5 - Aluminium Alloy

Question 1

What is al-alloy?

Answer 1

Alloys in which aluminium is the predominant metal

Question 2

What are some typical alloying elements?

Answer 2

Copper
Zinc
Manganese
Magnesium
Tin
Silicon

Question 3

What is the reason that composites are generally used instead of al-alloy?

Answer 3

Weight savings

Question 4

What is wrought al-alloy?

Answer 4

When the metal (cast ingot) is worked in solid form with the help of specific tools (rolling, forging, extrusion).

Question 5

What structures are wrought aluminium used for typically?

Answer 5

Primary

Question 6

What are rolled products (plate and sheet) typically used for, in what thickness?

Answer 6

Fuselage skin and stringers (<1-10mm)
Wing covers (25-50mm)
Bulkheads, spars (150mm)

Question 7

What are extrusions typically used for?

Answer 7

Stringers (J,Z,T, and other shapes)

Question 8

What are the benefits of forged al-alloy?

Answer 8

Good grain properties
Near net shapes, pretty much ready to go

Question 9

What are the wrought alloy designators (4 digits)

Answer 9

1 - alloy group/alloy addition
2 - modifications of orig al
3/4 - other alloying elements

Question 10

What are the cast alloy designators?

Answer 10

1 - major alloying element
2/3 - composition
0 - identifies as casting

Question 11

What does the presence of a letter prefix mean in a cast alloy?

Answer 11

Impurity level or the presence of a secondary alloying element

e.g. A201.0 is more pure than 201.0

Question 12

What is temper designation?

Answer 12

Indicates the method of strengthening

H - cold worked
T - heat treated

Question 13

What is the purpose of cold or heat treating al alloys?

Answer 13

Brings out some of the alloying elements creating deposits in between grain boundaries (makes the al harder)

Question 14

What methods are used to minimise corrosions of al-alloy?

Answer 14

Washing, hangaring, periodic repainting, moisture excluding compounds, preventing contamination (mercury especially)