CE 1201 Properties of Materials

Introduction to Materials Science

• Materials science is the foundation of all technological advancements
• Understanding materials and their applications is crucial for engineers
• Choosing the right material for a specific application is vital

Evolution of Engineering Materials

• No specific details provided

Classification of Engineering Materials

• Metals and Alloys: Steel, Cast Iron, Aluminum, Zinc, Copper, Brass, Bronze
• Ceramics and Glasses: Alumina, Magnesia, Silica, Silicon Carbide, Silicon Nitride
• Polymers: Polyethylene, Polystyrene, Polyvinylchloride, Epoxies, Natural Rubber, Wood
• Semi Conductors: Silicon, Germanium, Gallium Arsenide
• Composites: Concrete, Plywood, Fiberglass

Properties of Materials - Metals and Alloys

• Metals are composed of metallic elements and non-metallic elements in small amounts
• Atoms in metals are arranged in a very orderly manner and are relatively dense
• Metals show good mechanical properties and have large numbers of nonlocalized electrons
• Many properties of metals are directly attributable to these electrons
• Pure metals are low in strength and do not possess the required physiochemical and mechanical properties
• Alloys are made by melting or sintering two metals or metal and a non-metal

Ferrous Metals and Alloys

• Ferrous metals are metals that contain iron as their base constituent
• Iron imparts magnetic properties and makes them prone to corrosion
• Examples: Wrought iron, Cast iron, Steel
• Non-ferrous metals do not have iron in their composition and do not possess magnetic properties
• Examples: Copper, Aluminum, Zinc

Pig Iron Manufacturing Process

• Selection of ore: Hematite, Magnetite, Limonite, Siderite
• Calcinations, Roasting, and Smelting
• Reduction of impurities in a blast furnace
• Production of pig iron

Properties and Uses of Pig Iron

• Brittle
• Hard
• Not machinable at room temperature
• Used in producing wrought iron, cast iron, and steel

Wrought Iron

• Ferrous metal with very low carbon content (0-0.2%)
• Produced in a puddling furnace
• Has high ductility and corrosion resistance
• Used in producing gates, furniture, and home décor items

Steel

• Produced by refining pig iron
• Can be plain carbon or alloyed with less than 2% carbon
• Has good tensile strength, elasticity, and weldability
• Used in building, structural work, cutlery, and edge tools

Cast Iron

• Produced by melting pig iron with some scrap in a Cupola Furnace
• Has 2-4% carbon content
• Exists in three different forms: White cast iron, Gray cast iron, and Malleable cast iron
• Used in producing machine parts, bed plates, and drain covers

Gray Cast Iron

• Formed by slowly cooling molten iron
• Has high carbon and silicon levels
• Has a gray fractured surface due to the presence of graphite
• Has good compressive strength, but less tensile strength and shock resistance
• Used in cookware, electrical boxes, and disc brake rotors

White Cast Iron

• Formed by rapidly cooling molten iron
• Has low carbon and silicon levels
• Has a white fractured surface due to the presence of cementite
• Has high compressive strength, hardness, and abrasion resistance
• Used in teeth of a backhoe's digging bucket, coal pulverisers, and grinding mills

Malleable Cast Iron

• Formed by heat treating white cast iron to convert cementite into graphite nodules
• Has a lower carbon percentage than other cast iron
• Used in producing washers and other machinery parts### Properties and Uses of Malleable Cast Iron
• Malleable cast iron is a very tough iron that is machinable and ductile.
• Its properties make it suitable for:
  • Parts that are to be pierced, coined, or cold formed
  • Parts requiring maximum machinability
  • Parts requiring wear resistance
  • Parts that must retain good impact resistance at low temperatures

Ferrous Alloys

• Ferrous alloys are alloys that contain iron as their base constituent.
• Examples of ferrous alloys include:
  • Silicon steel
  • Tungsten steel
  • Stainless steel

Silicon Steel

• Silicon steel is an alloy of iron and silicon with important electrical applications (e.g. motors, transformers, etc.).
• It is commonly referred to as electrical steel.
• Silicon additions improve magnetic softness and increase electrical resistivity.
• Properties:
  • High electrical resistivity
  • Improved magnetic properties
• Uses:
  • Electrical motors
  • Transformers
  • Power generators

Tungsten Steel

• Tungsten steel is an alloy consisting of tungsten (W), steel, and traces of carbon.
• It has a series of excellent properties, including:
  • High hardness
  • High wear resistance
  • High strength
  • High toughness
  • High heat resistance
  • Corrosion resistance
• Uses:
  • Drill bits
  • Boring cutters
  • Saw blades

Stainless Steel

• Stainless steel is an alloy of steel that contains a minimum of 12% chromium.
• The chromium addition results in producing a thin layer of oxide on the surface of the steel, known as the 'passive layer', which prevents corrosion.
• Increasing the amount of chromium gives increased resistance to corrosion.
• Properties:
  • High strength
  • Corrosion resistant
  • Less electrical conductivity
• Uses:
  • Cookware
  • Surgical equipment
  • Civil engineering constructions
  • Jewelry and watches

Non-Ferrous Metals and Alloys

• Non-ferrous metals and alloys are metals that do not have iron in their composition.
• They do not possess any magnetic properties.
• Examples of non-ferrous metals and alloys include:
  • Copper
  • Aluminium
  • Zinc
  • Brass
  • Bronze

Non-Ferrous Metals

• Copper:
  • Properties:
    • High thermal and electrical conductivity
    • High ductility
    • High malleability
    • Slow corrosion rate
  • Uses:
    • Electric wires and cables
    • Electroplating
    • Electronics and related devices
    • Architectural material
• Aluminium:
  • Properties:
    • High strength to weight ratio
    • Low yield strength
    • Good thermal and electrical conductivity
    • Ductile, malleable, and easily machinable
  • Uses:
    • Vehicle bodies of automobiles and aircraft
    • External facades of buildings
    • Packaging cans
    • Cookware
• Zinc:
  • Properties:
    • Hard
    • Brittle
    • Fair conductor of electricity
    • Relatively low melting point
  • Uses:
    • Galvanizing steel
    • Producing alloys (e.g. brass, bronze)
    • Paint
    • Batteries

Non-Ferrous Alloys

• Brass:
  • Properties:
    • Corrosion resistance
    • Malleable
    • Relatively low melting point
    • Tough
    • Relatively high tensile strength
  • Uses:
    • Ornaments
    • Nuts and bolts
    • Musical instruments (e.g. trumpet)
    • Locks
    • Ammunition casing
• Bronze:
  • Properties:
    • Ductile
    • Relatively high tensile strength
    • Low melting point
    • Resistance to corrosion by seawater
    • Low friction
  • Uses:
    • Bearings and clips
    • Hammers, mallets, wrenches
    • Sculptures