Transcript Combined Blow v. Nitriding

EDSGN Kick Off Meeting – 2/27/2012
Steelmaking Basics and Project Overview
R. Zellers
Steelmaking Process Map - Iron
Steelmaking Process Map - Refining
Basic Oxygen Furnace – Raw Materials
Fluxes
Coolant
Fuel
BOF - Reactions
• Decarburization
2C + O2  2CO (reaction occurs in bath, CO to off gas)
2CO + O2  2CO2 (reaction occurs above bath, CO2 to off gas)
• Silicon Oxidation
Si + O2  SiO2 (reaction occurs in bath, SiO2 to slag)
• Manganese Oxidation
Mn + O2  MnO
• Aluminum Oxidation
4Al + 3O2  2Al2O3 + HEAT!
Chemistry of “Open” Steel
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C 0.04%
Mn 0.1%
Cr 0.01%
Cb 0.00%
Al 0.00%
BOF – Order of Reactions – Ellingham Diagram
Cr: 1/2
C + O2  CO2
Energy
Mn: 1/3
Si: All
Al: All
Ca: All
Temperature
Alloying – Why & Where?
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Aluminum – Deox, aluminum-nitride grain refining
Carbon – Strengthener
Calcium – Inclusion modification, castability
Chrome – Hardening, corrosion resistance
Columbium (Niobium) – Grain refining
Manganese – Strengthener, heat treatment hardening
BOF during tap – Good mixing, allows for “settling”
Ladle met facility – Greater control
Alloy Calculation
Example: LCAK Mn addition
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Aim: 0.5%
Already in steel from BOF: 0.1%
Needed from alloy: 0.4%
Heat Size: 440,000 lb
HC Mn: 78% Mn, 90% Recovery (note: “pure alloy” in project)
Calculation: (0.4% Mn/steel) * (440,000 lb steel) = 1760 lb Mn
(1760lb Mn) / (78% Mn/HC Mn * 90% Recovery) = 2500 lb HC Mn
Project
Part 1 – No Off Chemistries
• Separate advanced high strength steel (AHSS) from scrap autos
• Use mix of AHSS and low carbon aluminum-killed (LCAK) scrap
to make LCAK heat
Part 2 – Cost Savings
• Utilize AHSS scrap to make line pipe heat
• Calculate addition alloys needed