Austenitic Stainlees steel - NACE Compliance

[loz71]

Hi All,

I have a question on interpretation of NACE MR0175 in regard to compliance of Austenitic Stainless Steel (e.g. 304 / 316).

Table A.6 in Part 3 indicates that this type of material is acceptable as long as the hardness is not greater than 22HRc, it is solution annealed and is free from cold work intended to enhance mechanical properties.

It is the last two here that concern me, not the max hardness.

I see a lot of material certificates claiming that the material meets NACE MR0175, but commonly the yield strength is up on what i would expect from a material that has been solution annealed and the material has been cold drawn as a final process. How can that be shown to comply with the statement in Table A.6?

Cold drawing at the end of the processing is designed for dimensional tolerance but there will be an increase in properties that cannot be specified as 'incidental'.

Regards.

 

[SJones]

Review Inquiry #2016-04 in the Inquiries & Interpretations:

http://isotc.iso.org/livelink/livel...c=ll&objId=3340364&objAction=browse&sort=name

Given that ISO 15156-3 includes environmental limits for the application of austenitic stainless steels, it should not be within the remit of the material supplier to certify compliance because they will have no knowledge of the environmental exposure.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[loz71]

Thanks for the very quick reply to this and for the link. That pretty much answers my question. I believe the mills are cold drawing after annealing for dimensional tolerance and not necessarily straightening (on this occasion) but the key is that the work put in is not intentionally increasing the strength and it doesn't go above 22HRC. As the inquiry indicates there is no set upper limit on the yield strength.

I probably should have referred to the current edition of the NACE document also. This comment is not in 2009 edition.

I agree, compliance to NACE MR0175 / ISO 15156 can only be applicable to material processing and not on environmental exposure.

Thanks Again.

 

[ParickT]

The decision that a particular product / material form is suitable for use is the sole and only responsibility of the user while the fabricator must comply with the limitations set in the document. Actually "certifying" a material to comply is a commercial deviation from the original intent, because even if the fabrication has followed all the rules and limitations, the actual in-service behaviour is unmanageable from producers' point of view, so only the engineering assessment and experience of the user can tell if that is found suitable.