Determining DBTT from Limited CVN Results (17-4PH)

[Saucerito]

Hi,

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?

 

[EdStainless]

How about this



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P.E. Metallurgy, Plymouth Tube

 

[metengr]

More complete data

http://www.interlloy.com.au/our-pro...-precipitation-hardening-stainless-steel-bar/

 

[Saucerito]

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?

 

[Saucerito]

metengr,

Your link is not working for me.

 

[metengr]

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.

 

[metengr]

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.

 

[EdStainless]

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).

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P.E. Metallurgy, Plymouth Tube

 

[Saucerito]

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.

 

[metengr]

Try using 15 ft-lbs. This seems to be a threshold used in most construction codes or standards.