If you’re designing a part that will be formed, bent, or deep-drawn before or after machining — and it doesn’t need 6061-level strength — 3003-H14 is usually the right starting point. Its ~1.2% manganese addition gives it roughly 10–20% more strength than 1100 commercially pure aluminum without sacrificing the ductility that makes forming operations reliable. But that same ductility is exactly what makes it fussy on a CNC lathe or mill: the chip doesn’t break, the burr doesn’t cooperate, and surface finish degrades fast if you treat it like 6061.
What 3003 Actually Is — Grade, Family, and Standard References
3003 belongs to the 3xxx series of wrought aluminum alloys, defined by manganese (Mn) as the primary alloying element. It is not a heat-treatable alloy — its mechanical properties come from solid-solution strengthening by Mn and from cold work (strain hardening).
| Designation System | Identifier | Reference Standard |
|---|---|---|
| AA (Aluminum Association) | 3003 | ANSI H35.1 / ASTM B209 (sheet & plate) |
| UNS | A93003 | ASTM E527 / SAE J1086 |
| ISO | AlMn1Cu | ISO 209:2007 |
| EN (European) | EN AW-3003 / EN AW-AlMn1Cu | EN 573-3 |
| GB/T (Chinese) | 3A21 (approximate) | GB/T 3190-2008 |
Important: EN AW-3003 and AA 3003 have nearly identical chemistry, but EN 573-3 imposes slightly tighter limits on certain trace elements. GB/T 3A21 is the closest Chinese equivalent but differs in Fe+Si tolerance — if your drawing specifies 3A21, confirm whether EN or AA 3003 is an acceptable substitute before switching billet.
Chemical Composition and the Role of Each Element
The manganese in 3003 is not there for hardenability — unlike the Cr, Mo, or V in alloy steels, Mn in the 3xxx series stays primarily in solid solution and provides moderate strengthening without killing ductility.
| Element | Content (wt%) — ASTM B209 | Metallurgical Role |
|---|---|---|
| Si | ≤ 0.6 | Present as impurity + part of Al(Fe,Mn)Si dispersoid; excess can embrittle grain boundaries after brazing cycles |
| Fe | ≤ 0.7 | Forms Al₆(Fe,Mn) constituent particles; too much increases coarse intermetallics that hurt bendability |
| Cu | 0.05–0.20 | Small Cu addition mildly increases strength and improves corrosion resistance over binary Al-Mn |
| Mn | 1.0–1.5 | Primary strengthener — forms MnAl₆ dispersoids during homogenization; pins grain boundaries during recrystallization |
| Zn | ≤ 0.10 | Tramp element; kept low because Zn above ~0.15% can cause hot cracking in certain welding conditions |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | Remainder (≥ 96.8 typical) | — |
The Mn range matters in practice: a mill running at the low end (~1.0% Mn) produces sheet that forms more easily but has ~10% lower tensile strength than material near the upper limit (~1.4–1.5% Mn). If your part is at the edge of formability for a given temper, knowing which end of the spec window your supplier runs is worth asking.
Temper Designations and Mechanical Properties
Because 3003 is non-heat-treatable, all tempers beyond O (annealed) are achieved through cold work. The H1x series denotes strain-hardened only; H2x denotes strain-hardened and partially annealed.
| Temper | Tensile Strength (MPa) | Yield Strength (MPa, 0.2% offset) | Elongation (%, 50 mm gauge) | Hardness (HB) | Condition Reference |
|---|---|---|---|---|---|
| O (annealed) | 95–130 | ≥ 35 | ≥ 23 (1.6 mm sheet) | ~28 | ASTM B209; ASTM E8/E8M |
| H12 | 120–160 | ≥ 85 | ≥ 6 | ~35 | ASTM B209 (quarter-hard) |
| H14 | 140–180 | ≥ 115 | ≥ 4 (1.6 mm sheet) | ~40 | ASTM B209 (half-hard); EN 485-2 |
| H16 | 165–205 | ≥ 145 | ≥ 3 | ~47 | ASTM B209 |
| H18 | ≥ 185 | ≥ 165 | ≥ 2 | ~55 | ASTM B209 (full-hard) |
These values are minimum or range values per ASTM B209 for sheet and plate at room temperature. Note that elongation drops sharply between O and H14 — if your part requires tight-radius bending, H14 may already be too hard; O-temper or a partial anneal from H14 back to H22/H24 range may be necessary. H24 (strain-hardened + partially annealed to half-hard equivalent) is often specified for bending applications.
