|
Retrogressed and Re-Aged 7076-T6
|
|
Source：Internet Author：Unknow Pubdate：2008-05-09
|
|
wktaylor (Aeronautics)
25 Mar 08 17:57
Folks...
"Anyone-out-there" [DoD org, company, etc] using any form of the retrogression and re-aging heat treat processes [RRA-HT] for newly fabricated, or existing [old], 7075-T6 [-T6-RRA] parts FOR REAL???
I understand some huge benefits due to greatly increased SCC & exfoliation corrosion thresholds... almost to the capability of -T73 [-T76??] but with just a couple of KSI loss in FTu, FTy & FCy... and very little change in other properties from 7075-T6 "A" basis allowables [ref MIL-5 & MMPDS]. I also see the RRA-HT has been tested with other 7XXX alloys.
I Understand that ALCOA is using RRA-HT on their new 7XXX alloys... and giving them the -T77xxx proprietary HT designations [which also includes some intermediate stage cold-working].
Sooooo... the process appears to work... but does it have merit and any advocates for repair or replacement of existing parts [Depot or Major repair]???. 字串1
The obvious value for the RRA HT is ability to maintain the relative strength of 7075-T6 parts without seriously fretting over SCC & EXCO... problems plaguing the alloy in thick sections... even when shot-peened and buried in coatings, sealant and use of low-interference-fit fasteners.
Just so I am clear... The RRA process and some test applications are described in the following articles and documents.
http://www.udri.udayton.edu/NR/exeres/360D542B-1F6A-4FF3-B51C-FDEF8137A316.htm
http://www.tms.org/pubs/journals/JOM/JOMbyIssue.asp?issue=JOM\2003\January [lower section of the page]
http://desp.udri.udayton.edu/task_order_RZ01_Sjoblom.htm
http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=A392453&Location=U2&doc=GetTRDoc.pdf
http://findarticles.com/p/articles/mi_qa5348/is_200301/ai_n21325163 字串3
Regards, Wil Taylor
Rob130 (Aeronautics)
26 Mar 08 15:31
Will, I am fairly certain the C-130 engine truss mounts have been modified to 7075-T73. This was due to both corrosion and cracking problems in the mid-late 80's. I can provide a contact name at the US Coast Guard repair center who could offer additional information. Send me a pm and I will make the introductions.
Rob
wktaylor (Aeronautics)
26 Mar 08 15:45
Rob130..
I've seen the cracking problems with 7075-T6 die forged C-130 truss-mounts first hand... especially when abusively anodized WO shot-peening [anodize-crazing accelerates cracking tendency]
I am really looking for any application of RAA process to the -T6 temper... in-lieu-of over-aging to the -T73 temper.
Any info on 7075-T6-RAA applications??? Regards, Wil Taylor
字串8
（Click：）
|
| Previous：MIL-A-8625 Ty III Hard Anodize and Fatigue Next：Fatigue damage due to compressive load |
|
[ Add TO Favorites]
[TOP] [PRINT]
[CLOCE WINDOWS] |
|
|
|
