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Mod 6: Materials & Hardware > 6.1(a) > Flashcards

6.1(a) Flashcards

1
Q

What is a ferrous metal?

A

A ferrous metal is a metal that contains iron.

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2
Q

What is hardness?

A

Hardness is the property of a material that enables it to resist penetration, wear or cutting action

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3
Q

What is strength?

A

Strength is the ability of a material to withstand forces which tend to deform the metal in any direction, or the ability of a material to resist stress without breaking.

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4
Q

What is Elasticity?

A

Elasticity is the capability of an object or material to be stretched and to recover its size and shape after its deformation.

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5
Q

What is the Elastic limit of a material?

A

A metal’s elastic limit is the point beyond which the metal does not return to its original shape after a deforming force is removed. Soft materials such as lead, copper, and pure aluminium have very low elastic limits, while the elastic limit of hard spring steel is very high.

Low - Lead, copper and aluminium

High - Steel

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6
Q

What is Plasticity?

A

Plasticity is the property of a metal which allows it to be reshaped.

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7
Q

What is ductility?

A

Ductility is the property which allows metal to be drawn into thinner sections without breaking. Ductile metals are preferred for aircraft use because of their ease of forming and resistance to failure under shock loads. For this reason, aluminium alloys are often used for cowlings, fuselage and wing skins, and formed or extruded parts such as ribs, spars and bulkheads.

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8
Q

What is malleability?

A

Malleability is the characteristic of a material that allows it to be stretched or shaped by beating with a hammer or passing of the material through rollers without breaking.

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9
Q

What is toughness?

A

Toughness is the property of a metal which allows it to be deformed without breaking.

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10
Q

What is brittleness?

A

The property of a metal to break when, deformed, or hammered. It is the resistance to change in the relative position of the molecules within the
material.

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11
Q

What is conductivity?

A

Conductivity is the characteristic of a material which makes it possible for the material to transmit heat or conduct electrical current.

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12
Q

What is Durability?

A

Durability is the property of a metal that enables it to withstand force over a period of time.

Landing gear is an example of a durable component.

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13
Q

What is Thermal expansion?

How does this affect aircraft (design)?

A

Thermal expansion refers to contraction and expansion that are reactions produced in metals as the result of heating or cooling. Heat applied to a metal will cause it to expand or become larger.

Cooling and heating affect
the design of welding jigs, castings, and tolerances necessary for hot rolled material.

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14
Q

What is the opposite of toughness?

A

Brittleness

Remember: Toughness is the ability of a material which allows it to be deformed without breaking.

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15
Q

What is a metallic material?

A

Having the nature of metal or containing metal.

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16
Q

What is a Non- metallic material?

A

Non-metallic materials have the nature of containing no metal.

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17
Q

What is a ferrous material?

A

Iron or any allow containing iron.

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18
Q

What is a non-ferrous material?

A

Any metal which contains no iron.

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19
Q

What is Tensile Strength?

What unit is used to measure it and what i usedto represent it if the tensile strength of a material is very high?

A

When a piece of sheet metal is pulled from each end, the resultant force is called tension. The ability to withstand tension is called tensile strength.

Tensile strength is measured in pounds per square inch. When pounds persquare inch are very high, the value can be expressed using the letter K.

When a piece of sheet metal has a tensile strength of 70,000 psi it can be written as 70 KSI.

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20
Q

What is yield strength?

A

The amount of stress needed to cause a metal to deform is called yield strength. When a tensile load is applied to a material, it will resist any deformation until its yield point is reached. At this time it will actually stretch, without any increase in the stress that is applied.

When it stretches its molecular
structure changes enough to increase its strength, and it will resist any more deformation until the ultimate load is reached, at which time the material will break.

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21
Q

What is shear strength?

A

Shear strength is the ability of the metal to withstand being cut cross-sectionally in half.

A rivet holding two or more sheets of metal together resisting their sliding apart is an example of a shear load. When the rivets installed in a joint have more strength than the metal in the surrounding joint, it is said to be loaded in shear.

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22
Q

What is bearing strength?

A

Bearing strength is the ability of a joint to withstand any form of crushing or excessive compressive distortion of the metal. The installation of countersunk rivet heads will not provide a fully effective bearing area.

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23
Q

What is Fusibility?

A

The ability of metal to be fused by heating and melting is defined as fusibility. To fuse metal means to melt two or more compatible pieces of metal into one continuous part. The correct term is called fusion joining or
welding.

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24
Q

What is density and what is the density of water?

A

Density is actually the mass-per-unit volume of a material. SI unit kg/m^3

Density of water is 1 g/cm^3

( 0.03611 pounds/inch^2)

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25
Q

What is the density of the following:

Aluminium

Titanium

Iron

Copper

Lead

Gold

A
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26
Q

Describe the following stresses:

Tension

Compression

Torsion

Bending

Shear

A
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27
Q

Describe how bending occurs during flight (wings)?

