In article ,
GeorgeB wrote:

On Tue, 12 Jun 2007 03:05:30 GMT, Orval Fairbairn
wrote:

In article . com,
Lou wrote:

For all or you that are interested. I've made the brackets out
of 2024 and the 2024 bends harder, but doesn't seem to snap
as easy.
Lou

Of course, 2024-T3 doesn't snap as easily as 6061-T6! It is the "T
number" that determines brittleness (and stiffness).

Orval, stiffness is the same for the same alloy, and substantially the
same for all aluminum alloys, independent of heat treatment
conditions. "T-number" has nothing to do with stiffness.

No, it isn't! Try to bend some .025 6061-T3 and then some 6061-T6. You
will find the T2 bends more easily.


Yield strengths (and tensile, but yield is the one we USUALLY care
about) vary amont alloys and heat treatments.

That is why "T-number" controls stiffness, since bending is the result
of inelastic deformation. It takes more torque to bend a piece of T6 vs
T3 of the same alloy and thickness.


2024 is about 5% "stiffer" than 6061. 2024-T4 yields about 40% more
in tension than 6061-T6 before breaking.

Yes.