Overview
3003 is the workhorse non-structural aluminum — the default sheet metal alloy for cookware, beverage cans, ductwork, food containers, and any application where corrosion resistance and formability matter more than peak strength. By tonnage, 3003 is the single highest- volume aluminum alloy in the world — beverage can body stock alone consumes hundreds of thousands of tons annually.
The selection logic is simple:
- Formability — H14 forms well, O temper forms exceptionally well
- Corrosion resistance — excellent in atmospheric, food, and mild chemical service
- Weldability — excellent across all common processes
- Strength — adequate for sheet-metal applications, inadequate for structural service (yield ~20 ksi)
3003 is not heat-treatable. Strengthening comes from cold work (H tempers). The maximum strength achievable is ~200 MPa (29 ksi) UTS at H18 — about half of 6061-T6. For applications needing more strength, move to 5052 (similar corrosion, higher strength via work-hardening) or 6061 (heat-treatable, higher strength, slightly worse corrosion resistance).
Machining notes
3003 is not a machining grade. The soft, gummy chemistry produces long stringy chips and built-up edge problems. For light trimming and finishing of sheet-stamped parts, 3003 machines acceptably:
- Sharp uncoated or polished carbide
- Speed: 800–2000 SFM (high speeds break chips better)
- Feed: 0.005–0.020 in/rev
- Flood coolant mandatory
For production machined parts requiring 3003-like corrosion resistance, switch to 6061 or 5052 — both machine significantly better while providing similar or better corrosion behavior in most environments.
Temper selection guidance
- H14 — General-purpose sheet metal fabrication. The default unless specific reason to choose otherwise. Bends to ~1× thickness radius without cracking.
- H16/H18 — Higher strength applications without forming requirements. H18 is essentially non-formable.
- O — Severe forming (deep draw, hydroform). Subsequent cold work returns to H temper if needed.
Welding and joining
3003 is among the most weldable aluminum alloys. All common processes work routinely:
- TIG — most common for sheet metal fabrication
- MIG — production sheet welding
- Spot welding — beverage can body welding, automotive heat shields
- Brazing — 3003 is the standard tube alloy in copper-brass and aluminum-brazed heat exchangers
Filler selection:
- 4043 — general-purpose, easy to run
- 1100 — pure aluminum filler for food-contact welds where copper content of 4043 is undesirable
- 5356 — when joining 3003 to 5xxx-series (5052, 5083)
The non-heat-treatable nature simplifies welding — there’s no HAZ precipitate damage to worry about. Weld zones soften toward O temper (~5–7 ksi yield); design joints to account for this if structural strength matters.
Formability — the 3003 superpower
3003 is one of the most formable aluminum alloys. Practical guidelines:
- O temper — bends to 0× to 0.5× thickness inside radius for thin sheet; deep-draws to LDR (limiting drawing ratio) ~1.9
- H14 temper — bends to ~1× thickness inside radius; moderate deep-draw capability
- H18 temper — bends to ~2× thickness inside radius; minimum formability
For challenging form operations:
- Start in O temper
- Form to near-net shape
- Heat to partial-anneal temperature (230–340°C) to recover ductility if multiple forming steps needed
- Final cold-work to desired H temper if strength required
Corrosion considerations
3003’s atmospheric corrosion resistance is excellent for an aluminum alloy. The clean Al-Mn chemistry (no copper to drive galvanic cells, no zinc to promote SCC) gives 3003:
- Indoor service — essentially permanent without protection
- Outdoor service — pits very slowly; bare 3003 architectural sheet has multi-decade service life
- Food contact — FDA-acceptable for direct contact; the beverage can material for half a century
- Marine atmospheric — acceptable for non-immersed components; develops gray oxide but doesn’t pit significantly
- Mild chemical service — most organic acids tolerated, dilute ammonia OK, most salts OK
What 3003 doesn’t handle:
- Strong bases (pH > 9) — sodium hydroxide attacks aluminum; never use 3003 in caustic cleaning systems
- HCl, HF, concentrated H₂SO₄ — these attack aluminum regardless of grade
- Saltwater immersion — pits over time; use 5052 or 5083 for marine immersion
- Galvanic couples with copper, brass, or stainless steel in wet service — 3003 corrodes preferentially
Applications by industry
- Beverage cans — body stock for aluminum beverage cans is the highest-volume 3003 application globally. Can ends use 5182 (higher strength); the body is 3003-H19 typically.
- Cookware — pots, pans, baking sheets, bakeware. The non-toxic Al-Mn chemistry suits direct food contact.
- HVAC ductwork — sheet metal ductwork for commercial and industrial air handling. Lightweight, corrosion-resistant, easily fabricated.
- Heat exchangers — finned-tube heat exchangers (refrigeration evaporators, condensers, automotive radiators) use 3003 fins bonded to copper or aluminum tubes by brazing.
- Roofing and siding — commercial-grade aluminum roofing and industrial siding sheet. Pre-painted for outdoor applications.
- Storage tanks (mild service) — fuel tanks, water tanks, mild chemical storage. Welded fabrication.
- Signs — sign blanks and decorative architectural sheet.
- Decorative trim — anodized 3003 for architectural and consumer applications where uniform anodize color matters.
Failure modes worth designing around
Crevice corrosion under deposits or gaskets is the most common in-service 3003 corrosion mode. Oxygen depletion under deposits allows local acid generation and pitting. Design drainage, avoid horizontal joints in wet environments, and consider topical inhibitors for critical service.
Galvanic corrosion with steel, stainless, or copper fasteners through 3003 sheet is the second common failure. In moist service, the 3003 corrodes preferentially. Use compatible-metal fasteners (galvanized steel is closer to aluminum potential), isolation washers, or sealants in fastener holes.
Loss of cold-work strength at elevated temperature — H14 and H18 tempers anneal back toward O at 150–200°C. For service above 150°C, expect strength to drift toward O temper over time. Design to O temper properties for sustained-high-temperature service.
Stress concentration at sharp formed corners — H tempers are work-hardened and brittle compared to O. Sharp bends in H18 (less than 2× thickness inside radius) crack on forming and on cyclic loading. Standard sheet-metal practice (1× minimum for H14, 2× for H18) prevents this.
Fatigue cracking at fastener holes and stress concentrations in vibratory service. 3003 has modest fatigue strength (~60 MPa at 5×10⁸ cycles). For fatigue-loaded sheet, use 5052 or 6061 instead — both have ~2× the fatigue strength of 3003 H14.
Specifying 3003 for structural service is a common designer mistake — the alloy’s combination of formability and corrosion resistance makes it attractive, but the ~17–21 ksi yield is inadequate for any meaningful structural load. For structural sheet metal, use 5052 or 6061.