S32205 vs S31803 3

[Ahxl]

Hi everybody,

on a project, I have to choose the most suitable steel which won't suffer from Atmospheric Stress Corrosion Cracking.
Someone suggested me to use S32205 or S31803. Both are 2205.

i don't really see the difference, besides their chemical composition.
I cannot find some comparitive study and most of their mechanical parameters are almost the same.

Does anyone knowing these grades would accept to advise me?

Thank you in advance.

 

[XL83NL]

Refer to API TR 938 C. It's a very useful guide for use of DSS's. The introduction of that standard says, wrt 31803 and 32205;

Note that UNS S32205 is a “newer version” of UNS S31803 and is produced with higher nitrogen,
chromium, and molybdenum contents. ASME and ASTM standards for these grades are given in Table 2, while Table
3 provides the mechanical properties. Type 316L and other austenitic SS are included for comparison.

From a recent project, we've used 32205 and 31803 as 'dual certified', as long as a certain amount of nitrogen is present (N > 0.14%).
I believe this rerquirement came straight out of API TR 938 C (it also mentions 32205 and 31803 can be used as dual certified).

Go ahead on the webs, Im sure you will manage to get a copy of API TR 938 C.

 

[Ahxl]

Thank you for the answer.
But I have been looking on the internet.

The only way to get the copy of API TR 938 C is to pay and for what I need, I am not sure it would worth it.

 

[XL83NL]

That's up to you to decide.
$125 USD for a good technical report which may help
you on some fundamental and important decisions (maybe) to be made ...

 

[EdStainless]

What had evolved is that the 'better' mills were all making 2205 under S31803 and working to the high side of the chemistry range.
The alloy was more stable, had higher strength, and measurably better corrosion resistance than a more generic version of the chemistry.
They got a new UNS number reflecting the chemistry restrictions and have been adding it to specifications.
The safest route is to have it dual certified, this way if there is an older spec that only calls out S31803 you are still covered but you get the chemistry and properties of S32205.
If this material is more than a few mm thick you should also require A923 to assure that it was annealed correctly.

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Plymouth Tube

 

[Ahxl]

Ok! Thank you for the info!