Engineering Materials Topic 2 - Metals

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Engineering MaterialsTopic 2 - Metals
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Topic 2- Metals and its properties

• Engineering metals
• Ferrous metals
• Non ferrous metals and alloys
• Heat treatment of metals and alloys
• Corrosion

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Topic 2- Metals and its properties

• Learning Objectives
• 1. List the various types of engineering metals,
  their properties, selection criteria and
  processes
• 2. State the properties of the ferrous materials,
  their applications and their fatigue
  characteristics

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Topic 2- Metals and its properties

• Learning Objectives
• 3. State the properties of the non ferrous
  materials, their applications and fatigue
  characteristics
• 4. Describe the iron-carbon phase diagrams,
  time-temperature transformation curves and heat
  treatment methods.

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Topic 2- Metals and its properties

• Learning Objectives
• 5. Describe the nature of corrosion, factors
  affecting corrosions, types of corrosions,
  corrosion characteristics and the methods of
  corrosion control

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Topic 2- Metals and its properties

• Engineering metals
• Major categories
• Ferrous
• Contain iron as major ingredient
• Nonferrous
• May contain small of iron

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Topic 2- Metals and its properties

• Engineering metals
• Selection criteria
• Applications
• Alloying to enhance properties
• Process
• Method of production influence properties

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Topic 2- Metals and its properties

• Ferrous metals
• Production of iron and steel
• Blast furnace ( Fig 2-1 Page 27)
• Open hearth convertor (Fig 2-2 Page 29)
• Bessemer convertor ( Fig 2-3 Page 30)
• Electric Arc Furnace ( Fig 2-4 Page 30)
• Oxygen lance convertor ( Fig 2-5 Page 31)
• Continuous pour process ( Fig 2-6 Page 32)

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Topic 2- Metals and its properties

• Ferrous metals
• Carbon content
• 0.05 -0.32 Low carbon
• 0.35 0.55 Medium carbon
• 0.6 1.50 High carbon
• gt 2 Cast iron
• Impact of carbon on steel

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Topic 2- Metals and its properties

• Ferrous metals
• Categorisation of steel
• SAE or AISI (Fig 2-7 Page 36)
• Alloys in steels
• Application of steels
• Properties of steels and cast iron (Table B1
  Page 462)

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Topic 2- Metals and its properties

• Ferrous metals
• Tool steels
• Classes of tool steels
• Compositions
• Cast iron
• Types of cast iron

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Light metals
• Aluminum
• Chromium
• Copper, brass and bronze
• Magnesium
• Nickel
• Others

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Aluminum
• Bauxite ore
• Production process (Fig 3-1 Page 51)
• Properties
• Corrosion resistant, lightweight, good
  conductivity and high reflectivity
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Aluminum alloys
• Numbering system (Fig 3-2 Page 52)
• Applications
• Wiring and conductors
• Cast aluminum engine components
• Headlights, light fixtures and insulations
• Paint pigment

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Chronium
• Chromite ore
• Production process
• Properties
• High corrosion resistant, high hardness and good
  alloy element
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Alloy element
• With ferrous metals, nickel and bronzes
• Applications
• Plating material
• Refractory metal

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Copper, brass and bronze
• Copper
• Sulfide ores and smelting process
• Electroplating process (Fig 3-4 Page 56)
• Properties
• High thermal and electrical conductivity
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Copper alloys
• Copper-zinc alloy is brass
• Improve strength, ductility and machinability
• Copper-tin alloy is bronze
• Improve strenght, hardness and ductility
• Compositions and applications (Table 3-1 Page 57)

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Magnesium
• Seawater
• Production process (Fig 3-7 Page 60)
• Properties
• Lightweight, active metal and good alloy element
• Table B-1, Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Magnesium alloys
• Numbering system (Fig 3-8 Page 61)
• Applications
• Anodes for protection
• Lightweight applications where strength is
  required, such as extension ladders, space
  vehicles, aircraft and power tools

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Nickel
• Sulfide ore
• Production process
• Properties
• Hard, corrosion resistant, a good alloy element
  and polishes well
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Nickel alloys
• Designation system (Fig 3-9 Page 63)
• Applications (Alloys)
• Plating material
• Magnets
• Heating elements and thermocouples
• Jewelry and coins

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Precious metals
• Gold
• Quartz ores
• Properties
• Electrical conductivity, corrosion resistance and
  malleability.
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Gold alloys
• Applications
• Jewelry
• Plating material
• Dental caps, crowns and fillings

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Precious metals
• Silver
• Argentite and horn silver
• Properties
• Excellent malleability, ductility and electrical
  conductivity.
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Applications
• Plating material for electrical conductors
• Jewelry
• Light-sensitive compounds for photographic
  materials
• Brazing alloys and long-life batteries

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Precious metals
• Platinium
• Nickel ores
• Platinium group
• Properties
• Corrosion resistance and high melting point
• Table B-1 Page 461

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Topic 2- Metals and its properties

• Non ferrous metals and alloys
• Applications
• Corrosion resistant coatings
• Laboratory equipment, medical instruments and
  fine jewelry
• Catalyst for many reactions
• High resistance wires for furnaces

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Heating and cooling operations to alter
  properties of material
• Changes in the microstructures possibly through
  the addition of other materials
• Heat treatment ovens, flame sources and induction
  heating are common methods used in heat treatment
• Different quenching media can be used to control
  the cooling rate

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Heat treatment allows us to produce many
  specialty products and enhance material
  properties to develop applications which would
  otherwise not be possible.
• Machine tool industry
• Aerospace program
• Automotive components

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Iron-Carbon phase diagram (Fig 4-1 Page 72)
• This diagram serves as the basis for the heat
  treatment of steels.
• It illustrates the phase changes that iron goes
  through, the effect of carbon content and the
  temperature required to initiate change.

