Super Duplex SS F53 S32750 vs F55 S32760

[georgacus]

What is the difference between these two grades, if any? And what could be the reason for picking one over the other?

As far as I could see, F55 has tungsten in its chemical composition.

 

[metengr]

You might want to take a closer look between the two grades;

http://pmfirst.com/materials/super-duplex/

 

[EdStainless]

They are two different ways of trying to reach the same level of corrosion resistance.
There are a lot of papers on the heat treating and corrosion testing of these alloys.

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P.E. Metallurgy, Plymouth Tube

 

[JamesCKelly]

I think people tend to use them interchangeably, based on what is most available.

If it is a new, and critical, application I personally would have greater faith in the validity of the Swedish-generated corrosion data for S32750.