Key takeaways
- 1050 is 99.5% minimum aluminium with 85 MPa yield in H14 and about 30 MPa in O, so it is a corrosion and conductivity grade, not a structural one.
- Bend 1050-O at 0.5–1t and 1050-H14 at about 1–1.5t; a 90° bend at 1t in H14 stretches the outer fibre about 33% against 8–20% elongation, so a tight radius in H14 is a crack risk and the O temper is the safe route.
- Mill thickness tolerance on 1.0 mm 1050 sheet is typically ±0.06–0.10 mm, which is wider than the ±0.5 mm part tolerance we hold and has to be allowed for in the flat pattern.
- A 1050 weld in H14 loses its work hardening in the heat-affected zone and designs to 40–60 MPa, so a welded 1050 bracket is a cover, not a load path.
A drawing that says "aluminium, 2 mm" can be satisfied by 1050 aluminium at 85 MPa yield or by 6082-T6 at 260 MPa, and the two parts will not behave the same in the press brake, the weld fixture or the anodising tank. 1050 is the grade at the soft, pure end of that range: 99.5% minimum aluminium, excellent corrosion resistance, 231 W/m·K thermal conductivity and a near-colourless anodic film. It is also the grade that dents when a fitter drops a spanner on it.
The selection question is therefore not "is 1050 good aluminium" but "is the part strength-limited, form-limited or surface-limited". 1050 wins the surface and conductivity cases, ties on corrosion, and loses on strength to every common structural grade. The temper then decides whether it can be bent at 1t or has to be annealed first.
This guide covers the designations a buyer will see on a mill certificate, the properties that drive the part, the thickness tolerance that the mill supplies rather than the fabricator, and the forming and welding limits that catch out a first article.
Which 1050 aluminium grade you will be quoted
Four designations appear under the 1050 family, and they are not interchangeable on paper even when they behave alike in the shop.
- 1050 is the Aluminum Association designation, 99.5% minimum aluminium, used in ASTM B209. ASTM B209 covers the mechanical properties and thickness tolerances of aluminium sheet and plate, and it is the standard a mill certificate is checked against.
- 1050A is the EN 573-3 designation, also 99.5% minimum, and a mill certificate to EN 485-2 will say 1050A where an ASTM certificate says 1050.
- 1100 is 99.0% aluminium with 0.05–0.20% copper. The copper lifts strength slightly and drops conductivity; it also makes the anodised film less bright. If a quote is cheaper than the others, check whether it is 1100.
- 1200 is 99.0% aluminium with tighter impurities than 1100 and no deliberate copper addition. It forms like 1050 and is common in Europe.
- 1350 is 99.5% aluminium with a boron addition for electrical conductor use. It is not a general sheet grade, but it appears on busbar and winding drawings.
For a formed cover or trim, 1050 and 1050A are the same decision. For an electrical part, 1350 or 1050 with a conductivity callout is the right specification. For a part that needs a bright clear anodised finish, 1050 or 1050A, not 1100.
The properties that decide the part
| Property or decision | 1050 value | What it means for the part | Ganesh limit or note |
|---|---|---|---|
| Aluminium content | 99.5% minimum | Best corrosion resistance of the common sheet grades | Mill certificate checked against ASTM B209 or IS 737 |
| Yield strength, O | 20–35 MPa | Dead-soft, for deep drawing and rolling | Annealed sheet formed on the 200 T brake or press line |
| Yield strength, H14 | 85 MPa minimum | Stiff enough for covers, not for structural brackets | Quarter-hard is the usual cover and trim temper |
| Tensile strength, H14 | 105–145 MPa | Lower than CRCA at 340 MPa, at a third of the density | Design allowable set from the certificate, not the nominal |
| Elongation, O / H14 | 30–40% / 8–20% | O draws; H14 bends once at a generous radius | Bend radius 0.5–1t in O, about 1t in H14 |
| Density | 2.705 g/cm³ | 2.9 times lighter than steel at equal thickness | 0.8–40 mm custom-part range |
| Modulus | 69 GPa | A third of steel, so deflection governs before yield | Long panels reviewed for flatness and sag |
| Thermal conductivity | 231 W/m·K | Heat spreads fast; welds distort and cool quickly | Welding fixtures and sequence designed for the spread |
| Electrical conductivity | About 61% IACS | Busbar and conductor grade at equal cross-section | Cut and formed; conductivity tested by the customer |
| Melting range | 646–657 °C | No hot-dip galvanising, no high-temperature service | Coating cure stays at 180–200 °C metal temperature |
| Bend radius, 90° | 0.5–1t O, 1–1.5t H14 | Tight radii need the O temper or a heavier radius | Radius checked against temper before nesting |
| Weld strength, HAZ | 40–60 MPa | A welded joint is far below the H14 parent | Three CLOOS cells and 30+ manual stations |
| Anodising | 5–25 µm Type II, near-colourless | Bright clear film for reflectors and trim | Bought in; not an in-house process |
| Machinability | Poor, gummy, built-up edge | Not a grade for turned or milled features | Cut, formed and welded, not machined |
The modulus row is the one that changes designs. At equal thickness, a 1.5 mm 1050 cover is as stiff as a 1.04 mm steel cover, because stiffness scales with E × t³. It weighs 4.06 kg/m² against 8.16 kg/m² for the steel, so it is 50% lighter for the same stiffness. At equal mass the position reverses: 1050 is slightly less stiff, with a specific modulus of 25.5 kN·m/kg against 26.8 for steel. Aluminium buys stiffness at equal thickness, not at equal mass.
