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ME 140 - WORKSHOP TECHNOLOGY

Introduction Classification Ferrous Metals Non Ferrous Metals

ME – 140 WORKSHOP TECHNOLOGY FALL 2009 Instructor Asst. Prof. Ejaz Yaqub Asst. Prof. Rizwan Arshad Lecture 1 – Part II – Engineering Materials Department of Mechanical & Aerospace Engineering Institute of Avionics & Aeronautics (IAA) AIR University, E-9 Islamabad

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ME 140 - WORKSHOP TECHNOLOGY Introduction • Engineering materials are used to manufacture products Introduction • Type of material decides the kind of manufacturing

process that will be used to get the desired shape

Classification • It is important to know what kind of materials are available Ferrous Metals

• Material Properties - physical, chemical, mechanical, thermal, optical, electrical etc

Non Ferrous • A design engineer must have knowledge of engineering Metals

materials, their properties and applications to meet the functional requirements of the design product

• Additionally, one must understand the effects of manufacturing processes and heat treatment on the properties of the engineering materials 2

ME 140 - WORKSHOP TECHNOLOGY Examples of products in different Engg. Materials

Introduction Classification Ferrous Metals

[Stainless steel rods, Salem Steel Trading Co, India]

[Malleable cast iron pipe fittings , SDH China]

Non Ferrous Metals

[Pure Aluminum Pellets, EPSI Metals, Oregon, USA]

[Pure Copper wire] 3

ME 140 - WORKSHOP TECHNOLOGY Examples of products in different Engg. Materials

Introduction Classification Ferrous Metals

[Plastic bottles]

[A section of yew branch of wood]

Non Ferrous Metals

[Glass]

[Ceramic tiles] 4

ME 140 - WORKSHOP TECHNOLOGY Materials Classification

Introduction Classification Ferrous Metals Non Ferrous Metals

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ME 140 - WORKSHOP TECHNOLOGY Iron (Fe) • Ferrous materials have iron as their main constituent • Pure Iron is a soft metal having crystalline structure Introduction Classification Ferrous Metals Non Ferrous Metals

• Microstructure of pure iron looks like a map having fields separated by hedges Shape looking like fields Line like hedges

- Crystals - Where crystals join

• Average size of crystal – depends upon the metal treatment Crystal

Crystal boundary [Schematic diagram. Microstructure of pure iron] 6

ME 140 - WORKSHOP TECHNOLOGY Occurrence • Iron is found naturally in the form of ores • Iron ores chiefly exist in the form of oxides and carbonates Introduction Classification

• Iron ores are cleaned from earthly impurities before processed for getting iron

Ferrous Metals Non Ferrous Metals

[Main types of Iron Ore]

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ME 140 - WORKSHOP TECHNOLOGY Iron Ores

Introduction Classification Ferrous Metals

[Hematite (blood ore) from the US state of Michigan]

[Limonite]

Non Ferrous Metals

[Magnetite from the Kola Peninsula, Russia]

[Siderite from Poland] 8

ME 140 - WORKSHOP TECHNOLOGY Production of Ferrous Materials Ore Blast Furnace

Introduction

Smelting, Reduction Cupola

Classification

Reverberatory Furnace Puddling

Remelt Bessemer Converter

Ferrous Metals Non Ferrous Metals

Pig Iron

Cast Iron

Open Hearth Arc Furnace

Electric

Wrought Iron

High Frequency Furnace Remelt Crucible Steel

Steel for general use

Blister Steel Forge Shear Steel

Tool Steel

[Diagram showing production of the materials in the iron and steel group] 9

ME 140 - WORKSHOP TECHNOLOGY Main Types of Iron Pig Iron

Introduction Classification

Cast Iron

Ferrous Metals Non Ferrous Metals

Wrought Iron

Plain Carbon Steels

Dead Carbon steels Grey cast iron White cast iron

Low Carbon steels Medium Carbon steels

Alloy Steels

High speed Stainless

High Carbon steels Ductile cast iron Malleable cast iron

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ME 140 - WORKSHOP TECHNOLOGY Pig Iron (Carbon Content 3.5% – 4.5%) • Smelting and reduction of iron ore is carried out to produce pig iron in a tall structure call Blast furnace Introduction Classification Ferrous Metals

• Blast furnace is charged with ore, small quantities of coke and lime stone • Coke provide fuel – provides heat necessary to reduce iron oxide to iron • Limestone serves as flux – combines with

Non Ferrous nonmetallic part to produce slag Metals

• Hot air is blown into lower portion via the tuyeres • Slag over molten iron is tapped of from the hole and molten iron from hearth

[Blast Furnace]

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ME 140 - WORKSHOP TECHNOLOGY Pig Iron (Carbon Content 3.5% – 4.5%) • Molten pig iron can be further used in following ways ƒ Cast in pig beds ƒ Cast in pig casting machine ƒ Transferred in hot metal ladles direct to an Introduction adjacent steelmaking process Classification • Pig iron acts as the raw material for production of all

kinds of cast iron and steel products

Ferrous Metals Non Ferrous Metals

[Foundry pig iron. Courtesy: Hui Cheng, China]

[Double Strand Pig Casting Machine at Maryland Pig Co..] 12

ME 140 - WORKSHOP TECHNOLOGY Types of Pig Iron (on the basis of combined and free form of carbon) • Introduction Classification

Grey pig iron (Grades 1, 2 & 3) - soft type of pig iron ƒ ƒ

•

Ferrous Metals Non Ferrous Metals •

Approx. 3% carbon in free form (i.e., graphite form) Approx. 1% carbon in combined form

White pig iron - hard and strong ƒ

(Grades 4)

Contains almost all of the carbon in the combined form

Mottled pig iron (Grade 5) - average hardness and mottled appearance ƒ ƒ

Between the grey and white pig iron The free and combined forms of carbon are in almost equal proportion in mottled pig iron 13

ME 140 - WORKSHOP TECHNOLOGY Cast Iron • Cast iron is basically an alloy of iron and carbon Introduction

• Obtained by re-melting pig iron with coke, limestone and steel scrap in a furnace known as Cupola

Classification • Carbon content in cast iron varies from 2% – 4.5% Ferrous Metals

• Impurities of silicon, manganese, phosphorus and sulphur elements are present

Non Ferrous • Properties Metals ƒ Very brittle and weak in tension

ƒ Low cost, good casting characteristics, ƒ High compressive strength, high wear resistance ƒ Excellent machinability

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ME 140 - WORKSHOP TECHNOLOGY Producing Cast Iron

Introduction

• Obtained by re-melting pig iron with coke, limestone and steel scrap in a furnace known as cupola • Coke fire is lit first at the bottom.

Classification Ferrous Metals

• Cupola is charged by adding alternate layers of coke and pig iron along with limestone • Pig iron is mixed with a set proportion of iron and steel scrap

Non Ferrous Metals • Proportion depends upon the desired quality of melt

• When charge has burnt up, the blast is gradually increased and the cupola is closed • Iron melts and sinks to the bottom of the furnace 15

ME 140 - WORKSHOP TECHNOLOGY

Introduction Classification Ferrous Metals Non Ferrous Metals

[A cupola furnace in operation at Wayne State University, in Detroit, Michigan]

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ME 140 - WORKSHOP TECHNOLOGY Grey Cast Iron

Introduction

• Grey cast iron is grey in colour due to the carbon being in the form of graphite (C in free form in iron) • Produced in cupola furnace by refining pig iron • Composition

Classification Ferrous Metals Non Ferrous Metals

C Si Mn P S Fe

= = = = = =

2.5 to 3.8%. 1.1 to 2.8 % 0.4 to 1.0% less than 0.15% less than 0.1% Remaining

[Typical structure of grey cast iron] 17

ME 140 - WORKSHOP TECHNOLOGY Grey Cast Iron •

Introduction Classification Ferrous Metals Non Ferrous Metals

Properties 1. 2. 3. 4. 5. 6. 7.

When fractured it gives grey color. Easily casted Easily machined Lowest melting of ferrous alloys. High vibration damping capacity. High resistance to wear. High fluidity and hence can be casted into complex shapes and thin sections. 8. High compressive strength. 9. Low tensile strength. 10. Low ductility and low impact strength as compared with steel

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ME 140 - WORKSHOP TECHNOLOGY Grey Cast Iron • Introduction Classification Ferrous Metals Non Ferrous Metals

Applications 1. Machine tool structures such as bed, frames, column 2. Household appliances etc 3. Gas or water pipes for under ground purposes. 4. Man holes covers 5. Piston rings 6. Rolling mill and general machinery parts 7. Cylinder blocks and heads for I.C. engines 8. Frames of electric motor 9. Ingot mold 10. General machinery parts 11. Sanitary wares 12. Tunnel segment

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ME 140 - WORKSHOP TECHNOLOGY White Cast Iron • White color - carbon in combined form as iron carbide • Hardest constituent of iron • Produced by casting against metal chills or by regulating Introduction analysis • The chills are used when a hard and wear resistance surface is desired for products such as for wheels, rolls crushing jaw, Classification crusher plates Ferrous Metals Non Ferrous Metals

