Lecture 1-Eng Materials and Iron and Steel Making

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Industrial & Management Engineering Department

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Objectives1. To understand the meaning of manufacturing

process

2. To identify the types of manufacturing processes

3. To be aware of the principles of each production process

4. To identify the products produced by each process

5. To recognize the types and properties of engineering materials and select it for a certain product.

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Objectives (cont.)6. To know how iron and steel are produced and used.

7. To be aware of the different methods and techniques used in metal joining, principles and characteristics of each method.

8. To understand the principles of dimensional measurement, tools used in industrial measurements and how to determine the dimensions of a product.

9. To identify the elements of industrial cost and to know how to determine the production cost, volume and profit.

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Contents

Engineering MaterialsIron and Steel

CastingForming

MachiningWelding

Dimensional measurementsIndustrial cost analysis

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Reading Resources

1. Lecture Notes2. E.P. De Garmo, Materials and processes in

manufacturing, 8th Ed. , Prentice Hall, 1997, ISBN 0-02-328621-0

3. S. Kalpakjian, Manufacturing Processes for Engineering Materials, 4th Ed., Prentice Hall, 2003, ISBN 0-13-045373-0.

4. W.A.J. Chapman, Workshop Technology, part1, 5th Ed. E. Arnold limited, 1981, ISBN 0 7131 3287 6.

5. W.A.J. Chapman, Workshop Technology, part2,5th Ed. E. Arnold limited, 1979, ISBN 0 7131 3291 4.

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Marking Scheme

• 1st Exam. 7th week 30 marks• 2nd Exam. 12th week 20 marks• Final Exam. 16th week 40 marks• Cont. Assessment 10 marks

total 100 marksAttendance is mandatoryWorkshop is attended with white coat.Workbook should be at hand at workshop.

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CONTENTS

1. Definition of manufacturing2. Engineering Materials3. Nature of materials

Atomic Structure and the Elements• Atom – the basic unit of matter• Nucleus and electrons

Bonding between Atoms and MoleculesCrystalline StructuresNon-crystalline (Amorphous) Structures

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How to select materials for a specific product?

Car page 37

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Classification of Materials Properties

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Comparison of Engineering Materials Properties

Density Mechanical Strength

Ductility High Temp. stability

Metals High Medium High Good

Plastics Low Low Very High (thermoplastic)

Low (thermoset)

Not good

Ceramics Medium High Low Very good

Composites Low High Medium Not good

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Crystal Structure of materialsCrystals Atoms arrange themselves into various ordered configuration, called crystals.

Crystalline structure.The arrangement of the atoms in the crystal is called crystalline structure.

Unit cellThe smallest group of atoms showing the characteristic lattice structure of a particular metal is known as a unit cell.

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Crystal Structure of Metals

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Metallic materials• Ferrous

– Steel– Alloy steel– Cast iron

• Non- Ferrous– Aluminum– Copper– Gold– Silver– Lead , etc

Wrought IronPure iron is called wrought iron

Melting temperature = 1539 oC

Ductile

Crystalline unit

• BBC α iron

• FCC γ iron

• BCC δ iron

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Steel (Plain Carbon steel)

• It is an iron-carbon alloy• Has high ability for plastic deformation.• Has less than 2 % carbon of its weight• Called “Plain Carbon Steel” if it has some alloying elements.• Types:

1.Low carbon steel: < 0.25% C – structural steel.2.Medium Carbon Steel: 0.25% to 0.6% C – machine

parts for its good mechanical properties.3.High Carbon Steel: 0.6% to 0.9% C – high hardness

and wear resistance.4.Tool Steel: >0.9% C - cutting tools (drills,

tapes, milling tools, etc., ….)

0.9 2.00.60.25

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Alloy steelUndesired impurities in carbon steel: Sulphur – phosphorous –oxygen –nitrogen.Some elements are added to carbon steel to improve its mechanical properties such as chrome , tungsten, nickel, manganese.Types:

1. High strength structure steel: 0.1% (titanium, vanadium and boron )

2. Chrome steel : high wear resistance and refractory steel

3. Nickel-chrome steel: Stainless steel4. Manganese steel: High wear resistance.5. Tungsten steel: Tool steel (High speed steel HSS).

