If you need a 6000-series aluminum that turns like brass, 6262 is the alloy to reach for. Designated AlMg1SiCuPbBi under EN 573-3 and falling under UNS A96262, this heat-treatable wrought alloy was engineered precisely for high-speed automatic screw-machine work where 6061 clogs flutes, leaves ragged finishes, and kills tool life. In the T6 temper, 6262 delivers roughly 290 MPa tensile strength with a machinability rating around 80–85% of free-cutting steel — better than any other commercial 6xxx alloy. The trade-off is real: the intentionally added lead and bismuth eliminate welding as a viable joining method and reduce corrosion resistance slightly compared to 6061-T6. When post-production operations are limited to deburring, anodizing, and assembly, and the raw bar spends most of its life under a tool, 6262 is among the most productive aluminum grades a CNC shop can load into a bar feeder.
What Makes 6262 Different: Grade Identity and Standardization
6262 is often mistaken for “free-machining 6061,” and while that shorthand is useful in conversation, it glosses over compositional differences that affect heat treatment response, anodizing quality, and scrap handling. 6262 is covered by ASTM B211 (rolled or cold-finished bar, rod, and wire), ASTM B221 (extruded bar, rod, wire, profiles, and tube), and AMS 4150 for aerospace extrusion applications — though its use in flight-critical parts is rare due to the lead content.
The Chinese national standard GB/T 3190 designates a close equivalent as 2A90, though the overlap is approximate: 2A90 originated from a Soviet-era specification and has slightly different bismuth/lead tolerances. Aluminum Association registration confirms 6262 as the internationally recognized designation, and this is the name you should use on drawings to avoid supply chain confusion.
| Element | Weight % (min–max) | Purpose |
|---|---|---|
| Silicon (Si) | 0.40 – 0.80 | Mg₂Si precipitation strengthening |
| Iron (Fe) | 0.70 max | Impurity; controlled for ductility |
| Copper (Cu) | 0.15 – 0.40 | Enhances strength and age-hardening response |
| Manganese (Mn) | 0.15 max | Grain refinement; kept low for machinability |
| Magnesium (Mg) | 0.80 – 1.20 | Primary precipitation-strengthening element |
| Chromium (Cr) | 0.04 – 0.14 | Grain structure control during extrusion |
| Zinc (Zn) | 0.25 max | Residual; not an active alloying element |
| Titanium (Ti) | 0.15 max | Grain refiner |
| Bismuth (Bi) | 0.40 – 0.70 | Free-machining chip breaker |
| Lead (Pb) | 0.40 – 0.70 | Free-machining lubricant / chip breaker |
| Aluminum (Al) | Remainder | Matrix |
Two features stand out in the chemistry: the Pb+Bi total of 0.8–1.4%, and the deliberate absence of a significant Mn or Cr content beyond grain control. The lead and bismuth exist as discrete, soft, low-melting-point particles dispersed through the aluminum matrix. During cutting, these particles shear readily, creating a built-up-edge-breaking effect, lubricating the tool-chip interface, and nucleating chip fracture into short, easily evacuated segments rather than long, tangled ribbons. The low manganese cap (≤0.15%) avoids the hard, abrasive Mn-rich dispersoids that dull tools in 6082 or 6061 when cutting speeds climb above 300 m/min.
Supply Condition and Heat Treatment
6262 is overwhelmingly supplied as cold-finished round bar, hex bar, or extruded profiles in the T6 or T6511 temper. T6 means solution heat treated and artificially aged to peak strength; T6511 adds a controlled stretching step after solution treatment to relieve internal stress, producing bar stock that stays straight during machining — critical for long slender parts turned from one end.
The solution treatment temperature range is 520–535°C, followed by water quenching. Some mills apply a modified T6 practice (proprietary aging cycles near 170–175°C for 8–10 hours) to balance strength, machinability, and anodizing response. If you’re sourcing 6262 for cosmetic anodized parts, specify consistent heat treatment lot-to-lot, because over-aging shifts Mg₂Si precipitate distribution and can yield a duller, more matte anodic layer.
T4 (solution treated and naturally aged) is occasionally available but seldom specified because the natural aging drift continues for weeks after quenching, making dimensional stability unpredictable. T6511 bar stock — stress-relieved by stretching 1–3% after solution treatment — should be the default callout on any RFQ that involves parts longer than five diameters or thin-walled profiles.
