DT10: Ferrous and Non-Ferrous Metals

Ferrous and Non-Ferrous Metals

Ferrous metals (mild steel, high-carbon steel, stainless steel, cast iron); non-ferrous (aluminium, copper, brass, zinc, tin); alloys, properties and applications.

📋 Key Vocabulary and Concepts

For Ferrous and Non-Ferrous Metals, you must know:

• Ferrous
• Non-ferrous
• Alloy
• Mild steel
• High-carbon steel
• Stainless steel
• Cast iron
• Aluminium
• Copper
• Brass
• Zinc
• Tin
• Corrosion
• Galvanising
• Anodising
• Tempering

❓ Practice Questions

✅ Answers

1. Stainless steel has 10.5%+ chromium which forms a passive chromium oxide layer - self-healing, prevents rust even when scratched. Mild steel has no chromium and rusts rapidly.
2. Aluminium: density 2.7 g/cm3 vs steel 7.8 - 1/3 the weight, crucial for fuel efficiency; corrosion-resistant; good strength-to-weight when alloyed. Trade-off: more expensive and less stiff.
3. Brass: genuine gold appearance, naturally corrosion-resistant, heavy and tactile (premium feel), low friction, antimicrobial. Gold-anodised aluminium: lighter, cheaper, coating can scratch to reveal silver beneath. For a door handle: brass is superior.

🎯 Exam Tips

• Ferrous = contains iron (think ferrum = Latin for iron)
• Know that stainless steel is ferrous but does not rust - explain WHY (chromium oxide layer)
• State alloy composition: brass = copper + zinc, bronze = copper + tin

📝 Exam Technique

⚠️ Common Errors

✍️ Model Answer

📊 AO Deep Dive

📝 Exam Questions by Topic

• AQA Past Papers - Topic Questions -- AQA
• Edexcel Past Papers - Topic Questions -- Edexcel
• OCR Past Papers - Topic Questions -- OCR
• Eduqas Past Papers - Topic Questions -- Eduqas
• CCEA Past Papers - Topic Questions -- CCEA

🎬 Video Resources

• BBC Bitesize - Metals
• Metal Types and Properties (YouTube)

Detailed Notes

Ferrous Metals: Properties and Applications

Ferrous metals contain iron as their primary element, which gives them magnetic properties and makes them susceptible to rust (iron oxide formation) when exposed to moisture and oxygen. Mild steel (low carbon steel, 0.1-0.3% carbon) is the most widely used ferrous metal in UK manufacturing, valued for its excellent strength-to-cost ratio, weldability and machinability. High-carbon steel (0.6-1.5% carbon) is significantly harder and can be heat-treated to produce cutting tools and springs. Cast iron (2-4% carbon) has excellent compressive strength and vibration-damping properties, traditionally used for British engineering components like engine blocks and drain covers.

Stainless steel is a ferrous alloy containing a minimum of 10.5% chromium, which forms a self-healing passive oxide layer on the surface, providing corrosion resistance without the need for additional coatings. The most common grade, 304 austenitic stainless steel, is used extensively in UK food preparation, medical equipment and architectural applications. British Steel, though facing commercial challenges, remains part of the UK's industrial heritage, and understanding the properties of ferrous metals is fundamental to any GCSE D&T response involving structural or mechanical design.

Non-Ferrous Metals and Alloys

Non-ferrous metals contain no iron, making them naturally corrosion-resistant and non-magnetic. Aluminium is the most significant non-ferrous metal in UK manufacturing, valued for its low density (approximately one-third that of steel), excellent corrosion resistance (due to a natural aluminium oxide layer), and high thermal and electrical conductivity. Alloying aluminium with elements such as copper, magnesium and silicon significantly increases its strength. The 6061 and 7075 aluminium alloys are widely used in UK aerospace and automotive engineering. Dyson uses die-cast aluminium in their vacuum cleaner components for its strength-to-weight ratio.

Copper has exceptional electrical and thermal conductivity, making it essential for UK wiring regulations and plumbing systems. Brass (copper-zinc alloy) offers good machinability and an attractive gold appearance, used for decorative hardware and musical instruments. Bronze (copper-tin alloy) is harder and more wear-resistant than brass, historically significant in British manufacturing and still used for marine fittings and bearings. Titanium, though expensive, offers the highest strength-to-weight ratio of any structural metal and is used in UK aerospace and medical implant manufacturing by companies like Sheffield Forgemasters.

Metal Sustainability and UK Manufacturing Context

Metals are amongst the most recycled materials globally. Steel and aluminium can be recycled indefinitely without loss of properties, making them inherently sustainable when recycled content is specified. The UK recycles over 90% of its steel scrap, with electric arc furnace (EAF) technology allowing production from 100% recycled material. British Steel's Scunthorpe works and Tata Steel's Port Talbot plant are central to UK steel production, though both face decarbonisation challenges as the UK moves towards net-zero by 2050.

Aluminium recycling requires only 5% of the energy needed for primary production from bauxite ore, making recycled aluminium significantly more sustainable. In the UK, Novelis operates Europe's largest aluminium recycling facility in Warrington, processing over 400,000 tonnes annually. GCSE students should reference recycled metal content in NEA portfolios and understand the energy implications of primary versus recycled metal production. The shift towards hydrogen-based steelmaking in the UK represents a major industrial transition that demonstrates how new technologies address environmental challenges in traditional manufacturing.

Comparison

Metal Properties Comparison

Extended Practice