Aluminum

It is appropriate to briefly note at this stage some of the basic characteristics of wrought aluminum alloys that make them desirable candidates for a wide range of applications. Wrought alloys are addressed first, then cast alloys. Corrosion Resistance. As a result of a naturally occurring tenacious surface oxide film, many aluminum alloys provide exceptional resistance to corrosion in many atmospheric and chemical environments. Alloys of the 1xxx,3xxx,5xxx, and 6xxxsystems are especially favorable in this respect and are even used in applications where they are in direct contact with seawater and antiskid salts.

Thermal Conductivity. Aluminum and aluminum alloys are good conductors of heat, and while they melt at lower temperatures than steels, approximately 535 °C (1000 °F). They are slower than steel to reach very high temperatures in fire exposure.

Alloy Designation System – Wrought Alloys

• First digit – Principal alloying constituent(s)
• Second digit – Variations of initial alloy
• Third and fourth digits – Individual alloy variations (number has no significance but is unique)
  • 1xxx – Pure Al (99. 00% or greater)
  • 2xxx – Al-Cu Alloys
  • 3xxx – Al-Mn Alloys
  • 4xxx – Al-Si Alloys
  • 5xxx – Al-Mg Alloys
  • 6xxx – Al-Mg-Si Alloys
  • 7xxx – Al-Zn Alloys
  • 8xxx – Al+Other Elements
  • 9xxx – Unused series

Alloy Designation System — Casting Alloys

• First digit -Principal alloying constituent(s)
• Second and third digits – Specific alloy designation (number has no significance but is unique)
• Fourth digit – Casting (0) or ingot (1,2) designation
• Variations indicated by preceding letter (A,B, C)
  •  lxx.x – Pure Al (99.00% or greater)
  • 2xx.x – Al-Cu Alloys
  • 3xx.x – Al-Si + Cu and/or Mg
  • 4xx.x – Al-Si
  • 5xx.x – Al-Mg
  • 7xx.x – Al-Zn
  • 8xx.x – Al-Sn
  • 9xx.x – Al+Other Elements
  • 6xx.x – Unused Series

Tempers Designation System

• F – As-fabricated
• 0 – Annealed
• H – Strain-hardened (wrought products only)
• W- Solution heat-treated
• T – Thermally treated to produce tempers other than F,O,H (usually solution heat-treated,quenched and precipitation hardened)