3003 is the easy-forming, general-purpose aluminum sheet. It bends, spins and draws without fuss, welds easily and resists weather well. It is not strong, and it is not meant to be. It shows up in trim, ductwork, tanks and, most visibly, as the bright diamond tread plate on toolboxes, trailers and truck beds. We source 3003 sheet and tread plate and arrange the cut.
What 3003 aluminum is
3003 is a 3xxx-series alloy, which means manganese is the main alloying element, at roughly 1.2%, with a little copper. The manganese makes it noticeably stronger than commercially pure 1100 aluminum while keeping nearly the same formability and corrosion resistance.
It is not heat treatable. Like 5052, its tempers come from cold work at the mill, shown by the "H" code.
3003-H14 properties
| Property | Value | What it means in the shop |
|---|---|---|
| Tensile strength | 22 ksi typical | Light duty; not for structural members |
| Yield strength | 21 ksi typical | Dents and bends easily under load |
| Hardness | About 40 Brinell | Soft; scratches easily in handling |
| Density | 0.099 lb/in³ (2.73 g/cm³) | Similar weight to other common alloys |
| Weldability | Excellent | Very forgiving to TIG and MIG |
| Machinability | Poor | Gummy; fine to drill and trim, not for machined parts |
| Corrosion resistance | Very good | Handles weather well; 5052 is better in salt water |
Typical values for H14. Softer and harder tempers vary.
Typical uses
- Diamond tread plate for toolboxes, trailer fenders, steps and truck beds
- Ductwork, hoods, flashing and trim
- Tanks, liners and cookware
- Deep-drawn and spun parts
- Sign backs and general sheet-metal work where strength does not matter
Common tempers and finishes
H14 is half hard and the most common sheet temper. O is annealed, for spinning and deep drawing. H16 and H18 are harder, used where a bit more stiffness is wanted and forming is light.
Diamond tread plate in 3003 is commonly supplied in H22 temper with a bright finish, which is the shiny tread you see on truck toolboxes. Tread is also made in 6061 when a stronger walking surface is needed; see aluminum diamond tread plate for the options.
3003 vs 5052 aluminum
5052 is the step up. It is noticeably stronger, holds up better in salt water, and still bends well. 3003 forms even more easily and is softer to work, which matters for spinning, drawing and hand-formed trim. For a toolbox, fender or step that takes abuse, 5052 or 6061 tread gives more dent resistance; for cosmetic tread and light trim, 3003 does the job.
| 3003-H14 | 5052-H32 | |
|---|---|---|
| Tensile / yield (typical) | 22 / 21 ksi | 33 / 28 ksi |
| Forming | Excellent | Very good |
| Salt-water corrosion | Good | Excellent |
| Dent resistance | Low | Moderate |
| Common tread plate temper | H22, bright | Less common in tread |
Welding and machining 3003
3003 is one of the easiest aluminums to weld. 4043 or 1100 filler both work, and 5356 is fine when joining it to 5xxx alloys. Thin sheet warps easily, so tack often and keep heat input down. On tread plate, clean the bright surface well; the rolled pattern holds oil and dirt.
It is too soft for real machining. Drilling, punching, shearing and routing are all fine with sharp tools and some lubricant. Anything that needs tolerance and a machined finish should be 6061.