Metals and alloys

The following page of notes will cover:

• Ferrous Metals
• Non-ferrous Metals
• Alloys

Using these general rules will help you answer most questions relating to Ferrous Metals:

• As carbon content is increased, ferrous metals become more brittle and harder
• Ferrous metals contain iron which makes them magnetic
• Ferrous metals are prone to rust and corrosion due to the iron within the metals
• Ferrous metals tend to be used in construction and as tools due to their good mechanical properties

Low Carbon Steel (0.05% - 0.25% carbon content):

Advantages	Disadvantages
High ductility and toughness Good weldability and formability Relatively low cost Easily machinable	Lower strength compared to higher carbon steels Poor wear resistance Cannot be heat treated to increase hardness

Uses: Car body panels, Structural beams, Wire, Nails, Pipelines

Cast Iron (2.0% - 4.0% carbon content):

Advantages	Disadvantages
Good casting properties High machinability Good wear resistance Corrosion resistant	Very heavy Brittle Low tensile strength

Uses: Machinery, Cooking pots, Disk brakes, Pipes

High Carbon/tool steel (0.60% - 1.0% carbon content):

Advantages	Disadvantages
Extremely hard/strong Cheap in comparison to other hard materials	Brittle due to high carbon content Expensive Difficult to form/cut/weld

Uses: Drills, Expensive, Knives

Using these general rules will help you answer most questions relating to Non-ferrous Metals:

• Non-ferrous metals are more corrosion resistant than ferrous metals
• Non-ferrous metals tend to be more expensive than ferrous metals due to their rarity
• Non-ferrous metals tend to be lighter than ferrous metals

Aluminium:

Advantages	Disadvantages
Lightweight Corrosion resistant Good conductor of electricity Malleable	Cracks under stress Needs annealing when worked Does not withstand great loads

Uses: Aircraft, Engine parts, Utensils, Tins

Copper:

Advantages	Disadvantages
Good heat and electrical conductor Ductile Malleable Soft	Needs annealing when worked Danger of electrolysis when in contact with water Corrodes easily Expensive

Uses: Electrical cables, Circuits, Generators, Heating

Tin:

Advantages	Disadvantages
Malleable Ductile Corrosion resistant	Hard to recycle Not very strong

Uses: Furniture, Construction, Exterior furniture, Veneers

Zinc:

Advantages	Disadvantages
Corrosion resistant Self-healing Recyclable Durable	Low toughness Brittle when worked May corrode when in contact with water/moisture for a long time

Uses: Roofing, Castings, Batteries

Brass (Copper, Zinc):

Advantages	Disadvantages
Casts well Easy to machine Good conductor of heat and electricity Low friction coefficent	Susceptible to cracking when cold worked Needs to be constantly annealed Not very corrosion resistant

Uses: Ship propellers, Electrical components, Locks, Gears

Stainless Steel (Chromium, Nickel, Steel):

Advantages	Disadvantages
Corrosion resistant Heat resistant Can be recycled Good strength to weight ratio Hygenic/non-toxic	Expensive Hard to machine

Uses: Kitchen utensils, Medical tools, Construction

High Speed Steel (HSS) (Tungsten, Molybdenum, Chromium, Vanadium, Cobalt):

Advantages	Disadvantages
Excellent hardness at high temperatures High wear resistance Good toughness and strength Maintains cutting ability at high speeds	More expensive than carbon steels Difficult to machine and shape Requires specialized heat treatment

Uses: Drill bits, Milling cutters, Lathe tools, Saw blades, Router bits

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