Incoloy contamination

[bpeirson]

I am working with some Incoloy Alloy 825 (UNS 08825). Cross contamination with carbon steel is a big issue for the client. I am now wondering what effect cutting fluid containing sulphur would have on the Incoloy.

 

[kenvlach]

Sulfur can be very bad for Ni-alloys. A liquid forms between Ni and NiS at ~625[su]o[/sup]C.

Cutting fluids with sulfonated oils are worse than those containing MoS₂. The former burn and adhere to the surface under heavy cutting conditions. Remove all traces of organics and staining prior to passivation for removal of steel contamination (organics cause nitric acid to etch rather than passivate).

Degrease and then use a high pH electrocleaner – Oakite 90 is a good one – to remove any staining. Then do a normal passivation.

 

[bpeirson]

Thanks for the quick response. It was far more informative than what the local suppliers of cutting fluids could say.