Re-solution annealing of already age hardened 17-7ph 3

[engamopar]

Situation: 17-7PH Condition A, (already formed) parts were supposed to be heat treated to TH1050. SHould have turned out ~R40C.
Were instead age hardened to H10150- ~R28.
No concrete hardness was dictated by the customer's spec.
We just did not want to use in Cond "A". (Re: thread 294988 (22MAR2011).
What to do next? 1) Nothing - Use as is? 2) Re-solution anneal and then re-age harden to proper TH1050? 3) Scrap and start over? 4) Other? (please speciify)
Thanks in advance

 

[EdStainless]

I would first opt to use as is and do nothing. The parts are fine, just not as strong as you had expected. Though you should have a tensile test done. I have no idea what the properties will be in this overaged condition. You want to make sure that you have enough ductility.

If it won't hurt the surface finish or other features you could reanneal and then age.

Who screwed up? There is no standard for 17-7 to be aged at 1150, only at 1050.

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Plymouth Tube

 

[Metalguy]

Sound like the customer is expecting a strong part, so you need to get his concurrence.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[israelkk]

Hardness of PH steels is not guarantied. They are specified by tensile strength. For the same heat treatment such as TH1050 the hardness can vary by up to 10 RC while tensile strength is guarantied if purchased to spec.

 

[engamopar]

I screwed up in my presentation of the situation.
It's not that the heat treat was done to 1150 instead of 1050.
It's that it was done in-house to H1050 for 1hr instead of RH1050 or TH1050.
Pardon my ignorance but perhaps I have misunderstood the process.
Normally we buy 17-4Ph RAW material that is solution heat treated per AMS 5643.
We then, usually, AGE HARDEN machined parts to H900. We do nothing more
complicated than a bake-at-time-and temperature, and then cool-in -air AGE HARDEN.
No other additives, special atmospheres, etc. are introduced. If such are required,
we outsource to those that do since we are not so equipped.
In looking at TABLE 3 (SHEET8) of AMS2759/3D, I saw a requirement for
“Austenite Condition and Transformation…) to the immediate left of the “Aging” columns.
For the RH 1050 the austenite conditioning calls for “1750 deg F …” and the TH1050 calls
for such at “1400 deg F…”. I perceived these [austenite conditioning] requirements to be done as part of the AGE HARDENING PROCESS. Perhaps this is to been done as an intermediate process [outsourced] and then a final [internal] age harden at 1050 deg F (Bake-for-time at-temperature and air cool). Perhaps the intermediate [austenite conditioning] and final heat treating should have been outsourced together.
What we DID is buy a stamped part made from 17-7ph in COND “A” and then
upon receipt, perform (I believe erroneously) our "normal" in-house AGE HARDEN (Bake-for-time at-temperature and air cool)
for 1hr to 1050 deg F. I had thought the parts were going to be outsourced and processed to TH1050. As we did them internally, the resulting hardness is 23Rc.
Now that you know the whole story, I’m open to thoughts, suggestions as to how to procede.
Thanks in advance.

 

[EdStainless]

Send them out for re-heat treatment.

Thanks for the details.

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Plymouth Tube

 

[engamopar]

Will send out for re-Heat Treat - many thanks!