ss347

[212197]

which type of corrosion occurs is SS347?

 

[EdStainless]

Any kind that can happen in 304.
The only advantage to 347 (or 321) is that you can weld parts and be fairly sure that you won't get IGA in the HAZ.
Likewise if you operate in the range of 1200-1600F you should avoid IGA, though at the low end you may need to pre-stabalize in order for it to be effective.

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P.E. Metallurgy, Plymouth Tube

 

[XL83NL]

Knife line attack is something you won’t find in regular, say, 304 and 316 type stainless steels. KLA is, if I’m not mistaken, found in stabilised stainless steels.

 

[Deanlover]

Stabilisation heat treatment is required for TP347 to strengthen it's corrosion resistance.

 

[212197]

I read somewhere that caustic stress corrosion occurs in ss347.

 

[Chumpes]

Which type of corrosion occurs is SS347?

- generalized corrosion (thickness loss)
- localized corrosion (pitting, crevice)
- stress corrosion cracking

depending on the corrosive environment

 

[EdStainless]

Unless you are in some very unusually environment (boiling HCL) you do not get general attack on stainless steels.

In all stainless steels there are three main concerns;
-localized corrosion, pitting and crevice, nearly always related to Cl and pH.
-stress corrosion cracking, is austenitic SS this is a result of Cl and stress (residual and service)
-IGA, grain boundary attack related to improper heat treatment, side effects of welding, or incorrect service temperature

I can create IGA or KLA in any 300 stainless, if I can play with the HT and service temp.
The 300 alloys that are basically all 18-8 all end up with very similar responses.

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P.E. Metallurgy, Plymouth Tube

 

[MagBen]

347 was designed to stabilize carbon with Nb, so it will have superior IGA compared to typical 18-8 type alloys. Good for applications requiring intermittent heating between 800ºF and 1650ºF. good corrosion at humidity and nitric acid, not good in other acids, bad in sea water

 

[davefitz]

While corrosion of thin walled tubes is well addressed by SS347, thicker walled pressure vessels that operate above 643 C ( 1100) may have an issue with "stress releif" cracking if the alloy was stabilized with Niobium. In the case where the wall thickness exceeds 16 mm and the operating temp exc eeds 643 C then Ti stabilized alloys may be required.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick