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Quality problems still an issue for 15-5PH CRES sheet per AMS5862?
3

Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

(OP)
Guys...

In the late 2000s we [process/liaison/design engineers] were prohibited from specifying 15-5PH CRES sheet per AMS5862 due to inner-laminar defects/issues. As far as I'm aware, this 'prohibition' RE 15-5PH CRES sheet [material less than 0.187 thick] is still in-effect.

Apparently, when the vendor was rolling the billet-to-plate-to-sheet thicknesses they were introducing laminar discontinuities that were hard to detect. These defects were uncovered [my company/industry] when 'simple' formed parts failed during/just after forming and/or PHT. The word on the street was the OEM for this material was 'un-convinced' a problem existed and suggested sheet stock be 100% US-NDI inspected, if necessary. Some senior M&P engineers suggested this 'take-it or leave-it, no-matter-us' attitude by the vendor is what provoked the prohibition.

Please advise: is 15-5PH CRES sheet still exhibiting potential laminar problems... Or is this old news?

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

AMS 5862 specifies melting type be ESR or VAR which can help to alleviate de-laminar issue. on the other hand, you can always perform NDE test (say sonic) at early stage. E.G. UT at .5'', or .25'' heavy with a strict requirement (D2 level recommended). Why should we prohibit using it?!

RE: Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

15-5PH is designed for use at heavy thickness, beyond where 17-4 will develop uniform properties.
So unless you were using this spec in order to get re-melted material (and not go to the trouble of ordering remelted 17-4) I am not sure why someone would use 15-5 at light gage.
We were doing a heavy wall tube job some years ago in 15-5PH (3" OD x 1" wall). We annealed the billets, then aged them, then re-annealed them prior to extrusion. This gave us some grain refinement and better uniformity. Every time you age and re-anneal 15-5 or 17-4 the grain size gets finer and more uniform, which improves toughness with only a very slight loss of strength.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

(OP)
EdS... I generally concur with Your points. WE now use 17-4PH for all sheet-metal applications, because of 'the 15-5 prohibition' without any known issues.

Still the question remains: is 15-5PH CRES sheet per AMS5862 available today? IF so are there any remaining industry concerns [use without restrictions [US-NDI] or other prohibitions]?

Background, NOTE.

15-5PH Sheet was specified for most sheet metal PHT CRES part applications on my Acft when it under-went 2-significant/unique structural modifications starting in the 1980s.

Unsure as to exactly 'why' this occurred... but it was assumed by other M&P engineers that the 15-5PH was perceived to have 'slightly better properties over-all in the 1970s'... especially at H9xx PHT relative to 17-4PH... and... it was listed in a modification working document... M&P 'design cookbook', written in 1978... as the 'preferred PHT CRES for sheet metal' parts.

OH Yeah... and that same M&P 'cookbook' said it was ok to design to H900 [HT180]... which is generally considered NOT advisable today [poor SCC, low fracture toughness].

NOTE.
The ONLY acceptable applications for 15-5PH CRES H900, today, appears to be for: (a) bushings and (b) certain mechanical parts fully stress relieved after all machining operations, in-prep for finishes.





Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

I have never heard of such restrictions on the use of 15-5PH. I am not even sure how you would get such defects in remelted material.
In straight AOD I have see such things, but never in remelt.

Generally I approach PH stainless like this;
-Can you use AOD 17-4PH?
-If you need more formability look at 17-7PH
-If you have thicker parts look at 15-5PH
-If you need better toughness mover to remelted 13-8PH
And if you really need higher strength and can sacrifice toughness there is always C-465

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

Every time you age and re-anneal 15-5 or 17-4 the grain size gets finer and more uniform, which improves toughness with only a very slight loss of strength.

Interesting, learned something again. Star for that, Ed.

RE: Quality problems still an issue for 15-5PH CRES sheet per AMS5862?

15-5 offers superior transverse toughness and ductility plus a high degree of forgeability. From this perspective, it makes sense to use for heavy gaged applications. However, it is VERY common people order strip, sheet, plate and small diameter bar.

Quote (Still the question remains: is 15-5PH CRES sheet per AMS5862 available today?)

: Yes, we offer Strip and plate products to AMS 5862. Yet, the more common spec. is AMS 5659.

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