Property Behavior Across Temperature
3003 retains useful mechanical properties from cryogenic to moderately elevated temperatures, but there are limits:
- At −196°C (liquid nitrogen): Tensile and yield strengths increase roughly 30–50% above room-temperature values while elongation remains roughly stable. This makes 3003 suitable for cryogenic structural components (non-pressure-boundary) in liquefied gas handling equipment.
- At 150–200°C: Yield strength begins to degrade — at 200°C the yield strength of H14 temper can drop by roughly 25–40% compared to room temperature. Prolonged exposure above ~200°C also coarsens the MnAl₆ dispersoids, causing irreversible softening.
- Above 300°C: Rapid strength loss. Not recommended for structural use above ~250°C continuous service. It will not catastrophically fail but will creep significantly.
Data derived from ASM Handbook Volume 2 and matweb typical curves; specific values depend on temper history and test method per ASTM E21.
Corrosion Resistance: What the Manganese Buys You
3003 has corrosion resistance similar to 1100 aluminum — excellent in atmospheric exposure, fresh water, and many mildly acidic environments. The small Cu addition (0.05–0.20%) does not significantly degrade general corrosion resistance and may slightly improve resistance in some mildly alkaline conditions.
Key corrosion characteristics:
- Atmospheric: Forms a stable Al₂O₃ passive film; suitable for outdoor architectural and general industrial exposure without coating
- Water: Good resistance to fresh water, steam condensate, and potable water — widely used in roofing, siding, and heat exchanger fins
- Chemical: Resistant to many organic acids and neutral salts; attacked by strong alkalis (NaOH, KOH) and strong mineral acids (HCl, H₂SO₄ above 10%)
- Galvanic: Anodic to most structural metals — direct contact with steel or stainless steel in a wet environment will cause preferential corrosion of 3003 unless isolated
- Stress-corrosion cracking (SCC): Not susceptible in any temper, which is a key advantage over 2xxx and 7xxx series alloys
CNC Machining 3003: The Real Challenges
Anyone who has machined 3003 on a CNC lathe or mill knows the frustration: it doesn’t chip. The material is soft, ductile, and gummy. Instead of breaking into manageable C-shaped or 6-shaped chips, it produces continuous stringy ribbons that wrap around the tool, score the finished surface, and force the operator to pause and clear the work zone.
Why It Machines Differently from 6061
6061-T6 contains Mg₂Si precipitates that make the chip more brittle — it shears cleanly in a narrow zone ahead of the cutting edge. 3003 has no such precipitates. The Mn is in solid solution, and the material’s high ductility (20–40% elongation in O-temper) means the chip stretches before separating, producing long, unbroken ribbons. The built-up edge (BUE) tendency is also worse on 3003 because aluminum adheres readily to the tool rake face at the cutting temperatures involved.
Starting-Point Parameters — Conditional Reference Only
The values below are suggested starting points on a rigid CNC machine with proper workholding. They are not universal settings. Actual parameters depend on your specific machine stiffness, toolholder runout, coolant delivery pressure, workpiece geometry, and desired finish quality.
Turning (carbide insert, uncoated polished or TiB₂-coated, positive rake geometry)
| Operation | Cutting Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) | Notes |
|---|---|---|---|---|
| Rough turning | 200–400 | 0.15–0.40 | 1.5–4.0 | Higher speed helps reduce BUE; use high-pressure coolant directed at rake face |
| Finish turning | 300–500 | 0.05–0.15 | 0.25–1.0 | Sharp insert edge (no hone or light hone); polished rake face reduces aluminum adhesion |
Milling (solid carbide end mill, 2- or 3-flute for chip clearance)
| Operation | Cutting Speed (m/min) | Feed (mm/tooth) | Radial DOC (% of dia.) | Notes |
|---|---|---|---|---|
| Rough milling | 250–450 | 0.08–0.20 | 30–70% | 2-flute preferred for chip evacuation; avoid re-cutting chips |
| Finish milling | 300–500 | 0.03–0.08 | 5–15% | Wiper insert or sharp-edged polished carbide; climb milling preferred |
Drilling (HSS-Co or solid carbide, 118°–130° point angle)
| Hole Diameter | Cutting Speed (m/min) | Feed (mm/rev) | Notes |
|---|---|---|---|
| ≤ 6 mm | 80–150 | 0.05–0.12 | Peck drilling recommended to break chips; high-pressure coolant through drill if available |
| 6–12 mm | 100–180 | 0.10–0.20 | Parabolic flute drills help chip evacuation |
| > 12 mm | 120–200 | 0.15–0.30 | Pilot hole recommended above 20 mm |
These values are starting points, not guarantees. A light-duty benchtop machine will not achieve the upper end of speed ranges regardless of tooling. A rigid 40-taper VMC with high-pressure through-spindle coolant can push beyond them. If your part requires Ra < 0.8 μm on a turned surface, expect to need a secondary polishing operation — 3003 does not consistently hit sub-micron Ra directly off the tool.
