6201 Aluminium Alloy for Overhead Conductors
6201 is the heat-treatable aluminium-magnesium-silicon alloy used to make the wire in all-aluminium-alloy conductors (AAAC). Drawn and aged to T81, it is roughly twice as strong as hard-drawn EC aluminium wire while keeping a minimum conductivity of 52.5 % IACS under ASTM B398. That combination lets overhead lines span further with less sag and no steel core to corrode.
- Family
- Al-Mg-Si, heat-treatable
- Wire tempers
- T81, T83
- Conductivity
- ≥ 52.5 % IACS (6201-T81)
- Standards
- ASTM B398 / B399 · IEC 60104 · EN 50183
What 6201 is and why it is used
Overhead line designers have three common conductor families: AAC (pure aluminium), ACSR (aluminium on a steel core) and AAAC (aluminium alloy throughout). 6201 is what makes AAAC possible.
An AAC conductor of 1350 wire conducts well but is weak, so it sags heavily and needs short spans. ACSR solves the strength problem with a galvanised steel core, but the steel adds weight, has much higher resistance and can corrode where it meets the aluminium, particularly in coastal and industrial air. AAAC made of 6201 wire is strong enough to support itself across normal distribution and transmission spans, with uniform material throughout, lower weight than ACSR for the same strength class and no bimetallic corrosion.
The metallurgy is the same as other 6xxx conductor alloys: magnesium and silicon dissolve during solution treatment of the rod, then precipitate as Mg2Si during ageing of the drawn wire. 6201 carries more magnesium and silicon than 6101, so it reaches higher strength at the cost of a few points of conductivity.
6201 chemical composition (wt %)
| Element | Minimum | Maximum | Note |
|---|---|---|---|
| Silicon (Si) | 0.50 | 0.90 | With Mg forms Mg2Si |
| Iron (Fe) | — | 0.50 | |
| Copper (Cu) | — | 0.10 | |
| Manganese (Mn) | — | 0.03 | Held low for conductivity |
| Magnesium (Mg) | 0.60 | 0.90 | Main strengthening element |
| Chromium (Cr) | — | 0.03 | Held low for conductivity |
| Zinc (Zn) | — | 0.10 | |
| Boron (B) | — | 0.06 | Ties up transition elements as borides |
| Others, each / total | — | 0.03 / 0.10 | |
| Aluminium (Al) | Remainder |
Aluminum Association registered limits (UNS A96201). Some published tables show 6201 with Si 0.30 – 0.70 % and Cr up to 0.10 %; those figures are not the registered 6201 limits and should not be used for purchasing.
6201 tempers and properties
| Temper | Processing | Key requirement |
|---|---|---|
| T4 (rod) | Continuously cast and rolled rod, quenched | Drawing stock; see alloy wire rod |
| T81 | Solution treated, cold drawn, then artificially aged | ASTM B398: conductivity ≥ 52.5 % IACS (resistivity ≤ 32.84 nΩ·m at 20 °C) |
| T83 | As T81 but aged for higher conductivity | Higher conductivity with somewhat lower strength (ASTM B398 since its later revisions) |
IEC 60104 and EN 50183 classify Al-Mg-Si overhead-line wire by type rather than temper, with a stronger type and a more conductive type; 6201-T81 corresponds broadly to the stronger class. Minimum tensile strengths in all these standards depend on wire diameter, so take the exact value from the standard edition named in your contract.
Physical constants used in conductor design
- Density
- 2.70 g/cm³
- Resistivity at 20 °C (52.5 % IACS)
- 32.84 nΩ·m (0.03284 Ω·mm²/m)
- Coefficient of linear expansion
- About 23 × 10⁻⁶ per °C
- Modulus of elasticity (solid wire)
- About 69 GPa
Standards for 6201 wire and AAAC
| Standard | Scope | Region |
|---|---|---|
| ASTM B398/B398M | 6201-T81 and T83 wire for electrical purposes | Americas and many export markets |
| ASTM B399/B399M | Concentric-lay-stranded 6201-T81 conductors (AAAC) | Americas |
| IEC 60104 | Al-Mg-Si alloy wire for overhead line conductors | International |
| IEC 61089 | Round-wire concentric-lay overhead stranded conductors | International |
| EN 50183 / EN 50182 | Al-Mg-Si wire / overhead stranded conductors | Europe |
| IS 398 (Part 4) | Aluminium alloy stranded conductors (AAAC) | India |
Which standard governs depends on the utility and country. They differ in wire diameters, minimum strengths and conductor tables, so a conductor made to one is not automatically compliant with another.