Thickness tolerance is a mill property
1050 sheet is rolled to a thickness tolerance that depends on width and thickness, and the tolerance is wider than most designers expect. On 1.0 mm sheet the mill allowance is typically ±0.06–0.10 mm; on 2.0 mm it is around ±0.10–0.15 mm; on 3.0 mm it is wider again. That is a 10% variation on a 1.0 mm sheet before anyone cuts it.
Two consequences follow. First, a part tolerance of ±0.5 mm on a formed 1.0 mm bracket is achievable because the bend and the cut dominate, but a flatness or a flange-height callout that depends on the sheet gauge inherits the mill tolerance. Second, the flat pattern changes with the gauge: a 0.1 mm thickness change moves the bend deduction by roughly 0.05–0.1 mm per bend, which is small on one bend and visible on a part with six.
The drawing fix is to call the thickness as a nominal with the standard, such as "1.0 mm ±0.08, ASTM B209", and to put the critical dimensions on features that are cut or formed rather than on the raw gauge. If the part is a shim or a spacer where thickness is the function, specify the thickness tolerance and expect the mill to supply a ground or rolled-to-tolerance sheet, not standard stock.
Formability: where 1050 is excellent and where it marks
1050-O is one of the most formable sheet metals in common use. Elongation runs 30–40%, the strain-hardening exponent is high, and a 180° hem or a deep draw is routine. That is why the grade appears in cooking utensils, heat shields, reflector housings and drawn enclosures. The limits are surface and stiffness, not ductility.
Bending. At 90°, 1050-O forms at a 0.5–1t inside radius, and H14 needs about 1–1.5t. Bendability is not the tensile elongation test: the bend is localised and the neutral axis shifts, so a 1t radius can still work on a clean, deburred edge, but the margin is small and a laser burr or a coarse inclusion starts the split. Springback is modest in O, about 1–2°, and rises to 2–3° in H14 because the yield strength is higher. The bend line should run across the rolling direction where possible; a bend along the rolling direction at a tight radius is where a split starts. If the part needs both a tight radius and H14 stiffness, form it in O, because 1050 is not heat-treatable and there is no ageing step to restore strength. The choice is a larger radius, a thinner gauge with a stiffening rib, or a different grade.
Work the flat pattern before the blank is nested. For a 90° bend in 2.0 mm 1050-H14 at a 2.0 mm inside radius, with a K-factor of 0.44, the bend allowance is 1.571 × (2.0 + 0.88) = 4.52 mm. The bend deduction is 2 × 4.0 − 4.52 = 3.48 mm, so a part with two 40 mm flanges has a flat length of 80 − 3.48 = 76.52 mm. Move the radius to 3.0 mm and the deduction becomes 10.0 − 6.09 = 3.91 mm. That 0.43 mm per bend is enough to miss a ±0.5 mm overall tolerance on a part with two bends, which is why the radius belongs on the drawing and not in a shop default.
Deep drawing. 1050-O draws well, but the softness brings two shop problems. The blank gallops on the die radius and picks up aluminium, which then marks every subsequent part, so the tool needs polishing and a drawing lubricant with a boundary additive. And the low yield strength means the blank holder force window is narrow: too little and the flange wrinkles, too much and the wall thins. A 1.0 mm cup 80 mm in diameter typically needs a blank holder pressure of 1.5–2.5 MPa and a die clearance of 1.05–1.10t.
Orange peel and stretcher strains. A coarse grain size shows as orange peel on a stretched or formed surface, and temper-rolled H14 can develop Lüders lines at 2–5% strain. Both are cosmetic rejects on a visible part. Specify a fine grain size on the mill order, or form in O and accept the lower strength.
Marking. 1050 is soft enough that a laser-cut edge, a deburring tool or a jig location leaves a mark that shows through a thin anodised or painted film. Protective film on both faces during forming, and a clean, dedicated jig, are part of the process rather than a nicety.
Welding and the annealed zone
1050 welds cleanly with TIG or MIG using 1100 or 4043 filler. The oxide melts at about 2,072 °C against 660 °C for the metal, so the joint faces need wire brushing or machining within a few hours of welding; a 24-hour-old edge has already regrown enough oxide to cause porosity.
The strength story is less comfortable. H14 gets its 85 MPa from work hardening, and the weld thermal cycle anneals the heat-affected zone back toward O. A welded 1050 joint therefore designs to 40–60 MPa, and the heat-affected zone, not the weld metal, is usually the weak section. For a cover, a duct or a shield that is a valid joint. For a bracket that carries a machine load, it is not.
