Materials and Processes

Alloy 6061 is

A silicon and magnesium alloy and is used in applications where heat treatability, ease of forming, medium strength, and good corrosion resistance are needed.

Alloy 7075 is

a zinc alloy with copper and chromium added. It is heat treatable and has high strength.

Fill in the code letter that is used to identify each of the following treatments for aluminum alloy:

a.) As fabricated with no control over its temper: F b.) Annealed: O c.) Solution heat treated: T d.) Strain hardened: H

Identify the series numbers for aluminum alloys that have the following major alloys:

a.) copper: 2xxx b.) magnesium: 5xxx c.) zinc: 7xxx

When an aluminum alloy part is removed from the heat treatment oven and quenched, it is relatively soft. Over a period of a day or so, it increases its hardness and strength. This process is called

aging

Sitka spruce wood is used for

aircraft wing spars and fuselage stringers.

A steel part is nitrided by heating it in an atmosphere containing ??? gas.

ammonia

Monel is

an alloy of nickel and copper with small amounts of iron and manganese. It is used for applications that demand high strength and high corrosion resistance. It can be used for exhaust systems for aircraft engines.

The form of heat treatment that softens a metal is called

annealing

Thermoplastic resins

are softened by heat and will again become hard when they cool down. They are used for aircraft windshields and side windows.

Epoxy resins

are strong, resistant to moisture and chemicals, and have extremely good adhesion characteristics.

Titanium must

be protected from the air with a blanket of helium or argon gas.

Titanium can

be welded, is used for aircraft structures that are exposed to high temps such as the skins of aircraft, and turbine engines. It is corrosion-resistant.

Glass cloth that is woven with both warp and fill threads is called (bidirectional or unidirectional) cloth.

bidirectional

SAE 1020 steel has a carbon content of ??? %.

0.20

Comercially pure aluminum is identified by the code number

1100

Icebox rivets are aluminum alloy rivets that must be heat treated and stored in a subfreezing refrigerator until they are driven. Two alloys of which icebox rivets are made are:

2017, 2024

The aluminum alloy rivet that may be driven as it is received from the manufacturer without having to be heat treated is made of alloy

2117

Most welded steel aircraft structure is made of SAE steel

4130

Grade-A cotton fabric has a tensile strength of ??? pounds per inch.

80

Alloy 2024 consists of:

Aluminum alloyed with copper, and can be hardened by solution heat treatment.

What does 2xxx nickel steel apply to?

Between 3% and 3.75% nickel may be alloyed with carbon steel to increase its hardness, tensile, strength, and elastic limit without decreasing its ductility. It is used for aircraft bolts, cable terminals, keys, clevises, and pins.

Two methods of case hardening are:

Carburizing and nitriding

The form of heat treatment that hardens the surface of a metal while leaving the core relatively soft and tough is called

Case hardening

Stainless steel is called ??? and 300 contains

Corrosion-resistant steel. It contains approximately 18% chromium and 8% nickel.

2024 has

High strength, but is sucsceptible to corrosion.

What metals are alloyed in aircraft construction?

In order, copper, manganese, silicon, magnesium, magnesium and silicon combined, and zinc.

What does chrome-vanadium steel apply to?

It is used for wrenches and other hand tools used for extremely high strength and toughness.

What does 41xxx chrome-molybdenum steel apply to?

Most aircraft structural steel is a chrome molybdenum alloy that combines toughness and the ease of welding and machining. It is used on landing gears, fuselage frames, and engine mounts. It can also be used on engine cylinders.

What does 3xxx nickel-chromium steel apply to?

Nickel gives toughness to steel, and chromium hardens it. It is used for forged and machined parts where high strength, ductility, toughness, and shock resistance are needed.

Clad aluminum alloy has a coating of ??? rolled onto its surfaces to improve its corrosion resistance.

Pure aluminum

The most generally used metal for aircraft firewalls is

Stainless steel

What does 1xxx carbon steel apply to?

