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Heat Treating 17-4PH to H1025 ?

B

Beezer

Aluminum
Joined
Feb 12, 2009
Location
ON, Canada
I have a 15" piece of 1.5" OD 17-4ph, that I just picked up from the supplier and I need to heat treat it to H1025.

Currently is measures between 30Rc and 33Rc, which seems to be above what H1150 is suppose to be. It seems closer to a H1075 rating.

From what I could find online, to bring it to H1025, I need to heat treated at a temperature between 1015° F and 1035° F for 3.75 hours to 4.25 hours.

I am just wondering if I can bring it to a H1025 condition right away or do I need to bring it back down to a softer rating before making it harder?
 
It's already seen a higher temp to bring it to the 1150 (or 1075) H condition, so if you want it harder I think you'll have to solution HT it again, then "draw down" at the 1025 temp for the required time.

Read this thread for more info, at worst contact your friendly neighborhood metals service center and see if they have an applications guy who knows 17-4. If this is a critical part I think you should bite the bullet and have it professionally HT'd at a good shop.

Heat treating 17-4 stainless
 
Beezer said:
I have a 15" piece of 1.5" OD 17-4ph, that I just picked up from the supplier and I need to heat treat it to H1025.

Currently is measures between 30Rc and 33Rc, which seems to be above what H1150 is suppose to be. It seems closer to a H1075 rating.

From what I could find online, to bring it to H1025, I need to heat treated at a temperature between 1015° F and 1035° F for 3.75 hours to 4.25 hours.

I am just wondering if I can bring it to a H1025 condition right away or do I need to bring it back down to a softer rating before making it harder?
Click to expand...

If you just picked it up from the supplier, it should have come with certs.

Either way, 99.9% chance that it is "Solution Treated". That means its ready to be heat treated, and
when 17-4 is solution treated, it is in the low to mid 30's.. And yes, heat treating it to an H1150 makes it
softer, it also increases the machinability by about 50%, and all the heat treats take away almost all of the
"Stainlessy" machining properties, and it behaves more like an alloy steel (4140, 4340 etc).

You wouldn't find an H1075 at a supplier.. Occasionally you can find an H900 or an H1150, but its not
really common.. If you need to re-heat treat a PH grade, you can go to a higher temperature, but you can't
go lower without annealing and then re-solution treating.

Also. The Rockwell readings can be all over the map after heat treating. Its kind of a double check. The
real thing that matters is time and temperature. Mainly temperature. I still haven't out why all the basic HTs are
4 hours, except for an H900 which is 1 hour.
 
Milland said:
It's already seen a higher temp to bring it to the 1150 (or 1075) H condition, so if you want it harder I think you'll have to solution HT it again, then "draw down" at the 1025 temp for the required time.

If this is a critical part I think you should bite the bullet and have it professionally HT'd at a good shop.

Heat treating 17-4 stainless
Click to expand...

I should have been a bit more clear. I have no idea if it is condition H1150 or H1075 already. I just asked for a piece of 17-4ph. I will contact them to see if they know what type of 17-4 it is.

The last time I ordered a piece of 17-4, I took it to a proper heat treating company to bring it to H1025 specs. I found it to be expensive for such a small piece ($150). I have a electric kiln at work and thought I could do it there.
 
Dumb question. and/or thought.

No paperwork.. So its not critical. BUT... Why does it have to
be to an H1075.. That tells me you are working to a print and a spec.

And the kiln thing.. Again no paperwork.. And there is absolutely
nothing wrong with using a pottery kiln to heat treat in. Especially
the PH grades.

I'm not criticizing, I'm just curious what you are doing that doesn't require
certs and paperwork, but still specifies an H1075, which is really kind of
an oddball. Usually see the heat treats in 50 degree increments, though not
always, I've seen a bunch of 1025s.
 
Bobw said:
Dumb question. and/or thought.

No paperwork.. So its not critical. BUT... Why does it have to
be to an H1075.. That tells me you are working to a print and a spec.

And the kiln thing.. Again no paperwork.. And there is absolutely
nothing wrong with using a pottery kiln to heat treat in. Especially
the PH grades.

I'm not criticizing, I'm just curious what you are doing that doesn't require
certs and paperwork, but still specifies an H1075, which is really kind of
an oddball. Usually see the heat treats in 50 degree increments, though not
always, I've seen a bunch of 1025s.
Click to expand...

It is not critical, but I want it to be 1025, not 1075. I used material that was 1025 before, so I want to try and keep the material the same. Plus the 1025 machined really nicely the last time,so it is just my personal preference. In it's current state, it does not machine as nice as the 1025.
 
Beezer said:
It is not critical, but I want it to be 1025, not 1075. I used material that was 1025 before, so I want to try and keep the material the same. Plus the 1025 machined really nicely the last time,so it is just my personal preference. In it's current state, it does not machine as nice as the 1025.
Click to expand...

Its solution treated then.. You really shouldn't see much of a machinability difference from a 1025 to a 1075.
And machinability goes UP!!! after heat treat. Even an H900 which is dabbling with a 50C cuts pretty darn nice.

Cook her up. I think you are good to go.
 
Finally got the kiln working and did a test piece last week. I pre-heated the kiln to 1025° F and once at temp placed the material in the kiln. I let the material soak for just over 4 hours, allowing for am extra15 minutes for the material to reach the soak temperature. Removed the material after the 4 hours and let air cool overnight.
Using a KRAUTKRAMER Microdur 2 portable hardness tester, I am getting reading from 38-40Rc.

I was aiming for closer to a H1025, at around 35Rc.

For a lower hardness, perhaps closer to H1075, should I reduce the temperature and soak time?

I was also wondering if I am suppose to have the material already in the kiln, and allow it heat up with the kiln?

Thanks
 
Ask the supplier if it is in condition A (solution heat treated) then just age it correctly. Helps to have a circulating air tempering oven.
 
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