Typical AAAC constructions and calculated resistance
The table lists common stranding constructions with the calculated metal cross-section, overall diameter, metal mass and DC resistance at 20 °C using 6201-T81 at its 32.84 nΩ·m limit. Standard conductor tables add a small allowance (around 1 – 3 %) for the extra length of the helical strands, so published mass and resistance values are slightly higher.
| Strands / wire dia. (mm) | Area (mm²) | Overall dia. (mm) | Metal mass (kg/km) | DC resistance (Ω/km) |
|---|---|---|---|---|
| 7 / 2.29 | 28.8 | 6.9 | 78 | 1.1391 |
| 7 / 2.89 | 45.9 | 8.7 | 124 | 0.7152 |
| 7 / 3.63 | 72.4 | 10.9 | 196 | 0.4533 |
| 19 / 2.78 | 115.3 | 13.9 | 311 | 0.2848 |
| 19 / 3.10 | 143.4 | 15.5 | 387 | 0.2290 |
| 19 / 3.51 | 183.8 | 17.5 | 496 | 0.1786 |
| 19 / 3.93 | 230.5 | 19.7 | 622 | 0.1425 |
| 37 / 3.14 | 286.5 | 22.0 | 774 | 0.1146 |
| 37 / 3.52 | 360.1 | 24.6 | 972 | 0.0912 |
| 61 / 3.53 | 597.0 | 31.8 | 1612 | 0.0550 |
AAAC (6201) compared with ACSR and AAC
| Aspect | AAC (1350) | AAAC (6201) | ACSR |
|---|---|---|---|
| Conductor material | Pure aluminium | Al-Mg-Si alloy throughout | Aluminium over galvanised steel core |
| Wire conductivity | ≈ 61 % IACS | ≥ 52.5 % IACS | Aluminium ≈ 61 %; steel core adds strength, not conductance |
| Strength-to-weight | Low | High | High |
| Corrosion | Good | Very good, single metal | Risk at steel-aluminium interface |
| Typical use | Short spans, urban distribution | Distribution and transmission, coastal lines | Long spans, heavy ice loads |
For the same diameter AAAC usually has slightly higher DC resistance than AAC but much more strength; against ACSR it is lighter and avoids core corrosion, while ACSR remains preferred for very long spans and heavy ice.
Other uses of 6201
- Substation strung bus and jumpers: stranded 6201 conductor between gantries.
- Aerial bundled cable: alloy neutral messengers and phase conductors.
- ACAR conductors: 6201 wires combined with 1350 wires to tune strength and conductivity.
- Earthing and lightning protection: stranded alloy conductors where strength is needed.
6201 is occasionally extruded into conductive profiles, but for busbar and bus pipe the dedicated extrusion alloy is 6101, whose conductivity is guaranteed by ASTM B317.
References and standards
- ASTM B398/B398M – Aluminum-Alloy 6201-T81 and 6201-T83 Wire for Electrical Purposes
- ASTM B399/B399M – Concentric-Lay-Stranded 6201-T81 Aluminum Alloy Conductors
- IEC 60104 – Aluminium-magnesium-silicon alloy wire for overhead line conductors
- IEC 61089 – Round wire concentric lay overhead electrical stranded conductors
- The Aluminum Association – Electric conductor property limits and equivalent resistivity (Tables 16.3, 16.4)
6201 aluminium (aluminum) alloy: FAQ
What is 6201 aluminium used for?
Mainly as drawn and aged wire for all-aluminium-alloy overhead conductors (AAAC), plus ACAR, aerial bundled cable messengers and substation strung bus.
What is the conductivity of 6201-T81?
At least 52.5 % IACS under ASTM B398, equal to a maximum resistivity of about 32.84 nΩ·m at 20 °C.
What is the difference between 6201-T81 and T83?
Both are solution treated, drawn and aged. T83 is aged to give higher conductivity with somewhat lower strength.
Is 6201 the same as 6101?
No. 6201 has more magnesium and silicon, so it is stronger and slightly less conductive. 6201 is mainly a wire alloy; 6101 is mainly an extrusion alloy for busbar and bus pipe.
Why choose AAAC over ACSR?
AAAC is lighter for similar strength in many sizes, has no steel core to corrode and has lower AC losses. ACSR still suits very long spans and heavy ice loading.
Sourcing 6201 for conductor production?
Send the standard, wire or conductor size and quantity. Metline supplies rod, wire and conductor worldwide with test certificates.
