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

[WKTaylor]

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]

 

[MagBen]

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?!

 

[EdStainless]

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.

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P.E. Metallurgy, Plymouth Tube

 

[WKTaylor]

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]

 

[EdStainless]

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

 

[btrueblood]

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.

 

[MagBen]

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.

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