Unit 6a

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Questions and Answers

What is the primary benefit of continuous casting compared to ingot casting?

It requires fewer materials.

It increases productivity significantly. (correct)

It reduces the need for molds.

It is a more discrete process.

Steel ingots can weigh up to approximately 300 tons.

True

Name the two main casting processes used in steelmaking.

Casting of ingots and continuous casting

The _____ process requires 10-12 hours for the casting to solidify.

ingot casting Signup and view all the answers

Match the following characteristics with their corresponding casting processes:

Casting of ingots = Discrete production process Continuous casting = Semi-continuous process Molds made of high carbon iron = Used in both casting methods Solidification time reduction = Key advantage of continuous casting Signup and view all the answers

What is the primary raw material used in the Basic Oxygen Furnace (BOF) process?

Pig iron and scrap Signup and view all the answers

Coke is a byproduct of the electric arc furnace process.

False Signup and view all the answers

What is the main purpose of blowing pure oxygen in the Basic Oxygen Furnace?

To burn off impurities from molten pig iron. Signup and view all the answers

The _____ is responsible for about 70% of steel production in the U.S.

Basic Oxygen Furnace (BOF) Signup and view all the answers

Match the steel production methods with their characteristics:

Basic Oxygen Furnace (BOF) = Uses pig iron and pure oxygen Electric Arc Furnace = Uses scrap iron and stainless steel Blast Furnace = Uses iron ore and coke Slag Formation = Byproduct that removes impurities Signup and view all the answers

Which process is noted for producing better quality steel but at a higher cost?

Electric Arc Furnace Signup and view all the answers

What is the typical tap-to-tap time for a Basic Oxygen Furnace cycle?

Approximately 45 minutes. Signup and view all the answers

Slag formation is a beneficial process in steelmaking.

True Signup and view all the answers

What is pig iron primarily composed of?

Iron and carbon Signup and view all the answers

Wrought iron contains a higher percentage of carbon than pig iron.

False Signup and view all the answers

What is the temperature reached at the core of the blast furnace during pig iron production?

almost 1600 degrees C Signup and view all the answers

To create a ton of pig iron, _____ tons of ore are needed.

2 Signup and view all the answers

Which of the following materials is added to the blast furnace to aid in the production of pig iron?

Coke Signup and view all the answers

Match the following iron types to their characteristics:

Pig Iron = Hard and brittle, high carbon content Wrought Iron = Malleable and ductile, low carbon content Steel = Strengthened alloy with controlled carbon content Cast Iron = Cheap and easily moulded Signup and view all the answers

Adding chromium to steel enhances its resistance to corrosion.

True Signup and view all the answers

What is the primary advantage of using steel over iron?

Improved strength Signup and view all the answers

Study Notes

Metal Industry: Iron and Steel

Metals are derived from rocks called ore.
Hematite (Fe₂O₃) is the primary iron ore.
Other iron ores include magnetite (Fe₃O₄), siderite (FeCO₃), and limonite (Fe₂O₃-xH₂O).
Iron ores typically contain 50% to 70% iron, with hematite containing almost 70%.
Scrap iron and steel are also used as raw materials in iron and steel making.

Types of Metals

Ferrous Metals: Based on iron.
- Steels
- Cast irons
Non-Ferrous Metals: All other metals.
- Aluminum, magnesium, copper, nickel, titanium, zinc, lead, tin, molybdenum, tungsten, gold, silver, platinum, and others
- Superalloys

Steel Production

Iron Making: Iron is reduced from its ores.
Steel Making: Iron is refined to obtain desired purity and composition (alloying).
Steel: An iron-carbon alloy with 0.02% to 2.1% carbon.
Cast Iron: An iron-carbon alloy with 2.1% to about 4% or 5% carbon.
Steels and cast irons can also contain other alloying elements besides carbon

Blast Furnace

A refractory-lined, tall chamber (9-11m diameter, 40m height).
Ore, Coke, and Limestone are added at the top.
Hot air is blown into the furnace near the bottom to cause chemical reactions, generating heat.
Carbon dioxide (CO₂) reacts with carbon (from coke) to form carbon monoxide (CO), which is then used to reduce iron ore to molten iron.
Molten iron collects at the bottom and is removed periodically.
Impurities combine with limestone to form molten slag, which is also removed and cooled.
The process produces pig iron.

Pig Iron

Raw iron in ingot form, mostly iron with 4-5% carbon.
Cheap and easily moulded, used for drainpipes and engine blocks.

Wrought Iron

A refined form of pig iron with low carbon content (~0.3%).
Malleable, bendable, weldable, and easy to work with.
Used for tools, horseshoes, etc.

Steel

An alloy of iron with controlled carbon content (0.5% to 1.5%).

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Higher strength than iron.
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Used in buildings, infrastructure, tools, ships, and other applications.

Other elements are added to improve properties.

Steel Types

Alloy steels, tool steels, and stainless steels are produced with other elements added to improve properties and performance. -Example: Stainless steels need 11% chromium to resist corrosion and oxidation.

Pig Iron vs. Steel

Pig iron contains more than 2% carbon, is brittle, cannot be easily rolled or welded.
Steel contains less than 2% carbon, is stronger, can be rolled and welded.

Steel Production Processes

1. Iron Making: Raw materials (iron ore, coke, and limestone) are melted in a blast furnace.
2. Steel Making: Molten metal from the blast furnace is treated in a basic oxygen furnace (BOF) or electric arc furnace, adjusting its composition.
3. Steel Forming: Steel is shaped into various products using hot rolling and other techniques.
4. Manufacturing: Completed steel products are further processed.
5. Fabrication: The steel is further manipulated and shaped.
6. Finishing: Final finishing, quality control and packaging of the final product.

Casting Processes

Casting of Ingots: Steel is solidified into discrete ingots.
Continuous Casting: A semi-continuous process where steel is solidified into a continuous shape, and then cut into desired lengths.

Furnaces

Basic oxygen furnace (BOF): A widely used furnace in steel production that accounts for about 70% of American Steel production.
Electric Arc Furnace (EAF): Used to melt scrap and produce high-quality alloy steels (accounts for ~30% of US Steel production)

Other Raw Materials

**Coke:** Made from coal, supplies heat and carbon monoxide (CO) for iron reduction.

**Flux:** (limestone and dolomite), used to collect impurities and form slag.

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Description

This quiz explores the foundational concepts of the metal industry, focusing on iron and steel production. Learn about various iron ores, the types of metals, and the processes involved in steel making. Test your knowledge on ferrous and non-ferrous metals as well as steel alloy compositions.