22 Materials and heat treatment revision

Materials and Heat Treatment Revision

Material Classification

  • Metallic

    • Pure metals

    • Alloys

  • Non-metallic

  • Composites

  • Natural Materials

  • Thermoplastics

  • Thermosetting Plastics

  • Ceramics

Range of Materials and Their Applications

  • Cast Iron

  • Carbon and Alloy Steels

  • Stainless Steel

  • Aluminium

  • Aluminium Alloys

  • Copper

  • Brass

  • Bronze

  • Lead

  • Nylon

  • PVC

  • Perspex

  • Rubber

  • Wood

  • Glass

  • Glass Fibre

  • Epoxy Resins

  • Carbon Fibre

Forms of Supply

  • Sheet

  • Forgings

  • Plate

  • Pipe

  • Bar

  • Tube

  • Wire

  • Hot Rolled

  • Section

  • Cold Rolled

  • Extrusions

  • Castings

  • Wrought

Factors to Consider

  • Available forms of supply

  • Cost

  • Properties

  • Application

  • Manufacturing Capabilities

  • Material Reactivity

Material Properties

  • Ductility

    • Ability to be drawn out like wire

  • Malleability

    • Ability to be hammered into shape

  • Hardness

    • Resists scratching or denting

  • Toughness

    • Resists repeated bending or shock loading

  • Strength

    • Ability to support heavy loads

  • Brittleness

    • Breaks suddenly without much distortion

  • Plasticity

    • Maintains new shape after loading

  • Elasticity

    • Returns to original shape after loading

  • Conductivity

    • Conducts heat/electricity easily

  • Dielectric Strength

    • Resists flow of heat/electricity

Effects of Heat Application on Material Properties

  • Ductility

    • Increases

  • Malleability

    • Increases

  • Hardness

    • Decreases

  • Toughness

    • Decreases

  • Strength

    • Decreases

  • Brittleness

    • Decreases

  • Plasticity

    • Increases

  • Elasticity

    • Decreases

  • Conductivity

    • Increases

  • Dielectric Strength

    • Decreases

Suitability of Material Properties for Different Purposes

  • Thermal/Electrical Conductivity

  • Thermal/Electrical Resistance

  • Wear Resistance

  • Corrosion Resistance

  • Load Bearing Capacity

  • Shear Strength

  • Weight

  • Cost

Types of Heat Treatment

  • Hardening

    • Rapid cooling makes the material harder and more brittle

  • Tempering

    • Heated then air cooled – increases material toughness and strength

  • Annealing

    • Heated then cooled at a controlled rate – reverses work hardening, makes material more ductile

  • Normalising

    • Similar to annealing but cooled faster – increases material ductility and decreases hardness

Assessment Details

  • You may bring notes

  • Please bring your own pen!

  • We will start at 10:30

  • Good luck :)