Carbon Steel Gauges on Stainless Steel Bores

A. The problem is iron (and possibly fingerprint) contamination which could result in rusting or other corrosion.

ASTM A380 -96, Paragraph 8.5.2 "Finish-cleaned materials should not be allowed to come in contact with carbon steel. Acid cleaning of surfaces that have been in contact with such material may be necessary to prevent failure of the item when subsequently heated." However, Paragraph 1.3 notes "The degree of cleanliness required on a surface depends upon the application".

So, read the full standard and use your judgment. Passivation per ASTM 380, ASTM A967 or AMSQQP35 [canceled]C may be appropriate for critical applications.

A. I agree that iron on the surface is the problem, and it could cause corrosion later. You need to passivate the surface to remove the iron. You need to passivate per ASTM A967 or AMS2700A (Aerospace) or AMSQQP35 [canceled] (Aerospace). ASTM A380 is not a passivation specification and should not be used,it is only recommended practices. It is being amended to state that it must not be used as a specification. QQ-P-35C has been cancelled and no longer exists as a spec.

A. Re Passivation specifications: Strictly speaking, the QQ-P-35C [from DLA] cancellation applies to Department of Defence activities only. The only differences between it and AMSQQP35 [canceled] are cost ($59 for AMS, QQ-P-35C is free at the DoD's ASSIST website), and that any future versions will come from SAE. At present, merely certify to QQ-P-35C/AMSQQP35 [canceled] (and append /ASTM A967 and/or /ASTM A380 if your processing also satisfies either or both of those requirements). Commercial users dictate their requirements, and I doubt any jobshop will refuse ASTM A380 orders regardless of the fact that it is a 'Standard Practice' and not a 'Specification' a la AMS2700.