Defining acceptable Delta ferrite amounts in 316L SS
Defining acceptable Delta ferrite amounts in 316L SS
(OP)
Recently I had a corroded section of 316L SS analysed by a lab who did a chemical analysis and microexamaination on the metal.
They found the material's chemical composition within ASTM standards but the nickel was at minumum 10%.
The microexamination found the material to have excessive delta ferrite.
I asked if there was a standard to refer to that would state what might be an acceptable (average) amount of delta ferrite in 316L. They could not give me a standard. They said most companies have already defined what they will accept as standard either as a "count" over an area or as "percentage" based, on their experience.
1) can anyone assist me in finding a standard (ASTM, NACE?)
2) if not, what would you normally expect and how would you define it - count or percentage?
Thanks
They found the material's chemical composition within ASTM standards but the nickel was at minumum 10%.
The microexamination found the material to have excessive delta ferrite.
I asked if there was a standard to refer to that would state what might be an acceptable (average) amount of delta ferrite in 316L. They could not give me a standard. They said most companies have already defined what they will accept as standard either as a "count" over an area or as "percentage" based, on their experience.
1) can anyone assist me in finding a standard (ASTM, NACE?)
2) if not, what would you normally expect and how would you define it - count or percentage?
Thanks





RE: Defining acceptable Delta ferrite amounts in 316L SS
That said 10% is unusually high for cold-rolled material, less so for hot-rolled and not surprizing for a weld or a casting. Which do you have?
RE: Defining acceptable Delta ferrite amounts in 316L SS
The moly was 2.1 (spec is 2 - 3) and chromium was 16.43 (spec is 16 to 18).
The lab did not give me a count or percentage. They just said "large amounts".
That is why I am looking for some "standard" ASTM or NACE standard to refer to.
The product is sodium chlorate, so I really want to minimize any delta ferrite.
RE: Defining acceptable Delta ferrite amounts in 316L SS