Steels containing 0.10% and 0.30% carbon are low carbon steels and are used for making safety wire and secondary structural parts where strength is not critical.

Steel is hardened by heating it to a specified temperature and then quenching it in oil, water, or brine. The hardest and most brittle steel is obtained by quenching it in

brine

Ferrite is

carbon that exists in the steel in the form of iron carbide scattered throughout the basic iron structure.

An aluminum alloy sheet that has a coating of commerially pure aluminum rolled onto its surface is called ??? aluminum.

clad

Curing agents are used rather than catalysts when mixing (polyester or epoxy) resins.

epoxy

Plywood is made by

gluing sheets of thin wood veneer together with the grain of alternate layers lying at 45 degrees or 90 degrees to that of the adjacent layers. It can be molded into complex shapes in heated forms or molds.

Polyester fabric is shrunk on an aircraft structure with

heat

Under certain conditions magnesium can

ignite and burn.

Titanium can be welded by using ??? electric arc welding.

inert gas

If too much time elapses between the removal of a piece of aluminum alloy from the heat treatment oven and the time it is quenched, there is a danger of ??? corrosion forming inside the part.

intergranular

Kelvar

is aramid fiber that has a high tensile strength and excellent stiffness, toughness, and resistance to impact and is lighter than either glass or graphite.

A pure metal, as distinguished from an alloy, (is or is not) normally hardened by heat treatment.

is not

Graphite

is thin filaments of carbon, and are made into both bidirectional and unidirectional sheets. It is extremely stiff and strong, and is more brittle than kelvar.

The drawbacks about magnesium are:

it's highly susceptible to corrosion, and it has a tendency to crack when subjected to excessive vibration.

Kelvar is (lighter or heavier) than fiberglass fabric of equal strength.

lighter

Propellers were once

made of birch wood glued together in such a way that all the grain in all the layers ran in the same direction.

Polyester resins

must be mixed with styrene to make them easier to work with. They cure when heat causes the individual molecules to join together to form chains.

The form of heat treatment that relieves strains in a metal is called

normalizing

When a steel tubular fuselage is first welded, there are strains trapped in the structure. To relieve these strains, the structure is heated to a temperature above its critical temperature and allowed to cool in still air. This procedure is called

normalizing

What is the slowest quench?

oil.

Catalysts are used with (polyester or epoxy) resins to cause them to cure.

polyester

Artificial aging is done by holding a heat-treated aluminum alloy part at an elevated temperature for a specified length of time. This process is called ??? heat treating.

precipitation

Magnesium can be

rolled into thin sheets.

Polyester fabric is

shrunk onto an aircraft structure with heat and is finished with a special nontautening dope.

Linen and cotton fabrics are

shrunk with dope.

The reference wood used for aircraft construction is

sitka spruce

Aluminum alloy is softened by heating it in an oven and cooling it (rapidly or slowly).

slowly

When an aluminum alloy part is heated in an oven and then quenched, it is said to be ??? heat treated.

solution

precipitation heat treatment hardens a metal by

speeding the aging process up by heating it to a temperature lower than than that used for solution heat treatment. Is done by artificial aging.

A steel part may be made less brittle by heating it to a temperature quite a way below its critical temperature and allowing it to cool in still air. This procedure is called

tempering

The form of heat treatment that removes some of the hardness from hardened steel is called

tempering

Magnesium is

the lightest metal and doesn't have enough strength for aircraft structures, but when alloyed with manganese, aluminum, or zinc.

Resins that are reinforced with glass filaments to make aircraft structural components are (thermoplastic or thermosetting) resins.

thermosetting

Mahogany plywood can be

used for the outside skin monocoque structure.

Alloy 5052 is

used for welded applications such as fuel tanks and for rigid fluid lines. Magnesium is its chief alloying agent and cannot be heat treated, but can be hardened by cold working but not too excessively.

Thermosetting resins

will not soften when they are heated, and char and burn before they melt.

Long staple cotton fiber is

woven into a cloth 80 threads per inch in both directions of fill and warp.