I have written about this a couple of years ago.

The knives of my dinner cutlery service are and have been suffering from
a crusting on the blades only, when washed in the dish washer. All other
aspects of the service are OK.

I was advised at that time to remove any carbon steel knives from the
area and see how I got on.

I am down to the point of not putting anything other than the basic
knife, forks and spoons into the dishwasher, of the same set, along with
the plates we have eaten from and the knives are still coming out of the
dish washer with the same crusty brown marks on them. It is a raised
from the blade sort of thing and doesn't look like it is eating into the
metal.

Help anyone?

Dave