Tool Selection and Coolant Strategy
- Insert grade: Uncoated micrograin carbide (ISO K10–K20) often outperforms coated grades on 3003 because the polished uncoated surface generates less friction against the flowing chip. Avoid TiN and TiAlN coatings — their affinity for aluminum promotes BUE. If coating is needed for abrasion resistance, consider a thin diamond-like carbon (DLC) or TiB₂ coating specifically formulated for aluminum.
- Geometry: High positive rake angle (12°–18°), sharp cutting edge (minimal or no edge preparation), and polished chipbreaker groove specifically designed for aluminum. The chipbreaker should have a narrow land width — a wide land encourages the chip to slide rather than curl.
- Coolant: Flood coolant at high pressure (≥20 bar ideal, 5–10 bar minimum). Water-miscible semisynthetic or soluble oil at 7–10% concentration. The coolant’s primary job here is chip flushing, not just heat removal — if chips recirculate through the cutting zone, surface finish degrades within seconds. Mist lubrication is inadequate for production work on 3003.
- Tool life: In 3003, tool failure mode is rarely flank wear — it’s usually BUE accumulation that destroys surface finish long before the insert is mechanically worn. When finish degrades, check for aluminum welded to the cutting edge before assuming the insert is dull.
Surface Finishing and Post-Machining Treatment
3003 accepts conventional aluminum surface treatments, but its relatively high Mn content means the oxide layer formed during anodizing will have a slightly different hue and thickness compared to 6xxx-series alloys at the same process parameters.
- Anodizing (Type II, sulfuric acid): Produces a clear-to-light-gray coating 5–25 μm thick. The anodic layer on 3003 is typically slightly duller than on 6061 due to the Mn-rich intermetallics that don’t anodize uniformly. For decorative parts where color match matters, test-coupon your specific alloy lot with the anodizer before committing to production.
- Hard anodizing (Type III): Achievable but less common — 3003 is rarely used in applications demanding hardcoat. The Mn-containing intermetallics can cause localized burning at high current density.
- Chemical conversion coating (Alodine/Iridite, per MIL-DTL-5541 Type II): Excellent adhesion; commonly used as a paint base for 3003 sheet metal enclosures and panels
- Powder coating / wet paint: Standard pretreatment (degrease + conversion coat) provides good adhesion on 3003. Slightly rougher surface profile after blasting improves mechanical bonding.
- Tumbling / vibratory deburring: Effective for removing light burrs and breaking sharp edges on machined 3003 parts. Because the material is soft, use fine ceramic media and short cycle times — aggressive media can peen the surface.
When to Choose 3003 Over 5052 or 6061
These three alloys frequently compete for the same part number, especially in non-structural enclosures, brackets, and heat-exchanger components. The table below compares them in the most commonly specified tempers.
