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Is it necessary to dehydrogenate after phosphating ?

Dear Sir,
We need to do Antiseizure phosphating + Dehydrogenation for one of the gear, which is with the hardness above 55 HRC.
What is the difference between manganese phosphating and antiseizure phosphating ?
Sir,is it possible ?, to avoid dehydrogenation, skip the acid pickling step before phosphating.

Thanks in advance.
Rajan Pawar

Rajan Pawar
Buyer - Pune, Maharashtra, India
August 30, 2009

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Hi, Rajan. I have not heard the specific phrase "antiseizure phosphating", but manganese phosphating is intended for such purposes, so I believe they are the same thing. I have also not heard the word "dehydrogenate", but I assume it means what I would call "hydrogen de-embrittlement", which is done via baking for a few hours at about 450 - 500 °F.

It is possible to blast the oxide off the gears instead of pickling it off, and this will certainly reduce the pickup of hydrogen and the chance of a part breaking during processing. But manganese phosphating remains an acidic process with the potential for hydrogen embrittlement. If a failure would be critical, de-embrittlement is required.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 31, 2009

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Phosphating - in any flavor - iron, zinc, or manganese - is normally considered a hydrogen-embrittlement-free process; like mechanical plating, the deposit does not seal in the hydrogen. There have been instances of transient hydrogen embrittlement due to phosphating; all of the cases that I am familiar with resulted from the phosphated articles being subjected to stress before the hydrogen had a chance to escape (I'm talking about rush jobs where the parts were put into service less than 48 hours after phosphating!).

Tom Rochester
CTO - Jackson, Michigan, USA
Plating Systems & Technologies, Inc.


September 5, 2009

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Sir,

The components we are talking about are going under grinding operation after phosphating. By your experience, the articles are going under stress within 48 hrs. needs hydrogen de-embrittlement.
Thanks for sharing your views and opinions.
prevention is better than cure.

Rajan

Rajan Pawar
- Pune, Maharashtra, India
September 12, 2009