A

In flight, the lift force tries to bend the wings upward. As a
result the skin on top of the wing is subjected to a compression force, while the skin below is pulled by a tension force. The opposite occurs when the aircraft is on the ground.

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28
Q

What colour is iron?

A

Iron is silvery white in colour

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29
Q

What is High Carbon Steel?

example

A

Pig Iron with a carbon content > 0.5%

It is used where extreme hardness is required and malleability is not of primary concern.

Used for cutting tools and springs

Can be heat treated until extremely hard.

SAE 1050 and 1150

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30
Q

What is Medium carbon steel?

A

Pig iron with a carbon content of 0.3 - 0.5 %

Accepts heat treatment.

SAE 1030 and 1050

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31
Q

What is Low Carbon Steel?

A

Low carbon steel contains 0.1 - 0.29% carbon.

Used for secondary structural parts

Does not accept heat treatment satisfactorily.

SAE 1010 and 1030

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32
Q

What does the abbreviation SAE stand for?

What does this organisation do?

A

Society of Automotive Engineers.

An organisation that has established standards for materials and processes that are widely used in the aviation industry.

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33
Q

What type of material does the SAE 1030 code identify?

A

Plain Steel identified as medium carbon steel

1 = plain steel

0 = no alloying element

30 = 30 hundretdths of one percent of carbon.

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34
Q

In the SAE classification of steels, what does the first digit identify?

A

The first digit identifies the principal alloying element in the steel.

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35
Q

What is meant by the term ferrous metal?

A

Any metal that contains iron.

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36
Q

In the SAE classification of steels, what does the second digit identify?

A

The second digit identifies the percentage of the principal alloying element.

37
Q

In the SAE classification of steels, what do the last two digits identify?

A

The last two digits identify the percentage in hundredths of a percent of the carbon in steel.

38
Q

A steel containing between 0.1% and 0.3% carbon is designated as being what type of steel?

A

Low Carbon Steel

39
Q

Nitriding is a process carried out to produce what change in low carbon steel?

A

A hard surface is produced in the process of nitriding by converting the surface of the metal into an extremely hard aluminium nitride.

40
Q

What is the carbon content of medium carbon steel?

A

0.3 - 0.5%

41
Q

What is the carbon content of high carbon steel?

A

> 0.5 %

42
Q

When nickel is added to steel, what changes occur to the steel?

(Chromium also)

A

Nichel gives toughness to steel (and chromium hardens it)

43
Q

Why are the stainless steels in the 300 series classified as 18-8?

A

The corrosion resistant steel most often used in aircraft construction is known as 18-8 steel because of it’s content of 18% chromium and 8% nickel.

One of the distinctive features of 18-8 steel is that it’s strength may be increased by cold working.

44
Q

The ability to withstand a cross sectional load on a material is?

A

Shear Strength

45
Q

When a piece of metal is pulled from each end, the resultant force is called?

A

Tensile force ( Tension)

46
Q

What material is used to manufacture firewalls?

A

Stainless Steel

47
Q

If a piece of material is stretched under tension loads and when the loads are released the material returns to its original position what is this characteristic called?

A

Elasticity

48
Q

Name the temperature point where the carbon dissolves into the matrix and becomes a solid solution?

A

Eutectoid???

49
Q

What is the purpose of forcing oxygen through re-melted pig iron?

A

Oxygen can unite with the carbon and burn it out. A controlled amount of carbon and other elements can then be added in.

50
Q

Is pig iron considered as pure metal?

A

Yes & No??

51
Q

In what type of furnace is the steel used in aircraft made?

A

Electric Furnace

52
Q

Explain the process for annealing steel?

A

Full annealing is a process that makes the metal as soft as possible. It also improves ductility, refines the grain size and removes internal stresses.

Heated between 25 - 50 ^C above either upper critical or lower critical temperature depending on if above of below 0.83% carbon (inverted). Metal held at that temperature (soaking) until the carbon goes into solid solution with the matrix.

It is then allowed to cool slowly by shitting off heat but leaving in furnace or by packing the steel in hot sand or ashes. The carbon that precipitates out will be in large particles that do not bind the matrix tightly.

53
Q

Which constituent is most undesirable in steel?

A

Sulphur is one of the more undeirable constituents in steel.

54
Q

Describe how the normalizing process takes place?

A

Steel that has been forged, welded or machined usually has stresses left within the structure that could cause failure - These stresses must be relieved by a process called normalising.

Same temps as annealing (25-50 higher than upper/lower critical temp depending on higher or lower) inverted

Allowed to cool in still air.

Produces a fine grain structure.

55
Q

What constituent counteracts the effects of sulphur in steel?

A

Manganese

56
Q

What constituent when added to steel increases its strength, wear resistance and corrosion resistance?

