3 ms·

MIL-HDBK-5 [1] is a good publically-available source for strength allowables for several aerospace alloys, including multiple directions relative to the grain f

MIL-HDBK-5 [1] is a good publically-available source for strength allowables for several aerospace alloys, including multiple directions relative to the grain for some of them. The first relevant example I found was on page 3-86, extruded 2024, 2.250 - 2.499 inch cross-section. For ultimate tensile strength, F_tu, the L (in the direction of extrusion) allowable is 57 ksi, while the LT (perpendicular to the direction of extrusion) allowable is 39 ksi. That's a 30% drop in strength. [1] http://everyspec.com/MIL-HDBK/MIL-HDBK-0001-0099/MIL_HDBK_5J_139/ http://everyspec.com/MIL-HDBK/MIL-HDBK-0001-0099/MIL_HDBK_5J...

kragen 2y ago
this is a fantastic find, thanks!
buildsjets 2y ago
Thanks for posting that as I was about to! I will note that MIL-HDBK-5 is no longer valid for actual aerospace design, as it has been superseded by Battelle Institute's MMPDS Handbook, which is locked behind a very very tall paywall. The MIL-HDBK is still all perfectly good data. https://www.mmpds.org/ https://www.mmpds.org/
- abe_m 2y ago
  I think it is unfortunate the US government got rid of all their MIL and STD standards. You used to have a rich resource of technical specifications for materials, fasteners, fittings, etc for free access. Now they are pretty well all cancelled and have been moved to organizations like SAE and ASTM where they are hundreds of dollars per copy. For the metallurgical data, I'm curious if these successor organizations are actually generating any new data. Whenever I'm looking up references like that hand book, it appears they all summaries of investigations that happened back in the 1960's and earlier.
  - seec 2y ago
    That’s the problem of capitalism : you need it but too much of it becomes a disease for the society abusing it… Much of the western world is starting to feel the effects…
abe_m 2y ago
Thanks for slogging through that one to find an example. I've come across that handbook before, and went looking through it in the alloys I normally work with. In the alloys I normally see, the L and LT are either identical, or with a couple digits in the least significant digit. So it looks like the effect is very alloy dependent. I didn't see any of the steels having any notable directionality. Also Aluminum 6061 doesn't show any directionality either. Outside aerospace, I suspect that covers the majority of metal tonnage used.

kragen 2y ago

this is a fantastic find, thanks!

buildsjets 2y ago

Thanks for posting that as I was about to! I will note that MIL-HDBK-5 is no longer valid for actual aerospace design, as it has been superseded by Battelle Institute's MMPDS Handbook, which is locked behind a very very tall paywall. The MIL-HDBK is still all perfectly good data. https://www.mmpds.org/ https://www.mmpds.org/

abe_m 2y ago
I think it is unfortunate the US government got rid of all their MIL and STD standards. You used to have a rich resource of technical specifications for materials, fasteners, fittings, etc for free access. Now they are pretty well all cancelled and have been moved to organizations like SAE and ASTM where they are hundreds of dollars per copy. For the metallurgical data, I'm curious if these successor organizations are actually generating any new data. Whenever I'm looking up references like that hand book, it appears they all summaries of investigations that happened back in the 1960's and earlier.
- seec 2y ago
  That’s the problem of capitalism : you need it but too much of it becomes a disease for the society abusing it… Much of the western world is starting to feel the effects…

abe_m 2y ago

Thanks for slogging through that one to find an example. I've come across that handbook before, and went looking through it in the alloys I normally work with. In the alloys I normally see, the L and LT are either identical, or with a couple digits in the least significant digit. So it looks like the effect is very alloy dependent. I didn't see any of the steels having any notable directionality. Also Aluminum 6061 doesn't show any directionality either. Outside aerospace, I suspect that covers the majority of metal tonnage used.