Typical Mechanical Properties
The table below reports minimum and typical values for 6262-T6 (or T6511) per ASTM B211 for bar products. Values are tested at room temperature on separate production lots; elongation is measured on a 50 mm gauge length (4D for round specimens).
| Property | Minimum (ASTM B211) | Typical | Test Standard |
|---|---|---|---|
| Tensile Strength, Rm | 290 MPa (42 ksi) | 310–340 MPa | ASTM E8 / ISO 6892-1 |
| Yield Strength (0.2% offset), Rp0.2 | 240 MPa (35 ksi) | 255–280 MPa | ASTM E8 / ISO 6892-1 |
| Elongation at Break | 10% (min) | 12–17% | ASTM E8 |
| Brinell Hardness (500 kgf, 10 mm ball) | Not specified | 90–100 HB | ASTM E10 |
| Shear Strength | Not specified | 185–205 MPa | ASTM B565 |
| Fatigue Strength (5 × 10⁸ cycles, R=-1, smooth) | Not specified | ~90 MPa | Rotating beam |
| Modulus of Elasticity | ~69 GPa | 69 GPa | Standard for Al alloys |
A few important caveats on the numbers: the ASTM minimums are statistically defined acceptance thresholds, not design values. The shear strength roughly follows the 0.6 × UTS rule common to wrought aluminum alloys. The fatigue value of ~90 MPa at 5×10⁸ cycles is a laboratory average from smooth polished specimens; any notch, thread, or sharp corner reduces this substantially, and we strongly recommend separate S-N data or component-level testing for cyclically loaded parts.
The inclusion of Pb and Bi does not noticeably alter the modulus, density (approximately 2.72 g/cm³), or thermal expansion coefficient (23.6 × 10⁻⁶ /K at 20–100°C) versus other 6xxx alloys.
Corrosion and Environmental Behavior
6262-T6 in ambient indoor environments performs adequately — roughly equivalent to 6061-T6 in mild atmospheres — but the presence of lead and bismuth particles creates micro-galvanic cells that slightly degrade resistance in wet or chloride-bearing service. General corrosion rate in a neutral 3.5% NaCl salt spray (ASTM B117) is typically 1.5–2× that of 6061-T6. In freshwater immersion, performance remains acceptable provided the pH stays between 4.5 and 8.5.
The practical implications for machined parts are straightforward:
- Indoor mechanical components (handles, brackets, housings, optical mounts, pneumatic fittings): no corrosion concern under normal humidity.
- Outdoor exposure (vehicle trim, architectural hardware): requires protective anodizing or painting. Type II sulfuric acid anodizing to 10–15 µm thickness is standard; Type III hard anodizing provides better wear resistance but may dull the color.
- Contact with dissimilar metals: galvanic coupling with stainless steel or copper alloys is possible; isolate with a non-conductive barrier or specify anodizing plus organic seal.
- Food-contact or potable water: lead content disqualifies 6262. Use 6061 or 6063 in food-grade applications.
Stress corrosion cracking (SCC) susceptibility of 6262-T6 is low in the short-transverse direction, similar to 6061-T6, and is not a limiting factor in typical machined component geometries under 25 mm section thickness.
CNC Machining Behavior: Why This Alloy Cuts Differently
6262 earns its reputation at the tool tip. The Pb/Bi dispersion transforms chip morphology from the continuous, stringy ribbons characteristic of 6061 into short, C-shaped or comma-shaped chips that clear the cutting zone without wrapping around the tool holder or part — the single most common cause of downtime in unattended bar-fed turning of aluminum.
Chip control is not the only benefit. The free-machining additions also:
- Reduce cutting forces by approximately 15–25% compared to 6061-T6 at equivalent speeds and feeds, lowering spindle load on smaller machines.
- Produce a superior as-machined surface finish: Ra 0.4–0.8 µm is routine on a well-maintained turning center; Ra 0.2 µm is achievable with fine finishing passes and sharp polished inserts.
- Extend tool life by reducing adhesive wear (built-up edge formation) and abrasive wear, particularly on uncoated carbide and PCD tools.
