Aluminium for CNC Machining: 6061, 6082, 7075, 5083

Updated 2026-11-03 · 7 min read

For CNC machining, EN AW-6061 and EN AW-6082 are the general-purpose aluminium alloys, EN AW-7075 is the high-strength alloy and EN AW-5083 is the corrosion-resistant plate alloy that welds well. Supplier data sheets rate all four as good to machine, so the choice rests on strength, welding, corrosion resistance and anodising, and on the temper in which the material is delivered.

Which aluminium alloys are used for CNC machining?

Four wrought alloys cover most machined aluminium parts. EN AW-6061 (AlMg1SiCu) and EN AW-6082 (AlSi1MgMn) are heat-treatable magnesium-silicon alloys of medium strength. EN AW-7075 (AlZn5.5MgCu) is a heat-treatable zinc alloy and the strongest of the four. EN AW-5083 (AlMg4.5Mn0.7) is not heat-treatable. Its strength comes from magnesium, and EN 485-2 lists its plate in the O/H111 condition.

The four-digit numbers follow the Aluminum Association scheme, and the 2026 edition of EN 573-3 orders its alloys the same way. The compositions of 6061 and 6082 differ more than their names suggest. 6082 contains 0.40 to 1.0 % manganese. 6061 allows at most 0.15 % manganese and adds 0.15 to 0.40 % copper and 0.04 to 0.35 % chromium. They are not interchangeable without checking the drawing.

How do 6061, 6082, 7075 and 5083 compare?

Strength is the first filter. The table gives the EN 485-2 minimum values for 20 mm plate, a thickness that falls inside one table band for each of the four alloys.

Table 1. Plate of 20 mm in the usual delivery condition: EN 485-2 minimums and typical physical values

EN AW-6061EN AW-6082EN AW-7075EN AW-5083
Delivery conditionT651T651T651O/H111
Tensile strength Rm, min, MPa290295540270
Yield strength Rp0.2, min, MPa240240470115
Elongation A, min, %88615
Hardness, HBW (information only)888916175
Density, g/cm³2.702.702.802.66
Thermal conductivity, W/(m·K)170 to 200170 to 220130 to 160110 to 140

Source: EN 485-2 minimums as reproduced in the Bikar Metals data sheets for each alloy (thickness bands 12.5 to 40 mm for 6061, 12.5 to 60 mm for 6082, 12.5 to 25 mm for 7075, 12.5 to 50 mm for 5083); density and conductivity are Bikar's typical values.

On plate, 6061 and 6082 are close. The gap opens on extruded material. For pressed tube with a wall of 5 to 25 mm, the EN 755-2 minimums in the same data sheets are 260 MPa tensile and 240 MPa yield for 6061 T6, against 310 and 260 MPa for 6082 T6. The values depend on product form and thickness, and they are minimums, not typical results. The Bikar data sheets do not name the edition of EN 485-2 or EN 755-2 they reproduce, and EN 755-2 was replaced in 2025, so confirm limits against the edition on your order.

7075 has a minimum yield strength of 470 MPa against 240 MPa for 6061 and 6082, with a lower elongation and a higher density. 5083 has the lowest yield strength of the four in the H111 condition and the highest elongation.

How do the alloys differ in welding, corrosion and anodising?

Bikar rates each property from 1 (very good) to 5 (unsuitable). The ratings are supplier guidance, not a standard.

Table 2. Supplier ratings, 1 = very good to 5 = unsuitable

PropertyEN AW-6061EN AW-6082EN AW-7075EN AW-5083
Corrosion, normal atmosphere2141
Corrosion, seawater2 to 3241
MIG welding1152
Protective anodising1132
Decorative anodising3354
Machinability (heat-treated; 5083 work-hardened)2222

Source: Bikar Metals data sheets for EN AW-6061, 6082, 7075 and 5083, section "Other data". Bikar accepts no liability for anodising results or colour on decorative parts.

7075 is not welded by fusion in practice. If a part needs welded joints, choose 6061, 6082 or 5083, and expect the weld zone to be weaker than the parent metal: Aalco's data sheet for 6082 notes that strength is lowered in the weld zone. Welded assemblies that include machined interfaces are part of our welding and fabrication work.

