Metals

Question 1

White Cast iron
Carbon Content: 1.7-2.9%
Properties: brittle, very hard, cannot be machined
Uses: heavy machinery

Grey Cast:
Carbon Content: 2.5-4.0%
Properties: can be machined, easily cast, corrosion resistant
Uses: Cookware, disk brakes, machine components

Difficult to weld
High thermal conductivity

Answer 1

Mild steel:
Carbon Content: 0.15-0.30%
Properties: ductile, strength, malleable, High tensile strength.
Uses: General engineering, nuts and bolts

Medium carbon steel:
Carbon content: 0.30-0.70%
Properties: harder than mild steel but less ductile and malleable
Uses: Garden tools, springs

High Carbon steel:
Carbon Content: 0.70-1.40%
Properties: improved by heat treating
Uses: hammer heads, drills, cutting tools

Stop rusting by painting or galvanisation

Question 2

Aluminium
Melting point:650 degrees
Properties: lightweight, corrosion resistant, good conductor
Disadvantages: cracks under stress, constant annealing
Uses: aircraft, engine components, castings

Copper
Melting point: 1100 degrees
Properties: conductor of heat and electricity, corrosion resistant
Disadvantages: danger of electrolysis, needs annealing whilst working
Uses: electrical cables, central heating, printed circuits

Zinc 
Melting point: 420 degrees 
Properties: corrosion resistant 
Disadvantages: brittle when worked 
Uses: castings, batteries, galvanising

Answer 2

Stainless steel: 
Composition: chromium, steel nickel 
Advantages: corrosion resistant 
Disadvantages: expensive, hard to cut 
Applications:kitchen utensils, medical tools chemical and nuclear industries 

Duralumin
Composition: aluminium, copper, manganese
Advantages: lightweight, strong
Disadvantages: work hardens
Applications: aviation industry, automobiles

Brass
Composition: copper, zinc
Advantages: casts well, easy to machine, conductor of heat and electricity
Disadvantages: cracks when cold worked, constant annealing
Applications: central heating valves, electrical components, ships propellers, plumbing fittings

Question 3

Plasticity- ability of material returning to original shape after deforming force is removed

Ductility- ability of material to be drawn/stretched

Hardness- ability of material to withstand indentation, abrasion or scratching

Brittleness- tendency for a material to fracture

Malleability- deforming a metal by compression without tearing or cracking

Answer 3

Aesthetic properties- sensory qualities of a material

Functional properties- qualities of a material must possess in order to be fit for purpose

Mechanical properties- a materials reaction to physical forces

Question 4

Hack saw:

Teeth per 25mm: 25

Uses: General purpose metal saw

Notes: blade held in frame, kept in tension, teeth point away from handle, dusted through 90 degrees.

Junior Hack saw:

Teeth per 25mm: 32

Uses: small general purpose saw, used on most metals.

Notes: straight cuts on small pieces of work, held in tension by strung steel frame

Answer 4

Rip Saw:

Points per 25mm: 5

Length: 700mm

Uses: sawing along grain of large wood

Cross cut saw:

Points per 25mm: 7

Length: 600mm

Uses: sawing across grain of large timber

Tenon saw:

Points per 25mm: 14

Length: 250mm-350mm

Uses: Making joints and work on small wood