| Property / Consideration | 3003-H14 | 5052-H32 | 6061-T6 |
|---|---|---|---|
| Tensile strength (MPa, min) | 140 | 230 | 290 |
| Yield strength (MPa, min) | 115 | 160 | 240 |
| Elongation (%, min) | 4–6 | 8–10 | 8–10 |
| Machinability rating | Poor — gummy, stringy chips | Fair — better chip formation than 3003 | Good — clean chip formation, excellent finish |
| Formability (bending) | Excellent in O/H2x; good in H14 above 1T radius | Good — slightly tighter bends feasible | Poor in T6 — cracks at moderate bend radii |
| Weldability | Excellent — all common methods | Good — GTAW/GMAW; avoid oxy-fuel | Fair — strength loss in HAZ; requires post-weld heat treat |
| Corrosion resistance | Very good | Excellent (best of the three in marine) | Good — susceptible to intergranular attack if improperly aged |
| Cost (relative to 3003) | 1.0× (baseline) | ~1.15–1.3× | ~1.1–1.25× (varies by form) |
| Typical forms available | Sheet, plate, tube, foil, wire | Sheet, plate, tube | Sheet, plate, bar, extrusion, tube, forging |
Approximate comparison only. “Approximate equivalent” grades such as EN AW-3003 vs AA 3003 vs GB/T 3A21 are not directly interchangeable without confirming the specific composition windows, temper definitions, and property minima in the relevant specification. Do not substitute based on name alone.
Rule of thumb for selection: If the part needs forming (deep drawing, tight-radius bending, spinning) and strength is secondary → 3003. If it needs moderate strength plus corrosion resistance in a marine environment → 5052. If it needs strength, machinability, and the part geometry doesn’t involve tight-radius bending → 6061.
Common Applications
- Heat exchanger fins and tubes: 3003’s thermal conductivity (~160 W/m·K at 25°C in O-temper, per typical published values) and good corrosion resistance in condensate environments make it the dominant choice for residential and commercial HVAC fin stock
- Chemical storage tanks and piping: Used for non-pressure tanks handling mild chemicals, vegetable oils, and potable water
- Sheet metal enclosures, cabinets, and panels: Where forming ease outweighs the need for 5052-level strength
- Roofing and architectural trim: Good atmospheric corrosion resistance combined with formability for standing-seam and shaped profiles
- Cooking utensils and food processing equipment: Good thermal conductivity, non-toxic, and easy to clean
- Automotive heat shields and radiator components: Combines formability with adequate elevated-temperature performance for under-hood non-structural parts
- CNC-machined parts with subsequent forming: Parts machined from plate in O or H111 temper, then bent or formed as a secondary operation
Design and RFQ Checklist
When requesting CNC-machined parts in 3003, provide the following with your drawing or RFQ package:
- Full material specification: “AA 3003-H14 per ASTM B209” (not just “3003 Aluminum”). Include the temper — an O-temper part and an H18 part are not interchangeable.
- If formed after machining: Specify the as-machined temper vs. the as-formed required temper. The machinist may need to start with a softer temper if post-machining bending is planned.
- Surface finish requirement: Specify Ra in μm or μin, and note whether a secondary polishing or tumbling operation is acceptable to achieve it.
- Critical tolerances: Flag dimensions that cannot be met by standard ±0.13 mm (±0.005″) machining practices. Note that 3003’s high thermal expansion coefficient (~23.2 μm/m·°C) means a 20°C swing in shop temperature shifts a 100 mm dimension by ~0.046 mm.
- Anodizing or coating specification: If the part will be anodized, mention whether color matching is critical — the Mn content in 3003 affects anodic coating appearance. Provide the target standard (e.g., MIL-A-8625 Type II, Class 1).
- Quantity and whether this is a first-article or repeat order: This affects tooling and setup strategy.
Related Articles
- 5052 Aluminum CNC Machining: Formability, Welding & When to Use It Over 6061
- 6063 Aluminum for CNC Machining: What Extrudability Means for Your Part
- CNC Machining 6061 (AlMg1SiCu): Parameters, Tooling & Surface Finish Tips
- Machining 2017 Aluminum: When AlCu4MgSi Makes Sense for Your Part
References: ASTM B209-14 (Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate); EN 573-3 (Aluminium and aluminium alloys — Chemical composition); EN 485-2 (Aluminium and aluminium alloys — Sheet, strip and plate — Mechanical properties); ANSI H35.1/H35.1M (American National Standard Alloy and Temper Designation Systems for Aluminum); ASM Handbook Volume 2 (Properties and Selection: Nonferrous Alloys and Special-Purpose Materials). Thermal conductivity and thermal expansion values are typical published values at room temperature for 3003-O condition; always confirm with mill test certificate (MTC) for your specific lot.
Published: 2026-07-20 | Material: 3003 (AlMn1Cu, UNS A93003, EN AW-3003) — 3xxx Series Wrought Aluminum, Non-Heat-Treatable
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