Materials resistant to Hydrogen Embrittlement 2

[iainuts]

I'm looking for high strength stainless steels resistant to hydrogen embrittlement. I realize the 300 series are resistant and probably Nitronic 60, but I'm having other issues with those materials.

What I really need is a good list of materials that provides their susceptibility to hydrogen embrittlement, especially in a 100% H2 atmosphere. Something like a material compatibility list giving different levels of attack to various common materials.

Side note: are aluminum alloys susceptible to H2 embrittlement?

 

[ijzer]

See nelson curves. In principle all stainless steels are OK

 

[iainuts]

Thanks... I Googled "Nelson Curves" and found a single chart showing carbon steel at the bottom with pressure to 11,000 psi and temp around 440 F. Other materials are shown on this chart above the carbon steel line.
Ref:

http://books.google.com/books?id=KK...g=YX-HZr6PWqzxN1G3_Y0I5kB0Upo&hl=en#PPA368,M1

If a stainless steel or other material is operating in a pure H2 environment at up to 11,000 psi but below this temp (ie: atmospheric temp down to cryogenic temp) then I assume from this chart that no attack is predicted and the part is fine, regardless of material (ex: 17-4 PH) or condition (H900). Is that correct?

 

[metengr]

All stainless steels are really not ok when is comes to exposure to hydrogen. The ferritic and martensitic stainless steels and associated precipitation hardening stainless steels can be quite susceptible to hydrogen charging and embrittlement in service. The austenitic stainless steels are the least susceptible to hydrogen embrittlement because of the low diffusivity of nascent hydrogen in austenite.

 

[iainuts]

hmmm... ok, then what about these Nelson curves? If temperature is always ambient or below, does that allow the use of other types of steel?

One thing I've heard as a "rule of thumb" is to use steels with lower ultimate strength, say 80 ksi or so. Does this really help? If for example, I move away from the harder versions of 17-4 PH to a H1150 temper, does this help reduce embrittlement?

 

[metengr]

iainuts;
Yes, it will help. What exactly are you interested in for cryogenic application with the above materials? Normally, I would stick with the 3XX series austenitic stainless steels for cryogenic application in hydrogen service.

 

[iainuts]

Thanks metengr. Rather not disclose the use. All pressure retaining parts are 304 annealed, but some parts need other properties.

I take it aluminum is ok too?

 

[metengr]

Aluminum can be susceptible to hydrogen embrittlement if hydrogen charging occurs on the surface where the oxide has been removed.

 

[iainuts]

Thanks again. Would "hydrogen charging" occur in a pure H2 environment (no electric current either)? I'm not familiar with this term.

 

[metengr]

iainuts;
It depends on temperature, pressure and the presence of any contaminants either on the surface of the metal or in the gas that could result in the formation of nascent hydrogen (charging).

 

[iainuts]

One more - is Nitronic 60, annealed, susceptible to hydrogen embrittlement? I'm thinking it's not because it's an austenitic, but just want to verify.

 

[metengr]

I would proceed with caution regarding nitrogen strengthened alloys. You might find the paper below interesting;

http://www.ca.sandia.gov/matlsTechRef/chapters/2202TecHRef_2169SS.pdf

 

[btrueblood]

Thanks metengr, for that paper. I'll have to read it thru, as a cursory glance just has me more confused than ever. As you said, proceed with caution.

 

[TVP]

The Sandia website for Hydrogen has other good information as well. Use the following link to access it:

http://www.ca.sandia.gov/hydrogen/research/safetyCodesStandards/hydrogenCompatibleMaterials.html