brass residue on (hardened?) steel after cleaning good?

[coppercone2]

So I have been cleaning up some little bits for the small mill and I noticed if you do the soak in the new 'motorcycle freindly' rust remover and use a brass dremel brush on it afterwards, you get a brass residue on the steel.

I actually thought I was cleaning nickle plated brass blocks, till I got a bit of sand paper and revealed shiney steel underneath. (ran out of steel brushes)

Anyway, I think this brass 'plating' looks kind of cool, but does it hurt the tool in any way? Will it increase corrosion?

Since these are 'step blocks' used for milling vise, can it possibly increase their grip if they have a thin layer of soft brass on top?

[ataradov]

I've seen this effect used intentionally to make metal look "gold".  I doubt it will change anything other than visual appearance. The layer is way too thin.

[Gyro]

I suppose it might be possible that the softer brass could act as a low quality dry film lubricant by filling microscopic irregularities in the steel surface.

[coppercone2]

how does it get into the metal? Is it some kind of molecular reaction or is it just being cut off the brush by the uneveness of the steel surface and embedding into it like a paste?

[ataradov]

I'm not sure about the rust remover case, since most of the time this is used with heated steel. And in that case it is a mechanical transfer. Sort of like brazing of a very fine layer of bronze.

[T3sl4co1l]

Mechanical transfer, cold welding, probably not diffusion bonding.  Superficial.  Maybe just stuck into the pores and it wears off much more easily than a melted-in surface would.  Maybe more instantaneous heat is involved than it seems, on account of the high velocity.

Corrosion is probably slightly accelerated on account of the higher galvanic potentials.  At first the zinc content would provide galvanic protection, then as it depletes (exposing copper (dezincification) or iron), nearby iron would be corroded.  Corrosion requires an electrolyte, usually a microscopic amount of salt and ambient moisture.

Tim