Iron and Steel

Yangson Choi

Eunsoo An

Iron Ore

• Rock contains 30~70% of Fe

• Magnetite (Fe3O4), Hematite (Fe2O3).

• Also contains impurities C, S, P and Cu

• http://www.posco.co.kr/homepage/docs/kor/html/product/exper/s91c5000140c.html

• http://en.wikipedia.org/wiki/Iron_ore

Blast Furnace

• Iron Ore (Fe)

• Limestone (CaCO3)

• Coke (C)• Step 1 Heat Source and producing CO

– C + O2 → CO2 + 94.2kal

– C + 1/2O2 → CO + 26.5kal

– CH4 + 1/2O → CO + 2H2

– CO2 + C → 2CO

– H2O + C → H2 + CO

– http://www.posco.co.kr/homepage/docs/kor/html/product/exper/s91c5000110c.html

– IB Study Guides Chemistry, Geoffrey Neuss, Oxford pg 105.

• Step 2 Reduction of oxygen

– Fe2O3 + 3CO → 3CO2 + 2Fe Begins at 400°C

– FeO + CO → CO2 + Fe Begins at

700°C

– Fe3O4 + 4H2 → 4Fe + 4H2O

– Fe2O3 + 3C → 2Fe +3CO

– Fe becomes Pig Iron and CO2 escapes as form of Gas.

• Step 3 Limestone Flux (Reduce impurities)

– CaCO3 → CaO + CO2

– CaO + SiO2 → CaSiO3

– Also reduce Silica (SiO2), Alumina (Al2O3), Magnesia (MgO) or Calcia (CaO)

– CaSiO3 and etc forms ‘Slag’

– http://www.thepotteries.org/shelton/blast_furnace.htm

– IB Study Guides Chemistry, Geoffrey Neuss, Oxford pg 105

Conversion of Iron into Steel

• Scrap steel : Recycle, temperature control

• Limestone : Form Slag, reduce impurities

• Pig iron : Loose impurities

• Other elements : Make alloy

– http://www.posco.co.kr/homepage/docs/kor/html/product/exper/s91c5000110c.html

– IB Study Guides Chemistry, Geoffrey Neuss, Oxford pg 105.

• C + O2 → CO2

• P4 + 5O2 → P4O10

• Si + O2 → SiO2

• During this process other elements, such as chromium and nickels are also added to from the precise alloy required

– IB Study Guides Chemistry, Geoffrey Neuss, Oxford pg 106

Alloys

• Homogeneous mixture of metals, Or a mixture of metals and a non-metal.

• Their atoms have similar atomic radii and the crystal structure is not seriously disrupted

• Alter the physical properties

– IB Study Guides Chemistry, Geoffrey Neuss, Oxford pg 106

Heat treatment of steel

• Control heating and cooling of the steel to change the nature of the crystal structure in the steel.

• Change mechanical properties but not shape.

• Quenching– Cool rapidly– Very hard, high stress, very brittle

• Tempering– Heated to about 400~600°C and cool it slowly– More ductile, less stress, less brittle

• Annealing– Heated to about 1040°C – Most ductile, least stress, least brittle

– http://en.wikipedia.org/wiki/Tempering

– http://en.wikipedia.org/wiki/Annealing

Properties• Pure iron (C content < 0.035%)

– Good conductor, easily react• Parts of electronic machine, catalyst and alloy

• Steal (C content < 2.0%)– Strong, not much ductile

• Structural steel in buildings, machine, railroad track

• Carbon steel ( C content 2%~6.7%)– Very strong, brittle, cheep

• Tools, machine parts.– http://kin.naver.com/detail/detail.php?

d1id=11&dir_id=110202&docid=871431&qb=6rCV7LKg7J2YIOyiheulmA==&enc=utf8&section=kin&rank=1&sort=0&spq=0&pid=fpfkmloi5U4ssZZB5pVsss--302530&sid=SpSbhSVtlEoAABuefC8

• Stainless steel– Stainless, High oxidation-resistance– Alloys of iron, nickel, manganese, chrome and

tungsten• Knife, tableware, watch, cutlery, key, etc

– http://en.wikipedia.org/wiki/Stainless_steel

– http://www.posco.co.kr/homepage/docs/kor/html/product/exper/s91c5000110c.html