Workholding
Square bar clamps directly in a vice. For precision parts, skim one face and one edge first to create true datums, as extruded faces may have slight twist.
Square stock for milled parts
6061 Aluminium Square Bar
6061 square bar gives machinists four flat, square faces to clamp and reference, which makes it the quickest starting stock for milled blocks, brackets, keys and fixture parts. Metline supplies 6061 square bar in extruded T6511 and cold-finished T6, from about 6 to 200 mm (1/4 to 6 in), cut to length and certified to ASTM, AMS or EN standards, worldwide.
- Alloy
- 6061
- Tempers
- T6, T651, T6511
- Size
- about 6 – 200 mm square
- Standards
- ASTM B211 · B221 · EN 755-2
What is 6061 square bar used for?
Square bar is the natural stock for parts that are mostly prismatic: mounting blocks, clamp jaws, spacers, keys, manifold bodies and small brackets. Because the faces are already flat and roughly square to each other, a part can go straight into a vice without first being skimmed on all sides, which saves set-ups and material compared with sawing pieces from plate.
6061 is the most common alloy for this because it combines medium strength (typical yield about 276 MPa in T6) with clean machining, good dimensional stability in stress-relieved tempers, weldability and an excellent anodised finish. It is the "do-everything" choice when no other requirement pushes you to 2011, 7075 or a 5xxx marine alloy.
Square bar comes in two forms. Extruded square (usually T6511) is economical and available in large sizes; it has small corner radii and an extruded surface. Cold-finished square (T6 or T651) is drawn after extrusion for tighter size tolerance, sharper corners and a smoother surface, and is normally limited to smaller sizes.
6061 composition (wt %)
Composition limits as registered by the Aluminum Association and used in ASTM B211, B221 and EN 573-3.
| Element | Minimum | Maximum |
|---|---|---|
| Magnesium (Mg) | 0.80 | 1.20 |
| Silicon (Si) | 0.40 | 0.80 |
| Copper (Cu) | 0.15 | 0.40 |
| Chromium (Cr) | 0.04 | 0.35 |
| Iron (Fe) | — | 0.70 |
| Manganese (Mn) | — | 0.15 |
| Zinc (Zn) | — | 0.25 |
| Titanium (Ti) | — | 0.15 |
| Others, each / total | — | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Mechanical properties of 6061 square bar
| Product, temper and standard | Tensile min. | Yield min. | Elongation min. |
|---|---|---|---|
| Cold-finished square T6 / T651, ASTM B211 | 290 MPa / 42 ksi | 240 MPa / 35 ksi | 10 % |
| Extruded square T6 / T6511, ASTM B221 | 260 MPa / 38 ksi | 240 MPa / 35 ksi | 8 – 10 % |
| Extruded square T6, EN 755-2 (≤ 200 mm) | 260 MPa | 240 MPa | 8 % |
| Typical T6 | 310 MPa | 276 MPa | 12 % |
For square bar the size used for property bands is the side length (the thickness). Certificates list the values that apply to your size.
Physical properties of 6061-T6
- Density
- 2.70 g/cm³ (0.0975 lb/in³)
- Modulus of elasticity
- 68.9 GPa (10,000 ksi)
- Shear strength (typical)
- 207 MPa (30 ksi)
- Thermal conductivity
- 167 W/m·K
- Electrical conductivity
- 43 % IACS
- Coefficient of thermal expansion
- 23.6 µm/m·°C (20 – 100 °C)
- Melting range
- 582 – 652 °C
Extruded or cold-finished square bar?
| Point | Extruded T6511 | Cold-finished T6 / T651 |
|---|---|---|
| Size range | about 10 – 200 mm | about 6 – 75 mm |
| Side tolerance | Extruded tables (wider) | Cold-finished tables (closer) |
| Corners | Small radius from the die | Sharp or near-sharp |
| Twist and straightness | Controlled by stretching | Controlled by drawing and straightening |
| Residual stress | Low (stretched) | Low in T651; some in T6 |
| Typical choice for | Milled blocks, frames, general machining | Keys, gauges, parts with as-supplied faces |
If a face of the bar stays unmachined on the finished part, cold-finished bar avoids a skim cut. If every face is machined anyway, extruded T6511 is usually the better buy. Tolerances are given in ANSI H35.2 for ASTM orders, and EN 755-4 (extruded) or EN 754-4 (drawn) for square bar under EN orders.
