Stainless contamination and rust

[John Katt]

I was doing a little reading on stainless steel today and I ran across this paragraph, anyone ever have this issue with using belts that were previously used for high carbon steel?


A grinding wheel that has been contaminated by carbon or tool steel will embed steel particles and will smear iron across the surface. The grinder will irrevocably embed any grinding dust from a nearby station or which drifts down from the ceiling beams. Grinding coolant that has been circulated through a machine running carbon or tool steels is a major contributor when it comes to permanently contaminating the next piece of stainless. It pretty much means that stainless steel grinding must be in its own room, with its own dust control and coolant systems, completely isolated from other ferric materials being processed.

link to article http://www.nhml.com/rusting-by-stainless-steels.cfm

 

[Jesse Latham]

I have experienced rusted steel particles left behind by grinding discs and mild steel wire brushes on stainless steel fabrication. It is difficult to get rid of and you learn you need separate discs and stainless wire brushes. Jess

 

[mete]

I told you so !! BTW citric acid is being used instead of nitric in some applications as it's easier on the environment. Education and careful procedures can save you lots of trouble.

 

[james terrio]

Great article, thanks for the link. Passivation is important and beneficial for tool steels, too. Unpassivated D2 and 3V for instance, can develop nasty pitting and my understanding is, a lot of it comes from the kind of contamination you're talking about.

 

[John Katt]

I sure am glad I ran across this information now, I just started building my first stainless knife and would have been really upset to find rust on a brand new piece of 440C

fortunately I just bought brand new lower grit belts and did my rough in with those