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Cast IronIron-carbon alloy has >2% carbon.Has low relatively melting temperature.Preferred in casting operations.

Types:1. White cast iron:

carbon is united with iron in form of iron carbide - high brittleness – no industrial applications.

1. Grey cast iron: carbon is found in form of flacks – low hardness – used in manufacturing of machine structure.

1. Malleable cast iron:high impact resistance – made of white Cast iron that is heat treated.

1. Spheroid cast iron: ductile, strong - heat treated cast iron with magnesium

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Non ferrous materials• Aluminum:

– Aluminum• melting temperature = 658 oC.• Crystalline cell: FCC• Has good rust resistance – light in weight.• Used in manufacturing of electric cables.

– Aluminum alloys: • Wrought alloys – Casting alloys.• Used in manufacturing of ships, air crafts

• Copper– Copper :

• melting Temp.= 1083 oC - FCC – used in making electric cables.– Copper alloys:

1. Brass: copper + tin2. Bronze : copper + zinc3. Aluminum bronze : copper + aluminum

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The process of manufacturing iron from iron ore is called iron making.Iron is produced in a blast furnace

• Materials used in manufacturing Pig iron:1. Iron ore

(magnetite, hematite, contains up to 70% iron)iron oxides with earth impurities;

2. Cokereducing agent and fuel, providing heat for melting the metal and slag.

3. LimestoneCalcium silicate fluxes, forming a fluid slag

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The top of the furnace is equipped with the bell-like or other system, providing correct charging and distribution of the raw materials (ore, coke, limestone).

Air heated to 2200°F (1200°C) is blown through the tuners at the bottom.

Oxygen contained in air reacts with the coke, producing carbon monoxide:

2C + O2= 2COHot gases pass up through the descending materials, causing

reduction of the iron oxides to iron according to the following reactions:

3Fe2O3 + CO = 2Fe3O4 + CO2Fe3O4 + CO = 3FeO + CO2

FeO + CO = Fe + CO2

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The ore and coke are mixed by fluxes, forming slag which is capable to absorb the impurities.

The furnace is periodically tapped and the melt (pig iron) is poured into ladles, which are transferred to cast iron and steel making furnaces.

Pig iron usually contains 4 - 6.7% of carbon,2-4% of silicon, 1-2% of manganese and 1-1.2% of phosphorous.

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INCOMING

• Iron ore (0.5 – 1.5 “)• Pellets (lower iron

content ore)• Sinter (fine ore, small

coke, fine limestone)• Coke• Limestone (flux)• Hot blast (hot air)

Oxygen

OUT-COMING

• Pig Iron (molten)• Slag• Blast Furnace Gas

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Cast iron is an alloy of iron, containing up to 4% of carbon.

It is usually produced by cupola furnace.

Cupola is similar to the blast furnace.

The liquid cast iron is periodically (or continuously) removed through a spout.

Pig Iron (solid), coke and limestone flux are charged by means of an opening located in the upper half of the steel shell.

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Steel is an alloy of iron, containing up to 2% of carbon(usually up to 1%). 

Steel is produced from pig iron (liquid) by processes, involving reducing the amounts of carbon, silicon and phosphorous. 

The main steel making methods are:1. Basic oxygen furnace (basic oxygen converter) 

2. Electric‐arc furnace.

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The converter is capable to rotate about its horizontal axis, for charge loading and pouring the steel out of the converter.

The converter is equipped with the water cooled oxygen lance for blowing oxygen into the melt.

The oxygen converter uses no additional fuel.

The pig iron impurities (carbon, silicon, manganese and phosphorous) serve as fuel.

The oxygen converter has a capacity up to 400 ton and production cycle of about 1 hour.

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The electric-arc furnace employs 3 vertical carbon rodsas electrodes for producing arcs.

The heat, produced by the arcs, causes oxidizing phosphorous, silicon & manganese.

The oxides are absorbed into the slag.

By the end of the stage the slag is removed.

The function of this slag is refining of the steel from sulfur and absorption of oxides, formed as a result of de-oxidation.

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Unlimited scrap quantity may be melt

Easy temperature control

Deep sulfur refinement

Precise alloying