ASTM B221 6061-T6511 Aluminum Round Bar

What is 6061-T6511 aluminum round bar

T6511 describes a route, not a shape. The billet is extruded, solution heat treated and quenched, then stretched by a small permanent amount to flatten the residual stress left by quenching, and finally given a light straightening pass. That last step separates it from T6510: under ANSI H35.1, T6510 permits no straightening after stretching, while T6511 allows a minor pass to bring the bar within tolerance.

 

It is the standard temper for extruded bar and structural shapes, and the default in most stock catalogues. The stretching step is also why it suits automated machining - long parts hold tolerance once material comes off.

Route	Standard	Stretched?	Straightened after stretching?
Cold finished bar	ASTM B211	For T651	n/a - the draw sets the geometry
Extruded bar, T6510	ASTM B221	Yes	No
Extruded bar, T6511	ASTM B221	Yes	Yes, minor straightening allowed
Extruded bar, T6	ASTM B221	No	Yes, as needed

Temper definitions per ANSI H35.1 / Aluminium Association designations. T6510 and T6511 carry the same mechanical requirements in ASTM B221.

 

 

ASTM B221 dimensional tolerances for extruded aluminum round bar

Extruded bar does not carry the h8/h9 band that cold-finished bar does. ASTM B221 tolerances step with size, and the European and Chinese equivalents (EN 755-9, GB/T 6892) follow a similar pattern. The figures below are representative of standard tolerance classes.

Nominal diameter	Tolerance, plus and minus
Up to 10 mm	±0.10 mm
Over 10 to 30 mm	±0.15 mm
Over 30 to 50 mm	±0.20 mm
Over 50 to 80 mm	±0.25 mm
Over 80 to 120 mm	±0.30 mm
Over 120 mm	±0.50 mm

 

Parameter	Typical limit
Straightness	0.5–1.5 mm per metre of length
Twist	About 1.5° per metre of length
Cut-to-length tolerance	+6.4 / 0 mm

Representative values for standard tolerance classes per EN 755-9 and ASTM B221; tighter classes are available on some sizes. Because twist accumulates along the length, specify straightness over the full bar length rather than per metre if the part is long.

 

Chemical composition of 6061-T6511 aluminum round bar

Element	Content (wt %)	Element	Content (wt %)
Silicon (Si)	0.40–0.80	Chromium (Cr)	0.04–0.35
Iron (Fe)	0.70 max	Zinc (Zn)	0.25 max
Copper (Cu)	0.15–0.40	Titanium (Ti)	0.15 max
Manganese (Mn)	0.15 max	Others, each	0.05 max
Magnesium (Mg)	0.80–1.20	Others, total	0.15 max
Aluminium (Al)	Balance

Per ASTM B221 / B211 and EN 573-3 registered limits. Chromium and manganese matter more on extruded product than most buyers realise: their dispersoid particles pin grain boundaries and raise the recrystallisation temperature, which is part of what keeps the coarse grain ring described above in check.

 

Mechanical properties of 6061-T6511 aluminum bar

Requirement	ASTM B221 - T6510 / T6511	ASTM B211 - T651 cold finished
Tensile strength, minimum	262 MPa (38 ksi)	290 MPa (42 ksi)
Yield strength, minimum	240 MPa (35 ksi)	240 MPa (35 ksi)

Property	Typical value
Tensile strength	310 MPa (45 ksi)
Yield strength, 0.2 % offset	276 MPa (40 ksi)
Elongation	12 %
Brinell hardness	95 HB
Shear strength	207 MPa (30 ksi)
Fatigue strength, 5 × 10⁸ cycles	97 MPa (14 ksi)
Elastic modulus	68.9 GPa

The 262 MPa figure is the ASTM B221 acceptance minimum for the extruded product form, not a different alloy - the typical heat-to-heat result is the same 310 MPa as cold-finished bar. Typical values per ASM Handbook data; confirm against the mill test certificate for the specific heat and section.

 

specifications of 6061-T6511 aluminum round bar

Item	Term
Diameter range	6–300 mm standard; larger sections against the extrusion press schedule
Length	Standard stock lengths around 3 m and 6 m; cut-to-length from short pieces upward
Tolerance	ASTM B221 standard class; tighter classes and per-length straightness on request
Minimum order quantity	Flexible - trial lengths and full containers quoted on the same terms
Lead time	15–30 days from order confirmation, confirmed against the press schedule before you commit
Incoterms / payment	EXW, FOB, CFR, CIF, DAP · T/T, L/C at sight
Packing	Bundled with steel strap, interleaved or sleeved to protect the surface, seaworthy wooden case or pallet
Certification	EN 10204 3.1 standard; 3.2 and third-party inspection arranged on request

 

Weight per metre of 6061-T6511 aluminum round bar

At a density of 2.70 g/cm³, solid round bar follows kg/m = 0.002123 × d² with d in millimetres. The table below lists figures from a commercial metric stock range alongside the calculated value, so you can see how closely they track.

Diameter	kg/m (stock list)	Calculated	Diameter	kg/m (stock list)	Calculated
40 mm	3.393	3.40	140 mm	41.56	41.6
60 mm	7.634	7.64	200 mm	84.82	84.9
80 mm	13.57	13.6	250 mm	132.5	132.7
100 mm	21.23	21.2	300 mm	-	191.1

Stock list figures from a published metric Ø40–270 mm range; calculated column uses ρ = 2.70 g/cm³. Differences of a few tenths of a percent come from the density figure each supplier rounds to. For imperial sizes, multiply kg/m by 0.672 to get lb/ft.