• Composition

C Si Mg P S Fe

= = = = = =

3.2 to 3.6% 0.4 to 1.1 % 0.1 to 0.4% less than 0.3% less than 0.2% Remaining

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ME 140 - WORKSHOP TECHNOLOGY White Cast Iron •

Introduction Classification Ferrous Metals Non Ferrous Metals

Properties 1. Freshly broken surface shows a bright white fracture 2. Very hard due to carbon chemically bonded with iron as iron carbide (Fe3C) 1. Brittle 2. Excellent abrasive wear resistance 3. Extremely hard, therefore it is very difficult to machine 4. Solidification range is 2650-2065°F 5. Shrinkage is 1/8 inch per foot 6. High tensile strength 7. Low compressive strength

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ME 140 - WORKSHOP TECHNOLOGY White Cast Iron • Introduction Classification Ferrous Metals

Applications 1. For producing malleable iron castings 2. For manufacturing those component or parts which require a hard, and abrasion resistant surface such as rim of car 3. Railway brake blocks

Non Ferrous Metals

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ME 140 - WORKSHOP TECHNOLOGY Ductile Cast Iron • Small quantities of magnesium or cerium added to cast iron • Graphite content is converted into spheroidal or nodular form Introduction • It is well dispersed throughout the material Classification Ferrous Metals Non Ferrous Metals

• Composition

Carbon Silicon Magnesium Nickel Manganese Iron

= = = = = =

3.2 to 4.2% 1.0 to 4.0 % 0.1 to 0.8% 0.0 to 3.5% 0.5 to 0.1% Remaining

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ME 140 - WORKSHOP TECHNOLOGY Ductile Cast Iron •

Introduction Classification

Properties 1. High fluidity 2. Excellent castability, strength, 3. High toughness, excellent wear resistance 4. Pressure tightness, 5. Weldability and higher machinability in comparison to grey cast iron.

Ferrous Metals Non Ferrous Metals

[Ductile cast iron (Ferritic matrix), Courtesy: Toa Koki Ko Ltd. Japan] 24

ME 140 - WORKSHOP TECHNOLOGY

Introduction Classification Ferrous Metals Non Ferrous Metals

[(a) Schematic diagram of spheriodal cast iron (b) Ductile iron microstructure at 100x. Note carbon islanding effect around nodules, Courtesy: Apex Metal Co Ltd.] 25

ME 140 - WORKSHOP TECHNOLOGY

Introduction Classification Ferrous Metals Non Ferrous Metals

[Comparison among Grey, White and Spherodidal Cast Iron] 26

ME 140 - WORKSHOP TECHNOLOGY Malleable Cast Iron • Introduction • Classification

•

A malleable metal is one easily spread or flatten under pressure or hammering Produced by White heart and Black heart process Name given due to colour of fracture given by castings produced by each method

Ferrous Metals Non Ferrous Metals

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ME 140 - WORKSHOP TECHNOLOGY Malleable Cast Iron • White heart - Castings consisting of all carbon in combined form are packed in iron or steel boxes Introduction Classification

- These boxes are surrounded with a mixture of new and used haematite ore - Boxes heated from 900 to 950 deg. C

Ferrous Metals Non Ferrous Metals

- Temperature maintained for several days - During this time part of carbon is oxidised and remainder is dispersed in small specks through out the structure - Heating period is followed by very slow cooling for several days - Resulting casting is tough and can withstand hard treatment without fracture 28

ME 140 - WORKSHOP TECHNOLOGY Wrought Iron • Produced in a reverberatory furnace • Wrought iron is produced by Puddling process Introduction Classification Ferrous Metals Non Ferrous Metals

• Puddling leads to the oxidation of nearly all carbon and other elements from pig iron • Furnace hearth is lined with iron oxide, grey pig iron, and and millscale (oxide) are fed into it • Slag is formed when melting is complete • Slag is stirred into the melt and more millscale is added • This leads to the oxidation of carbon and other elements • After oxidation the iron becomes stiffer and pasty in form 29

ME 140 - WORKSHOP TECHNOLOGY Producing Wrought Iron • Assumed approximately as purest iron - 99.5% iron. • Contains a large number of minute threads of slag lying parallel to each other giving the metal a fibrous appearance Introduction when broken. • Said as a mechanical mixture of very pure iron and a silicate slag. Classification • Also be said as a ferrous material, aggregated from a solidifying mass of pasty particles of highly refined metallic Ferrous iron with which a minutely and uniformly distributed quantity Metals of slag is incorporated without subsequent fusion. Non Ferrous • Composition Metals C = 0.02 – 0.03% P = 0.05 – 0.25% Si = 0.02 – 0.10% S = 0.008 – 0.02% Mn = 0.0 – 0.02% Slag = 0.05 – 1.5% Fe = remainder 30