5083 has the best seawater rating. Gleich Aluminium warns that 5083 under load at temperatures above 70 °C risks stress corrosion cracking, so it is a poor choice for hot, loaded parts.

For anodised parts, 6061 and 6082 are the safe choices. 7075 anodises, but the supplier rating for a decorative finish is the worst of the four. ISO 7599 covers decorative and protective anodising, ISO 10074 covers hard anodising for wear resistance, see surface treatments for machined parts.

Which of the four machines best?

On the supplier ratings, none. Bikar gives all four the same rating of 2 (good) for machinability, and Gleich lists 5083 as good to machine. The ratings are coarse, and what differs in the shop is chip form.

Hydro rates aluminium machinability from A to E by chip form and surface finish: A is very small chips and an excellent finish, E is long continuous chips and a surface that is hard to keep. Harder and stronger alloys generally produce shorter chips, and soft wrought alloys produce extremely long chips that call for chip breakers. By that rule 5083 in H111, with a minimum yield of 115 MPa, is the alloy to expect long chips from. Aalco reports that 6082 in T6 and T651 machines well and produces tight coils of swarf when chip breakers are used.

Pick the alloy by function and let the tooling follow. The milling side of these parts is described on our CNC milling page.

What do T651 and T73 mean for a machined part?

The temper matters as much as the alloy. EN 515:2017 defines the designations. Aalco defines T651 as solution heat treated, stress relieved by stretching, then artificially aged. The "51" matters for machining: plate that is stress relieved by stretching has lower residual stress than plate in plain T6, so it moves less when material is removed from one side. Parts with deep pockets or large one-sided cuts should be ordered from a "51" plate or from material that is stress relieved in the same way.

7075 has a second variable. In a 1963 NASA test series of high-strength aluminium alloys, all alloys tested were highly susceptible to stress corrosion cracking in the short transverse direction except 7075-T73 and 2219-T87. T73 is the over-aged condition, and it costs strength: the EN 755-2 minimum for pressed round bar up to 25 mm is 485 MPa tensile and 420 MPa yield in T73, against 540 and 480 MPa in T6. The report is old, so check current material specifications, but it is the reason T73 is the temper specified for 7075 parts under sustained tensile stress across the thickness.

Which standards apply, and are they current?

Status as of 2026-10-30. Several of these standards were replaced or put into revision within the last two years.

  • Composition, EN 573-3: EN 573-3:2026 is valid from 2026-04-01 and replaced EN 573-3:2019+A2:2023. The DIN edition of 2026-05 adds EN AW-2007C, 2079, 4115A and 6084 and reorders the alloys to follow the Aluminum Association system. A draft amendment, EN 573-3:2026/prA1:2026, is at DIN dated 2026-07-10.
  • Plate, EN 485-2: the current published edition is the one DIN lists as DIN EN 485-2:2018-12, which replaced the 2016-10 edition. A revision, prEN 485-2:2025, is a draft at DIN, dated 2025-11-28.
  • Extrusions and bar, EN 755-2: EN 755-2:2025 replaced EN 755-2:2016.
  • Tempers, EN 515: EN 515:2017 is current; it was confirmed in 2022 and replaced the 1993 edition.

A drawing that cites EN 573-3:2019 or EN 755-2:2016 refers to a replaced edition. We did not compare the limits of the four alloys in this article between editions, because the full texts are paid. Name the edition on the order and on the certificate.

How do you specify the alloy on a drawing?

Write the designation in full, with temper and product form: for example "EN AW-6082 T651, plate" or "EN AW-5083 H111". Check five things before the drawing goes out:

  • The prefix EN AW and the temper are present. "6061" alone leaves the temper open.
  • The standards carry their years, for the reason in the previous section.
  • Any welding is stated, with the weld standard, because 7075 cannot take it.
  • The surface treatment names its standard, such as ISO 7599:2018 for protective and decorative anodising or ISO 10074:2021 for hard anodising. ISO 10074 is under systematic review in 2026.
  • The material certificate type is named. An EN 10204 type 3.1 certificate documents the actual lot, see EN 10204 certificates compared.
Deviation we seeA drawing that says only "Aluminium" or "6061" leaves the temper and product form open. Plate in T651 and extruded bar in T6 have different minimum strengths, so the supplier has to ask or assume. Agree the designation before the order.