 

Machining, welding and finishing 6061-T6511 aluminum bar

Machining

6061-T6511 is the default stock for CNC work: it rates good on the machinability scale and the stretching step keeps long parts from moving after the first heavy cut. Use sharp carbide with coolant and plan chip evacuation - the chips are long and stringy. Where the coarse grain ring reaches the surface, expect a rougher first-pass finish; a heavier roughing depth usually gets below it.

Welding

TIG and MIG both work with ER4043 or ER5356 filler. The heat-affected zone reverts toward T4 condition and keeps roughly 40–50 % of base strength - about 110–140 MPa yield locally - so design the joint to that figure or plan post-weld heat treatment. ER4043 resists cracking and flows better; ER5356 gives higher as-welded strength and matches the parent colour after anodising.

Finishing

Type II decorative and Type III hard anodising both take. Because the copper content of 6061 runs 0.15–0.40 %, clear anodised parts read slightly darker than the same part in 6063, and hard anodise grows about half the coating outward - a 50 μm layer means designing roughly 25 μm undersized per surface. Where mottling from the coarse grain ring is a risk, bead blasting or a minimum etch will usually carry it; say so on the order if appearance is being inspected.

 

 

Applications of 6061-T6511 aluminum round bar

Machine parts - shafts, pins, bushings, spacers, couplings, rollers, jig and fixture bodies

Fasteners and turned parts - screw-machine products, nuts, bolts, hydraulic and pneumatic fittings

Structural and framework - truss nodes, bracing, tower members, scaffold components, railing posts

Transport and marine - truck and bus body components, trailers, fittings above the waterline

General engineering - chemical equipment, textile and paper rolls, valve bodies, manifold blocks

 

 

About GNEE 

In business since 2008. GNEE has supplied aluminum products since 2008 and exports to more than 100 countries. 

Stock on common sizes, mill runs for everything else. Standard diameters and lengths are held in stock, so small and repeat orders ship without waiting for a press slot. Non-standard diameters, tempers and lengths are produced to order.

Large and small orders both accepted. Minimum order quantity is flexible - trial quantities and container loads are quoted on the same terms. Quote the quantity you actually need rather than padding it to hit a threshold.

Lead time 15 to 30 days from order confirmation for standard specifications. We confirm the date against the current production schedule before you commit, not after.

Documentation with every shipment. EN 10204 3.1 mill test certificate is standard; 3.2 and third-party inspection can be arranged on request.

Technical answers, not stock-list answers. Our sales engineers read drawings and ask about the service condition - load, environment, fabrication method - before recommending a grade or temper. If a specification is wrong for the job, we say so before you buy.

 

6061-t6511 Aluminum Round Bar MTC

6061-T6511 Aluminum Round Bar Packaging

FAQ

What does T6511 mean on aluminum round bar?

It identifies the production route: solution heat treated, quenched, then stress relieved by stretching, with a minor straightening pass allowed afterward. Under ANSI H35.1, T6510 is the same without the straightening. ASTM B221 covers the extruded product, and T6511 is the standard temper for extruded bar and shapes.

Is there a size limit on 6061-T6511 aluminum bar?

Stretcher capacity sets it. Published distributor ranges put T6511 extruded rod at roughly 0.25–9.0 in while the same listing carries T6 extruded rod to 22.0 in, so above about 9 in most suppliers quote T6 unless the size is run to order. Ranges vary by supplier - say the temper you need rather than assuming the default.

What tolerance does ASTM B221 allow on round bar?

Diameter tolerance steps with size, around ±0.10 mm up to 10 mm and ±0.50 mm above 120 mm in standard classes. Straightness typically runs 0.5–1.5 mm per metre, twist about 1.5° per metre, and cut lengths +6.4 / 0 mm. These are representative standard-class figures, not the h8/h9 band you get on cold-finished bar.

Why did my anodised 6061-T6511 parts come out mottled?

Almost always the coarse grain ring. The outer band of an extruded bar recrystallises into much larger grains, and that band takes the anodic coating differently, giving streaking or blotching around the surface. Fixes are practical: heavier roughing to get under the ring, minimum etch time with no hot caustic, or bead blasting before anodising.

What is the difference between 6061-T6511 and 6061-T651?

Product form and route. T651 is normally cold-finished bar to ASTM B211 with a 290 MPa minimum tensile and drawing-grade tolerance; T6511 is extruded bar to ASTM B221 with a 262 MPa minimum and looser dimensional tolerance. Both are stretched for stress relief, and typical test results are the same 310 MPa.

What are the MOQ and lead time?

MOQ is flexible and small orders are accepted on standard sizes. Lead time is 15–30 days from order confirmation, and we confirm the actual date against the press schedule before you commit.

Which documents come with the shipment?

EN 10204 3.1 mill test certificate with heat number, chemical analysis and mechanical test results. EN 10204 3.2 and third-party inspection can be arranged on request.

Is 6061 aluminum subject to Chinese export control?

No. 6061 is not among the high-strength aluminum categories controlled as dual-use items under Chinese export control regulations. Those categories cover grades such as 7075, 7050, 2024, 2014, 2017, 7A04, 2195, 7068, 7055 and 7150, which GNEE does not export. 6061-T6511 round bar ships without an export licence review.

 

Request A Quote For 6061-T6511 Aluminum Round Bar

 

Send six things and you get a price rather than a questionnaire: diameter, temper (T6511 or T6 - especially above 200 mm), length or cut lengths, quantity, tolerance or straightness requirement if it differs from standard class, and destination port. If the part will be anodised, mention it; we can advise on stock removal for the coarse grain ring before you cut steel.

 

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