I'd like to know an approximate DBTT for 17-4PH in the H1025 condition. I've found some limited CVN data (Link) but this doesn't give a clear DBTT. Is there a specific impact energy that can be considered a minimum for ductile behavior?
Thanks. The table illustrates that the H1025 condition will have a higher impact strength than 17-4PH treated at 800F, but at what point is the material considered brittle?
The description of brittle fracture behavior at a particular temperature is qualitative and based on a minimum CVN impact value. For example one can select 10 ft-lbs or less as brittle fracture. Or one can select 5 ft-lbs or less. You need to decide on what minimum CVN value can be tolerated by design.
Saucerito;
It works for me. As you scroll down the page there is a more complete list of CVN values for 17-4 PH based on HT condition and temperature range from 10 def F down to -320 deg F.
You didn't like my grainy pictures. They are out of the very old Armco handbook, but that is the only source of such data.
Typically people use H1050 down to -40 and H1150 down to -125F (or so)
This agrees with NASA data from 1967.
I will caution you that the transverse properties can be much worse than Longitudinal.
I have worked on projects where T was critical and we used extensive HT procedures to get it (homogenize, cool, anneal, cool, over age, cool age, cool, form and machine, anneal, cool, final age, cool).
How does one go about choosing a minimum CVN impact value? I know this is a broad question, but I'm trying to determine the temperature range at which a torsional fracture would change from a ductile failure due to max shear stress to a brittle failure due to max tensile stress.
BTW, I was able to view metengr's link on my phone.
