non-standard double aged condition of 17-4PH

[matin5751]

Hi
Is there anybody to have good experience about doing double aged condition of 17-4 PH round bars diameter around 500mm? same as 620C / 550C or 760C / 580C or 650C / 550C or so on?

I want to know the effect of double aging on yield and U.T.S strength and impact energy too.

Please if anybody has any experience please tell me.

Thanks

 

[EdStainless]

Have you tried looking up the 17-4PH handbook? There are curves in it that cover this question.
In general exposure to 800F for up to 10 hrs has little lasting effect on room temp properties,
At 900F you start seeing some shift in properties in 2 hrs.
If the material was first aged at 1050F or higher the effect is less, but it is still there.
And it is what you would expect, increased strength and reduced ductility, but no change in hardness.


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[matin5751]

Thanks for your prompt reply.

I want to add my history for 3 diameters of 17-4PH round bars here.

On some of them I have done: Solution + 24hr under zero +PH
On some of them I have done: Solution + 24hr under zero +PH +PH

As you can see the results are not according to handbook or other related standard except green one for 650 mm diameter.

I mentioned my requirements to on top of the picture. as you can see my main problem is impact energy.

With this situation I am thinking about doing double non-standard PH as I mentioned in my 1st request "same as 620C / 550C or 760C / 580C or 650C / 550C or so on"

Please send your comments if any.

Thanks
Matin

 

[EdStainless]

Why do you think that 24hr at 0 is needed?
The Mf of the is alloy is about 100F, there is no reason to go colder.

It looks like your properties are similar to those for H1050/1075.
Since your properties from that aging fall short you have two options.
Either age at higher temp, or re-anneal them and re-age.
As you re-anneal and re-age this alloy the grain size will get finer, the strength is little lower each time, and the toughness will increase.
I would try a full re-heat treatment rather than double aging. Double aging will tend to have more variable results.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[matin5751]

Thanks

Yes you are OK about 24 hrs under zero but I think it doesn't produce any damage for the parts.

- About aging at higher temp , I have done in 605C/5hrs and I am waiting for the results.

I will inform you but I am afraid of decreasing R0.2% under my requirements (min 900MPa).

- About re-annealing them and re-aging, unfortunately I can not do that because the parts were brazed in around annealing temp and I can not go again in that temp.


Best regards
Matin

 

[matin5751]

Hi
I have received the mechanical properties of the samples with new PH temperature (605C / 5hr).

As you can see not only we didn't receive to our impact requirements , but also we missed our R0.2% too.

Please send your comments if any.

Best regards
Matin

 

[matin5751]

Hi my dear

If anybody knows about effect of double precipitation hardening on the above material to reach my requirements, please send his /her the comments.

I think with my received results , it seems which I have to do double PH but I don't have any experience for that. For example doing 700C/ 4hr and 600C/ 4hr or reverse .

Please send your comments or your experience results if any.

Regards
Matin