A

Chromium

57
Q

What process will relieve the stresses in steel, brought about by forging, welding or machining?

A

Normalising

58
Q

When you melt two pieces of a metal so as to join them together to form one piece, what is the characteristic of the metal called?

A

Fusibility / fusion joining / welding

59
Q

What is the chief constituent of a ferrous metal?

A

Iron

60
Q

When iron is poured from the furnace, it is in a form commonly known as?

A

Pig Iron

61
Q

The greater the carbon contents in steel, the better the ability to?

A

Increases hardness

Better ability to resist penetration, wear or cutting action / indentation.

62
Q

Carbon steels come in how many different classifications?

A

3 - High/medium/low carbon steel

63
Q

When you remove some of the hardness from steel, what is this process known as?

A

Tempering

64
Q

How can you make a reasonable estimate of the temperature of steel during the heat treatment process if you do not have a pyrometer?

Degrees Celsius

A

A reasonable estimate of its temperature can be made by observing it’s colour.

65
Q

Name the colour that goes along with each of the following temperatures of steel?

A
66
Q

Describe the pack carburizing method of case hardening?

A

Carburising sets out to increase the carbon content on the surface of a low-carbon steel.

Pack carburising - Fire clay container

Carbon rich material - charcoal

927 ^C

Carbon monoxide combines with gamma iron in surface

depth depends on soaking time.

67
Q

When you want to create a hard wearing surface around a soft tough core in a piece of material, what is this process known as?

A

Case Hardening

  1. Carburising
  2. Nitriding
68
Q

Describe the gas carburizing method of case hardening?

A

Similar to pack carburising but carbon monoxide is produced by a gas.

69
Q

Describe the liquid carburizing method of case hardening?

A

High carbon surface

Heated in molten bath of sodium cyanide or barium cyanide

Any part not to be case hardened can be copper-plated.

->Won’t infuse.

70
Q

Explain the tempering process of steel?

A

Tempering reduces hardness and brittleness

Heated to a temp considerably below it’s critical temp and held till soaking.

Cooled in still air to room temp.

71
Q

What material is formed when you mix carbon and iron?

A

Steel

72
Q

What determines how metals should be classified?

A
73
Q

What is the density of steel?

A

7.9 g/cm^3

74
Q

Under the SAE classification of steels, what are the following:

1XXX

T13XX

2XXX

3XXX

4XXX

41XX

5XXX

A

1XXX = Carbon Steels

T13XX = High Manganese

2XXX = Nickel Steels

3XXX = Nickel-Chromium Steels

4XXX = Molybdenum steels

41XX = Chromium-Molybdenum

5XXX = Chromium Steels

75
Q

What is the lower critical point or when the change starts in most steels?

A

723 ^C

76
Q

What is the benefit of using Molybdenum in aviation and what has it replaced?

A

Molybdenum is used to stop corrosion. It gives it a refined grain structure (water molecular level).

Also increases impact strength and its elastic limit.

Molybdenum steels have practically replaced carbon steel in the fabrication of fuselage tubing, engine mounts, landing gears, and other structural parts.

77
Q

What does AISI stand for?

A

American and Iron Steel Institute.

78
Q

What are the disadvantages of stainless steel?

A

Stainless steels are more difficult to cut and form than many materials.

Stainless steels have much greater expansion coefficient than other steels, and they conduct heat at a lower rate; this makes welding more difficult.

Many of the stainless steels lose their corrosion resistance under high temperatures.

79
Q

Draw the graph of the different phases of iron between the following temps:

1539, 1400, 907, 767

A
80
Q

What is Allotropy/Allotropic

A

An allotropic metal is one that can exist in more than one type of lattice structure eg iron. depending on temp.

81
Q

Pg 18 of notes - new section

Austenite

Ferritic Martensitic

A
82
Q

What is the basic classification of metals used in aircraft structural applications?

A

Ferrous and Non-Ferrous

83
Q

Why are the most widely used stainless steels in the 300 series called 18-8?

A

These corrosion resistant steels contain 18% chromium and 8% nickel.

One of the distinctive features is that their strength may be increased by cold working.

84
Q

Name the temperature point where the carbon dissolves into the matrx and becomes a solid solution?

A

Eutectoid point - 723^C

85
Q

What process is used to counteract the effects of sulphur in steel?

A

Manganese is added during the coking process.

The coking process removes impurities.

86
Q

Explain the tempering process of steel.

A

Tempering draws out some of the hardness.

It is heated to a temperature considerably below the critical temperature and allowed to soak. Then cooled at room temperature in still air.

87
Q

What type of material does the SAE 1030 code identify?

A

Plain steel with 30% carbon

88
Q

What constituent when added to steel increases it strength, wear resistance and corrosion resistance?

A

Chromium

89
Q

Yes, pig iron is a pure element.

A

Mod 6: Materials & Hardware (18 decks)

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