- Allow aggressive drilling and tapping without the packing and galling that plague 6061 in deep-blind holes.
Starting-Point Machining Parameters
The values below are starting references for 6262-T6 / T6511 on a rigid CNC machine with flood coolant and sharp carbide tooling. They are not guarantees; actual parameters must be adjusted for your specific machine’s spindle power, workpiece rigidity, toolholder runout, coolant delivery, and surface finish requirements.
| Operation | Cutting Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) | Insert Geometry |
|---|---|---|---|---|
| Rough turning | 250–400 | 0.15–0.40 | 1.5–4.0 | CNMG 432, positive rake, sharp edge |
| Finish turning | 350–500 | 0.05–0.12 | 0.2–0.8 | CCGT or DCGT, polished flank, 0.4 mm nose radius |
| Part-off / grooving | 150–250 | 0.03–0.08 | Blade width | 2–3 mm wide insert, high-positive |
| Operation | Cutting Speed (m/min) | Feed per Tooth (mm) | Radial DOC (ae) | Axial DOC (ap) |
|---|---|---|---|---|
| Rough slotting | 200–350 | 0.08–0.20 | Full slot | ≤ 1 × D |
| Side milling / profiling | 250–400 | 0.10–0.25 | 0.25–0.5 × D | ≤ 1.5 × D |
| Finish contouring | 300–500 | 0.04–0.10 | 0.1–0.3 mm stock | Full depth |
| Operation | Speed (m/min) | Feed (mm/rev) | Tool | Note |
|---|---|---|---|---|
| Ø 3–6 mm drilling | 80–150 | 0.05–0.15 | Carbide, 140° point | Peck every 3×D for holes > 6 mm |
| Ø 8–12 mm drilling | 100–180 | 0.12–0.25 | Carbide or HSS-Co | Through-coolant if deep |
| M3–M8 tapping | 15–30 | Per pitch | Spiral-flute, uncoated HSS | Roll-form taps work well on 6262 |
Tooling and Coolant Recommendations
- Turning inserts: Uncoated micrograin carbide with a sharp cutting edge and high-positive rake angle outperforms most coated inserts because 6262 does not generate enough heat or abrasion to justify a coating. If coating is desired, TiB₂ (titanium diboride) provides the best aluminum-specific adhesion resistance. PCD (polycrystalline diamond) inserts become economical in production runs exceeding 10,000 parts and routinely achieve Ra ≤ 0.2 µm without a separate finishing pass.
- End mill selection: Polished-flute, high-helix (35–45°), 2- or 3-flute uncoated micrograin carbide. Avoid 4-flute cutters unless hogging at low radial engagement; the chip gullet clogs in slotting.
- Coolant: Flood coolant (5–8% soluble oil in water) directed at the tool–workpiece interface at a minimum 10 bar pressure for turning, 20+ bar for deep drilling. MQL (minimum quantity lubrication) works for light finishing passes but is not recommended for roughing or drilling deeper than 2×D.
Surface Finishing and Post-Machining Treatment
The Pb/Bi dispersion slightly affects appearance and coating adhesion. Anodizing is the most common finishing route:
- Clear (natural) anodizing: Produces a slightly grayer, less silvery tone than 6061 or 6063 because lead and bismuth particles do not anodize and remain embedded in the oxide layer. Acceptable for functional parts; may be rejected for cosmetic applications requiring bright silver finish.
- Dyed anodizing: Dark colors (black, dark blue, dark red) mask the gray undertone effectively. Light or bright colors will appear muted.
- Hard anodizing (Type III): 25–50 µm thickness achievable. Adhesion is generally good; test adhesion on first-article parts especially on 90° edges where oxide growth stresses concentrate.
- Electroless nickel plating: Works well if a zincate pre-treatment is applied. Provides uniform coverage in blind holes and threads.
- Chromate conversion coating (Alodine): Suitable for corrosion protection without dimensional change. The golden iridescent color may appear patchy over Pb/Bi-rich areas — this is cosmetic, not functional, but specify acceptance criteria if appearance matters.
