Aluminum 1100

Aluminum 1100 (UNS A91100) is a commercially pure aluminum with a minimum of 99.00% aluminum and a small, controlled copper addition of 0.05-0.20%. It’s the strongest of the 1xxx pure aluminum grades, and it offers excellent corrosion resistance, high thermal and electrical conductivity, a bright reflective finish and outstanding formability.

1100 isn’t heat treatable. Its strength comes only from cold work, so it’s supplied in the soft annealed O temper or in strain-hardened tempers from H12 through H18. In the annealed condition it can be deep drawn, spun, stamped and bent to tight radii without cracking, and it welds easily by all common methods. Its tradeoff is low strength, roughly 13 ksi tensile annealed and 24 ksi in full-hard H18, so it isn’t used for structural parts.

Typical uses include heat exchanger and fin stock, chemical and food processing equipment, spun hollowware and cooking utensils, reflectors, nameplates and dials, rivets, electrical parts, and general sheet metal work.

Tech Steel & Materials offers the alloy Aluminum 1100 in 3 sub-type specifications, each in multiple and customized shapes/forms:

• AMS QQ-A-225/1 (Bar, Rod or Wire)
• AMS QQ-A-250/1 (Plate or Sheet)
• WW-T-700/1 (Tubing)

Forming: 1100 has the best cold formability of any common aluminum alloy. In the O temper it can be deep drawn, spun, stretch formed, roll formed and bent flat on itself. It can be cold worked heavily without intermediate annealing, and it hot forges easily.

Machining: it’s soft and gummy in the annealed condition, so it machines best in the harder H14-H18 tempers. Use sharp tools with high rake angles, high speeds and plenty of lubricant to avoid built-up edge. Carbide and high-speed steel tooling both work well.

Welding: 1100 welds readily by GTAW, GMAW, resistance and gas welding, and it’s also easy to braze and solder. Use ER1100 filler when welding it to itself. To join 1100 to 6061 or other 6xxx alloys, ER4043 filler is the usual choice because it resists hot cracking. Welding anneals the heat-affected zone back to O-temper strength.

Finishing: it anodizes to a clear, uniform finish and responds well to chemical brightening and polishing, which is why it’s popular for reflectors and decorative parts.

Typical room-temperature properties by temper. These are typical values, not specification minimums.

Elongation ranges cover 1/16 in. sheet (lower value) to 1/2 in. round specimens (higher value). Fatigue strength is based on 500 million cycles.

1100 is often compared with 3003, the next step up in strength among non-heat-treatable alloys, and with 6061, the most common heat-treatable structural grade. Typical values are shown.