to about 0.25% carbon. It is malleable and can be easily shaped.
(b) High-carbon steel has a higher percentage of carbon (about 0.6–1.2%) than mild steel. This makes it harder and stronger, but also more brittle and less malleable.
(c) Stainless steel is made by adding chromium (and often nickel) to iron. The chromium forms a protective oxide layer, which stops the steel from rusting easily.