Introduction And Ferrous Materials Flashcards
1
Q
What is the definition of density?
A
The measure of mass per unit volume
2
Q
What is the definition of fatigue?
A
When a metal is subjected to cyclic loads, it will start to crack after sufficient repetitions
3
Q
What is the definition of elasticity?
A
When a material returns to its original shape after the deforming force has been removed
4
Q
What is the definition of Unit Stress?
A
The force per unit area
5
Q
Name the three simple stresses
A
Tensile
Compressive
Shear
6
Q
What is combined stress?
A
A combination of tensile and shear stresses
Or
A combination of compressive and shear stresses
7
Q
What is tensile stress?
A
The stretching or lengthening effect on a material
8
Q
What is compressive stress?
A
The compressive or shortening effect on a material
9
Q
What is shear stress?
A
The effect caused by layers on a material to slide over each other from opposite directions
10
Q
What does Poisson’s Ratio state?
A
That the more the material is stretched, the thinner the material gets
11
Q
What is the definition of hardness?
A
The ability to resist penetration/wear or cutting action
12
Q
What is the definition of strength?
A
The ability to withstand forces which tend to deform the metal in any direction
13
Q
What is the definition of plasticity?
A
The ability for a metal to be reshaped
14
Q
What is the definition of ductility?
A
The ability to be drawn (stretched) into thinner sections without breaking
15
Q
What is the definition of malleability?
A
The ability of a material to be beaten, rolled or stretched into a new shapw without breaking
16
Q
What is the definition of toughness?
A
The ability to deform without breaking
17
Q
What is the definition of Brittleness?
A
The ability to break easily when deformed/hammered
18
Q
What is the definition of conductivity?
A
The ability to transmit heat or energy
19
Q
What is the definition of durability?
A
The ability for a metal to withstand forces applied over a period of time
20
Q
What are metallic materials?
A
A substance containing metal or a metal itself
21
Q
What is a non-metallic material?
A
A substance containing no metal
22
Q
What is a ferrous material?
A
A substance containing iron or any alloy that also contains iron
23
Q
What is a non-ferrous material?
A
A metal which contains very little or no iron
24
Q
What are the 4 elastic properties?
A
Elastic limit
Yield Strength
Ultimate Tensile Strength
Breaking Point of Sample
25
What is the Elastic Limit?
The maximum point of stress to which a material may be subjected and still return to its original shape.
26
What is the Yield Strength?
The maximum stress that can be applied without permanent deformation
27
What is the Ultimate Tensile Strength?
The maximum value of Tensile Stress that a material can withstand without breaking
28
What is the Breaking Point of a Sample?
The Modulus of Elasticity : the ratio of stress to strain within the proportional limit of a material in tension or compression
29
What are the three lightweight materials used for aircraft?
Aluminium
Magnesium
Titanium
30
What is a crystal?
A rigid body in which the constituent particles are arranged in a repeating system
31
What is a basic building block of a crystal called?
A Unit Cell
32
What does BCC stand for and how many atoms does it have in its unit cell?
Body centred cubic
9 atoms on the corners of the cube and one in the centre
33
What does FCC stand for and how many atoms are in its unit cell?
Face centred cubic
14 atoms on the corners and the centre of each face
34
What does HCP stand for and how many atoms does it have in its unit cell?
Hexagonal Close Packed
17 atoms
35
Name some examples of FCC types
```
Iron if ABOVE 910 degrees Celcius
Aluminium
Copper
Gold
Nickel
Silver
```
36
Name some examples of BCC types
Iron if BELOW 919 degrees Celcius
37
Name examples of some HCP types
Cobalt
Magnesium
Titanium
Zinc
38
What is an example of a ferrous material?
Steel
39
What is the base material for steel?
Iron
40
What is iron primarily alloyed with to make steel?
Carbon
41
What are characteristics of pure iron?
Soft
Malleable
Ductile
42
How is cast iron formed?
Molten iron alloyed with 2% of carbon and is poured into a mould
43
How is steel made?
Pure iron is melted in a blast furnace and introduced to carbon with other alloying elements to achieve desired characteristics
44
Why is cast iron not favourable?
It is not strong
45
Name some examples of alloying ingredients for steel and their alloying properties
Carbon - primary hardening agent
Sulphur - decreases ductility
Silicon - de oxidiser
Phosphorous - increases strength and hardness
Chromium - increases corrosion and oxidisation resistance
46
What are the carbon percentages for LCS, MCS and HCS?
LCS - 0.1 -0.3%
MCS - 0.3 - 0.5%
HCS - 0.5 - 1.05%
47
How are the types of steels represented?
As a 4 digit number
48
What do the first and last 2 number denote in the material designation?
First 2- steel and alloys used
| Last 2 - the % of carbon
49
What are the designations based on?
The AISI numbers and SAE numbers
50
What does AISI mean?
American Iron and Steel Institute
51
What does SAE stand for?
System of Automated Engineers
52
What must steel have for heat treatment to happen?
Must have carbon
53
What type of heat treatment is used to decrease the hardness of steel?
Tempering
54
What is the process to harden steel?
The material is heated above critical temperature allowing carbon to dispense uniformly in the iron matrix
The alloy is then cooled rapidly by quenching it in a quenching medium
55
What are the three types of quenching mediums?
Water
Oil
Brine
56
What is the most rapid quench medium?
Brine
57
What is the steel known as if the quench is too quick?