Applications Where 6262 Outperforms 6061
6262 does not exist to replace 6061 across the board. It wins in specific scenarios where machining time, tool cost, surface finish, and scrap rate from chip-related stoppages dominate the part cost:
- Pneumatic and hydraulic fittings: The combination of anodized corrosion protection, good pressure-holding integrity, and high-speed turning makes 6262 the standard choice for bulkhead connectors, banjo bolts, and compression fitting bodies. The chip breaks cleanly during internal boring of small-diameter through-holes.
- Optical and camera components: Lens housings, filter rings, and adjustment barrels benefit from the fine thread quality, low burr formation, and vibration-damping mass of 6262-T6. Black anodizing provides the required non-reflective surface.
- Electronic heat sinks and RF housings: 6262 machines into thin-walled enclosures and finned heat sinks without distortion during slotting. The thermal conductivity (~170 W/m·K) is essentially identical to 6061.
- Automotive sensor housings and fuel system components: Mass-produced turned parts where cycle time per part and process reliability in unattended night-shift running are critical KPIs.
- Small-bore valve bodies and manifolds: Intersecting drill holes deburr more cleanly than in 6061, reducing manual rework.
Comparison: 6262-T6 vs. 6061-T6 vs. 2011-T3
Designers weighing 6262 against alternatives should compare same-temper data from the same product form and size range. The table below compares cold-finished bar ≤ 50 mm:
| Property | 6262-T6/T6511 | 6061-T6/T6511 | 2011-T3 |
|---|---|---|---|
| Tensile Strength (MPa, typ.) | 310–340 | 310 | 380–415 |
| Yield Strength (MPa, typ.) | 255–280 | 275 | 295–325 |
| Elongation (%, typ.) | 12–17 | 12–17 | 10–15 |
| Machinability (% free-cutting steel) | 80–85 | 50–60 | 90–95 |
| Weldability | Poor (Pb/Bi) | Good (TIG/MIG) | Poor (Pb/Bi) |
| Anodizing quality | Good (slightly gray) | Excellent | Fair–Poor (Cu-rich) |
| Corrosion resistance | Good | Very good | Fair (Cu-rich; needs protection) |
| Typical cost index (bar) | 100 (baseline) | 90–95 | 110–120 |
2011-T3 machines even faster (90–95% machinability rating) but carries a significant corrosion penalty from its 5–6% copper content and yields poor anodizing results. 6061-T6 is more weldable and more corrosion-resistant but at the cost of roughly 30–40% longer cycle time in turning operations and far more chip-control headaches. 6262 occupies the sweet spot for parts that need good strength, acceptable corrosion resistance, cosmetic anodizing, and high-volume screw-machine productivity — and that sweet spot is why it shows up on so many purchase orders for turned aluminum components.
RFQ Checklist for 6262 Machined Parts
When requesting a quotation for 6262 components, the following information helps shops quote accurately and produce conforming parts on the first run:
- Material specification: “Aluminum 6262-T6511 per ASTM B211” or “6262-T6 per ASTM B221” — do not write “aluminum” alone. Specify bar vs. extrusion and preferred mill source if you have a qualified supplier.
- Drawing with tolerances: ISO 2768 or ASME Y14.5 general tolerances plus any tighter geometric controls. Note critical-to-function dimensions explicitly.
- Surface finish requirements: Ra target (e.g., Ra ≤ 0.8 µm on sealing surfaces, Ra ≤ 1.6 µm elsewhere) and applicable standard (ISO 4287 or ASME B46.1).
- Anodizing specification: Type II or Type III, thickness, color (include RAL or Pantone reference for dyed finishes), and sealing method. If cosmetic anodizing on a visible surface, provide an appearance acceptance standard (photographic reference or A-zone/B-zone/C-zone classification).
- Quantity and delivery schedule: Annual volume, batch size, and lead-time expectations.
- Inspection requirements: Dimensional inspection report format (FAI per AS9102 or simplified ISIR), material certification (EN 10204 3.1 or mill test report), and any NDT or pressure-test requirements.
- Thread and edge specifications: Thread class (e.g., 6H, 2B), chamfer requirements, and edge-break callouts. Undefined sharp edges on 6262 lead to unnecessary deburring labor cost.
Send your 2D and 3D files, material specification, target quantity, and surface finish requirements through the quote form on this site, and our engineering team will review geometry, tolerances, and machine selection before returning a detailed quotation within one business day.
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