Aluminum

• Aluminum


  The most plentiful metal on Earth, representing 8% of its crust. Although plentiful, it exists primarily as oxides.
• Aluminum is second only to steel in terms of production.
• Characteristics of Aluminum

  1. One-third the density of steel
  2. Good thermal and electrical conductivity
  3. High strength-to-weight ratio
  4. Can be given a hard surface by anodizing and hard coating
  5. Has alloys that are weldable
  6. Will not rust
  7. High reflectivity
  8. Can be die cast
  9. Easily machined
  10. Good formability
  11. Non-magnetic
  12. Non-toxic
• Casting Methods

  • Sand casting
  • Permanent mold casting
  • Die casting
• Forming Methods

  • Extrusion
  • Rolling
  • Roll forming
  • Brake forming
  • Cutting operations
  • Embossing
  • Drawing
  • Superplastic forming
• Uses of Aluminum

  1. It is used to make door and window frames.
  2. Aluminum structural members are becoming popular.
  3. Aluminum wires are used as conductors of electricity.
  4. It is used as a foil.
  5. Aluminum powder serves as pigments in paint.
• Two Types of Aluminum Alloys

  1. Wrought
  2. Cast alloys
• Alloying Elements


  Enhance the physical properties of aluminum for specific purposes creates these alloys.
• Alloying Elements:

  • None
  • Copper
  • Manganese
  • Silicon
  • Magnesium
  • Magnesium and Silicon
  • Zinc
  • Other elements
  • Unused series
• Welding requires that the tough oxide coating on aluminum be broken and kept from reforming during welding.
• Arc welding is generally performed in the presence of an inert gas that shields the weld from oxygen in the atmosphere.
• Two common processes by which aluminum's welded are:

  • Gas Metal Arc Welding, GMAW
  • Gas Tungsten Arc Welding, GTAW
• GMAW process, the filler wire also serves as the electrode.
• GTAW uses a tungsten electrode and a separate filler wire.
• Fastening

  • Bolts can be either aluminum or steel.
  • Rivet fasteners are made of aluminum and are cold driven.
• Both bolt and rivet joints are designed based on the shear strength of the fastener and the bearing strength of the material being fastened.
• The alloys used for airplanes are usually given extra protection by painting or “cladding” with a thin coat of a corrosion-resistant alloy
• Painting is generally not needed for medium-strength alloys used for structural applications.
• Galvanic corrosion occurs when aluminum is in contact with any of several metals in the presence of an electrical conductor, such as water
• The best protection for this problem is to break the path of the of the galvanic cell by painting, using an insulator, or keeping the dissimilar metals dry.