Can 6061-T6 aluminum be bent?
Yes, at a generous radius. 6061-T6 sheet needs an inside bend radius of about 1.5-3 times the thickness and cracks on tighter bends; form in O or T4 and age afterwards when the design needs sharp corners.
6061-T6 is a fully aged, moderately ductile alloy with about 12% elongation in sheet, and that limits how tightly it bends. The rule of thumb on a press brake is an inside radius of 1.5x thickness on sheet up to about 1.6 mm (0.063"), rising to 2-3x thickness on 3-6 mm (1/8-1/4") plate, with the bend axis across the rolling direction where possible. Try to put a sharp, 1t bend in T6 and the outer surface cracks along the bend line, sometimes visibly, sometimes as a fine orange-peel tear that fails later in service. 5052-H32 bends at roughly 1t, which is why sheet-metal shops prefer it for boxes and brackets and use 6061 where strength or machining matters more than forming.
When the part needs both T6 strength and a tight bend, change the sequence. 6061-O (annealed) bends at 0-1t and 6061-T4 at about 1-1.5t; form the part in one of those tempers, then solution treat (if from O) and artificially age to T6. Aging T4 to T6 is about 8 hours at 175 °C (350 °F) with little distortion; a full solution treatment from O involves a 530 °C (985 °F) soak and a water quench, which warps thin sheet and needs fixturing. Forming T4 and aging is the common compromise on aircraft and vehicle parts. T4 stock has a shelf life: it ages naturally at room temperature and gets less formable over weeks, so form it soon after purchase or after re-solution treatment.
Springback is larger than on steel because the modulus is a third as high: expect 8-15° on T6 at a 2t radius and plan for overbend or bottoming. Bend deduction tables for steel do not apply; ask the shop for their K-factor (about 0.40-0.45 for T6 at 2t). Bending across a machined pocket, a weld or a heat-affected zone concentrates strain and cracks first. Grain direction matters more than on most metals: a bend with its axis parallel to the rolling direction can crack at a radius that is fine across it.
Press Brake Forming for 6061 parts: where to send them
What to specify
- Temper at forming and temper at delivery: "form in T4, age to T6" or "bend in T6 at 2t minimum radius", never just "6061"
- Inside bend radius on every bend, at 1.5-3t for T6 depending on thickness; call out the direction relative to grain when it matters
- Bend angle tolerance, typically +/-1°, and flatness of flanges; expect springback allowances to be worked out by the shop
- Bend relief and minimum flange length (at least 4t plus the radius) so the brake tooling can hold the part
- Cosmetic faces: state which side may show tooling marks; ask for urethane film or a polished V-die on visible surfaces
- Post-forming operations and their sequence: weld, machine, age, anodize
Pitfalls
- Sharp inside corners on T6: 1t or less cracks the outside of the bend; open the radius or change the temper
- Bending along the grain: same radius, same alloy, cracks along the bend where the cross-grain bend was fine
- Springback surprises: the flat pattern and K-factor for steel or 5052 give the wrong angle and length on 6061
- T4 stock that has sat on the shelf for months has naturally aged and bends more like T6 than the data sheet says
- Welding after forming softens the bend region and the weld zone; both become the weak points in T6
- Bending through a hole or slot edge within about 2t of the bend line distorts the feature and tears from it
Frequently asked questions
- What is the minimum bend radius for 6061-T6?
- About 1.5x thickness on thin sheet under 1.6 mm (0.063"), 2x on 3 mm (1/8") and 3x or more on 6 mm (1/4") plate, bending across the grain. Tighter radii crack. 6061-O bends at 0-1t and T4 at about 1-1.5t.
- Is 5052 or 6061 better for bending?
- 5052-H32 bends at about 1t, welds without a strength penalty and is the default sheet-metal aluminum. 6061-T6 is stronger and machines better but needs 1.5-3t radii. Choose 5052 for formed boxes and brackets, 6061 for machined or heavily loaded parts.
- Can I anneal 6061 to bend it and then re-harden it?
- Yes. Anneal to O at about 415 °C (775 °F), form, then solution treat at about 530 °C (985 °F), quench and age at 175 °C (350 °F) for 8 hours to T6. The quench distorts thin parts, so forming in T4 and aging only is the usual route.
