3xxx Aluminum Coil: Where 3003 and 3105 Fit.

What defines the 3xxx series?

Aluminum alloy designations use four digits. The first digit identifies the alloy series, and for the 3xxx series the main alloying element is manganese. The Aluminum Association keeps the registry of designations and composition limits, published as the Teal Sheets. As listed there, 3003 is a manganese alloy with copper additions and 3105 is a manganese alloy with magnesium additions.

The alloys in this series cannot be hardened by heat treatment. They gain strength by cold work such as cold rolling, and the H temper designation records how the strain hardening was done, and that is why temper designations matter so much on a coil order.

Where do 3003 and 3105 sit among Orbit's alloys?

Orbit rolls 1050, 1100, 3003, 3105, 5005, 5052 and 5754. The 3xxx pair sits between the commercially pure 1xxx alloys and the magnesium-based 5xxx alloys. Strength values differ between series and depend on temper and gauge, so compare the tables of the standard on your order in the same temper. That is why the comparison table below asks questions instead of ranking alloys.

When does a 3xxx alloy fit?

A reasonable starting rule: consider 3xxx when the part is formed by roll forming or bending, when commercially pure aluminum would be too soft for the use, and when the finished surface will be coated. Orbit supplies coil for rolling shutters, roofing, gutters and downspouts, cladding, ACP, signage, license plates and truck and trailer panels. For each, the alloy should be checked against your specification, and the existing guides on roll forming and roofing and gutters set out the questions in detail.

The rule is a starting point, not a ruling. A tight bend radius or a large flat panel can move the answer toward a different temper or alloy.

When should you look at 1xxx or 5xxx instead?

If the part needs the formability and surface of commercially pure aluminum, read the 1xxx guide. If the part needs more strength than a 3xxx alloy offers in a workable temper, read the guide to the 5xxx alloys. For a head-to-head view of 3105 and 3003, see the mechanical properties comparison.

One caution applies to flat panels. The elastic modulus of the aluminum alloys is nearly the same, so changing alloy does not by itself make a panel stiffer. Gauge, panel size, support spacing and stiffening features govern deflection.

Why does temper matter for 3xxx coil?

Because these alloys are not heat treatable, temper records the cold work and any thermal treatment applied. The O temper is annealed. The H tempers carry more cold work as the second digit rises, which raises strength and lowers formability. A strength value without its temper is incomplete, since the same alloy appears in several tempers with different values.

The alloy and temper guide explains how to read the designations, and the datasheet reading guide shows how to tell a requirement from a typical value.

How do you check a 3xxx delivery against the order?

1. Read the alloy, temper, thickness and width on the coil tag and on the certificate, and compare each with the purchase order line.
2. Compare the reported chemistry with the composition limits for the designation, and the reported mechanical properties with the requirement in the standard the order names.
3. Match the lot reference on the certificate to the tag on each coil.
4. Record any difference, with a photo of the tag, before the coil is cut, coated or formed, and send it to the supplier.

The certificate guide explains how to read each field.

What belongs on the order?

State the alloy, temper, thickness and width, and name the standard you work to, such as ASTM or EN depending on your market. Ask for the alloy and temper to appear on the mill test certificate so the delivery can be checked against the order. If the temper is open, give the forming operation and bend radius and ask the supplier to propose a temper against them.

Alloy and coating are separate decisions, so settle the coating system and finish in the same request. A short note on exposure and panel size is enough for Orbit to reply with questions rather than guesses.

Common questions

References

• The Aluminum Association: International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys (Teal Sheets): the registry of designations and composition limits.
• Orbit rolled aluminum coil: the alloys and thickness range Orbit rolls.