15-5 PH Condition 1025 Heat Treat Per AMS 2759/3

[jallenc]

My Customer material requirement was 15-5 PH per AMS 5759. An additional requirement was to heat treat to condition H1025 per AMS 2759.
I purchased material from the Mill as Cond 1025H but was not certified to AMS2759 for the heat treat. The Mill says that his Condition H1025 is for unfinished bar and that final Heat Treat to condition H1025 per AMS 2759/3 should be accomplished by us since we are manufacturing a completed machined part. I'm confused, My customer says they will not accept the parts.

 

[cjohnso0]

Hi jallenc,

We make all of our parts for aerospace, so I've got some experience with this.

Your customer will not accept the parts because they were not certified to heat treatment per AMS2759/3. The parts are not meeting their requirements.

Do you have AMS2759? There are many very specific requirements in AMS2759 for the HT process. If the material is not certified to this specification, there is no proof that it meets these requirements, or that all steps were taken.

Do you have certs for the material that prove it is AMS5759? If so, you should be able to re-solution and precipitation HT your material to AMS2759/3. I would speak with the customer on this. Of course, this makes it tough if the parts are complete, but not impossible. At the end of the day, you need to meet all material, dimensional, and processing requirements required by the customers Purchase Order. They typically will not go out on a limb with aerospace parts, as their is a very significant safety issue with doing so.

Regards,

Chris

 

[jallenc]

Thank you for the response. That's what I thought would be said. It's now up to our MRB Engineer to make disposition as I have rejected the parts for not being processed to the drawing requirement. Unfortunately, the rejected detail is part of an assembly, which means disassembly, stripping and reprocessing (heat treat), and then complete remaining processes. The Engineer might say to submit to Customer for a "use as is" disposition although I don't want to submit because I believe the customer will not accept the parts and have this rejection affect our Quality rating, but not my call.

 

[dgapilot]

It kind of falls on the Customer MRB, not yours unless you are covered under their Production Certificate. If it is an aircraft part, and it doesn't meet Type Design, it isn't going to be Airworthy.

 

[WKTaylor]

Jallenc…
First…
AMS5759 is some obscure cobalt alloy: I think You mean AMS5659. AMS5659 is for 15-5PH bar, forgings rings, extrusions

The base spec AMS5659 was originally intended to present an “all-purpose” wrought product that was solution heat treated and left in a state that could then be precipitation heat treated to any one of several stable/final temper conditions [H1150, H1100, H1075, H1025, H925* or H900*] per MIL-H-6875, AMS-H-6875 or [now] AMS2759/3 [See MMPDS for strength levels, these temper conditions]. This PHT could be accomplished on the raw stock… or if desired… during rough machining, but prior to finish machining [ease of machining and to avoid warpage/distortion in final machined part].

HOWEVER, AMS5659 was recently revised: The raw wrought stock can be procured per the AMS spec in any of these heat treated conditions… when specified on the contract [H1150, H1100, H1075, H1025, H925* or H900*]: otherwise it would be supplied in the SHT condition [NOT a final temper condition]. The process for precipitation hardening to each of these Hxxx conditions is embedded within the spec and replaces PHT per AMS2759/3.

It sounds to me that Your raw material “buyer” purchased the raw material in the H1025 condoition, perhaps based on the drawing callout or the supplier’s recommendation, based on the drawing callout. In this case, this presents a catch-22 for You. IF the intent was to PHT the raw stock before machining, or if PHT sequence was left undefined on the drawing, then essentially Your buyer/suppier saved you all a bunch of in-process work and time. IF however, there was an explicit or implicit need to PHT during machining [often to reduce machining effort, or fight distortion, etc], then the situation is much more complex.

In the first scenario [OK to PHT prior to machining], then the disposition [MRB action] should be very straight forward: Intent of AMS2759/3 was met by PHT per the procurement specification. NOTE. MMPDS-07 makes NO distinction between raw stock PHT per AMS5659 or AMS2759/3. This should be fairly straight forward disposition if You have a good relationship with Your customer.

HOWEVER, IF PHT MUST be accomplished during machining processing [for whatever reason], then the raw stock is in the wrong condition and would have to be discarded/replaced [a “sad” option at best]; or the raw stock would have to be re-SHT HT, then rough machined, then PHT to condition H1025… all per AMS2759/3.

**Note. H900 & H925 are fairly high-strength SCC-prone temper conditions that would be unwise to apply to raw stock used to make parts requiring extensive/significant machining.

Have fun.


Regards, Wil Taylor

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