6.2(a) Flashcards
What is meant by the hardness of a material?
Hardness is the ability of a material to resist penetration, wear and indentation.
Explain what is meant by the strength of a material?
Strength is a material’s ability to withstand force, or resist stress without breaking.
Explain the term ductility in reference to materials?
Ductility is a material’s ability to be drawn or stretched into thinner sections without breaking.
Ductile materials are favored for aircraft design as they are easily formed and have a resistance to failure.
What is meant by the elastic limit of material?
The elastic limit is the point at which permanent deformation occurs.
The stress at which a material will rupture in tension, compression or shear is?
Ultimate strength
One cubic centimetre of water weighs one gram, and is said to have a density of one. Aluminium has a density of 2.7, what will a cubic
centimetre of aluminium weigh?
2.7 grams
What classification of material is aluminium?
Non-ferrous?
What is the raw material from which aluminium is made?
Bauxite
What is the melting point of aluminium?
660 ^C
In wrought aluminium alloys what alloy is portrayed by the AA numbering system 2024?
HT?
2XXX = Copper
AA = Aluminium Association
Heat Treatable
In wrought aluminium alloys what alloy is portrayed by the AA numbering system 3003?
HT?
3XXX = Manganese
AA = Aluminium Association
Non Heat Treatable
In wrought aluminium alloys what alloy is portrayed by the AA numbering system 5056?
HT?
5XXX = Magnesium
AA = Aluminium Association
Non Heat Treatable
In wrought aluminium alloys what alloy is portrayed by the AA numbering system 7075?
HT?
7XXX = Zinc
AA = Aluminium Association
Heat Treatable
In wrought aluminium alloys what alloy is portrayed by the AA numbering system 1100?
Pure Aluminium (99% min purity)
AA = Aluminium Association
Non Heat Treatable
How can the strength of 2024 aluminium alloys be increased?
Can be heat treated.
For maximum strength the metal must be quenched immediately so it will have the smallest grain size possible. This will offer good protection against corrosion.
How can the strength of aluminium alloy 5056 be increased?
Non heat treatable aluminium alloys are hardened by alloying and strain hardening.
‘Cold worked’, ‘work hardened’ and ‘strain hardened’ refer to hardening processes such as rolling, drawing, bending or pressing.
5XXX = Magnesium
What do the following parts in a 2024 – T3 represent?
2024:
T3:
2024 = 2000 series which is Copper alloying element
T3: Solution heat treated and cold worked
How can the strength of pure aluminium be increased?
Non Heat treatment Aluminium Alloys: 1, 3 , 4 and 5XXX
Non heat treatable aluminium alloys are hardened by alloying and strain hardening
Explain the different steps of the heat treatment process of aluminium alloys?
The strength of certain aluminium alloys can be increased by a process of heat treatment.
Heated in furnace and soaked at a certain specified (high) temperature and then quenched in water
This is known as ‘Natural Aging’
It gains its hardness over a period of several days in a process of aging.
What is meant by the term precipitation heat treatment?
Precipitation heat treatment or Artificial Aging.
The process of solution heat treated or natural aging may be sped up or increased by returning the metal to the oven and heating to a temp lower than that used prev.
The component is then removed and allowed to cool in still air.
What do we mean when we talk about the soak period during heat treatment?
A Soak period is the length of time that a furnace must hold the specified temperature at in order to ensure uniform heating across the component.
Different alloys and indeed thicknesses will have different soak times
Give the following basic temper designations
F:
H:
W:
T:
F = As fabricated
H = Strain Hardened (Wrought Products only)
W = Solution Heat treated
T = Heat treated to produce stable tempers other than F, O or H.
Give the sub divisions of the H temper
H1:
H2:
H3:
H designates cannot be heat treated as must be strain hardened. ie 1, 3, 4 and 5XXX
H1: Strain hardened only
H2: Strain hardened, then partially annealed
H3: Strain hardened, then stabilized
Give the sub-divisions of the following T temper
T2:
T3
T4
T42
T6
T62
T2 = Annealed (Same as O)
T3: Solution heat treated and cold worked
T4: Solution heat treated and naturally aged
T42: Solution heat treated from O temper to demonstrate response to heat treatment by the user, and naturally aged to a substantially stable condition
T6: Solution heat treated and artificiall aged.
T62: Solution heat treated from ‘‘O’’ (annealed), ‘‘F’’ as fabricated temper to demonstrate response to heat treatment by the user, and artifically aged
What is meant by the term “cladding” of aluminium alloy?
Sheets of aluminium alloys are clad with a thin layer of pure aluminium on both sides as a means of corrosion protection.
Aluminium alloys are corrosive, pure aluminium is not.
Welded during rolling process.
The thickness of the clad layers is about 3 - 5 % of the material thickness.
What does the term “AlClad Sheet” mean?
An ink print on US sheet metal that reads Alclad, Clad or Alc indicates that the sheet is clad.
What is a major disadvantage of using magnesium as an aircraft material?
- Magnesium is highly susceptible to corrosion.
- It has a tendency to crack when it is subjected to vibration (Not good for aircraft …)
- Not easily worked at room temperature
- Under certain conditions, magnesium can ignite and burn; particularly magnesium dust and fine chips. A magnesium fire should be extinguished by smothering it with dry sand or a dry poweder extinguisher. It is a class D (Metallic fire
What is the principal value of monel as a material?
High Strength
High resistance to corrosion.
Low coefficient of expansion (exhaust apps)
Non-magnetic
In weight what is the difference between steel and aluminium?
Steel = 7.9 g/cm3
Aluminium = 2.7 g/cm3
5.2 diff
Name the advantages of aluminium compared to mild steel?
Low Density
Ease of fabrication and diversity of form
High strength to weight ratio
Good corrosion resistance
What percentage of purity is required to class aluminium as being pure?
99%
What does the term alloying mean?
An Alloy is a metal made by combining two or more elements, to give greater strength or resistance to corrosion.
What is one of the most outstanding properties of titanium?
High strength
Light weight
High strength to weight ratio
Excellent corrosion and temperature resistance
Why is titanium used in areas of the aircraft that generate high temperatures?
because of its high temperature resistance
What are the four most commonly used non-heat treatable aluminium alloys and what are their uses?
The four commonly used non heat-treatable aluminium alloys are 1100, 3003, 5052 and 5056.
1100 - low pressure tubing, rivets and reciprocating engine baffles.
3003 - construct wing tips and prop spinners.
5052 - low pressure tubing and storage tanks for hydraulic fluids, fuel, oil and other liquids.
5056 - rivet stock.
What is the special condition relating to ‘cladding’?
Clad material must not be solution heat treated more than 3 times.
What should all heat treatment of aircraft parts be done in accordance with?
All heat treatment of aircraft parts has to be done in accordance with the aircraft manfacture processing specifications.
How are Aluminium alloys classified?
XXXX
First digit = alloying element
Second digit = Modification of alloy
Third and fourth digits = purity of aluminium
What is the aluminium production flow chart?
What is an important caution in relation to Heat treated components and installation on aircraft?
