Chapt 2

Question 1

What are the types of crystal structures?

Answer 1

BCC(Body centred cubic)
FCC(Face centred cubic)
HCP(Hexagonal close packed)/
CPH(Close packed hexagonal)

Question 2

Examples of BCC crystal structure

Answer 2

Chromium
Alpha iron
Tungsten

Question 3

Examples of FCC

Answer 3

Aluminium
Copper
Nickel
Gold
Silver

Question 4

Examples of HCP/CPH

Answer 4

Magnesium
Zinc
Titanium(low temp)

Question 5

How to draw BCC FCC

Answer 5

BCC a cube, every corner 1 atom and 1 atom in the middle

FCC a cube, every corner 1 atom, every face centre 1 atom

Question 6

How to draw CPH HCP

Answer 6

Hexagon faces, connect them, every corner 1 atom, triangle in the middle, every corner of triangle 1 atom, 1 line through the whole drawing and both ends 1 atom

Question 7

Which has the fastest cooling rate
1) chilled crystals
2) columnar grains
3) large equiaxed grains

Answer 7

1

Question 8

Which has undirectional cooling

1) chilled crystals
2) columnar grains
3) large equiaxed grains

Answer 8

2

Question 9

Which has the slowest cooling rate

1) chilled crystals
2) columnar grains
3) large equiaxed grains

Answer 9

3

Question 10

Characteristics of Fine Grains

Answer 10

Fine Grains have better strength and toughness
(Big grains have lower S and T)
(Smaller and compact grains have higher S and T)

Question 11

Definition of Cold Working

Answer 11

The plastic deformation of a metal below its recrystallisation temperature

Question 12

What happens to grains after CW

Answer 12

The grains become distorted

Question 13

Characteristics of distorted grains

Answer 13

Harder
Brittle
Stronger

Question 14

What characteristics do the grains have before CW

Answer 14

They are ductile

Question 15

List some processes of CW

Answer 15

Rolling, Deep drawing, Wired Drawing

Question 16

What is plain carbon steel made of?

Answer 16

Alloy of iron, carbon, silicon and maganese

Question 17

What are the impurities that are added unintentionally?

Answer 17

Sulphur and phosphorus

Question 18

What does allotropism mean

Answer 18

Ability of a substance to exist in more than one physical form

Question 19

Examples of some allotropic elements

Answer 19

Iron, carbon, titanium

Question 20

What temperature does pure iron melt

Answer 20

Above 1538 degree celcius

Question 21

Type of plain carbon steel and their carbon %

Answer 21

0.77%< hypo eutectoid

Shd be 0.8%< but its btr to be specific i guess

0.77% - 0.83% eutectoid

Shd be 0.8% standard

> 0.83% hyper eutectoid

Shd be >0.8%

Question 22

Properties of Austenite

Answer 22

Gamma iron(not a property but yes)
(Only can be seen at 723 degree celcius)

Solid of carbon in FCC
Very soft
Very ductile
Non magnetic

Question 23

Properties of Ferrite

Answer 23

Alpha iron

Solid of carbon in BCC
Very soft
Very ductile
Magnetic

Question 24

Properties of cementite

Answer 24

A compound, iron and carbon

Very hard
Brittle

Question 25

Properties of Pearlite

Answer 25

Stronger and harder than ferrite Tougher than cementite ALTERNATE LAYERS OF FERRITE AND CEMENTITE

Question 26

Effects of carbon content

Answer 26

When carbon increases, pearlite increases, UTS increases and hardness increases BUT Corrosion resistance, ductility and toughness, machinability and weldability decreases

Question 27

What type of steel has 0.05%-0.15% carbon, what is the properties and application

Answer 27

Dead mild steel, soft and ductile. rods, tubes, chain and car body

Question 28

What type of steel has 0.16%-0.30% carbon, what is the properties and application?

Answer 28

Mild steel, soft and ductile, ship plate, steel sections

Question 29

What type of steel has 0.31%-0.6% carbon, what is the properties and application?

Answer 29

Medium carbon steel, good combination strength and toughness, gears, crankshafts, axels, camshafts

Question 30

What type of steel has 0.61%-0.80% carbon, what is the properties and application?

Answer 30

High carbon steel, high strength, railway rails, wrenches, screw drivers

Question 31

What type of steel has 0.81%-1.40% carbon, what is the properties and application?

Answer 31

Carbon tool steel, high hardness & wear resistance, axes, files, chisels, drills