reheat treatment 17-4 to H1075 3

[wonderlandinirvine]

The 17-4 part was heat treated to H1075. Because conformity problem, could we reheat treated to H1075 again? Will this affect the material properties (strength, fatigue, toughness)? Thank you.

 

[Kwan]

You can typically retemper twice without effect. One way to verify this is look up the AMS spec for the material. I think 17-4PH spec will give you information on the limit of retempering.

 

[israelkk]

What do you mean by "conformity problem"?
Usually you can repeat the heat treatment however if the properties of the heat treated part are inconsistent with the spec a second time treatment may not help. It may be a problem with the quality of the purchased alloy.

 

[wonderlandinirvine]

Thank you both Kwan and israelkk for being so nice to answer. We sent the 17-4 part for heat treatment (H1075) to a shop which isn't certified by the customer. We are thinking to send the part to a customer-certified shop to have second time heat treatment (H1075), but don't know if this will be valid.

Kwan, could you kindly give me the info regarding the limit of retempering? I check AMS 5643M and didn't find it.

Thank you.

 

[WKTaylor]

wonderlandinirvine

a few critical questions...

What spec was the part SUPPOSED to be heat treated to?

What spec was the part ACTUALLY heat treated to?

Is your HT processor generally rliable... or is this a "typical problem" with them???

Is the part finsh-machined [meets drawing dimensions and was ready for finish]... or is it in the rough-machined condition [all surfaces still to be machined]?

Did the processor heat treat one or more test specimens with the part?

Is there more than one part in the "lot"?

Did the processor, or can the processor, evaluate the part heat treatment per the required spec [as opposed to the inspection requirements of the spec actually used]... and have the specimen or a randomly selected part be destructive/metallurcgically testd? if so, then there MIGHT be a chance to get the customer to accept the part(s) if NDI is OK per their spec.

Caution:

Warpage/distortion is a REAL possibility if part(s) is/are reprocessed. Finish-machine part(s) is/are likely to distort beyond drawing limits. if the part is still in the rough machined state, then You might have a real-possibility for successful re-HT.

I recently evaluated a batch of fully machined aluminum parts where the vendor admitted to unauthorized deviations from the drawing. The obligatory test specimens conclusively proved the parts were mechanically and metallurgically inferior to the drawing requirements... and the entire lot was condemed.


Regards, Wil Taylor