Unless all ground areas are to be passivated after grinding, the tools used (grinding discs, saw blades etc) must be ‘iron free’, and must not have been used previously on carbon steels.
Discs which are not iron free will impregnate the surface of the stainless with carbon steel
, which will produce unsightly rust coloured staining on the stainless. This corrosion
product in turn is corrosive to stainless steel
, and will initiate attack of the stainless.
Most suppliers of metal working consumables have special ‘iron free’ discs for stainless steels.
You can also perform a simple test to ensure that discs are safe to use on stainless steel. A scrap piece of stainless is dressed with a sample of the candidate discs, then sprayed with tap water
and left wet overnight. Satisfactory discs will not produce a rust coloured stain.
If all the ground areas are passivated after grinding, the contaminants introduced by the grinding consumables will be dissolved away, and it is not essential to use iron free discs.