6.2 Non Ferrous Flashcards
Why is titanium used in the aircraft industry
High strength, light weight, temperature resistance and corrosion resistance
Weight is approx 56% that of steel but strength is the same
What components would be manufactured out of titanium
Cooler sections of gas turbine engines, cowlings and baffles around engines and skin parts which are susceptible to higher temperatures
What rules must the operator follow when machining titanium
- Use low cutting speeds
- High feed rates
- Plenty of cutting fluid
- Always use sharp tools
- Never stop feeding while tools are still moving
What must always be on standby when machining titanium
A fire extinguisher as the dust can catch fire and titanium doesn’t dissipate heat well
What two precautions must be observed when working with titanium
- At about 1950°f titanium will ignite in the presence of oxygen and burn with an incandescent flame
- its affinity for nitrogen is even more pronounced because it will ignite at around 1500°f
Why are the characteristics of 99% pure cast aluminium
- Highly corrosion resistant (due to non porous oxide coating that forms on its outer layer)
- Extremely mailable
- Light weight
Is cast aluminium suitable for use on aircraft
Not really it is too mailable
Has much better properties when alloyed with other metals
However it is used for aircraft wheels and crank cases
How is wrought or cast aluminium identified
By a 4 digit number (AA number)
Aluminium Association of America
Which aluminium are most susceptible to corrosion
2024 and 7075
How are aluminiums susceptible to corrosion protected
They are clad with pure aluminium with 1% zinc on both sides
What is the thickness of the protection cladding layers placed on aluminium for surface protection
3-5% of the materials thickness
When informations or specifications are printed on aluminium what does this also correspond to
It is printed in the same direction as the grain structure
What is work hardening
Also known as strain hardening or cold working. Strengthening metal by plastic deformation
Suitable for Pure aluminium, copper, low carbon steels
What is annealing
Heating an alloy to an elevated temperature, soaking them at this temperature and cooled slowly in still air or switched off furnace
What is solution heat treatment
Aluminium alloys are heated in either molten sodium or potassium nitrate bath or hot air furnace
Once the metal has been soaked sufficiently it is removed and quenched (no more than 10 seconds can elapse between taking out of the furnace and quenching)
After a metal has been solution heat treated how are they then hardened
- Cold working
- Natural age hardening
- Artificial ageing or precipitation hardening
What is natural age hardening
Will occur at room temperature, copper precipitates the grain boundaries and hardens over course of a few days
What is artificial ageing or precipitation hardening
Temperature is raised to between 120°c and 190°c depending on alloying element
Raises final strength of the alloy
How can age hardening be slowed down
By freezing the alloy immediately after the quenching process has occurred
What are the most common heat treatable alloys which are naturally age hardened
2117, 2017 and 2024
How many times can a clad material be eat treated
Normally 3
What are the basic temper designations
F,O,H,W,T
F - As fabricated
O - Annealed
H - Strain hardened (non heat treatable products only)
W - Solution heat treated
T - Heat treated to produce stable tempers other than F,O or H
Hat is T3, T4 and T6
T3 - solution heat treated and cold worked
T4 - solution heat treated and naturally aged
T6 - solution heat treated and artificially aged
What is H1, H2, H3
H1 - Strain hardened with out thermal treatment
H2 - Strain hardened and partially annealed
H3 - Strain hardened and Stabilised by low temperature heating
What are HX2, HX4, HX6, HX8, HX9
HX2 - 1/4 hard HX4 - 1/2 hard HX6 - 3/4 hard HX8 - full hard HX9 - extra hard
What are the disadvantages of magnesium
- Highly susceptible to corrosion
- Difficult to work with
- Highly flammable
What are the advantages of magnesium
- High strength to weight ratio
- Non magnetic which makes it ideal for manufacturing instrument casings
What must be done to pure magnesium to make it suitable for the construction of aircraft parts
Must be alloyed with other elements
How can magnesium alloys be heat treated
- Solution heat treated
- Precipitation hardening
- Annealing
What is GLARE
Glass Reinforced Laminate
What does GLARE consist of
Alternating layers of aluminium and glass fibre prepreg layers
What is the autoclave curing cycle
The process of how a laminate is made
How many grades of GLARE have been developed
6
What is the thickness of aluminium used in GLARE
0.2-0.5mm
What is the meaning of Glare 4b-4/3-0.4
- A glare laminate with fibre orientation according to the Glare 4B definition in the glare table
- 4 layers of aluminium and 3 fibreglass layers
- An aluminium layer thickness of 0.4mm
What are the properties of glare
- High strength
- Fatigue resistant
- Damage tolerant
- Impact and blast resistant
- Fire resistant
- Thermal isolation
Where would glare be used
- Fuselage skin material
- The leading edges of wings
- Specialised blast resistant containers
- Cargo floors and liners
