3. OUTLINE
INTRODUCTION
TYPES OF STEEL
PROCESS OF STEEL MAKING
1. Basic Oxygen Furnace (BOF)
2. Electric Arc Furnace (EAF)
3. Secondary steelmaking
4. INTRODUCTION
Steel is recyclable and hence is a “green
material”
Steels are alloys of irons and others
elements
Henry Bessemer (1813-1898) was the first
one developed process steel making
inexpensively
5. TYPES OF STEEL
Depending upon the
percentage of carbon
There are 3 types of steel
are: carbon steel, stainless
steel (inox) and alloy steel
6. BASIC OXYGEN FURNACE (BOF)
Be a method of primary
steelmaking
Carbon-rich molten Pig
iron (MPI) steel
(low-carbon steel)
converter
7. BOF PROCESS
1. Filling the furnace with the
ingredient
• Charging scrap steel into the
vessel, followed by hot metal
2. Blowing oxygen:
• Blowing high purity oxygen at
high pressure
3. Charging the fluxes:
• Forming slag
• May adding alloy
8. BOF PROCESS
4. Sampling and temperature
measurement
Sampling: checking the chemical
content of the steel
5. Tapping the steel
Tapping the slag out the container
Modern
BOS
vessel
about 40
minutes
350
tons of
steel at
a time
9. ELECTRIC ARC FURNACE (EAF)
Heating charged material by means of an electric arc
Being used to produce special quality steels (steels alloyed
with other metals)
Being charged with "cold" material, normally steel scrap
Mills producing steel (EAF technology ) “mini-
mills”
Making 150 tonnes in each melt (90 minutes)
10.
11. EAF PROCESS
Similar to BOF process
Some basic differences:
BOF process
• Using iron ore
• Self-sufficient in energy
• High in the capital
investment costs
EAF process
• Using scrap
• Using the heat
generated by arc
• Investment costs
lower than BOF
proccess
14. OBJECTIVES OF SECONDARY STEEL MAKING
De-oxidation => Removal of Oxygen
Desulphurization => To sulfur concentrations as low as
0.002%
Alloying => Addition of alloying elements
Micro cleanliness => Removal of nonmetallic inclusions
Inclusion morphology => Changing the composition of
remaining impurities to improve the microstructure of the
steel
Superheat control => +/- 5 degree C
16. AOD (ARGON OXYGEN DECARBURIZATION) PROCESS
A process primarily used
in stainless steel making
High grades alloys with
oxidizable elements:
chromium and aluminum
17. AOD PROCESS
The metal will be transferred to an AOD vessel after
initial melting.
The metal will also be subjected to three steps of
refining:
- Decarburization
- Reduction
- Desulphurization
18. CLU (CREUSOT-LOIRE-UDDEHOLM) PROCESS
Be similar to AOD process for making
stainless steels
Use liquid from an electric arc (EAF)
Use superheated steam as the diluting gas
instead of argon (Ar) gas
Be a mixture of oxygen, steam, argon,
nitrogen and air is blown from the bottom
19. CLU PROCESS
The steam presence: control the temp around 1650-
1680*C
The steam dissociates in the steel, so H2: Ar (AOD
process) and O2: a refining medium
This process helps: control steel bath temperature and
take heat from the steel bath.
Whilst a typical integrated (i.e. BOF-route) steel mill today costs ~$1100 per tonne of installed capacity, a medium-size EAF-route mini-mill today costs under $300 per tonne in terms of the initial capital outlay.
