Duplex vs aust vs Inconel alloys in H2S
Duplex vs aust vs Inconel alloys in H2S
(OP)
"We would suggest the following tentative ranking, which intuitively seems correct, as it puts materials with fully austenitic (fcc) microstructure ahead of those with partially or fully ferritic/martensitic (bcc) structure, in terms of resistance to cracking in H2S media: Incoloy 825> 316 > 22%Cr duplex > weldable 13%Cr"
Your thoughts/comments on the same.
Your thoughts/comments on the same.
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The black holes of nature are the most perfect macroscopic objects there are in the universe: the only elements in their construction are our concepts of space and time.





RE: Duplex vs aust vs Inconel alloys in H2S
I have a problem with generalizations concerning the suitability of materials for a particular service. If a generalization statement is made it should be fully qualified as to specific environments or better yet exclude certain environments. People tend to make literal interpretations of such statements. I’ve certainly got burned several times.
What work with H2S that I’ve been involved in certainly wouldn’t have involved any general statement. I have found that H2S corrosion problems are in the same league as Amine corrosion problems, that is each particular environment requires a particular study and recommendation.
There are too many variables in materials recommendation to generalize other than say this is a very good starting point for study or survey.
RE: Duplex vs aust vs Inconel alloys in H2S
There are a lot more considerations, but the quotation stands as a valid one.
RE: Duplex vs aust vs Inconel alloys in H2S
Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The black holes of nature are the most perfect macroscopic objects there are in the universe: the only elements in their construction are our concepts of space and time.
RE: Duplex vs aust vs Inconel alloys in H2S
In a situation of "simple" H2S exposure then fully ferritic/martensitic materials processed and controlled in accordance to NACE M 01 75 work fine.
RE: Duplex vs aust vs Inconel alloys in H2S
RE: Duplex vs aust vs Inconel alloys in H2S
RE: Duplex vs aust vs Inconel alloys in H2S
The stress cracking is an outcome of the corrosion mechanism when hidrogen is the product. Concerning the last, the more Cr content the better (up to 12-13 %Cr, over that some detrimental effects on other sides need to be evaluated, regardless of the microstructure. That is because of the passivation effect of the anodic Cr in the steel. Less hidrogen hence less SC susceptibility.
But once you get hidrogen in the metalic net it combines to get hidrogen molecule with a huge volume expansion and that creates the internal stresses deriving in induced fragility of the metal. So you must care about how soft your steel is as to mitigate this effect. It is normally accepted that a rockwell hardness less than 22 is acceptable (NACE). You are closer to get this in ferritic-perlitic structure than you can be on martensitic structure. Which one do you want to prevail? Best economically is 13Cr ferritic but it is soft and delicate. More resistance?. Use 13Cr martensitic (super 13Cr)Do you want something in the middle, use austenitic structure, or better both: ferritic+austenitic (duplex)