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.
H900 has rather low toughness & is susceptible to SCC. Might suggest you consider H950 after re-solution annealing. Tensile strength is not everything.
Phosphoric acid does remove rust, slowly.
A 5% solution of H2PO4 that is widely available is trademarked Coca-Cola. I'd use the regular, not the diet. Vaguely recall sugar helps modify things. Antique dealers have used a Coke soak to (slowly) clean up old iron stuff
If this is too ludicrous...
Most knowledgable corrosion engineer I know is Sheldon Dean, Dean Corrosion Technology, Allentown, Pennsylvania tel 610-439-1054
www.deancorrtech.com The Rolled Alloys & Outokumpu guys are good, Dean has industrial experience with a broad range of alloys.
6%Mo grades such as N08926, a.k.a. Cronifer 1925hMo, are normally welded with 625 (ERNiCrMo-3) so that, in spite of Mo segregation, the weld bead will still meet corrosion resistance of the base metal.
Other 6Mo stainlesses, which may be more available in the size and product form you need...
Stainless alloys which can resist corrosion in undersea applications include the superaustenitic grades AL-6XN (UNS N08367) made in the US, and 254 SMO (UNS S31254) from Outokumpu in Avesta, Sweden.
The superduplex stainless steels, such as SAF 2507 (UNS S32750, 1.4410) and ZERON 100 (UNS...
Wonder if it is possible to cool 1600kg fast enough, from whatever is that specified anneal temperature, to end up with any ductility? Have you checked the hardness of this casting?
Agree w EdStainless in all points.
Do think it would be cool to know exactly which superduplex alloy is involved.
Whatever is "Grade 5" it does not refer to a specific alloy chemistry.
If you are saying that Nitronic 50 fails by stress corrosion cracking (SCC), then I would use AL-6XN/254 SMO, whichever is available.
If in fact Nitronic 50 WORKS and is available, I'd seriously consider using it.
Yeah, the 6%Mo grades are better but AVAILABILITY of the parts you want + good...
Simplest, and available/weldable, choice for seawater is one of the 6% molybdenum stainless grades. AL-6XN is stocked by Rolled Alloys in many sizes and forms, as is 254 SMO by Outokumpu. Better crevice corrosion resistance than 316.
Duplex 2205 is better than 316, widely available; more...
Just curious - that cast HSLA isn't a grade that would embrittle, is it, at the nominal 850F/454C temperature used for hot dip galvanizing?
In any event, the weldment should be stress relieved before hot dip to avoid cracking from molten zinc.
304 stainless, 18Cr 9Ni, is not suited for long term service at 1750F. It will get thin and go away, disappear, from oxidation.
You might try 310 (nominal 25Cr 20Ni, actually available stuff is 310S UNS S31008)
It will still gall.
In Ancient Times General Electric's jet engine guys in...
Ammonia may crack the Cu alloy but sulfer from sewage corrodes them. Copper alloy heat exchanger tubing not so good in rivers for this reason. The Susquehanna comes to mind.
I worked for a supplier of specialty heat and corrosion resistant alloys. Metallurgist, wrote all the technical data sheets.
Corrosion data, CPT, tensile, yield are all very interesting and surely must be considered.
But there is one more very important material property.
And that is...
