6061 T651 Aluminium Round Bars

The reason to pay for T651 instead of T6 is not strength - it is what happens after the first cut. As-quenched T6 carries residual stress from the quench; remove metal from one side and the part moves. Industry-reported post-machining movement runs 0.010 to 0.030 in on T6 against under 0.002 in on stress-relieved T651. On a datum face or a mating bore, 0.010 in is a failed inspection.

 

What is 6061-T651 aluminum round bar

6061 is a heat-treatable Al-Mg-Si alloy. Its strength comes from Mg₂Si: solution treatment dissolves the magnesium and silicon into solid solution, the quench freezes them there, and artificial aging precipitates fine particles that block dislocation movement. In the T6 condition that puts typical tensile strength near 310 MPa and yield near 276 MPa - roughly five times the yield of the same alloy annealed.

 

T651 is T6 plus one extra step: the bar is stretched by a small permanent amount after aging. That plastic stretch flattens the residual stress pattern left by quenching, so when you machine one side away there is far less imbalance to release. T6511 is the same idea on extruded product - stretched, with a light straightening pass allowed afterward.

 

Temper	Stress relieved?	Tensile min. (ASTM)	Post-machining movement	Typical use
T6	No	290 MPa (42 ksi), B211 / B209	0.010–0.030 in	General bar, simple parts, welded assemblies
T651	Yes - stretched	290 MPa (42 ksi), B211	Under 0.002 in	Cold-finished bar for heavy material removal, tight flatness
T6511	Yes - stretched + straightened	262 MPa (38 ksi), B221	Under 0.002 in	Extruded bar, rod and structural shapes

Post-machining movement figures are industry-reported ranges, not GNEE measurements. Minimum tensile values are ASTM requirements by product form: B211 covers cold-finished bar, B221 covers extruded bar. The extrusion minimum sits lower because of the product form, not because the alloy is weaker - typical values are the same across all three tempers.

 

 

6061 aluminum round bar specifications

Item	Specification
Alloy / temper	6061-T651 (cold finished); 6061-T6511 (extruded). T6, T4 and O available on request
Material standards	ASTM B211 (cold-finished bar, rod, wire), ASTM B221 (extruded bar), AMS 4027, AMS-QQ-A-225/8, EN 754-2, EN 755-2, ISO 6362, GB/T 3191
Diameter range	3–300 mm (0.125–12 in) cold finished; extruded to 400 mm on enquiry
Length	1000–6000 mm standard; cut-to-length service, fixed or random lengths
Diameter tolerance	Cold finished h8 / h9 by size; extruded to EN 755-2 or ASTM B221
Straightness	Cold-finished bar is held to commercial straightness; tighter on request for shaft work
Surface	Mill finish, bright drawn; polished on request
Processing	Extrusion, cold drawing, forging; cutting, CNC machining, anodizing, powder coating
Equivalent designations	AA 6061 · UNS A96061 · EN AW-6061 · ISO AlMg1SiCu · WNR 3.3211 · BS HE20

Send an Inquiry Now

 

Chemical composition of 6061 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 B211 / B221 and EN 573-3 registered limits. The magnesium-to-silicon ratio is what makes 6061 heat treatable: the two combine as Mg₂Si, and the precipitation of that phase during aging is the strengthening mechanism. Chromium is added to control grain structure during ingot preheat and recrystallization.

 

Mechanical properties of 6061-T651 aluminum bar

 

Product form / standard	Temper	Tensile min.	Yield min.
Cold-finished bar - ASTM B211	T6 / T651	290 MPa (42 ksi)	240 MPa (35 ksi)
Extruded bar - ASTM B221	T6511	262 MPa (38 ksi)	240 MPa (35 ksi)
Sheet and plate - ASTM B209	T6 / T651	290 MPa (42 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

Typical values per ASM Handbook data for 6061-T6/T651; confirm against the mill test certificate for the specific heat and section. Elongation steps down as diameter increases, so a heavy section does not carry the same elongation as a small drawn bar.

 

Weight per metre of 6061 aluminum round bar

Weight follows the section at a density of 2.70 g/cm³. For a solid round bar: kg/m = 0.002123 × d² with d in millimetres. Multiplying kg/m by 0.672 gives lb/ft.

Diameter	kg/m	lb/ft	Diameter	kg/m	lb/ft
10 mm	0.212	0.143	80 mm	13.6	9.13
16 mm	0.543	0.365	100 mm	21.2	14.3
20 mm	0.849	0.571	120 mm	30.6	20.5
25 mm	1.33	0.892	150 mm	47.8	32.1
30 mm	1.91	1.28	180 mm	68.8	46.2
40 mm	3.40	2.28	200 mm	84.9	57.1
50 mm	5.31	3.57	250 mm	132.7	89.2
60 mm	7.64	5.14	300 mm	191.1	128.4

Calculated values. Check against a published stock list if freight or handling limits are tight - a 133 mm (5.25 in) bar works out to 37.8 kg/m, against 25.43 lb/ft on a commercial stock listing for that size.

