Aircraft Metals – Non Ferrous Characteristics

Practice vocabulary flashcards covering non-ferrous aircraft metals, their properties, heat treatments, and material testing methods as discussed in the lecture notes.

Non-ferrous

Metals that have elements other than iron as their base; they are non-magnetic.

Bauxite

The ore from which aluminium is obtained.

Wrought aluminium alloys

Alloys with a compressed and tightened grain structure forced into shapes like tubes or skins; used extensively in aircraft construction.

Cast aluminium alloys

Brittle alloys with a coarse grain structure produced by pouring liquid metal into a mould; used for aircraft wheels and engine crankcases.

Aluminium four-digit index system

A numbering system where the first digit identifies the major alloying element and the second digit indicates alloy modification.

2024 and 7075

The two most widely used aluminium alloys in aviation.

Cladding

A process where a thin layer of pure aluminium ($3\% - 5\%$ of the thickness) is applied to each side of reaching base material to increase corrosion resistance.

AZ31

The most popular magnesium alloy used in the aircraft industry to produce flat parts attached to ribs or brackets.

Hot-dimpling

A process of heating magnesium parts before forming to prevent cracking.

Alpha-beta alloys (Titanium)

The most versatile titanium alloys; they have medium strength in the annealed condition and higher strength when heat treated.

Ti-8Al-1Mo-1V

The standard identification number for alpha titanium, also known as Ti-B-i-I, containing $8\%$ aluminium, $1\%$ molybdenum, and $1\%$ vanadium.

Monel

A nickel alloy containing about $68\%$ nickel and $29\%$ copper with small amounts of iron and manganese; used in exhaust systems and rivets.

Inconel

A nickel alloy containing about $80\%$ nickel and $14\%$ chromium; used in turbine engines due to strength and corrosion resistance at high temperatures.

Brass

A copper alloy containing zinc and small amounts of other elements; used in bushings and fuel metering valves.

Bronze

A copper alloy containing tin; used in bearings and valve seats.

Beryllium copper

An alloy consisting of approximately $97\%$ copper, $2\%$ beryllium, and nickel; used for precision bearings and diaphragms.

Solution heat treatment

The process of heating an aluminium alloy to between $440^\circ\text{C} - 525^\circ\text{C}$ ($825^\circ\text{F} - 980^\circ\text{F}$) to allow alloying elements to mix with the base metal.

Quenching

The rapid cooling of a heated alloy in a medium like cold water; must occur within $10$ seconds of removal from the furnace for aluminium.

Natural ageing

The process where heat-treatable alloys become hard and gain strength at room temperature over time.

Precipitation heat treatment

Also known as artificial age hardening; it involves reheating metal between $160^\circ\text{C} - 260^\circ\text{C}$ to accelerate the hardening process.

Annealing

A process that softens metal and decreases internal stress by heating to $415^\circ\text{C}$ and cooling slowly to $260^\circ\text{C}$ at $25^\circ\text{C}$ per hour.

-T3

An aluminium temper designation meaning solution heat treated followed by strain hardening.

-T6

An aluminium temper designation meaning solution heat treated followed by artificial ageing (precipitation heat treated).

Alloy 5052

An important non-heat treatable aluminium alloy containing $2.5\%$ magnesium and chromium; used for fuel or oil tanks.

Strain hardening

Also known as cold working or work hardening; it strengthens metal by mechanically working it at temperatures below its critical range.

Hx8

The hardness designation for full-hard strain-hardened material.

Hardness

A metallic material's resistance to plastic deformation caused by a force applied through an indenter.

Barcol tester

A portable hardness tester used for relatively soft materials like brass, copper, aluminium alloys, or plastics.

Riehle tester

A portable hardness tester ideal for testing cylindrical tubes.

Fatigue strength testing

Mechanical testing involving cyclic loading to determine fatigue life and identify critical locations in a structure.

Limit load

The maximum load an aircraft is expected to see at any point in its service life.

Ultimate load

The limit load multiplied by a safety factor (generally $1.5\times$); it accounts for unexpected events or emergency conditions.

Yield tensile strength

The point where deformation of the material is unrecoverable.

Necking

A phenomenon in a tensile test that occurs after maximum load or forces have been reached.