The Armour Archive

I have a T6 aluminum kite shield for sale. It comes with a shield basket, arm straping and burgundy car edging. Nice shield but I no longer have a use for it. Asking $80 plus shipping. Pictures to come soon.

Edward

T6 is the heat treat info for the Al. The type of Al is the number like 6061, or 7075. I bet it is 6061 T6, most common grade average machining grade Aluminum.

One of my new guys is looking for a kite and may be interested depending on size and condition. Can you post the measurements when you put up the pics?

Thanks,

-Valerian

Dibs!


How can I pay you?

(pending photo)

I have a question... is the higher the number mean the stronger? meaning, is 7075 stronger than 6061?

Yes, 7075 is stronger than 6061, but it doesn't relate to the number being higher, that is the type of alloy mix. It is like expecting a Mustang with a 328 engine to be slower than a Chevy Silverado 1500 because it has a smaller number.

Here is the post I saved to my messages so I wouldn't have to find the info again.

T6 means jack if you don't know what the alloy is.

Matweb.com shows about 26 different alloys of aluminum in T6 that aren't cast aluminums.

2024 T6 Ultimate tensile strength is 61900 psi
6061 T6 is 42000 psi
7075 T6 is 76000 psi (nearly 2x of 6061)

Mild steel is 60900 psi.

The T rating is the method of hardening/artificially aging the material.

Yeppers,

Most engineering and machinist handbooks have this sort of info. I get most of mine from Machinery's Handbook from Industrial Press.


In addition to the great information above, you also have to look at things like how resistant to corrosion an alloy is and also how brittle it is. Just because something has a higher strength doesn’t mean it is better. 7075-T6 has a nasty problem if stress corrosion cracking whereby it basically just starts to crack if it has pressure on or in it and there is any sort of corrosive medium like salt water or sweat.

Also, one has to remember than the elastic properties of metals (how bendy and stretchy it is) has nothing to do with how strong it is. Bendiness and stretchiness has to do with a number called Young’s modulus, or the elastic modulus. This number gets the variable E and is virtually the same across each material. If you want something to bend less, or stretch less, picking a stronger version of the same material, like going from weak aluminum to a higher strength grade will not change how much it bends, just how much bending it can take before it breaks. If you want something to be stiffer and bend less you need to either pick an enterly different material with a higher E, like go from aluminum (E = 10 Mpsi approx.) to steel (E =29 Mpsi approx.), or you need to change the shape.

The number, like 6061, 7075, 1050, 5554, etc tells you the chemical composition of that alloy.

Also, 6061, for example, can come in many different tempers (-O,-T4,-T6, ) which each have different strengths. The higher the number, like T6, doesn’t mean it is stronger. 5254-H38 is stronger than 5254-H112, for example.

Also, as a side note, and something that commonly gets missed, is that welding and heating up metals, like aluminums, change the temper. If you are welding with 6061-T6 which has a strength of 45 ksi, once you weld it, it loses almost all of its strength and it is no longer –T6. You need to assume it is 6061-O afterwards and has a strength of 18 ksi.

Each material has a different number/letter system for the alloy and temper.

Steel can be like: 1020, 5140-400,
Stainless can be like: 304, 316, 17-4PH-H1025
Titanium can be like: Ti6Al4V


Please keep in mind:
-Strength and elasticity are different and not related. You can have strong materials that are really stretchy and weak materials that are really stiff and any combination of that.
-Depending on the alloy and the temper a metal can go from so weak it will fall apart in your hands to so strong it can be surprising.
-Every material (Steel, aluminum, titanium, etc.) has many many many different alloys which are all different and wonderful in their own way. Some are strong but rust (high carbon steel that are used in swords), others are weaker and don’t. Some materials are elasticy some are stiff. Some are light, some are heavy. You need to know what you are dealing with before you can say which is better or worse for you. Don’t just assume aluminum is aluminum or that titanium is somehow always better.

Oh, and one other thing.

There is no magic to how these numbers are arrived at. They figured out how strong these materials are by making them and then testing them with load cells and sensors.

If in one book it says one material has a strength of 42 ksi and in another book it says 48 ksi, well it is probably around 42 or 48 ksi. It is not like someone magically knows that it should be exactly 46.293464812 ksi. It is not an exact, white coat and thick-glasses science. Basically, if you are designing something and using math to figure out how strong to make it you include a safety factor to ensure that even if it is weaker than you think, by a bit, it will be fine.

Also, it is not like they do the tests once. They test the materials over and over again and take the average for what they put in the books. Often, they put in a number that is slightly conservative in the book to ensure people don't use their number and then have their bridge fall down.

*Bump*

Totally interested still. Need to see it before I buy it though

I'm going to have to pass.

I've just ordered an aluminium kite from Windrose. $84 new

Thanks.

-GH