Guides / Alloys

6061 or 7075? Pick by Load, Welding and Finish

September 21, 2026 by The Alu CNC Parts editorial desk / how this is checked

6061-T6 and 7075-T6 are the two alloys almost every machined aluminum part gets drawn in. The comparison usually gets reduced to “7075 is stronger”, which is true and not very useful, because strength is rarely the reason a part fails to work out.

Here is the comparison that matters when you are deciding what to put on the drawing.

The numbers, side by side

Property	6061-T6	7075-T6
Yield strength	~276 MPa	~503 MPa
Tensile strength	~310 MPa	~572 MPa
Elastic modulus	~68.9 GPa	~71.7 GPa
Density	2.70 g/cm³	2.81 g/cm³
Weldable	Yes	No, not structurally
Corrosion resistance bare	Good	Poor
Relative material cost	1x	2x to 3x

The row people skip is the modulus. It is nearly identical between the two. Stiffness comes from geometry, not from the alloy, so if your part is flexing too much, adding a rib or thickening a wall will do far more than switching to 7075. The upgrade raises the load at which the part takes a permanent set. It does not stop it from bending under normal load.

When 7075 earns its price

Reach for 7075 when the part is genuinely load limited and you have run out of room to make it bigger:

Clamps, levers and linkage arms where the section is fixed by what it has to fit between.
Suspension and motion components carrying real forces in a package that cannot grow.
Parts that see repeated shock loading and would take a set in 6061.
Thin sections where 6061 would need to be thicker than the space allows.

Weight is the other common reason, though the logic is indirect. 7075 is slightly denser than 6061. You save weight not because the material is lighter but because you can remove more of it and still carry the load.

When 6061 is the right answer anyway

For most parts it is, and not only because it is cheaper.

It welds. This is the decisive one. If the part joins to anything by welding, 7075 is out. It cracks in the weld and the temper is destroyed by the heat. 6061 welds well, though the heat affected zone loses strength and is often re-heat-treated afterward on parts that matter. For welded parts that also live in salt water, 5083 is the better answer.

It anodizes cleanly. 6061 takes a clear or coloured Type II anodize evenly and repeatably. 7075 contains far more zinc and copper, and it comes out darker and less consistent, particularly across batches. On a part people look at, or a set of parts that have to match each other, that alone decides it.

It resists corrosion bare. 7075 corrodes noticeably faster if the coating is scratched, and it is more prone to stress corrosion cracking. Outdoors or anywhere near salt, 7075 needs its coating to stay intact in a way 6061 does not.

It is stocked everywhere. Shops hold 6061 in a wide range of plate thicknesses and bar sizes. 7075 in an unusual thickness can mean a mill order and a two week wait before anything is cut. Designing to standard stock sizes avoids most of that.

What actually changes on the quote

Machining time between the two is broadly comparable. 7075 is often described as the nicer of the two to cut, with better chip breaking and a cleaner surface, while 6061 can be gummy and leave a built-up edge if feeds are wrong.

So the price gap is mostly material, and how much it stings depends on how much material you throw away. A thin bracket cut from plate wastes little, and the 7075 version may be only slightly more expensive. A part machined from a solid block down to a fraction of its starting weight pays the material premium on everything that ends up in the chip bin.

That is the practical test. Work out roughly what the starting block weighs, not what the finished part weighs, and you will know whether the alloy upgrade is a small line on the quote or the largest one. The cost breakdown covers the other lines.

A short decision path

Does it need welding? Use 6061, or 5083 if it also lives in salt water.
Is a cosmetic or colour matched anodize required? Use 6061.
Is it actually yielding or taking a permanent set in 6061? Move to 7075.
Is it only deflecting too much? Change the geometry, not the alloy.
None of the above? Use 6061 and spend the saving on tighter tolerances where they matter.

If you are still unsure, describe what the part does and what is going wrong with it, and let the shops quoting it propose the alloy. It is a question they answer every week.

Sources

Figures in this guide are checked against the following. Published values are typical ranges for test material, not a guarantee for your part.

Frequently asked questions

Is 7075 twice as strong as 6061?

In yield strength, close to it. 7075-T6 runs around 503 MPa against roughly 276 MPa for 6061-T6. Stiffness is a different matter. Both alloys have nearly the same modulus, around 70 GPa, so a 7075 part deflects about as much as a 6061 part of the same shape under the same load. Swapping alloys raises the point where the part yields, it does not make it noticeably stiffer.

Can 7075 be welded?

Not in any way you should rely on for a structural part. 7075 is prone to hot cracking in the weld and the heat affected zone loses the temper that made the alloy worth using. If the part has to be welded, design it in 6061 or 5083, or split it into machined pieces that bolt together.

Does 7075 cost more to machine as well as to buy?

The material costs roughly two to three times more per kilo. Machining time is broadly similar, and 7075 often gives a cleaner surface and better chip control than 6061. The price gap on the quote is mostly material, which is why it hurts most on parts where a large block is cut down to a small finished shape.

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