Metals

Ferrous Metals are needed to be treated if they are with any contact with any moisture, so they will not rust. Non - ferrous metals are more expensive and they are not magnetic unlike the ferrous metal so they do not rust.

Types of metals
the range of metals are available and can be categorise in either ferrous or non ferrous, but they can be further separated into alloys or non - alloys.

Ferrous metals

-Cast iron -
- Steels
- mild steel
-medium carbon steel
- high carbon steel

Non Ferrous metals
Aluminium
copper
lead
tin
zinc

Alloys
-Ferrous alloys
Stainless Steel
High speed steel
Die (tool) steel

-Non ferrous alloys
Brass
Bronze
Duralumin(s)

alloys and alloying
Alloying changes other characteristics of the material (e.g copper + zinc = brass Changing the colours of the metal to a yellow/gold making the material attractive to purchasers)
To obtain a better range of properties and characteristics two or more metals can be mixed together to produce an alloy.

Work hardening and heat treating metals
Work hardneing occurs when the material is 'cold worked' by , for e.g. bending or rolling or hammering or drawing.
Heat treatments are those processes of heating and cooling metals in a controlled way , in order to achieve a beneficial change in the properties of the material . The more common heat treatments are:

• Annealing
• Hardening
• Tempering
• normalising

Annealing - annealing is a heat treatment that reverses the internal stresses associated with work hardening.

Hardening - this heat treatment changes the way the carbon atoms within the steel affects the strength and hardness of the material.

Tempering - The heat treatment that follows the hardening of medium and high carbon steels.