PWHT 17-4PH
PWHT 17-4PH
(OP)
In reading the ASM Welding Hanbook Volume 6, pg 483-484, there seems to be a strong preference to weld 17-4PH material in the annealed condition, then after weld we should age harden to the desired condition (in my application, final condition will be ~H1050).
If this sequence is not possible, the ASM goes on to recommend a variation of the above (if we cannot weld in annealed condition) we may solution treat the finished weldment, then age harden it.
In either case, can anyone tell me the particulars of the solution treatment (i.e., temperature, holding time, heating rate and cool down rates) and also the age hardening particulars (i.e., temperature (1050 deg F in my case?), holding time, temperature rates)? A reference (I can’t find it in the ASM) for such information would also be appreciated.
Would also like to understand why in the postweld situation we need for a 2-step process, i.e., why solution treat (anneal) then age harden. Isn't the welding partially annealing the welded area?
Thanks in advance.





RE: PWHT 17-4PH
You can weld in either the annealed condition or the overaged condition. You don't really want to weld in the higher strength conditions because of the risk of cracking.
Then you anneal, usually 1900F-1950F. I don't remember if AMS 5604 has any information on the annealing times.
Aging is usually +/-10F from the stated temp. For 1050F you would use a 4 hour age cycle.
Buy the applicable AMS spec. You need it.
For some kinds of general industrial use people weld annealed plate and then go straight into aging. The HAZ of the weld ends up at lower strength than the rest of the part because it is overaged (welding + aging).
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RE: PWHT 17-4PH
http://www.sae.org
RE: PWHT 17-4PH
htt
Look up the 17-4 PH precipitation hardening
stainless steel data bulletin
RE: PWHT 17-4PH
1. If the designers decide that the annealed condition is satisfactory for the final weldment, then the PWHT should only consist of a solution heat treatment; but if they want a final condition of H1050 , then I still have to solution heat treat followed by precipitation hardening - IS THIS CORRECT?
2. For GTAW welding 1/2" plate and SMAW welding 3/4" plate what may be the recommended kJ heat input? (cannot find this in the AK Steel Web site or ASM handbook)
Thankyou again.
tc
RE: PWHT 17-4PH
If you want low strength and high ductility then you use the overaged condition.
You two choices for fabrication are:
1. Start with annealed plate, weld with matching filler, anneal, age
2. Start with annealed plate, weld with matching filler, age
The second option will give you lower strength in the HAZs.
I am not sure on the heat input, all of my work is autogenous.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
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RE: PWHT 17-4PH
If you are going to weld 17-4PH, I would recommend using heat inputs for the SMAW and GTAW processes similar to welding on austenitic stainless steel. The 17-4PH grade does not require preheat for thickness less than 4".
Regarding PWHT, here is an excerpt from ASM Handbook Volume 6 (by the way, I would suggest you re-review this volume on welding of 17-4PH material, there is plenty of information)
RE: PWHT 17-4PH
Actually that excerpt from the ASM handbook was exactly what caused me to post my original questions. I found it to be somewhat confusing until yourself, Ed & TVP explained things more clearly to me.
As for the heat input question, I still haven't found a good source for that data, whether it is GTAW or SMAW on any material. Any suggestions?
tc
RE: PWHT 17-4PH
In lieu of heat input, I would recommend you monitor the interpass temperature during welding with no preheat. I would recommend a maximum interpass temperature of 350 deg F.