L12 Material Codes

Question 1

What is the main, first distinction made among industrial materials?

Answer 1

Ferrous metals (iron-based) and Non-ferrous (all the others)

Question 2

Why are ferrous alloys the most common engineering material?

Answer 2

• Iron ores are relatively abundant
• Relatively economical extraction and fabrication
• Versatile material and alloys of wide range of properties can be made

Question 3

What are the two main types of ferrous alloys?

Answer 3

Cast irons and Steels

Question 4

What is a steel, what is the typical carbon content in steels?

Answer 4

They are Iron-Carbon alloys with usually <1.4% wt. carbon

Question 5

What is the typical carbon content in Cast Irons?

Answer 5

They are Iron-Carbon alloys with usually 3 - 4.5% wt. carbon

Question 6

Plain carbon steels

Answer 6

Fe + C + Mn
ONLY (no other deliberate additions)

Question 7

Alloy steels

Answer 7

Fe + C + Mn + other additions

Question 8

Classification of Steels

Answer 8

Steel –> Low Alloy, High Alloy
Low Alloy –> Low-carbon (plain or high strength, low alloy), medium-carbon (plain or heat treatable), high-carbon (plain or tool)
High Alloy –> (tool or stainless)

Question 9

Classification of Cast Irons

Answer 9

Cast Irons:
* Gray iron
* Ductile (nodular) iron
* White iron
* Malleable iron
* Compacted graphite iron

Question 10

Iron & Steel Production

How is Iron and Steel produced?

Answer 10

• Iron Oxide (Fe₂O₃) ores + Carbon Monoxide (3CO) –> Pig Iron 4% C (2Fe) + Carbon Dioxide (3CO₂)
  PIG IRON FROM BLAST FURNACE
• From this liquid Pig Iron (4% wt carbon), we can proceed to steel making, or use it as a cast iron at this higher wt %. (pig iron can be refined into cast iron, and must oxidize carbon [remove gas and slag] to get steel)
• Basic Oxygen System - produce steel by blowing oxygen onto the molten metal, to adjust carbon content
• Molten steel (0.2-1.2 % carbon) is continuously cast and hot worked

Question 11

What is slag?