17-7PH

[Fatihah Khalid]

I have 1 part need to use 17-7PH and do treatment of H1025.
However, after machining very hard to control with this treatment and thus supplier propose to use pre heated material 17-4PH which comes along with H1025.
Is it possible? Do I need to check if the HRC of using 17-4PH is same as using 17-7PH?

 

[EdStainless]

To make parts out of 17-7PH you HT the raw stock to the T(1400) condition.
Then machine and final age to TH1050.
This is the only common HT for 17-7PH.
The 17-7PH spec is for 150/180 ksi 38HRC minimums.
the actuals will be more like 180/195 ksi 42HRC.
Matching this in 17-4PH is tricky.
H1000 should get you similar properties, but the minimums are lower so you results may vary.

 

[MechyMarco]

Why 17-7? Why not just use 17-4 H1150. Can buy it off the shelf economically and not worry about any ageing dimension issues. Plus you get essentially guaranteed mechanical properties.

 

[ShataCastings]

This is a part we are producing, using 17-4PH H1075

 

[EdStainless]

The nice thing about 17-7 is that if you do the 1400F step before machining then there is no (very very little) dimensional change with final aging.
With 17-4 you would either have to finish after aging or adjust size to accommodate the change.