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• BBC structure of Ferrite and Pearlite at low
  temperature
• Above 13330F, it changes structure to FCC
  Austenite
• Cooling rate will decide it converts back to
  Ferrite and Pearlite or a harder grain structure
  called Martensite (formed from the Pearlite
  portion)

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Microstructures of iron and steel (Page 76 86)
• Time-Temperature Transformation Curves
• The basis for all treatment of steels
• Fig 4-4 Page 87
• Ps, Pf, Ms Mf
• Critical cooling rate

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Heat treatment methods
• Methods of softening steels
• Normalising
• Heating to austenite range, and letting it remain
  there for 1 hour per inch of thickness, and
  letting it cool in still air at room temperature
• Good machinability

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Annealing
• Slow cooling of metal from the austenite
  temperature range
• Heated by 100C to 380C into the austenite range
  and held according to thickness
• Temperature is then slowly reduced (20C to 50C
  per hour until it passes the pf line)
• Full annealing, resulting in large uniform grain
  structure

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Other forms of annealing
• Box annealing
• Process annealing
• Spheroidizing
• Tempering

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Hardening of steels
• Quenching
• Simply a controlled cooling process
• Fig 4-6 Page 91
• Different quenching mediums
• Oil
• Water
• Brine

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Hardening of steels
• Tempering
• Reheating immediately after hardening to a
  temperature below transformation temperature and
  cooling it to increase the ductility and
  toughness of the steel
• Heated to between 3750C and 4300C and remain
  there depending on thickness, then allowed to cool

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Hardening of steels
• 3 types of tempering
• Martempering
• Austempering
• Isothermal quenching and tempering

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Hardening of steels
• Surface hardening
• Carburizing
• Placing low carbon steel in a high carbon
  atmosphere and heating into the red-heat range
• Fig 4-7 Page 93

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Hardening of steels
• Surface hardening
• Nitriding
• Same process as carbonizing but with nitrogen
  which have same effects
• Fig 4-8 Page 94

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Topic 2- Metals and its properties

• Heat treatment of metals and alloys
• Hardening of steels
• Surface hardening
• Cyaniding
• Carbonitriding
• Flame hardening and induction hardening
• Fig 4-9 Page 95

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Topic 2- Metals and its properties

• Corrosion
• Major category
• Dry corrosion
• Metal-gas reaction
• Wet corrosion
• Galvanic cell

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Topic 2- Metals and its properties

• Dry Corrosion
• Happen at ambient or elevated temperature
• Corrosion film a result of oxidation reaction
• Examples
• Alumina formation
• Ferrous oxide formation

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Topic 2- Metals and its properties

• Dry Corrosion
• Effects of alloys
• Effects of gases during production of metals
• Grey cast iron growth
• Nickel chromium alloys fractrure
• Nickel based alloys embrittlement
• Catastrophic oxidation

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Topic 2- Metals and its properties

• Wet Corrosion
• Galvanic Cell
• Anode
• Cathode
• Electrolyte
• Dissolved oxygen
• Galvanic series (Fig 2-9 Page 45)

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Topic 2- Metals and its properties

• Wet Corrosion
• Example of rusting metals
• Iron becomes ionised by losing 2 electrons
• and enters solution as ferrous ions
• Ferrous ions further oxidised to ferric ion
• At cathode, electrons are intercepted by
• oxygen atoms to form hydroxil groups
• Ferric ions combine with hydroxil groups to
  form ferric hydroxide which is rust

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Topic 2- Metals and its properties

• Wet Corrosion
• Examples
• Galvanised iron (zinc coated low carbon steel)
• Iron protected as long as zinc is present
• Tin coated iron
• Protection ends when coating is damaged
• Sealed cans protection

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Topic 2- Metals and its properties

• Wet Corrosion
• Types
• Uniform
• Preferential
• Crevice
• Galvanic
• Pitting

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Topic 2- Metals and its properties

• Wet Corrosion
• Types
• Intergranular
• Selective leaching
• Erosion
• Hydrogen damage
• Biological

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Topic 2- Metals and its properties

• Wet Corrosion
• Factors that affect corrosion mechanism
• Metal composition and structure
• Environmental surface defects
• Structural design
• Applied or internal stresses
• Temperature
• Aeration
• Chemistry of electrolyte

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Topic 2- Metals and its properties

• Wet Corrosion
• Corrosion protection
• Anodic protection
• Sacrificial anodes
• Anodic passivation
• Cathodic protection
• Inhibitors