Ferrous Materials

Question 1

What does a ferrous material contain

Answer 1

Iron

Question 2

How do you make steel

Answer 2

Pure iron is remelted where carbon is introduced, the amount of carbon give the required characteristics.

Question 3

What is iron melted in

Answer 3

A blast furnace

Question 4

Low carbon

Answer 4

0.1-0.3% Carbon

Question 5

Medium carbon

Answer 5

0.3-0.5% Carbon

Question 6

High carbon

Answer 6

0.5-1.05% Carbon

Question 7

Alloying with Sulphur

Answer 7

Decrease ductility

Question 8

Alloying with Manganese

Answer 8

Adds strength and hardness

Question 9

Alloying with Silicon

Answer 9

Adds strength and hardness (worst the

An manganese)

Question 10

Alloying with Phosphorus

Answer 10

Increases strength, hardness and corrosion resistance

Question 11

Alloying with Nickel

Answer 11

Increases hardenablity and impact strength

Question 12

Alloying with Chromium

Answer 12

Increases corrosion resistance and oxidation resistance

Question 13

Alloying with Molybdenum

Answer 13

Increases the hardenablity and impact strength

Question 14

Alloying with Vanadium

Answer 14

Increases yield strength and tensile strength

Question 15

Alloying with Titanium

Answer 15

Improves toughness

Question 16

What does AISI stand for

Answer 16

American iron and steel institute

Question 17

Digits in the AISI

Answer 17

First two = alloying element

Last two = percentage of carbon

Question 18

What is Tempering

Answer 18

A method used to decrease the hardness, thereby increasing ductility and toughness.
Relieves stresses

Question 19

What is Hardening

Answer 19

Material is heated above its critical temperature, allowing carbon to disperse uniformly into the iron,
Cooled rapidly by quenching, if too quick its structure will become to brittle

Question 20

What is annealing

Answer 20

Softens and relieves its internal stresses, the steel is heated to its critical limit, soaked at this temperature, cooling very slowly.

Question 21

What is Normalising

Answer 21

Steel is heated to 100 F above critical limit, soaked for a prescribed time and cooled at room temp,
Relieving internal stresses

Question 22

What is Quenching

Answer 22

The rate at which steel will cool down, it is governed by the quenching medium, brine is the best quench.

Question 23

What does CRES stand for

Answer 23

Corrosion resistant steel

Question 24

Properties of CRES

Answer 24

Corrosion resistance, strength, toughness and resistance to high temperature

Question 25

Negative properties of CRES

Answer 25

Greater coefficient of expansion and not suitable in high temperature environments

Question 26

Austentic

Answer 26

``` Chromium or nickel and chromium nickel magnese alloy Non magnetic Limited use 200/300 series Cannot be heat treated ```

Question 27

Ferritic

Answer 27

``` 15-30% chromium 400 series Small amounts of aluminium Carbon below 1% Magnetic Cannot be heat treated ```

Question 28

Martensitic

Answer 28

``` 12-18% chromium 400 series High carbon content Heat treatable Least corrosion resistance ```

Question 29

Precipitation hardening

Answer 29

``` Little carbon 15-17% chromium 4-7% nickel Heat treatable Corrosion resistance ```

Question 30

High strength low alloy steel

Answer 30

Iron based Can be hardened to high strengths 300M used on landing gear

Question 31

Hydrogen embrittlement

Answer 31

Occurs in ferrous and titanium alloy | Hydrogen migrated through the material, reacts producing methane, build up in pressure then cracks occur

Question 32

What is stress concentrations

Answer 32

The misuse of tools leading to scratches, general damage to surface finish

Question 33

Types of surface protection

Answer 33

``` Cadmium Paint Aluminium spraying Silver plating Chromium and nickel plating ```

Question 34

What is Galvanic corrosion

Answer 34

Potential is a measure of how dissimilar metals will corrode when placed against each other

Question 35

Case hardening

Answer 35

Some steel components require a hard durable surface

Question 36

Two methods of case hardening

Answer 36

Carburising | Nitriding

Question 37

Carburising

Answer 37

Produces a thin layer of high carbon steel on the surface Heating to 900 C Followed by heat treatment Carbon absorbed 1mm every 5-6 hours

Question 38

Pack carburising

Answer 38

Heating to 1700 F Surrounded by charcoal Carbon penetrates surface to harden it Metal is quenched

Question 39

Gas Carburising

Answer 39

Object placed in furnace | Filled with carbon rich gas

Question 40

Liquid Carburising

Answer 40

Object heated to a sensible temp | Put in salt bath at 900 C

Question 41

Flame hardening

Answer 41

Steel heated with a oxy actene touch | Quenched with a jet of water

Question 42

Induction hardening

Answer 42

Whole circumference heated by an induction coil

Question 43

Nitriding

Answer 43

Improves final surface finish Hardened, tempered and ground Introduction of nitrogen