Warm/Hot Joggling 7055 Extrusion 1

[aerodog]

Most hot joggling involves stretching of the material.

The application we are considering will involve some
stretching of the section and compression in the web.

To be more specific, it is a "Z" section and only
one flange gets joggled .050 for a "T" stringer.

In the compression area, the material will need to go
somewhere, we are wondering if at elevated temperatures,
we can push the material into the web and allow it
to thicken?

 

[WKTaylor]

aerodog...

7055-T?????? extrusion.

Regards, Wil Taylor

 

[aerodog]

Wil,

The project is a development program.

The decision has yet to be made on whether to
stretch the extrusion in "O" then heat treat
or stretch in "W".

In either case, when joggled, it will be in
the "T" condition, so I suspect "T4" by
definition but I have yet to see a drawing,
planning or specification.

aerodog

 

[WKTaylor]

aerodog...

Per MIL-HDBK-J [MMPDS-01 too], 7055 comes in (3) mill tempers... AMS4324 = -T74511, AMS4336 = -T76511 and AMS4337 = -T77511.

Per AMS2770 there is NO defined heat treatment for 7055.

>>>>> If You heat treat or severely strain this material (other than light contour forming of -T74511), then You will probably have to re-develop mechanical allowables. <<<<<

You may want to consider having the 7055 material vendor incorporate the "temper" [thermal and strain hardening] into the raw-over-sized extrusion when basic fabrication is accomplished [such as "stretching-to-contour" the raw-extrusion] AT THEIR FACILITY: then hog-out Your features, such as steps [IE: Joggles] and thickness changes, flange-width changes, etc. This way They can guarentee that the countoured part meets the intent of the "-Txxxx" condition ready for finall machining by Your company or machining vendor. NOTE: a certain ammount of material removal [all surfaces] is recommended for this alloy in most tempers, to eliminate surface discrepancies [oxidation, mill-marks and residual strain], that may be present in thicker raw extrusions (check with vendor)

Regards, Wil Taylor