rust contamination of stainless steel: aluminum particles

[kapot]

When small iron/steel particles fall down on stainless steel parts, these particles will oxidise by presence of moisture. Iron oxides are created and in addition oxygen is prevented to enter the area and stainless steel becomes active. Contamination corrosion of stainless steel does occur.
My question: What if the small particles are not made of iron, but made of aluminium (or p.e. zinc)? What will happen? Will the same occur?

 

[gr2vessels]

No Aluminium will not affect the adversely the Styainless Steel;- in fact is common practice to protect expensive Duplex and Super-duplex equipment on off-shore platforms with aluminium thermal spray...No, the Zinc even in paint form could affect adversely the Stainless Steel. Particularly when in contact with hot or molten Zinc, this could potentially lead to the cracking of the pressurized equipment (for details read info on the net).
cheers,
gr2vessels

 

[Rich2001]

The Zinc- Stainless cracking as gr2vessels mentioned is called " Solid Metal Embrittlement"

At ambient temperatures there is minimla problem. However above 419C the diffusion rate of the zinc is mildly agressive. Above 750C the zinc diffuses into the austentic stainless steel forming a nickel-zinc intermetallic compound at the grain boundaries, the nickel depleted ferrite zones cause internal stresses to rise and a crack occurs... basically unzipping the structure.

Vita sine litteris mors est.

 

[kapot]

Thanks,
I thought that due to the difference in corrosion potential of zinc and aluminum with stainless steel AND in the presence of moisture galvanic corrosion will occur.
We grit blast aluminum parts and stainless steel parts in the same area. My concern is that the stainless steel parts may be contaminated by aluminum dust particles and then by condensation galvanic corrosion will corrosion?

 

[fdac]

Galvanic effects will not be an issue for the stainless, it will be more noble than either Al or Zn. If anything the Al or Zn will provide some galvanic protection to the SS.

Separate to galvanic effects, zinc on stainless is generally a no-no due to the embrittlement issue at high temperatures, but as Rich2001 said, at ambient temperature it's probably not a big issue.

 

[Metcorr]

As Rich-2000 has reported as: 'The Zinc- Stainless cracking as gr2vessels mentioned is called " Solid Metal Embrittlement"

Should that not be called as ' Liquid Metal Embrittlement' instead?

MetCorr