Metals

There are three different types of metals:

1. Ferrous

2. Non - ferrous

3. Alloys

Ferrous Metals

• These contain iron and are magnetic
• They are created in a Blast Furnance with iron ore, limstone and coke

Examples:

• cast iron
• mild steel
• high carbon steel

General properties of ferrous metals:

they conduct electricity, they are strong, they are tough

Non - Ferrous Metals

• they don't contain iron
• they don't conduct electricity

Examples:

• aluminium
• zinc
• copper
• lead

Non - Ferrous Metals

• they don't contain iron
• they don't conduct electricity

Examples:

• aluminium
• zinc
• copper
• lead

Alloys are a mixture of two or more materials to change/enhance their properties

Benefits of alloying:

• change the melting point
• change the colour/ apperance
• change the conductivity

Examples of alloys:

• stainless steel: corrosion resistant, high impact resistance, good strength to weight ratio, attractive appearance
• brass
• bronze

The metallic structure is a crystalline and work hardening allows the structure to be changed and affects the properties

1. Annealing - heating the metal then allowing it to cool slowly to reduce internal stresses and allowing it to become softer and more ductile

2. Hardening - heating the metal then quenching it (rapid cooling) so that it hardens and becomes brittle

3. Tempering - this is usually a common follow up to Hardening when the metal is brittle. The metal is heated then allowed to cool slowly so that the toughness increases but the hardeness is reduced

4. Normalising: the metal is heated and cooled so that the crystals are uniform and the same size

5. Carburising: the metal is 'baked' in a carbon - rich compound to allow it to be strong on the outside without affecting the inside