problemi lamiere decapate in ferro 15/10

[gadec]

Good evening,

I attach some pictures to try to expose you to a problem that we are experiencing in the company. on a pallet containing about 40 "sheets" of 2000x1000 sheet of 15/10 thick of decapato we noticed that on some of them appear on the longer side of reddish spots. I can't say if it's rust, the only certain thing is that if you intervene promptly (in the arc of a couple of hours) these stains with a little diluent go away, otherwise if the sheet is "fished" after some days these stains persist and we don't know how to remove them.
the supplier has assured us that the material that supplied us respects the norm un 10204. Could it be a cause due to the rolling process? any of you are expert in this matter?
each image refers to a distinct "sheet" that we have set aside waiting to find a solution.
Thank you for the advice you can give me.

 

[MBT]

If it's rust... You can put all the diluent you want and it doesn't come away!
at the limit is a slight layer of oxide.
What are the plates on?
were protected?
What do you mean, he's gone? Not even carding?
Do you hear anything?
If you scratch it with a hard object, remains the sign?

 

[paolino]

I'm not an expert. .
They look like sheets left in stock, where maybe they took a little wet, formed on a little condensation and made some oxide. or something else above has made some oxide always because of moisture/condense and is "cultivated" above... boh!
to see it seems stuff that with the canvas comes away