ME 140 - WORKSHOP TECHNOLOGY Producing Wrought Iron

Introduction Classification Ferrous Metals Non Ferrous Metals

[Reverberatory Furnace for producing wrought iron] 31

ME 140 - WORKSHOP TECHNOLOGY Wrought Iron

Introduction Classification Ferrous Metals Non Ferrous Metals

The microstructure of wrought iron, showing dark slag inclusions in ferrite (iron) 32

ME 140 - WORKSHOP TECHNOLOGY Wrought Iron • Properties 1. Easily shaped by hammering, pressing, forging, etc. 2. It is never cast and it can be easily bent when cold. 3. It is tough and it has high ductility and plasticity Introduction 4. Forged and welded easily. High resistance towards corrosion. Classification 1. It can accommodate sudden and excessive shocks loads 2. High resistance towards fatigue Ferrous 3. Ultimate tensile strength - 2,500 kg/cm2 - 5,000 kg/cm2 Metals 4. Ultimate compressive strength - 3,000 kg/cm2. 5. Can be elongated considerably by cold working. Non Ferrous 6. High electrical conductivity. Metals 7. Melting point - 1530°C. 8. It has elongation 20% in 200 mm in longitudinal direction and 2–5 % in transverse direction. 1. Its poison’s ratio is 0.30. 2. It can be easily formed when cold, without the outer side cracking at the formed portion. 33

ME 140 - WORKSHOP TECHNOLOGY Wrought Iron • Applications

Introduction

1. Making chains, crane hooks, railway couplings, 2. Water and steam pipes. 3. Plates, sheets, bars, structural works etc.

Classification Ferrous Metals Non Ferrous Metals

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ME 140 - WORKSHOP TECHNOLOGY Steel • Alloy of iron and carbon - carbon content max. upto 1.5% • Upto 1.5 %Carbon occurs in the form of iron carbide having the ability to increase hardness and strength of the steel Introduction • Steels are classified as, Classification • Plain Carbon Steel • Alloy Steels Ferrous Metals Non Ferrous Metals

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ME 140 - WORKSHOP TECHNOLOGY Plain Steels

Introduction

• Dead Mild steel • Carbon content – 0.1 -0.125 % • Applications: wire rod, thin sheets, solid drawn tubes etc.

• Mild Steel • Carbon content – 0.15 – 0.3 % Classification • Applications: boiler plates bridge work, structural sections Ferrous Metals

• Medium Carbon Steel • Carbon content – 0.3 – 0.5 % Non Ferrous • Applications: axles, drop forgings, high tensile tubes Metals

• Carbon content – 0.5 – 0.7 % • Applications: springs, locomotive tyres, , hammers etc • Carbon content – 0.7 – 0.9 % • Applications: shear blades, wood chisels etc. 36

ME 140 - WORKSHOP TECHNOLOGY Plain Steels • High Carbon Steel (Cast Steel, Carbon Tool Steels)

Introduction Classification Ferrous Metals

• Carbon content – 0.9 – 1.1 % • Applications: cold chisels, press dies, punches, screwing dies, wood working tools • Carbon content – 1.1 – 1.4 % • Applications: razors, hand files, drills, gauges, metal cutting tools

Non Ferrous Metals

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ME 140 - WORKSHOP TECHNOLOGY Alloy Steels • High Speed Steel (HSS)

Introduction

• 18% tungsten, 4% chromium and 1 % vanadium, 0.8 carbon and remaining iron.

Classification

• Name given since these steels can be operated as cutting tools at high speeds

Ferrous Metals

• Cutting tool speed is 2 to 3 times higher than HCS cutting tool

Non Ferrous Metals

• Steels have the property of retaining their hardness even when heated to red heat • Generally used for making lathe cutting tools, planner cutting tools, shaper cutting tools, slotting cutting tools, drills, reamers, broaches, milling cutter and punches. 38

ME 140 - WORKSHOP TECHNOLOGY Alloy Steels • Stainless Steel

Introduction Classification Ferrous Metals

• Contains chromium together with nickel as alloy and rest is iron • Minimum chromium content of 12% for film formation • 18% is sufficient to resist the most severe atmospheric corrosive conditions

Non Ferrous Metals

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