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Poor cleaning of 301 grade extra hard

Q. We found brown colour contamination on the strip after reducing the thickness (70% reduction at Sendzimir mill) and after degreasing.
It is appearing on 301 grade SS and the reduction is 70% or more.
We use hot alkaline 70 degree C,and rinse twice at two different tanks.
Can anybody help me to fix this problem?

Mohamed Abdul Jaleel
In charge of Production - Jakarta, Indonesia
July 15, 2010

A. Dear Mohamed Abdul Jaleel

Perhaps a bit late, this reaction, but could it be that your brown discolouration comes from the presence of the Mn in the SS 301? Maybe it forms a film of oxide (the oxide is known as a very strong, brown dye.)
In that case, a treatment in sulfuric of hydrochloric acid after the cleaning should remove the brownish discolouration.

Best regards,

Harry van der Zanden
Harry van der Zanden
- Budapest, Hungary
August 18, 2010

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