Non Ferrous Flashcards
What is the most widely used non ferrous material used in aircraft
Titanium
Advantages of Titanium
High strength to weight ratio
Temperature resistance
Corrosion resistance
Disadvantages of titanium
Horrible to work with
Flammable
When exposed at high temperatures in the presence of oxygen or nitrogen it will ignite
Pure Aluminium
Extremely malleable - to soft for aircraft use
Alloyed with other metals to increase strength
Excellent corrosion resistance
Very lightweight
Cast aluminium
Cast aluminium has a grain structure that is very coarse, thus the metal is brittle. Cast aluminium is used in construction of aircraft wheels and engine crankcases.
Wrought aluminium
Wrought, its grain structure is compressed and tightened as it is forced into shapes of plates, rods, extrusions or skins. Wrought aluminium (used extensively in aircraft construction) is either non-heat- treated or heat-treated.
Identification of Aluminium
Four digit number
1st digit - major alloying element
2nd digit - Alloy modification
Last two digits - different alloys in the group
Clad
A layer of pure aluminium with 1% zinc as a means of corrosion protection
3-5% thickness of the material
Ink print corresponds to material grain structure
1100 Pure aluminium
Commercially pure Soft Ductile Good workability Corrosion resistance NON HEAT TREATABLE
3003 Manganese aluminium
Most widely used
In trades strength up to 20%
Good corrosion resistance and workability
NON HEAT TREATABLE
5052 Magnesium aluminium
Most common High strength Good fatigue strength Good workability NON HEAT TREATABLE
2011 Copper aluminium
Most free-machining
Corrosion resistance
Good strength and hardness
HEAT TREATABLE
2017 Aluminium
Good machinablity High strength Tough Ductile HEAT TREATABLE
2024 Aluminium
Best known High strength Excellent fatigue resistance Low corrosion resistance Usually anodised finish or in clad form
7075 Zinc aluminium
High strength - density ratio
Non-weldable
Poor corrosion resistance
Normally clad
Annealing
Heat the alloy to the required temperature
Hold/soak for a length of time
Cool steadily in cool air
Solution
Alloy is heated in either molten sodium or potassium nitrate
Temperature is held to within plus or minus 50°C, long enough for the copper to be taken into the solid solution with the aluminium matrix
Cooled within 10 seconds else inter granular corrosion will occur.
Cold working
Will cause the copper to precipitate at grain boundaries and harden the alloy.
Natural ageing
Copper penetrates grain boundaries hardening the aluminium over several days
Artificial ageing
Temperature is raised to between 1200C and 1900C, depending on alloying element, this increases the precipitation hardening process and also raises the final strength of the alloy
Code T4
Heat treated, naturally aged
Code T3
Heat treated, cold worked
Code T6
Heat treated, artificially aged
Basic temper states
F = Fabricated O = Annealed H = Strain hardened W = Solution heat treated T = Heat treated to produce stable tempers
Magnesium alloys
Lighter than aluminium Hard to work with Easily corrodes Highly flammable Difficult to work with
Identification of Magnesium alloys
American Society for Testing Materials (ASTM) is the most widely used. The first two letters indicate the principal alloying elements. The letter corresponding to the element present in the greatest quantity is used first; if they are equal, they are listed alphabetically. The letters are followed by numbers which represent the nominal compositions of the principal alloying elements in weight (%) rounded to the nearest whole number .
Glass Reinforced Laminate
Member of the fibre metal laminates family Consists of aluminium and glass fibres Fatigue resistance Flame resistance Corrosion resistance
