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Cleaning nitrided parts without getting pitting
Q. We are facing problem of cleaning of small gears which are carbonitrided in Sealed Quench Furnaces. The gears are heavily sooted, which are not cleaned by any means ... we have to tumble them. Please suggest any another method.
DESHPANDE SWAPNIL S.- Pune, Maharashtra, India
2003
A. Hi Deshpande. The details of your tumbling operation may not be as they ought, but I think tumbling (or another mechanical process) is the right way to deal with this problem. Chemically removing that soot is probably not feasible.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
October 2014
Q. I am Kailash Chandran form Faridabad, India representing an automobile company.We are doing carbonitriding on our components made of cold rolled low carbon steel , Grade - DD(Deep Draw).
The components gets pitted on finishing operation performed after carbonitriding. finishing operation is done in a barrel with cleaning media consisting of some chemical powder & pebbles.
Please advise whether this defect could be attributed to carbonitriding or not.
- Haryana, India
2005
A. Not sure I understand problem correctly; however, pitting is not occurring in the mechanical barrel system, unless you are experiencing long time cycles using a lot of liquid and/or chemical. Problem sounds like too much chemical causing a reaction.
AF Kenton
retired business owner - Hatboro, Pennsylvania
2005
A. Perhaps you can put some components that have not been carbonitrided through the barrel as well, and see if they become pitted. That might give some guidance to whether it is the carbonitriding or the barrel operation that is responsible.
Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
2005
A. The carbonitrided component may have retained austenite in the microstructure of the surface layer. The retained austenite is a soft phase and hence during barreling operation, pitting marks may come on the grains which are soft. You may check the microstructure of the surface to find out the percentage retained austenite. Regards.
J.B.Ketkar- Mumbai, India
May 2, 2011
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