6061 square bar sizes and weights
Weight per metre = 0.0027 × a² kg (a = side in mm, density 2.70 g/cm³). Values ignore corner radii and are slightly high for extruded bar. For other sizes use the bar weight calculator.
| Side (mm) | Approx. inch | kg per metre | kg per 3 m bar | lb per foot |
|---|---|---|---|---|
| 6 | 0.24 | 0.097 | 0.29 | 0.065 |
| 8 | 0.31 | 0.173 | 0.52 | 0.116 |
| 10 | 0.39 | 0.270 | 0.81 | 0.181 |
| 12 | 0.47 | 0.389 | 1.17 | 0.261 |
| 15 | 0.59 | 0.608 | 1.82 | 0.408 |
| 16 | 0.63 | 0.691 | 2.07 | 0.464 |
| 20 | 0.79 | 1.08 | 3.24 | 0.726 |
| 25 | 0.98 | 1.69 | 5.06 | 1.134 |
| 30 | 1.18 | 2.43 | 7.29 | 1.633 |
| 35 | 1.38 | 3.31 | 9.92 | 2.223 |
| 40 | 1.57 | 4.32 | 12.96 | 2.903 |
| 45 | 1.77 | 5.47 | 16.40 | 3.674 |
| 50 | 1.97 | 6.75 | 20.25 | 4.536 |
| 60 | 2.36 | 9.72 | 29.16 | 6.532 |
| 70 | 2.76 | 13.23 | 39.69 | 8.890 |
| 75 | 2.95 | 15.19 | 45.56 | 10.206 |
| 80 | 3.15 | 17.28 | 51.84 | 11.612 |
| 90 | 3.54 | 21.87 | 65.61 | 14.696 |
| 100 | 3.94 | 27.00 | 81.00 | 18.143 |
| 120 | 4.72 | 38.88 | 116.6 | 26.126 |
| 150 | 5.91 | 60.75 | 182.3 | 40.822 |
| 200 | 7.87 | 108.00 | 324.0 | 72.573 |
Inch sizes:
| Side (in) | Side (mm) | lb per foot | kg per metre |
|---|---|---|---|
| 1/4 | 6.35 | 0.073 | 0.109 |
| 3/8 | 9.52 | 0.165 | 0.245 |
| 1/2 | 12.70 | 0.293 | 0.435 |
| 5/8 | 15.88 | 0.457 | 0.680 |
| 3/4 | 19.05 | 0.658 | 0.980 |
| 1 | 25.40 | 1.171 | 1.74 |
| 1-1/4 | 31.75 | 1.829 | 2.72 |
| 1-1/2 | 38.10 | 2.634 | 3.92 |
| 1-3/4 | 44.45 | 3.585 | 5.33 |
| 2 | 50.80 | 4.682 | 6.97 |
| 2-1/2 | 63.50 | 7.316 | 10.89 |
| 3 | 76.20 | 10.535 | 15.68 |
| 3-1/2 | 88.90 | 14.339 | 21.34 |
| 4 | 101.60 | 18.728 | 27.87 |
| 5 | 127.00 | 29.263 | 43.55 |
| 6 | 152.40 | 42.139 | 62.71 |
Lengths and processing
- Standard lengths
- 3 – 3.66 m (10 – 12 ft), extruded up to about 6 m
- Cut pieces
- Saw-cut blocks and blanks to drawing
- Rectangular sizes
- For non-square sections see 6061 flat and rectangular bar
Milling and machining 6061 square bar
Milling
Use 2- or 3-flute carbide end mills with polished flutes, high spindle speed and good chip evacuation. Air blast or flood coolant prevents chip recutting.
Distortion
T6511 or T651 keep parts flat when pockets are machined. Rough, release clamps and then finish when tolerances are tight.
Drilling and tapping
Drills and taps cut cleanly in T6; use form taps for strong threads in blind holes.
