Letter 15010

Chemical removal of heat treating scale and oxides

Looking for suggestions on removing heat treating scale from carbon steel parts prior to tempering and subsequent grinding. Would be interested in any experience with commercial products, or "home-brewed" pickling solutions. Thank you.

Fred Pickard
- York, PA

I would like to suggest electrocleaning the workpiece. It is the reverse from the electroplating process, causing the dirt on the surface of the workpiece to fall off.

Hartarto Ciputra
- Surabaya, Indonesia

First of two simultaneous responses ++

There are dozens of approaches and formulas. Some based on galvanic phenomena, some based on chemical attack (either highly acidic or heavily chelated), some based on the reducing potential of melt or fused salts. It depends very much on budget, type and volume of work and established facilities. Get a good book on the subject. A web search, no matter how thorough, will never be a substitute for a good specialized book. May I suggest to you the ASM Metals Handbook.

Guillermo Marrufo
Monterrey, NL, Mexico

Second of two simultaneous responses ++

I will suggest a 3 in 1 degreasing solution before tempering; this will remove scales and oil.

Harish Chitkara
- Madras

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