Distortion is the other constraint. Thermal conductivity of 231 W/m·K spreads heat into the panel, and the expansion coefficient of 23.6 µm/m·K turns that heat into movement. A 1,200 mm 1050 panel with a seam weld can bow 8–10 mm unless it is tacked in sequence, clamped in a fixture and allowed to cool in the fixture. Thin 1050 is less forgiving here than 5052, because the lower yield strength gives it less resistance to the shrinkage stress.
What Ganesh runs on 1050
1050 sheet is nested and cut on the 12 kW fibre laser with its 40 ft × 16 ft bed, or on the 6 kW and 3 kW support machines for thinner gauge, then formed on the 200 T 5-axis press brake with a 4,450 mm bed and a Delem control. Deep-drawn and pressed 1050 parts run on the 20–300 T mechanical presses with tooling from the in-house tool room, where progressive dies, welding fixtures and checking fixtures are built. Welded 1050 covers and ducts go through three CLOOS robotic MIG cells or the 30+ manual stations, with fixtures designed in-house. Coating is the seven-tank pretreatment line and the 18 ft × 14 ft powder booth; anodising is bought in. The plants hold ISO 9001:2015 and ISO 14001:2015.
We do not quote 1050 for milled pockets or tight-tolerance holes, because it is gummy and built-up edge ruins the finish. If a part needs those features, the grade should be 6061 or 6082, and the drawing should say so.
What to put on the drawing
- Designation and standard: 1050 or 1050A to ASTM B209 or IS 737, not "commercial aluminium".
- Temper: O for drawing and tight bends, H14 for covers and stiffness, with the temper the design allowable assumes.
- Thickness with its tolerance, because the mill tolerance is wider than the part tolerance and has to be declared.
- Every bend radius and the bend direction relative to the rolling direction.
- Flat pattern or a note that the supplier develops it, with the bend deduction method agreed at quotation.
- Weld process, filler and the heat-affected zone allowable if the weld is in a load path.
- Finish: anodising class and film thickness, or powder system with the cure ceiling and colour reference.
- General tolerance callout, usually ISO 2768-1 medium, plus the critical features separately.
The materials and grades hub carries the other grade guides, and aluminium sheet metal bending guidelines covers springback and tooling by temper. If the part is laser cut before forming, laser cutting aluminium sheet and plate explains the edge and dross behaviour. Send the drawing through request a quote with the temper and annual quantity, and the flat pattern is checked before the first blank is cut.
When 1050 is the wrong grade
1050 is the wrong choice when the part is sized by strength or stiffness, when it needs machined features, when it will be welded into a load path, or when it must resist abrasion. Those are the cases covered in when 1050 aluminium is the wrong material for a part. The short version: 1050-H14 at 85 MPa needs 5.6 mm to match 2 mm of CRCA at 240 MPa, which removes the mass advantage entirely, and a 5052 or 6061 substitution is usually the cheaper correct answer.
Frequently asked questions
What is the difference between 1050 and 1050A aluminium?
Both are 99.5% minimum aluminium. 1050A is the EN designation with a tighter limit on silicon and iron, and 1050 is the Aluminum Association designation used in ASTM B209. For sheet metal parts they behave the same; state the standard and the temper so the mill certificate can be checked.
Is 1050 stronger or weaker than 5052?
Weaker. 1050-H14 yields about 85 MPa against 193 MPa for 5052-H32, and 1050-O is around 30 MPa. 1050 wins on corrosion resistance, thermal and electrical conductivity, and bright anodising, not on strength.
Can 1050 aluminium be welded?
Yes, with 1100 or 4043 filler, and it welds cleanly. The heat-affected zone anneals to the O temper, so a welded H14 part designs to 40–60 MPa. Distortion is the bigger problem because the thermal conductivity is 231 W/m·K.
What thickness of 1050 sheet is available?
Common mill stock runs from 0.5 mm to 6 mm, with foil below 0.2 mm and plate above 6 mm available to order. Our custom-part range is 0.8–40 mm, but 1050 parts are usually specified between 0.8 mm and 3 mm.
Does 1050 anodise clear?
Yes. With no copper or silicon to colour the film, 1050 anodises to a near-colourless, bright finish, which is why it is used for reflectors, nameplates and trim. The film is 5–25 µm for Type II, and the soft substrate still scratches through it.
Sources and further reading
- ASTM B209 — Aluminium and aluminium-alloy sheet and plate · reviewed 3 Nov 2026
- IS 737 — Wrought aluminium and aluminium alloy sheet and strip for general engineering · reviewed 3 Nov 2026
- ISO 2768-1 — General tolerances for linear and angular dimensions · reviewed 3 Nov 2026
Specifying 1050 for a formed part?
Send the drawing with temper, thickness and bend radii. We check the flat pattern and the formability before the blank is nested.
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