What are the main types of metal, and how do their properties decide their uses?
Identify the main types of metal (ferrous, non-ferrous and alloys) and describe their properties and uses
A clear answer to the N(A)-Level D&T outcome on metals. The difference between ferrous, non-ferrous metals and alloys, key properties such as strength and corrosion resistance, and how properties decide their uses.
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What this dot point is asking
SEAB wants you to know the main types of metal, which are ferrous metals, non-ferrous metals and alloys, and to describe their properties and uses. As with all materials, the key idea is that properties decide uses: a metal is chosen because its strength, weight or corrosion resistance suits the job.
The answer
The three groups of metal
- Ferrous metals contain iron. They are usually strong and often magnetic, but most will rust unless protected. Example: mild steel, used for car bodies and frames.
- Non-ferrous metals contain no iron. They do not rust in the same way and are often lighter or better conductors. Example: aluminium, used where lightness matters; copper, used for wiring and pipes.
- Alloys are mixtures of two or more metals, or a metal with another element, made to improve properties. Example: stainless steel (iron with chromium) resists rust; brass (copper with zinc) is hard and looks attractive.
A simple test for ferrous metal is a magnet: most ferrous metals are magnetic, most non-ferrous metals are not.
Properties of metals
Useful properties to know:
- Strength. Carries large loads without breaking, so metals suit frames and structures.
- Hardness. Resists scratching and wear, useful for tools and edges.
- Malleability. Can be hammered or pressed into shape without cracking.
- Ductility. Can be drawn into wire.
- Corrosion resistance. Resists rust or tarnish; vital outdoors.
- Conductivity. Conducts heat and electricity, key for wiring and cookware.
Why alloys exist
A pure metal may be too soft or rust too easily. Mixing it makes an alloy with better properties. Adding chromium to iron makes stainless steel that resists rust; mixing copper and zinc makes brass that is harder and more attractive than copper alone. Alloys let designers get exactly the properties a job needs.
Matching property to use
Aluminium's lightness suits drink cans and bike frames; copper's conductivity suits wiring; mild steel's strength and low cost suit hidden frames; stainless steel's corrosion resistance suits cutlery and outdoor rails. Always justify a metal choice by the property the job needs.
Examples in context
Example 1. A bicycle frame. Lightness and reasonable strength matter, so aluminium is often chosen over heavier mild steel, and it resists corrosion in the rain without rusting like untreated steel.
Example 2. Kitchen cutlery. Cutlery must resist rust and stains from food and washing, so stainless steel is used; its chromium content stops the rust that plain mild steel would suffer.
Try this
Q1. State whether each is ferrous, non-ferrous or an alloy: mild steel, aluminium, brass. [3 marks]
- Cue. Mild steel is ferrous, aluminium is non-ferrous, brass is an alloy.
Q2. Name the property that makes copper suitable for electrical wiring. [1 mark]
- Cue. Good electrical conductivity.
Q3. Explain why alloys such as stainless steel are made. [3 marks]
- Cue. A pure metal may be too soft or rust easily, so mixing it into an alloy improves properties, for example adding chromium to iron gives corrosion resistance.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original6 marksExplain the difference between a ferrous metal, a non-ferrous metal and an alloy. Give one example of each.Show worked answer →
A ferrous metal contains iron and is usually magnetic; it can rust unless protected. Example: mild steel.
A non-ferrous metal contains no iron, so it does not rust in the same way and is often lighter. Example: aluminium.
An alloy is a mixture of two or more metals (or a metal and another element) made to improve properties. Example: stainless steel (iron mixed with chromium) or brass (copper and zinc).
What markers reward: ferrous contains iron and can rust (often magnetic), non-ferrous contains no iron, and an alloy is a mixture made to improve properties, each with a correct example.
Original4 marksA designer is making an outdoor handrail and is deciding between mild steel and stainless steel. Explain which property makes stainless steel a better choice outdoors, even though it costs more.Show worked answer →
Stainless steel resists corrosion because it contains chromium, so it does not rust when exposed to rain like mild steel does. Outdoors, mild steel would rust and weaken or stain unless constantly protected, while stainless steel stays strong and looks clean with little maintenance. The extra cost is justified by the lower maintenance and longer life outdoors.
What markers reward: corrosion resistance as the key property, the contrast that mild steel rusts outdoors, and the trade-off that higher cost is worth it for durability and low maintenance.
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