9.4 - Property Suitability

Question 1

What are the types of carbon steel?

Answer 1

High carbon
Medium carbon
Low carbon (mild steel)

Question 2

What’s the carbon % in steel?

Answer 2

<1.8%

Question 3

What’s the carbon % in grey cast irons?

Answer 3

3.2-3.5%

Question 4

What are low carbon steels?

Answer 4

Cheapest and most widely used group of steels, they’re the weakest by still stronger than most non-ferrous metals and alloys, can be easily hot / cold worked

Question 5

Uses of low carbon steels?

Answer 5

Pressing out panels for car bodies and general sheet-metal applications

Question 6

What are medium carbon steels?

Answer 6

Harder, tougher, more expensive and stronger than low carbon steels, but less ductile and can’t be bent when cold without risk of cracking (greater force needed too)

Question 7

Low carbon steel carbon %?

Answer 7

<0.3%

Question 8

Medium carbon steel carbon %?

Answer 8

0.3-0.6%

Question 9

How to toughen low carbon steels?

Answer 9

Heating and quenching with water, they cannot be hardened

Question 10

Uses of medium carbon steels?

Answer 10

Crank shafts, forgings, axles (mechanically stressed components)

Question 11

What is high carbon steel?

Answer 11

Hardest, strongest, and most expensive steel, but less tough than medium carbon steel, available as hot rolled bars or forgings

Question 12

High carbon steel carbon %?

Answer 12

> 0.6%

Question 13

High carbon steel uses?

Answer 13

Cold drawn wire (piano wire)

Used to make chisels, cutting tools and drill bits

Question 14

What’s the effect of carbon on iron?

Answer 14

0% carbon - v high duct, low hard, lower strength

0. 9% - v high strength, high hard, v low
1. 4% - slightly lower strength, slightly higher hard, low duct

Question 15

Properties of copper?

Answer 15

High strength
Very ductile (cold worked, annealed stretch twice length)
Corrosion resistant
Good conductor

Question 16

Uses of copper?

Answer 16

Electrical conductors and switchgear components (second only in conductivity to silver)
Copper powders used for sintered components

Question 17

Non ferrous metals and metal alloys?

Answer 17

Copper
Brass (alloy)
Tin bronze (alloy)
Aluminium
Zinc

Question 18

Properties of brass?

Answer 18

Alloy of copper and zinc
Properties based on amount of zinc, dezincification occurs in sea water, so tin is added
Brass castings are coarse grained and porous

Question 19

How to machine brass?

Answer 19

Depends on hot rolling from cast ingots, then cold rolling to give mechanical strength

Question 20

Properties of tin bronze?

Answer 20

Alloy of copper and tin
They have deoxidising agent to prevent tin from oxidising during casting and hot working (becomes scratchy), agents include zinc in gun metal alloys

Question 21

Properties of Aluminium?

Answer 21

1/3 as dense as steel
Much weaker, strength/weight ratio weaker
Good conductor
Corrosion resistant, but not marine environments

Question 22

Uses of aluminium?

Answer 22

Stressed components, eg on aircrafts (alloys)

Question 23

Commercial aluminium?

Answer 23

Contains 1% silicon to improve stiffness and strength, loses qualities as a result

Question 24

Use of tin bronze?

Answer 24

Castings