A code like 6063-T6 or 5052-H32 tells you two things: the alloy (its chemistry) and the temper (how it has been processed). Getting both right on a purchase order avoids most disputes over strength, bending and finish. This guide explains the wrought alloy series and the common temper codes used in Indian aluminium trade.
The four-digit alloy system
Wrought aluminium alloys use a four-digit number. The first digit shows the main alloying element. The full system is described under alloy designation system.
| Series | Main alloying element | Heat treatable? | Typical uses |
|---|---|---|---|
| 1xxx | none (99% or more aluminium) | No | foil, electrical conductors, chemical equipment, reflectors |
| 2xxx | copper | Yes | aerospace and high-strength machined parts |
| 3xxx | manganese | No | cookware, roofing, can bodies, heat exchangers |
| 4xxx | silicon | Mostly no | welding and brazing wire, brazing sheet cladding |
| 5xxx | magnesium | No | marine, tanks, truck bodies, pressure vessels |
| 6xxx | magnesium and silicon | Yes | extrusions, structures, windows, solar frames |
| 7xxx | zinc | Yes | high-strength structural and sports parts |
| 8xxx | other elements (for example iron, lithium) | Varies | foil (8011), some conductor and specialised alloys |
Commonly traded examples include 1050 for general sheet and foil, 3003 for utensils and roofing, 5052 for marine and tank work, and 6063 for architectural extrusions. In the 1xxx series the last two digits show minimum purity: 1050 means at least 99.50% aluminium.
Casting alloys use a different system (for example A356, LM6 or ADC12), so do not mix the two when writing a specification.
Temper codes
The temper is written after a hyphen. It describes how the metal was shaped, hardened or heat treated. See temper designation for a fuller reference.
- F (as fabricated): no controlled strain hardening or heat treatment. Properties are not guaranteed.
- O (annealed): fully soft, the lowest strength and best formability. Used for deep drawing and spinning, such as utensil circles.
- H (strain hardened): for non-heat-treatable alloys (1xxx, 3xxx, 5xxx). Strength comes from cold rolling.
- T (thermally treated): for heat-treatable alloys (2xxx, 6xxx, 7xxx). Strength comes from solution treatment and ageing.
Understanding H tempers
H tempers have two digits after the H. The first shows the process route; the second shows hardness, from 2 (quarter hard) to 8 (full hard).
- H1x: strain hardened only. H12 is quarter hard, H14 half hard, H16 three-quarter hard, H18 full hard.
- H2x: strain hardened, then partly annealed. H24 has similar strength to H14 but better formability.
- H3x: strain hardened, then stabilised by a low-temperature treatment. Used mainly for 5xxx alloys; 5052-H32 is a very common sheet temper.
Understanding T tempers
- T4: solution heat treated and naturally aged at room temperature. Moderate strength with good formability.
- T5: cooled from the hot working temperature (for example at the extrusion press) and then artificially aged. Common for 6063 window and door sections.
- T6: solution heat treated and then artificially aged for higher strength. 6061-T6 and 6063-T6 are widely specified.
- T651: T6 plus controlled stretching to relieve stress, which reduces distortion when the plate or bar is machined.
Using codes in a purchase order
- Always write alloy and temper together, for example 6082-T6, not just 6082.
- Name the standard you are buying to, such as an IS, ASTM or EN product standard, so mechanical property limits are clear.
- Ask for a mill test certificate showing chemistry and tensile results for the lot.
- If you will bend, draw or weld the material, tell the supplier. They may suggest a softer temper or a different alloy.
- Do not assume tempers are interchangeable. H14 and H24 may have similar strength but behave differently in forming.
Common mix-ups
Buyers sometimes order a heat-treatable alloy in a temper it cannot reach, or expect a non-heat-treatable alloy like 5052 to be available in T6. Others order 6061 when 6063 would extrude better and finish more cleanly. If in doubt, describe the end use and let suppliers propose options. For flat products, our sheet grades buying guide goes into more detail.
Sourcing on AluminumBazaar
When you post a requirement for sheets and coils or extrusions, include alloy, temper, size, tolerance and quantity. The sourcing desk gathers quotes from verified rollers and extruders and checks that the offered alloy and temper match your specification.