Hi Ariel,
could be a possibility but, it does not even show laminations etc either. The blade gets discoloured (covered with a dirty dark purple layer and has to be 'cleaned' using very fine abrasive paper) ....is that normal ?
There seems to be a pattern but I can't get it 'defined'. When I cleaned the rust from the blade I used a lot of oil to lubricate the abrasive paper, and coated the blade thoroughly 'between cleanings' ...could the oil penetrate the surface and possibly create a barrier to the acid
(bearing in mind I do not have a 'mirror finish'.....there is still a certain amount of pitting which would require too much metal removed from the blade.