6.1

Question 1

What is slag?

Answer 1

When any impurities float to the surface in a furnace

Question 2

What happens to steel when carbon levels are increased?

Answer 2

Hardness and tensile strength increases

Question 3

Low carbon steels contain how much carbon?

Answer 3

0.1-0.3%

Question 4

Medium carbon steel contains how much carbon?

Answer 4

0.3-0.5%

Question 5

High carbon steel contains how much carbon?

Answer 5

0.5-1.05%

Question 6

What does AISI stand for?

Answer 6

American iron and steel institute

Question 7

What do the first two digits in alloy steel designation stand for?

Answer 7

The primary alloying elements

Question 8

What do the last two digits in alloy steel designation stand for?

Answer 8

The percentage of carbon contains in the alloy

Question 9

For example if an alloy steel was designated XX30, what does this indicate?

Answer 9

It has 0.3% carbon

Question 10

What is the quenching process?

Answer 10

Heat up a metal a and rapidly cool in water, oil, or brine

Question 11

What determines hardness in steel?

Answer 11

The amount of carbon

Question 12

What is the fastest way to quench?

Answer 12

By using brine (salt water)

Question 13

What is the slowest way to quench?

Answer 13

By using oil

Question 14

What is a eutectoid?

Answer 14

When a metal can exist in more than one form at the same temperature

Question 14

What is stainless steel also known as?

Answer 14

Corrosion-resistant steel (CRES)

Question 14

What are 200 and 300 series steels classified as?

Answer 14

Austenitic steels

Question 14

What are 400 series steels classified as?

Answer 14

Ferritic and martensitic steels

Question 15

Where are precipitation-hardened stainless steels used?

Answer 15

Airframe

Question 16

Where are high-strength low-alloy steels used?

Answer 16

Landing gear

Question 17

What is the purpose of heat treatment?

Answer 17

To improve mechanical properties

Question 18

What are the four types of heat treatment?

Answer 18

1. Annealing
2. Normalising
3. Hardening
4. Tempering

Question 19

What is annealing?

Answer 19

Heating 50F above critical temperature and allowing to soak

Question 20

What is the purpose of annealing?

Answer 20

To release internal stresses and to make it soft

Question 21

What is normalising?

Answer 21

Heating 100F above its critical temperature and allowing to cool slowly in air

Question 22

What is the purpose of normalising?

Answer 22

To release internal stresses and make it stronger

Question 23

What is hardening?

Answer 23

Heating above the critical temperature and then quenching

Question 24

What is the purpose in hardening?

Answer 24

It increases hardness

Question 25

What is tempering?

Answer 25

Heated below critical temperature and held at Temperature then slowly cooled

Question 26

What is the purpose in tempering?

Answer 26

To release internal stresses caused by rapid cooling (hardening)

Question 27

What is hydrogen embrittlement?

Answer 27

When hydrogen enters a grain structure and reacts with carbon to form methane which leads to cracks

Question 28

How can hydrogen embrittlement be removed ?

Answer 28

By baking at 375F for at least 3 hours

Question 29

What are the three steel alloy rework precautions?

Answer 29

- stress concentrations - hydrogen embrittlement - untempered martensite

Question 30

How should metal removal be done?

Answer 30

By hand or with slow-speed hand-held power tools

Question 31

When do stainless steels require protective treatment?

Answer 31

When in contact with light weight alloys

Question 32

What is galvanic corrosion?

Answer 32

When two dissimilar metals corrode by being next to each other

Question 33

What is necessary for galvanic corrosion to take place?

Answer 33

An electrolyte (eg. Water)

Question 34

What does it mean if a metal is less noble?

Answer 34

It is more susceptible to corrosive attack

Question 35

What does it mean if a metal is more noble?

Answer 35

It is less susceptible to corrosive attack

Question 36

What does it mean if a metal has a lower number on the galvanic scale?

Answer 36

It is less noble

Question 37

What does it mean if a metal has a higher number on the galvanic scale?

Answer 37

It is more noble

Question 38

Why is case hardening completed?

Answer 38

To make low carbon steel components hard and tough

Question 39

Why is case hardening not completed on high carbon steels?

Answer 39

Because they will become more brittle

Question 40

What type of metals aren’t suitable for case hardening?

Answer 40

Non-ferrous metals

Question 41

What is carburising?

Answer 41

When a thin layer of high carbon steel is produced on the surface of a low carbon steel component

Question 42

What are the three types of carburising?

Answer 42

- pack carburising - gas carburising - liquid carburising

Question 43

What temperature is carburising completed at?

Answer 43

Up to 1700F

Question 44

What is pack carburising?

Answer 44

Heating whilst packed into a carbon rich material

Question 45

What is gas carburising?

Answer 45

Heating in a carbon dioxide rich atmosphere

Question 46

What is liquid carburising?

Answer 46

Heating in a bath of either sodium cyanide or barium cyanide

Question 47

What is flame hardening?

Answer 47

Heating the surface above the transition temperature with a torch and then quenched immediately with water jets from the same torch

Question 48

What material can flame hardening be carried out on?

Answer 48

Steels with at least 0.4% carbon and after they have been normalised

Question 49

What is induction hardening?

Answer 49

When an induction coil surrounds the component and heats with eddy currents in the surface of the steel and then quenched

Question 50

What is nit riding?

Answer 50

Heating metal to 1000F in ammonia which allows nitrogen into the surface