Martensitic
58
What characteristics does a martensitic structure have?
It is the hardest alloy
| Too brittle for aircraft use
59
What affects the hardness of steel?
The amount of carbon
60
If there is more carbon in steel, the steel is...
More hard
61
What are the different types of heat treatment?
```
Tempering
Annealing
Hardening
Normalising
Quenching
```
62
What is annealing?
Heating a material and allowing it to cool slowly to increase softness and toughness and relieve internal stresses
63
What is normalising?
When you heat steel to 100F above its upper critical unit, soak it for a given time and then cool it at room temp
64
What are the names of the groups that steel is divided into depending on their structure?
Ferrite
Austenite
Cementite
Pearlite
65
What are the three GENERAL groups that steel is divided into based on their structure ?
Ferrite
Austenite
Martensitic
66
What does CRES stand for?
Corrosion Resistant Steel
67
What process makes a substance less corrosive?
The addition of Chromium
68
How are CRES identified?
By 3 digit numbers
200
300
400
69
What are the 200 and 300 series known as?
Austenite
70
What are the 2 types of 400 series known as?
Ferrite
| Martensitic
71
What type of series is commonly used in aircraft?
300 Austenite
72
What are the 4 disadvantages of CRES?
Difficult to cut
Greater coefficient of expansion
Experienced technicians required
Not suitable in high temperature environments
73
What sort of alloy is an Austenite?
Chromium-nickel and chromium-nickel-manganese alloys
74
What sort of properties does an Austenite have?
```
18% or more chromium than nickel
3.5%-22% of nickel
Contains stabilising alloys
200-300 series
Cold work
Strain hardened
Non magnetic
```
75
What properties does a 400 series Ferrite have?
```
Contains 15% - 30% chromium
BCC
400 series
Small amounts if aluminium
Magnetic
Annealed and relatively low strength
```
76
What properties does a Martensitic 400 series have?
```
400 series
12%-18% chromium
High Carbon content
Heat treatable
Least corrosion resistant
```
77
Precipitation Hardening (steel) properties
```
Little carbon
15%-17% chromium
4%-7% nickel
Solution heat treated
Can be hardened to very high strengths
Corrosion resistant
```
78
What is the base alloy of a high strength low carbon steel?
Iron
79
Name an advantage of High Strength Low Carbon Steels
Can be hardened to very high strengths
80
What type of series is used on the landing gear?
300M
81
What is hydrogen embrittlement and what sort of materials are mainly used for it?
The process for hydrogen to get into the grain boundaries of steel. The carbon reacts with the hydrogen in steel and increases the pressure and causes it to crack.
Mainly ferrous and titanium alloys
82
What are the 2 steel alloy precautions?
Stress concentrations
| Hydrogen embrittlements
83
What are the precautions to take for stress concentrations?
The misuse of tools leading to scratches and general damage to surface finish
84
What is a precaution to take for hydrogen embrittlement?
Ensure all precautions are taken to prevent embrittlement
85
What are methods to surface protect CRES materials?
Cadmium plates
Zinc spray
Chromium
86
What does surface protection on CRES materials do?
Avoid galvanic corrosion of light alloys
87
What is galvanic corrosion potential?
The measure of how dissimilar metals will corrode when placed against each other in an assembly
88
The further apart the metals in the corrosive list, the...?
The stronger the ability to corrode
89
Which metal will corrode?
The metal higher in the list
90
What is steel case hardening not suitable for?
Non- ferrous material
91
What is case hardening?
The process of hardening the surface
92
How many processes are there for case hardening and what are they?
4 processes
Carburising
Flame hardening
Induction hardening
Nitriding
93
Which out of the two processes of case hardening is the most common?
Caruburising
94
What is carburising?
Carburising produces a thin layer of high carbon steel around a softer low carbon steel core by introducing the material to carbon
95
How many carburising methods are there and what are they called?
3 methods
Pack carburising
Gas carburising
Liquid carburising
96
What is the process of pack carburising?
Heats up the component to 1700F temperatures whilst it is packed into a carbon rich materials such as charcoal. The carbon from the charcoal then penetrates the surface of the metal which causes it to harden
97
For pack carburising, what is the quenching medium?
Quenching medium is oil
| Water causes the hard case to peel
98
What is the process of gas carburising?
Component is placed in a basket and then into a furnace and is passed through a suitable carbon rich gas. Carbon penetrates the surface and makes it harder.
99
What is the process of liquid carburising?
The component is heated at a suitable temperature then immersed into a hot salt bath at 900 degrees C
100
What is flame hardening?
Heat treatment for uniform compositions
The surface is heated to above upper temperatures by means of oxyacetylene torches and then quenched with a water jet built into an assembly
101
What is induction hardening?
The whole circumference of a material is heated simultaneously by an induction coil and quenched with a water jet built into an assembly
102
What is nitriding and its process?
The introduction of nitrogen to a substance For an improved surface finish
It heats up the material to 1000F in an ammonia rich environment. The ammonia breaks down and nitrogen is released and penetrates the surface of the material.
103
The selection of materials should be a compromise between...?
The cost and quality
104
What are the material characteristics of iron?
It is dense, soft and malleable
105
What is the process used to relieve stress in high strength steel after machining?
Normalising
106
If hydrogen embrittlement is suspected in a material, what should you do ?
Heat it up
107
What does heating up the material do if you suspect hydrogen embrittlement?
Reverts the material back to its normal state