Frequently asked questions

What is the difference between 6061 and 6082 aluminium?
Both are Mg-Si alloys, but 6082 contains 0.40 to 1.0 % manganese where 6061 allows at most 0.15 %, and 6061 adds 0.15 to 0.40 % copper. On T651 plate the EN 485-2 minimums are almost equal (290 and 295 MPa tensile strength at 20 mm). On pressed tube with 5 to 25 mm wall, EN 755-2 gives 6082 T6 a minimum of 310 MPa against 260 MPa for 6061 T6.
Is 7075 aluminium weldable?
Not by fusion welding in practice. The supplier rating in Bikar's data sheet is 5 (unsuitable) on a scale of 1 to 5 for gas, TIG and MIG welding. Parts in 7075 are machined from solid or joined mechanically.
Which aluminium alloy is best for anodising?
For protective anodising, Bikar rates 6061 and 6082 at 1 (very good), 5083 at 2 and 7075 at 3. For decorative anodising the ratings are 3 for 6061 and 6082, 4 for 5083 and 5 for 7075. Anodising colour cannot be guaranteed from the alloy alone, so agree a sample.
Which temper should I order for a milled aluminium plate part?
Stress-relieved plate is the safer order for heavy milling: T651 for 6061, 6082 and 7075. T651 means solution heat treated, stress relieved by stretching, then artificially aged. 5083 plate is not heat-treated and is delivered in the O/H111 condition.
Which standard gives the chemical composition of EN AW alloys?
EN 573-3. The edition valid since 1 April 2026 is EN 573-3:2026, which replaced EN 573-3:2019+A2:2023. Name the edition with its year on drawings and orders.

Sources

  1. EN AW-6061 data sheet: composition per EN 573-3, EN 485-2 and EN 755-2 values, ratings (Bikar Metals)
  2. EN AW-6082 data sheet: composition per EN 573-3, EN 485-2 and EN 755-2 values, ratings (Bikar Metals)
  3. EN AW-7075 data sheet: composition per EN 573-3, EN 485-2 and EN 755-2 values, ratings (Bikar Metals)
  4. EN AW-5083 data sheet: composition per EN 573-3, EN 485-2 and EN 755-2 values, ratings (Bikar Metals)
  5. EN AW-5083 plate, H111: stress corrosion note above 70 °C (Gleich Aluminium)
  6. Aluminium alloy 6082 T6/T651 plate: temper definition, machining, weld zone (Aalco Metals)
  7. Three factors affect aluminium's machinability: chip form ratings A to E (Hydro)
  8. Stress Corrosion of High-Strength Aluminum Alloys, NASA MTP-P&VE-M-63-8, 1963
  9. EN 573-3:2026 (EVS, national adoption, valid from 2026-04-01)
  10. DIN EN 573-3:2026-05, replaces DIN EN 573-3:2024-03, alloys added (DIN Media)
  11. DIN EN 573-3/A1:2026-08, draft amendment EN 573-3:2026/prA1:2026 (DIN Media)
  12. EN 573-3:2019+A2:2023, withdrawn 2026-04-01 (EVS)
  13. EN 755-2:2025, replaces EN 755-2:2016 (Genorma)
  14. NS-EN 755-2:2025, published 2025-07, replaces NS-EN 755-2:2016 (Standards Norway)
  15. DIN EN 485-2:2026-01, draft of prEN 485-2:2025 (DIN Media)
  16. DIN EN 485-2:2016-10, withdrawn, replaced by DIN EN 485-2:2018-12 (DIN Media)
  17. EN 515:2017, wrought aluminium temper designations, confirmed 2022 (Genorma)
  18. ISO 7599:2018, decorative and protective anodic oxidation coatings (ISO catalogue)
  19. ISO 10074:2021, hard anodic oxidation coatings (ISO catalogue)

Questions on a drawing? sales@ertas.engineering

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