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How to clean heated iron

I am rolling iron from 1.2 mm to .5 mm. after the rolling process iron becomes hard for this we heat the iron coils for softening but this makes iron black in color. What can I do to make it look white or make it come back to its original color. I have seen stainless steel been treated with a chemical to remove the blackness due to heating but the same chemical does not work for iron.

Amit Bansal
TRADER - DELHI, India
2004

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The black color is the iron surface oxidized to FeO and Fe3O4. You have 2 options:

1) Removal of oxide by a combination of mechanical and chemical means. Start by bending the coil through 4 staggered rollers to bend it down, up and straight. Follow with an abrasive brush, pass through a heated, inhibited sulfuric acid pickling solution, rinse, water blast rinse, dry, inspect and re-roll to desired finish.

2) Avoid oxidation using a controlled atmosphere furnace ò neutral gas mixture (non-oxidizing, non-carburizing) or inert gas or vacuum. Note: the coil must be cleaned of lubricants, etc. prior to annealing.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2004