 

Machining and fabrication of 6061-T651 aluminum bar

Machining

6061 in T6 and T651 conditions rates "good" on the aluminium machinability scale, and T651 is the temper shops specify when the part will lose a lot of metal. Use sharp carbide tooling with adequate coolant to avoid built-up edge, and plan chip control - the chips are long and stringy and will wrap on the tool and the chuck. Because aluminium's modulus is low, clamping force deflects thin sections; soft jaws with distributed contact help.

Welding

6061 welds by TIG and MIG, but the heat-affected zone is the constraint: welding heat coarsens and partly dissolves the Mg₂Si precipitates, so the HAZ reverts toward T4 condition and keeps only about 40–50 % of the base strength - roughly 110–140 MPa yield locally. Fusion welds land near 165 MPa as-welded with ER4043 and 186–207 MPa with ER5356; friction stir welding keeps noticeably more of the parent strength.

ER4043 (Al-5Si): lower crack sensitivity, better puddle fluidity, the shop default. Turns dark grey after anodizing.

ER5356 (Al-5Mg): higher as-welded strength, better colour match after anodizing, better in saltwater. Use it for visible architectural and marine welds.

Design the joint to the HAZ strength, or plan post-weld heat treatment - filler choice alone does not restore T6 properties.

Finishing

6061 takes Type II decorative and Type III hard anodizing. Two things to allow for: the copper content (0.15–0.40 %) makes natural-colour anodize slightly darker than 6063, and hard anodize grows roughly half the coating outward and half inward - a 50 μm coating means designing the part about 25 μm undersized per surface. For paint, a chromate conversion or equivalent conversion primer is the standard preparation.

 

Applications of 6061-T651 aluminum round bar

Machine parts and tooling - shafts, spindles, couplings, bushings, jigs, fixtures, machine bases, hydraulic and pneumatic manifolds

Fasteners and fittings - screw-machine products, nuts and bolts, valve bodies, flanges, pipe fittings

Transport - automotive and truck chassis components, suspension parts, bicycle components, rail car fittings

Structural and architectural - brackets, bracing, truss nodes, railing posts, scaffolding components

Marine-adjacent hardware - masts, deck fittings, winch components, cleats and hardware above the waterline

Sporting and consumer goods - climbing and archery equipment, camera and optical mounts, handlebar and frame components

 

 

Ordering aluminum round bar: MOQ, lead time, packing, certification

Item	Term
Minimum order quantity	Flexible - trial quantities and container loads quoted on the same terms
Lead time	15–30 days from order confirmation; confirmed against the current schedule before you commit
Incoterms	EXW, FOB, CFR, CIF, DAP
Payment	T/T, L/C at sight
Packing	Bundled with steel strap, internal protective film, seaworthy wooden case or pallet; end caps on polished bar
Certification	EN 10204 3.1 standard; 3.2 and third-party inspection arranged on request
Cutting	Cut-to-length, chamfering, sawing to drawing

 

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 rolling 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.

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.

 

 

FAQ

What is the difference between 6061-T6 and 6061-T651 round bar?

Strength is effectively the same - both carry a 290 MPa minimum tensile in ASTM B211 and reach about 310 MPa typical. The difference is residual stress. T651 is stretched after aging, which flattens the quench stress pattern; industry reports put post-machining movement under 0.002 in for T651 against 0.010–0.030 in for T6. If the part has a tight datum or loses a lot of metal, T651 is the cheaper option once you count scrap.

Is T651 or T6511 the right call for round bar?

It follows the production route, not the shape. Cold-finished bar is supplied to ASTM B211 and is normally T651. Extruded bar is supplied to ASTM B221 and is normally T6511 - stretched, with a light straightening pass allowed. Both are stress relieved; the B221 minimum tensile is lower at 262 MPa because of the product form.

What diameter and length can you supply?

Cold-finished bar runs 3–300 mm diameter; extruded bar goes to 400 mm on enquiry. Standard lengths are 1000–6000 mm with cut-to-length service. Diameter tolerance on cold-finished bar is h8 or h9 depending on size.

What is the minimum order quantity and lead time?

MOQ is flexible - we quote trial quantities and full containers on the same terms. Lead time is 15–30 days from order confirmation, and we confirm the actual date against the production schedule before you commit.

Can 6061-T651 aluminum bar be welded?

Yes, by TIG or MIG with ER4043 or ER5356 filler. The heat-affected zone keeps roughly 40–50 % of the base strength, so design the joint to that reduced figure, or plan for post-weld heat treatment. ER4043 resists cracking better; ER5356 gives higher as-welded strength and matches the parent colour after anodizing.

Which documents come with the shipment?

EN 10204 3.1 mill test certificate is standard on every order, showing 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-T651 round bar ships without an export licence review.

Request A Quote For 6061-T651 Aluminum Round Bar

Send the six things we need and you get a price, not a questionnaire: diameter and tolerance, temper (T651 or T6511), length or cut lengths, quantity, surface or finishing requirement, and destination port. If you are unsure whether T6 will hold your tolerance, tell us the tightest datum on the part and we will answer from the geometry.

Hot Tags: 6061 T651 Aluminium Round Bars, China 6061 T651 Aluminium Round Bars manufacturers