Welding
Weldable with ER4043 or ER5356 filler. Expect HAZ softening to roughly T4 strength.
Anodising
Machined faces anodise evenly. Edge-break the corners before anodising so the coating does not chip.
Standards and equivalents
| System | Designation | Standard for square bar |
|---|---|---|
| ASTM / ASME | 6061 | ASTM B211 (cold-finished), ASTM B221 (extruded) |
| SAE AMS | 6061-T6 / T651 / T6511 | AMS 4117, AMS 4150, AMS 4173 |
| European | EN AW-6061 | EN 754-2 / EN 755-2; tolerances EN 754-4 / EN 755-4 |
| Other | UNS A96061 · Werkstoff 3.3211 · JIS A6061 · GB 6061 | JIS H4040, GB/T 3191 |
Applications of 6061 square bar
- Jigs and fixtures: locators, clamp jaws, risers and tooling blocks
- Automation: sensor mounts, gripper fingers, cam blocks and end stops
- Fluid power: small manifold and valve bodies drilled from solid
- Frames: machine frames, guards and supports where solid section is needed
- Power transmission: keys and keystock (cold-finished square)
- Architecture and furniture: balusters, handles and decorative posts, often anodised
6061 square bar versus alternatives
| Option | When it is better than 6061 square bar |
|---|---|
| 6082-T6 square bar | European projects specifying EN AW-6082; slightly higher strength in large sections |
| 7075-T6 / T651 square bar | Highly loaded parts and tooling that need about twice the yield strength |
| 2011 or 2024 square bar | High-volume machining (2011) or fatigue-critical parts (2024) kept away from corrosion |
| 6061-T651 plate | Parts wider than about 150 – 200 mm, or where many parts nest in one sheet |
| 6063 square bar | Decorative parts where finish matters more than strength |
How to order 6061 square bar
- SpecifyAlloy and temper (for example 6061-T6511 square, 50 × 50 mm), shape and size, length or cut pieces, quantity, and the governing standard (ASTM B211, ASTM B221 or EN 755-2).
- QuoteWe confirm availability, tolerance class, certification and delivery terms (EXW, FOB, CIF or DAP) for your destination.
- ProcessBars are cut to length or to blanks on request, end-marked with alloy, temper and lot number, and inspected for size, straightness and surface.
- DocumentEach shipment carries a mill test certificate to EN 10204 3.1 with chemistry and tensile results, plus the packing list; third-party inspection on request.
- ShipBundles are wrapped and packed in seaworthy wooden cases or on pallets and sent by sea or air to your port or door.
References and standards
- ASTM B211/B211M – Aluminum and Aluminum-Alloy Rolled or Cold Finished Bar, Rod, and Wire
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- SAE AMS 4150 – 6061-T6 extrusions
- EN 755-4 – Extruded square bars: tolerances on dimensions and form
- The Aluminum Association – Aluminum Standards and Data
6061 aluminium (aluminum) square bar: frequently asked questions
How much does 6061 square bar weigh?
Weight per metre is 0.0027 × a² kg with the side a in mm. A 25 mm square bar weighs about 1.69 kg/m, a 50 mm bar 6.75 kg/m and a 100 mm bar 27 kg/m. A 1 in square bar weighs about 1.17 lb/ft.
Does extruded 6061 square bar have sharp corners?
Not quite. Extruded bar has small corner radii from the die. Cold-finished square bar has sharper corners and tighter tolerance. If sharp corners matter, order cold-finished or allow for a skim cut.
Which temper of 6061 square bar is best for machining?
T6511 (extruded) or T651 (cold-finished), because they are stretched to relieve quench stresses and stay flat when pockets or slots are machined.
Is 6061 square bar strong enough for fixtures?
For most fixtures, yes. Its typical yield of about 276 MPa and good stiffness-to-weight ratio suit jigs and automation parts. For wear surfaces, hard anodise or add steel inserts.
Can you cut 6061 square bar into blocks?
Yes. Bar can be saw-cut into blocks to your sizes and packed to protect the faces in transit.
Need 6061 square bar?
Send size, temper, length and quantity. We will reply with availability, certification and a delivered price.
